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Combined Spinal-Epidural Anesthesia?

Joseph Eldor, MD

Preface
Origin
Soresi technique
Curelaru technique
Needle-through-needle technique
Eldor needle technique
Huber needle technique
Eldor, Coombs and Torrieri technique
Indications
Problems
The twin theory
Failed spinal or epidural anesthesia
One needle technique for combined spinal-epidural anesthesia
Aspiration pneumonia prevention by the CSEA
Intraoperative challenges
Anesthesia and public image
Huber needle and Tuohy catheter
Total spinal anesthesia: The origin of CSEGA
What is anethesia?
Use of ephedrine in CSEGA
Cardiovascular effects of CSEGA
Cord ischemia and preemptive analgesia
CSEA for Cesarean section
Corning
Bier
A new look at the lumbar extradural space pressure
Do not rotate the epidural needle
Epidural rostal augmentation of spinal anesthesia
Metallic particles in the needle-through-needle technique
Superselective spinal anesthesia
CSEA in uncommon disease
CSEA for laparoscopic operations
Postoperative epidural analgesia
Unilateral spinal anesthesia
CSEA for abdominal operations
CSEA for thoracic operations
Anesthetic risk factors
Medico-legal aspects of CSEA
Spinal opioid pruritus and emesis
Endocrine responses to spinal or epidural anesthesia
Epidural unilateral blockade
Combined spinal-epidural anesthesia: The anesthesia of choice
Epidural catheter strength
Epidural catheter paresthesias
CSEA and anticoagulation
Combined spinal-epidural analgesia in labor
Combined spinal-epidural anesthesia for orthopedic operations
Combined end-multiple lateral holes (CEMLH) epidural catheter
Double-hole pencil-point spinal needle
Epidural catheter test dose in the combined spinal-epidural anesthesia
Spinal and epidural opioid analgesia
The choice of the anesthesiologists
Epidural catheter malposition
Woolley and Roe case
Anesthetic costs
From the skin to the spinal-epidural spaces
Myint case
Spinal needles
Meningitis post spinal-epidural anesthesia
Preemptive analgesia and combined spinal-epidural anesthesia
Sympathetic innervation and CSEA
The politics of anesthesiology
Preconclusion
Conclusion


Preface

CSEA (combined spinal-epidural anesthesia) and CSEGA (combined spinal-epidural-general anesthesia) are new modalities of anesthesia for almost any patient at any age. This book highlights the subject from various points of view. It doen`t intend to teach. It`s goal is to encourage the anesthesiologists to practise what they already know in the best way they think is good for themselves while being a patient. It is a kind of a balanced anesthesia which uses techniques instead of drugs to accomplish the ideal kind of anesthesia for the patients. This new frontier in anesthesia should open a new era of anesthetic quality and cost-effectiveness. However, in the second edition of Principles and Practice of Obstetric Analgesia and Anesthesia, edited by Bonica JJ and McDonald JS, and published in 1995 by Williams & Wilkins, there are 1344 pages. The chapter on epidural analgesia and anesthesia contains 127 pages. That on subarachnoid block - 26 pages. On subarachnoid/epidural combination there is only half a page with only 2 references in the chapter on cesarean section. So, the new combined spinal-epidural anesthesia gained only 0.03% of the space in a book published in 1995 on the practice of obstetric analgesia and anesthesia. This is really not its present worth, neither its future...


"It has long been an axiom of mine that the little things are infinitely the most important" (Arthur Conan Doyle).

"If pain could have cured us we should long ago have been saved" (George Santayana).

"The greatest evil is physical pain" (St. Augustine of Hippo).

Origin

The first epidural analgesia was done by Corning (1) in 1885 inadvertently. Lumbar dural puncture was introduced in 1891 by Wynter (2) in England and Quincke (3) in Germany. Von Ziemssen (4) in 1894 suggested the feasibility of injecting drugs by means of lumbar dural puncture. Bier (5), a surgeon at the Royal Chirurgical Clinic in Kiel, was the first to inject cocaine into the spinal space. It was between August 16 and 27, 1898. It took 52 years since Corning`s discovery of the epidural analgesia and 39 years since Bier`s spinal anesthesia that these two compartments were first combined by Soresi (6) in 1937. It took another 42 years until Curelaru (7) in 1979 used this combined spinal-epidural anesthesia again. Even the discoveries of Corning and Bier are 13 years apart. However, the first anesthesia (maybe it was combined spinal-epidural anesthesia - who knows?...) was done by God (8) "caused a deep sleep to fall upon Adam" for rib extraction. The combined approach can also have its origin in the Bible: "Two are better than one" (9). Or you can look at it from Mark Twain`s point of view: "Name the greatest of all the inventors. Accident". 1. Corning JL. Spinal anaesthesia and local medication of the cord. NY Med J 1885;42:483-485 2. Wynter WE. Lumbar puncture. Lancet 1891;1:981-982 3. Quincke HI. Die technik der lumbalpunktion. Verh Dtsch Ges Inn Med 1891;10:321-331 4. Von Ziemssen HW. Allgemeine behandlung der infektionskrankenheiten. Jena 1894 5. Bier A. Versuche uber Cocainisirung des Ruckenmarkes. Dtsch Ztschr Chir 1899;51:361-369 6. Soresi AL. Episubdural anesthesia. Anesth Analg 1937;16:306-310 7. Curelaru I. Long duration subarachnoid anaesthesia with continuous epidural block. Praktische Anasthesie Wiederbelelung und Intensivtherapie 1979;14:71-78 8. Genesis 2:21 9. Ecclesiastes 4:9

Soresi technique

Soresi (1) used a fine needle without stilet and introduced it into the epidural space using the hanging drop technique. While in the epidural space he injected 7-8 ml of dissolved novocain. Then he pierced the dura and poured another 2 ml of dissolved novocain into the spinal space. This gave his patients anesthesia for a period of 24-48 hours! He and his colleagues employed this method in over 200 patients. He concluded that "by combining the two methods many of the disadvantages of both methods are eliminated and their advantages are enhanced to an almost incredible degree". 1. Soresi AL. Episubdural anesthesia. Anesth Analg 1937;16:306-310

Curelaru technique

Forty two years later, the Swedish anesthesiologist, Curelaru (1), while working in Bucharest, Romania, tested on 150 patients the method of spinal anesthesia with continuous epidural block. The punctures of the epidural and subarachnoid spaces were done through two intervertebral spaces. The puncture of the epidural space was performed 1-2 intervertebral spaces higher than the subarachnoid. Anesthesia was always started with the introduction of an epidural catheter. After introducing the epidural catheter, the puncture of the subarachnoid space was done, followed by subarachnoid injection of the anesthetic solution. Curelaru concluded its advantages as "the possibility of obtaining a high quality conduction anaesthesia, virtually unlimited in time, the ability to extend over several anatomical regions the surgical field, minimal toxicity, the absence of postoperative pulmonary complications and the economy". 1. Curelaru I. Long duration subarachnoid anaesthesia with continuous epidural block. Praktische Anasthesie Wiederbelelung und Intensivtherapie 1979;14:71-78

Nedle-through-needle technique

Coates (1) from England and Mumtaz, Daz and Kuz (2) from Sweden, in two separate letters in the same issue of Anaesthesia, in 1982, first described the insertion of a long spinal needle through the epidural needle for performing the combined spinal-epidural anesthesia. Coates found the technique "simple, reliable and relatively quick to perform". After injecting the anesthetic solution into the subarachnoid space, the spinal needle is withdrawn and an epidural catheter is threaded through the same lumen of the epidural needle, through which the spinal needle was inserted. 1. Coates MB. Combined subarachnoid and epidural techniques. A single space technique for surgery of the hip and lower limb. Anaesthesia 1982;37:89-90 2. Mumtaz MH, Daz M, Kuz M. Combined subarachnoid and epidural techniques: Another single space technique for orthopaedic surgery. Anaesthesia 1982;37:90

Eldor needle technique

The Eldor needle (1) was first described in 1990. The Eldor needle is a combined spinal-epidural needle which is composed of an 18 gauge epidural needle with a 20 gauge spinal conduit. This is a specialized needle for the combined spinal-epidural anesthesia. There is no need of long spinal needles. The epidural catheter can be inserted before the spinal anesthetic injection. The Eldor needle facilitates the insertion of very small gauge spinal needles through its spinal conduit, so significantly reduces the incidence of post-dural puncture headache. There is no danger of epidural catheter protrusion through the dural hole made by the spinal needle. There are no metallic particles production while the spinal needle passes through the bent epidural needle tip, as in the needle-through-needle technique. The procedure of the Eldor needle is quite simple and straightforward. First, the spinal needle is introduced into the guide needle as far as the distal end of the latter. Then, the now Eldor needle is introduced into the selected intervertebral space and the epidural space is located using the well-known indicator methods. After that the epidural catheter is introduced into the epidural space, confirming its position by the test dose technique. Then, the spinal needle is slowly pushed in to puncture the dura, until cerebrospinal fluid is obtained. The anesthetic solution is injected through the spinal needle into the spinal space. Subsequently, the spinal needle is slowly withdrawn from the guide needle and then the Eldor needle is withdrawn, leaving the epidural catheter in position in the epidural space. 1. Eldor J, Guedj P. Une nouvelle auguille pour l`anesthesie rachidienne et peridurale conjointe. Ann Fr Anesth Reanim 1990;9:571-572

Huber needle technique

Huber (1), the inventor of the "Tuohy" epidural needle, also patented in 1953 an hypodermic needle with an "auxiliary outlet being disposed in transverse alignment with the channel outlet" (2). Hanaoka (3) described in 1986 its use in 500 patients. This needle has a very small hole behind the epidural needle tip ("back eye"). A small gauge spinal needle is inserted through that hole and punctures the dura. After withdrawing the spinal needle an epidural catheter is introduced through the epidural needle. 1. Eldor J. Huber needle and Tuohy catheter. Reg Anesth 1995;20:252-253 2. Huber RL. Hypodermic needle. US Patent No. 2,748,769 3. Hanaoka K. Experience in the use of Hanaoka`s needles for spinal-continuous epidural anaesthesia (500 cases). 7th Asian Australasian Congress of Anaesthesiologists Abstracts. Hong Kong, 1986;161-162

Eldor, Coombs and Torrieri technique

Eldor (1) and Torrieri (2) described in separate letters, in 1988, an epidural needle with a spinal needle attached to it. Through the spinal needle a longer spinal needle is inserted into the subarachnoid space, while an epidural catheter is introduced through the epidural needle into the epidural space. A few months before the publication of these letters, Coombs (3) applied for a patent on the same device. 1. Eldor J, Chaimsky G. Combined spinal-epidural needle (CSEN). Can Anaesth Soc J 1988;35:537-8 2. Torrieri A, Aldrete JA. Letter to the Editor. Acta Anaesthesiologica Belgica 1988;39:65-66 3. Coombs DW. Multi-lumen epidural-spinal needle. US Patent No. 4,808,157

Indications

Combined spinal-epidural anesthesia is like "to paint the fence" from both its sides. The indications are those of the spinal or epidural alone and even more. Rawal (1) made a survey in 17 European countries on their anesthetic choices in 1992. 17% of the procedures were performed under central blocks. Among these blocks - 56% were spinal; 40% - epidural and 4% - combined spinal-epidural anesthesia. The commonest indication for combined spinal-epidural blocks was hip replacement surgery (28.2%), followed by hysterectomy (19%), knee surgery (14.4%), Cesarean section (14%), emergency Cesarean section (13%), femur fracture in elderly patients (7.2%) and prostatectomy (5.6%). This under-utility of regional anesthesia (only 17% of the procedures) is in contrast to how the anesthesiologists would like to be anesthetized in case they need an operation: In 1986, Broadman et al. (2) confirmed that 92% of the anesthesiologists preferred regional over general anesthesia for their own hypothetical surgery, while 74% preferred a regional technique for their own elective extremity surgery. This is in accordance with a previous survey done in 1973 by Katz (3) in which 68% of the American anesthesiologists surveyed preferred regional anesthesia for their own anesthetic during an unspecified elective surgical procedure. The spectrum of indications for the combined spinal-epidural anesthesia ranges from labor analgesia (4,5) to high abdominal and even thoracic and head operations (6) by the adjuvant use of an endotracheal tube ventilation. The dosages of the local anesthetics with or without opioids that are injected into the spinal and epidural spaces are now evaluated in various hospitals around the world. The dosage combinations are enormous. The story has only begun. 1. Rawal N. European trends in the use of combined spinal epidural technique - A 17-nation survey. Reg Anesth 1995;20 (Suppl):162 2. Broadman LM, Mesrobian R, Ruttiman U, McGill WA. Do anesthesiologists prefer a regional or a general anesthesia for themselves? Reg Anesth 1986;11:557 3. Katz J. A survey of anesthetic choice among anesthesiologists. Anesth Analg 1973;52:373-5 4. Abouleish A, Abouleish E, Camann W. Combined spinal-epidural analgesia in advanced labour. Can J Anaesth 1994;41:575-8 5. Arkoosh VA, Sharkey SJ, Norris MC, Isaacson W, Honet JE, Leighton BL. Subarachnoid block analgesia: Fentanyl and morphine versus fentanyl and morphine. Reg Anesth 1994;19:243-246 6. Eldor J. Combined spinal-epidural-general anesthesia. Reg Anesth 1994;19:365-6

Problems

Blumgart et al. (1) found that the mechanism of extension of spinal anesthesia by extradural injection of local anesthetics is largely a volume effect. Using extradural saline 10 ml and extradural bupivacaine 0.5% 10 ml - the extension of the block was found to be similar in the saline or the bupivacaine groups, and significantly faster than the group which received no extradural injection after spinal injection of 1.6-1.8 ml of 0.5% hyperbaric bupivacaine. Suzuki et al. (2) found that spinal puncture with a 26 gauge spinal needle, with no spinal anesthetic injection, immediately before epidural injection of 18 ml 2% mepivacaine resulted in rapid caudal spread of analgesia as compared to an epidural anesthetic alone. They attributed it to the flow of local anesthetic into the subarachnoid space through the perforation produced by the spinal needle. In all the techniques, except the Eldor needle and Curelaru`s double-space techniques, there is inability to perform the epidural catheter test dose due to the fact that the epidural catheter is inserted after the subarachnoid local anesthetic injection. This can result in epidural catheter malposition in the subarachnoid space or intravascular with a danger of total spinal, delayed cardiorespiratory arrest due to opioid overdosage (3,4) or convulsions. Due to the insertion of the spinal needle through the bent tip of the epidural needle in the needle-through-needle technique there is friction that produces metallic microparticles that can be introduced further into the epidural space by the epidural catheter insertion (5,6). If there is a delay in epidural catheter threading in the needle-through-needle technique there is a partial spinal anesthesia while using the hyperbaric anesthetic solution (7), with the need to supplement it further through the epidural route. The incidence of epidural needle or catheter unintentional dural puncture ranges from 2.5% (8) to 0.6% (9) and even 0.26% (10). However, using the needle-through-needle technique the chances are greater because of the same pathway shared by the spinal needle and the epidural catheter in the epidural space and the force exerted by the friction between the spinal needle and the epidural needle`s tip that can advance forward the epidural needle causing an unrecognized dural tear by the epidural needle, through which an epidural catheter can be threaded inadvertently. 1. Blumgart CH, Ryall D, Dennison B, Thompson-Hill LM. Mechanism of extension of spinal anaesthesia by extradural injection of local anaesthetic. Br J Anaesth 1992;69:457-460 2. Suzuki N, Koyanemaru M, Onizuka S, Takasaki M. Dural puncture with a 26-gauge spinal needle affects epidural anesthesia. Reg Anesth 1995;20 (Suppl):118 3. Myint Y, Bailey PW, Milne BR. Cardiorespiratory arrest following combined spinal epidural anaesthesia for caesarean section. Anaesthesia 1993;48:684-686 4. Eldor J, Guedj P, Levine S. Delayed respiratory arrest in combined spinal-epidural anesthesia. Reg Anesth 1994;19:418-422 5. Eldor J, Brodsky V. Danger of metallic particles in the spinal-epidural spaces using the needle-through-needle approach. Acta Anaesthesiol Scand 1991;35:461 6. Eldor J. Metallic particles in the spinal-epidural needle technique. Reg anesth 1994;19:219-220 7. Fan SZ, Susetio L, Wang YP, Cheng YJ, Liu CC. Low dose of intrathecal hyperbaric bupivacaine combined with epidural lidocaine for cesarean section - a balance block technique. Anesth Analg 1994;78:474-7 8. Dawkins CJM. An analysis of the complications of extradural and caudal block. Anaesthesia 1969;24:554-563 9. Tanaka K, Watanabe R, Harada T, Dan K. Extensive application of epidural anesthesia and analgesia in a university hospital: Incidence of complications related to technique. Reg Anesth 1993;18:34-38 10. Macdonald R, Lyons G. Unintentional dural puncture, Anaesthesia 1988;43:705

The twin theory

Spinal anesthesia is a safe, cost-effective and reliable form of anesthesia. Many anesthesiologists would regard the epidural as an insurance against unsatisfactory spinal anesthesia, aiming to provide complete anesthesia by the subarachnoid route (1). Another approach is the use of a minimal dose of spinal anesthesia for a shorter duration with the flexibility of epidural reinforcement if necessary. For many years in many anesthetic departments around the world there was a philosophy that extradurals are for young people and the intrathecal route for the old, with few exceptions. Seeberger et al. (2) addressed the question: Is the spinal or the epidural technique better? Two hundred and two patients younger than 50 years underwent spinal or epidural anesthesia. Spinals were performed with 24-gauge Sprotte needles and epidurals with 18 gauge Tuohy needles and catheters. The failure rate of both techniques was 5%. Patient acceptance was high in both groups (97% in the spinal; 93% in the epidural). The authors concluded that spinal anesthesia was superior, because of better quality of anesthesia, no risk of intoxication, less time needed to perform the block, and less expensive kits. However, using the combined spinal-epidural anesthesia there is no more a question of which is better, as Greene and Brull (3) wrote: "Epidural and spinal anesthesia are indeed related to each other, but only to the same extent as cousins, or, at best, siblings; monozygotic twins they are not". 1. Brownridge P. Epidural and subarachnoid analgesia for elective caesarean section. Anaesthesia 1981;36:70 2. Seeberger MO, Lang ML, Drewe J, Schneider M, Hauser E, Hruby J. Comparison of spinal and epidural anesthesia for patients younger than 50 years of age. Anesth Analg 1994;78:667-73 3. Greene NM, Brull SJ. Physiology of spinal anesthesia. 4th ed. Baltimore:Williams & Wilkins, 1993, p.IX

Failed Spinal or Epidural Anesthesia

Failure of regional anesthesia has been reported to be in the order of 4% (1,2). The failure rate of spinal anesthesia alone ranged between 3.1% - 17% involving 100 to 1,891 patients respectively (3,4). Johr et al. (5) investigated the incidence of failed spinal anesthesia in a Swiss teaching institution. Of 3,004 blocks 197 (6.5%) did not provide satisfactory analgesia. The 197 failures included: absent blockade - 36; failure to obtain CSF - 6; level too low - 90; duration too short - 36; intensity too weak - 28; unclear - 1. However, 531 (17.4%) blocks were excessively high (45 - cervical level; 2 - required intubation). The management of the 197 failed blocks included: additional spinal anesthesia - 117; epidural anesthesia - 2; local infiltration - 1; general anesthesia - 30; IV supplementation - 47. Manchikanti et al. (6) found that the failure rate with sole use of spinal anesthesia ranges between 0.46% and 35% . Epidural analgesia sometimes falls short of perfection due to the variable "compartmentalisation" of the epidural space (7). Shesky et al. (8) studied in 1983 the dose-response of bupivacaine for spinal anesthesia. Sixty males having transurethral surgery were studied using 10-, 15- and 20 mg doses of glucose-free bupivacaine as either a 0.5 or a 0.75% solution. Both 15 and 20 mg of either concentration of bupivacaine provided satisfactory spinal anesthesia. However, three of 20 patients receiving 10 mg dose required supplementation with general anesthesia. Lyons et al. (9) used a 26G spinal needle through the Tuohy epidural needle for the combined spinal-epidural anesthesia. Unsuccessful spinal anesthesia occurred in 8 of the 50 patients (16%). In four patients, anesthesia was provided by the epidural route, while in the remainder another intrathecal injection was made using a different intervertebral space. Lesser et al. (10) evaluated the use of a 30G spinal needle through the Tuohy epidural needle for the combined spinal-epidural anesthesia. Unsuccessful spinal anesthesia was in 12 of the 50 patients (24%) studied. Six failures were due to unsuccessful dural puncture and six to inadequate block. Due to requirement of large doses of local anesthetics for epidural block there is a risk of toxic complications (11,12). In spite of large doses epidural block may fail to provide adequate analgesia in up to 25% of patients due to difficulty in blocking sacral roots (13-15). Failure to obtain CSF when using the needle-through-needle technique may occur despite successful dural puncture if the needle orifice is occluded, for example by a nerve root. It may also happen if dural puncture has failed to occur because the spinal needle is too short or is placed too laterally as the epidural needle may have entered the epidural space at an angle (16). One technical problem of the needle-through-needle method is the occasional difficulty in threading the catheter into the epidural space after injection of the spinal solution. If some minutes are spent in replacing the epidural needle, the spinal solution may become relatively "fixed" on the dependent side (17). However, when spinal and epidural anesthesia are combined, recourse to general anesthesia becomes a very rare event. 1. Milne MK, Lawson JIM. Epidural analgesia for Caesarean section. A review of 182 cases. Br J Anaesth 1973;45:1206-10 2.Moir DD. Local anaesthetic techniques in obstetrics. Br J Anaesth 1986;58:747-59. 3. Tarkkila PJ. Incidence and causes of failed spinal anesthetics in a university hospital: a prospective study. Reg Anesth 1991;16:48-51 4. Levy JH, Islas JA, Ghia JN, Turnbull C. A retrospective study of the incidence and causes of failed spinal anesthetics in a university hospital. Anesth Analg 1985;64:705-10 5. Johr M, Hess FA, Balogh S, Gerber H. Incidence and management of failed spinal anaesthesia in a teaching institution: A prospective evaluation of 3,004 epidural blocks. Acta Anaesthesiol Scand 1995;39:A421 6. Manchikanti L, Hadley C, Markwell SJ, Colliver JA. A retrospective analysis of failed spinal anesthetic attempts in a community hospital. Anesth Analg 1987;66:363-6. 7. Husemeyer RP, White DC. Topography of the lumbar epidural space. A study in cadavers using injected polyester resin. Anaesthesia 1980;35:7-11. 8. Sheskey MC, Rocco AG, Bizzari-Schmid M, Francis DM, Edstrom H, Covino BG. A dose-response study of bupivacaine for spinal anesthesia. Anesth Analg 1983;62:931-5. 9. Lyons G, Macdonald R, Mikl B. Combined epidural/spinal anaesthesia for Caesarean section: Through the needle or in separate spaces? Anaesthesia 1992;47:199-201. 10. Lesser P, Bembridge M, Lyons G, Macdonald R. An evaluation of a 30-gauge needle for spinal anaesthesia for Caesarean section. Anaesthesia 1990;45:767-8. 11. Abouleish E, Bourke D. Concerning the use and abuse of test doses for epidural anesthesia. Anesthesiology 1984;61:344-5. 12. Thorburn J, Moir DD. Bupivacaine toxicity in association with extradural analgesia for Caesarean section. Br J Anaesth 1984;56:551-3. 13. Larsen JV. Obstetric analgesia and anaesthesia. Clinics in Obst Gyn 1982;9:685-710. 14. Thorburn J, Moir DD. Epidural analgesia for elective Caesarean section. Technique and its assessment. Anaesthesia 1980;35:3-6. 15. Kileff ME, James FM, Dewan DM, Floyd HM. Neonatal neurobehavioral responses after epidural anesthesia for Cesarean section using lidocaine and bupivacaine. Anesth Analg 1984;63:413-7. 16. Patel M, Samsoon G, Swami A, Morgan BM. Flow characteristics of long spinal needles. Anaesthesia 1994;49:223-225. 17. Carrie LES. Epidural versus combined spinal epidural block for Caesarean section. Acta Anaesthesiol Scand 1988;32:595-596.

One needle technique for combined spinal-epidural anesthesia

Vitenbeck (1), in 1980, described the use of combined spinal-epidural anesthesia in 210 patients using the same needle for the spinal and the epidural injections. He first injected 1-2 ml Dicaine 0.2% into the subarachnoid space. Five minutes later he injected through the same needle, which was withdrawn into the epidural space, 25-37 ml of Dicaine 0.2-0.3% in distilled water with adrenaline 1:1,000. Anesthesia lasted for 2.5-3.5 hr. In only 3 patients he needed to induce general anesthesia because the operation lasted more than the effect of the regional anesthesia. Only 2 patients (0.9%) had postdural puncture headaches. 1. Vitenbeck IA. Associated spino-peridural anesthesia as a variant of conduction anesthesia during operation. Vestn Khir 1981;126:123-128.

Aspiration pneumonia prevention by the CSEA

In a review of maternal mortality published in 1991 (1) Glassenberg quoted statistics collected up to the mid-1980`s in the UK, USA and Sweden. Over the preceding decade, aspiration as a cause of maternal death had fallen to two deaths per million births, or one death per 30,000 anesthetics, still seven times the aspiration fatality rate for the non-obstetric surgical population, and closely associated with failed intubation. Dennis W. Coombs (2) wrote in 1983 an editorial entitled "Aspiration pneumonia prophylaxis". He said that "unfortunately, the magic prophylactic bullet is not available yet for all situations". However, instead of a "cimetidine prophylaxis" it is suggested to use the "CSEA prophylaxis"... 1. Glassenberg R. General anaesthesia and maternal mortality. Semin Perinatol 1991;15:386-396. 2. Coombs DW. Aspiration pneumonia prophylaxis. Anesth Analg 1983;62:1055-8.

Intraoperative challenges

Although developments in anesthesia and surgery have improved overall surgical outcome during recent decades, there is still concern about the detrimental effects of operative procedures, such as myocardial infarction, pulmonary complications, thromboembolism, gastrointestinal paralysis, immunosuppression,etc., that cannot be attributed solely to imperfections in surgical technique (1). Edwards et al. (2) studied 100 patients undergoing transurethral surgery, who were allocated randomly to receive either general or spinal anesthesia. The overall incidence of myocardial ischemia increased from 18% to 26% between the preoperative and postoperative periods, but no significant difference between the two anesthetic techniques. Nakatsuka et al. (3) used spinal anesthesia combined with epidural anesthesia in nine patients with ischemic heart disease having femoral-distal artery bypass surgery. A 20-gauge epidural catheter and a 24-gauge spinal catheter were inserted. Epidural anesthesia was initiated using 10-12 ml of 2% lidocaine and switched to continuous epidural anesthesia with 0.5% bupivacaine (5-7 ml/hr). Spinal bupivacaine 0.75% was injected up to 5 mg through the spinal catheter as needed to manage surgical pain of lower leg and foot. Seven out of 9 patients required additional spinal anesthesia. Juelsgaard et al. (4) examined continuous spinal anesthesia vs single dose spinal anesthesia vs general anesthesia in 44 elderly patients scheduled for hip surgery and receiving medication for angina or displaying ECG signs of coronary sclerosis. In the continuous spinal anesthesia they injected 1.5 ml isobaric bupivacaine 0.5% with 0.5 ml increments to establish T10 anesthesia. In the single dose spinal anesthesia group they injected 2.5 ml isobaric bupivacaine 0.5%. The general anesthesia consisted of fentanyl, thiopentone, N2O/O2 and enflurane. There were only 3 hypotensive events in the continuous spinal group (3/10 patients) compared to 24/13 patients in the single dose spinal group and 29/11 patients in the general anesthesia group. There was only 1 ischemic event in the continuous spinal group compared to 93 ischemic events in the single dose spinal and 11 in the general anesthesia group. These benefits of continuous spinal anesthesia can be obtained also in the combined spinal-epidural anesthesia, while the spinal injections can be done in incremental doses of 0.5 ml plain bupivacaine through the spinal needle or at a reduced dose of 1-1.5 ml injected slowly into the spinal space, and then supplemented by the epidural route, if necessary. 1. Kehlet H. Postoperative pain relief: A look from the other side. Reg Anesth 1994;19:369-377. 2. Edwards ND, Callaghan LC, White T, Reilly CS. Perioperative myocardial ischemia in patients undergoing transurethral surgery: a pilot study comparing general with spinal anaesthesia. Br J Anaesth 1995;74:368-372. 3. Nakatsuka M, Long SP, Shy DG. Spinal anesthesia combined with epidural anesthesia for peripheral vascular emergency with dual catheters. Anesth Analg 1994;78:S309. 4. Juelsgaard P, Sand NPR, Felsby S, Dalsgaard J, Brink O, Thygesen K. Continuous spinal anaesthesia vs single dose spinal anaesthesia vs general anaesthesia: Perioperative holter monitoring of patients with coronary atherosclerosis. Acta Anaesthesiol Scand 1995;39:A428

Anesthesia and public image

Swinhoe and Groves (1) pinponted again the low public image of anaesthesiology and anaesthesiologists. Their paper was commented by anaesthesiologists from other countries who showed the same trend (2,3). Keep and Jenkins (4) showed in 1978 the same finding that only 67% (65% in Swinhoe and Groves` report) of the patients thought an anaesthesiologist was a medical doctor. Their conclusion was that there is a need to give information sheets to patients preoperatively on the ward. It is possible to attack this genuine problem from another point of view: In 1973, Katz (5) surveyed American anesthesiologists and found that 68% preferred regional anaesthesia for their own anaesthetic during an unspecified elective surgical procedure. In 1986, Broadman et al (6) confirmed that a majority of anaesthesiologists still preferred regional over general anaesthesia for their own extremity surgery. In their survey, 92% of the anaesthesiologists preferred regional over general anaesthesia for their own hypothetical emergency surgery, while 74% preferred a regional technique for their own elective extremity surgery. It is possible that if most anaesthetics are done by the regional techniques there will be much time for the awakened patient to learn that the person at the top of the operating table is not less important than the person who stands behind the sterile curtain... and both of them are medical doctors. So, anesthesiologists have to treat their patients as they would like to be treated while they are patients - and they have already chosen : Regional anaesthesia. This shift in the anaesthetic profession towards the regional techniques will be also a shift in the public recognition and appreciation of anesthesiology and anesthesiologists. 1. Swinhoe CF, Groves ER. Patient`s knowledge of anaesthetic practice and the role of anaesthetists. Anaesthesia 1994;49:165-6. 2. Gajraj NM, Bala AS. Patient`s knowledge of anaesthetists. Anaesthesia 1994;49:559. 3. Ali S, Vivekanaandan P, Tierney E. Patient`s perception of the anaesthetist and anaesthesia. Anaesthesia 1994;49:644-5. 4. Keep PJ, Jenkins JR. As others see us. The patient`s view of the anaesthetist. Anaesthesia 1978;33:43-5. 5. Katz J. A survey of anesthetic choice among anesthesiologists. Anesth Analg 1973;52:373-5. 6. Broadman LM, Mesrobian R, Ruttiman U, McGill WA. Do anesthesiologists prefer a regional or a general anesthetic for themselves? Regional Anesthesia 1986;11:S57.

Huber needle and Tuohy catheter

On April 23, 1941, Edward B. Tuohy (1) presented his experience of continuous spinal anesthesia in the Proceedings of the Staff Meetings of the Mayo Clinic. The method of continuous spinal anesthesia was first used in the Mayo Clinic in November 1940 according to the technic and equipment advocated by William T. Lemmon (2). It consisted of a special operating table mattress, special spinal needles, 18 gauge, with stylet, which were soft and malleable, a 10 ml Luer-lok syringe with special stopcock connections and rubber tubing to connect the spinal needle with the glass syringe. The rubber-covered mattress had a gap 7 inches (18 cm) in length which lied beneath the lumbar portion of the spinal column when the patient was lying on the mattress. Three years later, on March 1944, Tuohy (3) described an alternative method in lieu of a malleable needle for continuous spinal anesthesia: Use of an ureteral catheter. The idea of using an ureteral catheter for continuous spinal anesthesia came to Captain Tuohy, who served then in the Medical Corps, Army of the United States, from the reports of the use of the ureteral catheter for caudal anesthesia (4,5) and for continuous subarachnoid drainage of meningitis advocated by Love (6). On June 14, 1944, Major Tuohy (7) who was then the chief of anesthesia and operative section, Percy Jones General Hospital, Battle Creek, Mich., described this technic before the section on Anesthesiology at the Ninety-Fourth Annual Session of the American Medical Association in Chicago. In the following article published on May 26, 1945 in JAMA Tuohy (7) said that "the direction (cephalad or caudad) which the catheter will advance in the subarachnoid space after the tip of the catheter leaves the end of the guiding needle cannot be predicted positively; however, if the round tip of the catheter is bent slightly before it is introduced into the lumen of the needle, I have found that the catheter will advance cephalad in most cases". In a later article published in 1945 Tuohy (8) mentioned for the first time a 15 gauge needle with Huber point. Using this kind of needle he could "direct the catheter either cephalad or caudad as desired". No reference was given by Tuohy to the use of the name of Huber. Cousins and Bridenbaugh (9) in their textbook on Neural Blockade mentioned that Tuohy "performed continuous spinal anesthesia by means of a ureteral catheter introduced in the subarachnoid space through a needle with a Huber point". No reference is given to the "Huber point", besides that of Tuohy, who also did not give any reference, as noticed before. Ronald Miller (10) in his textbook of Anesthesia gives a nice photograph of an "18-gauge Huber needle for continuous spinal catheter insertion", but with no reference. No other textbook in anesthesia tells us who was Huber whom his needle or his "point" revolutionized regional anesthesia. Medline search gave only articles on Huber-point needle in the port-a-cath implantable device, but with no reference to the question of who was Huber or when did he first describe his needle or his "point". The point is that, there is no reference in the medical literature of Huber`s description of his needle. A search in U.S. patents brought to U.S. patent No. 2,409,979 applied on March 14, 1946 by Ralph L. Huber from Seattle, Washington. He described there an hypodermic needle with a "transversely curved wall...end portion". In a recent correspondence said Winnie AP (11) that "history will recall what is published, not what is patented; and no subsequent publication will make up for failure to describe a new piece of technology in the medical literature". Winnie is right, at least for the last 50 years concerning Huber`s contribution to anesthesia. However, there is some injustice in the history of anesthesia on that subject. Every anesthesiologist knows what is the Tuohy needle. No anesthesiologist till now knows that the Tuohy needle is the Huber needle. Tuohy only used it for the introduction of the Tuohy catheter. I do not believe that all the companies which sell these "Tuohy needles" will change now its name to Huber needles, but maybe in the year 2,045... 1. Tuohy EB. Continuous spinal anesthesia. Proceedings of the Staff Meetings of the Mayo Clinic 1941;17:257-259. 2. Lemmon WT. A method for continuous spinal anesthesia. Ann Surg 1940;111:141-144. 3. Tuohy EB. Continuous spinal anesthesia: its usefulness and technic involved. Anesthesiology 1944;5:142-148. 4. Adams RC, Lundy JS, Seldon TH. Continuous caudal anesthesia or analgesia: a consideration of the technic , various uses and some possible dangers. JAMA 1943;122:152-158. 5. Manalan SA. Caudal block anesthesia in obstetrics. J Indiana M. A. 1942;35:564-565. 6. Love JG. Continuous subarachnoid drainage of meningitis by means of a ureteral catheter. JAMA 1935;104:1595. 7. Tuohy EB. The use of continuous spinal anesthesia utilizing the ureteral catheter technic. JAMA 1945;128:262-264. 8. Tuohy EB. Continuous spinal anesthesia: A new method utilizing a ureteral catheter. Surg Clins N. Am 1945;25:834-840. 9. Cousins MJ, Bridenbaugh PO. Neural Blockade in Clinical Anesthesia and Management of Pain. J.B. Lippincott Co., 2nd ed. 1988;p.11. 10. Miller RD. Anesthesia. 3rd ed., Churchill Livingstone 1990;Fig. 45-8. 11. Winnie AP. A letter to Ostheimer GW. March 17, 1994.

Total spinal anesthesia: The origin of CSEGA

Evans (1) described in 1928 the possible complications of spinal anesthesia. Concerning respiratory paralysis he wrote:" If respiration should cease , keep cool. Raise the lower jaw, pull the tongue forward and begin artificial respiration at a uniform rate. Mouth to mouth insufflation is the most convenient and efficacious method of artificial respiration". Twenty years before, in September 1908, before the Congress of the International Society of Surgery, in Brussels, Thomas Jonnesco (2) from Bucharest, described his new method of general spinal anesthesia and reported 14 cases operated upon by his method. Bier, who 10 years ago established the first human surgical spinal anesthesia, rejected it (2). In a later paper in 1910 Jonnesco wrote: "It is an error to confuse lumbar rachianesthesia, conceived by Corning and popularized by Bier, with my method. As I have many times emphasized , my method is a new one and altogether distinctive, because I have generalized spinal anaesthesia , adopting it to all operations on any part of the body" (3). Patients given high spinal anesthesia frequently either lapse into what appears to be normal sleep or may actually lose consciousness (4-7). If patients with high spinal anesthesia are given an inhalational anesthetic such as nitrous oxide-oxygen , very low concentrations of anesthetic gases are required to maintain unconsciousness (8). Reduction in the strength of nociceptive input may contribute to loss of consciousness by diminishing the strength of arousing stimuli arriving at cortical structures (9). Studies with C14 labeled lidocaine in dogs have shown that the foramen magnum is not a physiological barrier, for autoradiographs and tissue samples reveal the presence of radioactivity in intracranial parts of the CNS after a relatively modest epidural dose (10). Total spinal anesthesia has been used as a method of general anesthesia for abdominal surgery (11) and for the treatment of intractable pain (12). Gillies and Morgan (13) described a patient in whom a total spinal anesthesia resulted after 18 ml of inadvertent subarachnoid injection of 0.5% bupivacaine. Spontaneous respiration was noted 120 minutes later and consciousness regained after further 65 minutes. Return of respiration after 17 ml 1.5% lignocaine which resulted in total spinal analgesia occurred after 45 minutes and consciousness after further 80 minutes (14). Four patients with intractable pain were treated by total spinal anesthesia. Power spectral analysis of heart rate and peripheral blood flow variations were studied. Vagal activity was depressed as well as the sympathetic activity innervating the cardivascular system, so the heart rate and peripheral blood flow variations were totally eliminated (15). Total spinal block can be elicited even after an epidural test dose like the 36 year old parturient of Palkar et al. (16) who developed hypotension and extensive sensory and motor block including respiratory paralysis and aphonia after injection via the epidural catheter of 3 ml lidocaine 1.5% (45 mg) with 1:200,000 epinephrine (15 microgram). The patient remained fully conscious and alert and spontaneous respiration recommenced in five minutes. Three patients were studied to determine the changes in regional skin temperature and blood flow during extensive sympathetic blockade following total spinal anesthesia. The temperature of the truncal area, arm and leg decreased by 1 degree C, whereas the temperature of the hand and foot increased by 3 degrees C (17). Total spinal block was induced by 2% lidocaine in adult mongrel dogs. Heart rate, mean arterial pressure, cardiac index and left ventricle dp/dt max decreased significantly (18). Ephedrine 0.5 mg/Kg elevated HR, MAP, LV dp/dt max and SVR (19). Total spinal anesthesia blocks the vagus as well as the sympathetic nervous system and decreases heart rate variation, suggesting that neural control of the heart via the autonomic nervous system is abolished after total spinal anesthesia (17). Matsuki et al. (20) described a patient with primary aldosteronism who was anesthetized by total spinal anesthesia using an epidural catheter inserted at L3-4 into the subarachnoid space. The trachea was intubated after intravenous injection of thiopentone 250 mg and suxamethonium 40 mg, and oxygen 3 liters/minute and nitrous oxide 2 liters/minute inhaled. The intraoperative course was smooth and intraoperative muscle relaxation excellent. Adrenaline, noradrenaline and dopamine in the plasma remained within normal ranges. Mets et al (21) described a case of an unplanned version of CSEGA: A 24 year old parturient received an epidural analgesia during labor. Then she was scheduled for cesarean section for failure to progress. A total dose of 30 ml 0.5% bupivacaine was administered incrementally via the epidural catheter which resulted in a patchy block that was inadequate for surgery. Twenty minutes after the last injection of epidural local anesthetic a spinal anesthesia was done which resulted in a high block that necessitated tracheal intubation and ventilation. Controlled ventilation maintained with 50% N2O and 0.5% isoflurane in oxygen until delivery of the baby after which the isoflurane was stopped and 70% N2O in oxygen was administered. No further muscle relaxation was required for the remainder of the operation which lasted 45 minutes. The patient was extubated at the end of the operation uneventfully. 1. Evans CH. Possible complications with spinal anesthesia. Their recognition and the measures employed to prevent and to control them. Am J Surgery 1928;5:581-593. 2. Jonnesco T. Remarks on general spinal analgesia. Br Med J 1909;2:1396-1401. 3. Jonnesco T. Concerning general rachianesthesia. Am J Surgery 1910;24:33 4. Koster H, Kasman LP. Spinal anesthesia for the head, neck and thorax: its relation to respiratory paralysis. Surg Gynecol Obstet 1929;49:617. 5. Vehrs GR. Spinal anesthesia: Technic and clinical application. St Louis : The C.V. Mosby Co., 1934. 6. Jones RGG. A complication of epidural technique. Anaesthesia 1953;8:242. 7. Huvos MC, Greene NM, Glaser GH. Electroencephalographic studies during acute subtotal denervation in man. Yale J Biol Med 1962;34:592. 8. Greene NM. Hypotensive spinal anesthesia. Surg Gynecol Obstet 1952;95:331. 9. Kendig JJ. Spinal cord as a site of anesthetic action. Anesthesiology 1993;79:1161-2. 10. Bromage PR, Joyal AC, Binney JC. Local anaesthetic drugs: Penetration from the spinal extradural space into the neuraxis. Science 1963;140:392. 11. Evans TI. Total spinal anaesthesia. Anaesth Intensive Care 1974;2:158-63. 12. Yamashiro H, Hirano K. Treatment with total spinal block of severe herpetic neuralgia accompanying median and ulnar nerve palsy. Masui 1987;36:971-5. 13. Gillies IDS, Morgan M. Accidental total spinal analgesia with bupivacaine. Anaesthesia 1973;28:441-5. 14. DeSaram M. Accidental total spinal analgesia. A report of three cases. Anaesthesia 1956;11:77. 15. Goda Y, Kimura T, Goto Y, Kemmotsu O. Power spectral analysis of heart rate and peripheral blood flow variations during total spinal anesthesia. Masui 1989;38:1275-81. 16. Palkar NV, Boudreaux RC, Mankad AV. Accidental total spinal block : a complication of an epidural test dose. Can J Anaesth 1992;39:1058-60. 17. Kimura T, Goda Y, Kemmotsu O, Shimada Y. Regional differences in skin blood flow and temperature during total spinal anaesthesia. Can J Anaesth 1992;39:123-7. 18. Kobori M, Negishi H, Masuda Y, Hosoyamada A. Changes in respiratory , circulatory, endocrine, and metabolic systems under induced total spinal block. Masui 1991;40:1804-9. 19. Kobori M, Negishi H, Masuda Y, Hosoyamada A. Changes in systemic circulation under induced total spinal block and choice of vasopressors. Masui 1990;39:1580-5. 20. Matsuki M, Muraoka M, Oyama T. Total spinal anaesthesia for a Jehovah`s Witness with primary aldosteronism. Anaesthesia 1988;43:164-5. 21. Mets B, Broccoli E, Brown AR. Is spinal anesthesia after failed epidural anesthesia contraindicated for cesarean section? Anesth Analg 1993;77:629-31.

What is anesthesia?

Definitions of the state of anesthesia: 1. Drug-induced unconsciousness; the patient neither perceives nor recalls noxious stimulation (1). 2. Reversible oblivion and immobility (2). 3. Paralysis, unconsciousness, and attenuation of the stress response (3). 4. Sensory block, motor block, blocking of reflexes, and mental block (4). 5. All separate effects used to protect the patient from the trauma of surgery (5). Jorgensen et al. (6) studied the anesthetic choice of 705 patients of outpatient surgery candidates prior to speaking to the anesthesiologist. Sixty five percent preffered general anesthesia, 22% - spinal anesthesia, and 12% were unsure. Of those who had spinal anesthesia previously, only 33% would select it in the future. Conversely, 70% of patients who had general anesthesia would prefer it again. Concerns about spinal anesthesia were : paralysis, nerve damage, being awake, infection, inadequate anesthesia, backache, fear of needle and headache. The use of regional anesthesia in residency training programs has increased from 21.3% in 1980 to 29.8% in 1990, primarily because of a two-fold rise in the use of epidural anesthesia (7). Advantages of spinal anesthesia: Obviates the need for deep general anesthesia, profound muscle relaxation, cheap, easy to perform, danger of toxic drug signs - negligible. Disadvantages of spinal anesthesia: hypotension, postoperative headache, some patients prefer to be asleep during operation. The combined spinal-epidural anesthesia combines the rapid onset and good muscle relaxation of subarachnoid block with the ability to supplement analgesia through the epidural catheter, intraoperatively and after the operation. Reynolds et al. (8) using plain lumbar x-rays and CT after injection of iodized oil into the extradural space of 19 subjects recorded the depth of the extradural space at the caudal end: 8.3 1.95 mm (at the level of T12). Westbrook et al. (9) found even a smaller ligamentum flavum-dura mater depth at the L2-3 level: 3.951.1 mm by using the magnetic resonance imager of 39 subjects. Pitkin (10) describing spinal anesthesia in 1928 wrote that "in 1912, its use was confined to very elderly people, those considered as `bad risks` and to whom we were afraid to give ether". Koster (11) described in 1928 his experience of spinal anesthesia also in operations of the head, neck and thorax. He wrote: "Any one who can do a lumbar puncture can induce spinal anesthesia; the method is reasonably `fool proof` ". Babcock (12) in 1928 summarized his experience of 24 years with spinal anesthesia: "In no other known way can so profound and extensive an anesthesia be produced by so small a dose of a drug and with so little general toxicity". Bromage (13) stated in 1967 that "the beautiful precision and economy of a subarachnoid block is lacking in epidural anesthesia". Greene and Brull (14) in their preface to the fourth edition of "Physiology of Spinal Anesthesia" have written: "Epidural and spinal anesthesia are indeed related to each other, but only to the same extent as cousins or, at best, siblings; monozygotic twins they are not". 1. Prys-Roberts C. Anaesthesia: a practical or impractical construct? Br J Anaesth 1987;59:1341-5. 2. Eger EI. What is general anesthetic action? Anesth Analg 1993;77:408-9. 3. Pinsker MC. Anesthesia: a pragmatic construct. Anesth Analg 1986;65:819-27. 4. Woodbridge PD. Changing concepts concerning depth of anesthesia. Anesthesiology 1957;18:536-50. 5. Kissin I, Gelman S. Components of anaesthesia. Br J Anaesth 1988;61:237-42. 6. Jorgensen NH, Harders M, Hullander RM, Leivers D. Survey of preference for spinal vs. general anesthesia: Education makes a difference. Reg Anesth 1993;18:S53. 7. Kopacz DJ, Bridenbaugh LD. Are anesthesia residency programs failing regional anesthesia? The past, present and future. Reg Anesth 1993;18:84-87. 8. Reynolds AF, Roberts PA, Pollay M, Stratemeier PH. Quantitative anatomy of the thoracolumbar epidural space. Neurosurgery 1985;17:905-907. 9. Westbrook JL, Renowden SA, Carrie LES. Study of the anatomy of the extradural region using magnetic resonance imaging. Br J Anaesth 1993;71:495-498. 10. Pitkin GP. Controllable spinal anesthesia. Am J Surg 1928;5:537-553. 11. Koster H. Spinal anesthesia, with special reference to its use in surgery of the head, neck and thorax. Am J Surg 1928;5:554-570. 12. Babcock WW. Spinal Anesthesia. An experience of twenty-four years. Am J Surg 1928;5:571-6. 13. Bromage PR. Physiology and pharmacology of epidural analgesia. Anesthesiology 1967;28:592-622. 14. Greene NM, Brull SJ. Physiology of spinal anesthesia. Williams & Wilkins, 4th ed., 1993.

Use of Ephedrine in CSEGA

Ephedrine is the sympathomimetic drug which is most widely used to sustain blood pressure during spinal anesthesia. The active principal was isolated from the chinese herb ma huang in 1885 by Yamanashi (1). Butterworth et al. (2) found that a mixed adrenergic agonist such as ephedrine more ideally corrected the noncardiac circulatory sequelae of total spinal anesthesia in dogs than did either a pure alpha (phenyl-ephrine) or a pure beta-adrenergic agonist (isoproterenol). Butterworth et al. (3) also demonstrated in dogs the effectiveness of dobutamine and dopamine as possible alternatives to ephedrine for the pharmacologic correction of the noncardiac circulatory sequela of total spinal anesthesia. Goertz et al. (4) investigated the effect of ephedrine on left ventricular function in patients without cardiovascular disease under high thoracic epidural analgesia combined with general anesthesia. Ephedrine improved left ventricular contractility without causing relevant changes of left ventricular afterload. 1. Goodman L, Gilman A. The pharmacological basis of therapeutics. New York, The Macmillan Co., 1941, p.1383. 2. Butterworth JF, Piccione Jr W, Berrizbeitia LD, Dance G, Shenim RJ, Cohn LH. Augmentation of venous return by adrenergic agonists during spinal anesthesia. Anesth Analg 1986;65:612-6. 3. Butterworth JF, Austin JC, Johnson MD, Berrizbeitia LD, Dance GR, Howard G, Cohn LH. Effect of total spinal anesthesia on arterial and venous responses to dopamine and doputamine. Anesth Analg 1987;66:209-14. 4. Goertz AW, Hubner C, Seefelder C, Seeling W, Lindner KH, Rockemann MG, Georgieeff M. The effect of ephedrine bolus administration on left ventricular loading and systolic performance during high thoracic epidural anesthesia combined with general anesthesia. Anesth Analg 1994;78:101-5.

Cardiovascular effects of CSEGA

Combining epidural analgesia with general anesthesia in humans reduces the hemodynamic demand on the heart (1-3) and provides more stable intraoperative hemodynamics (4). In animal experiments epidural analgesia has inhibited sympathetic coronary constriction secondary to a flow-limiting stenosis (5), reduced infarct size (6) and reduced ST-segment changes on the electrocardiogram in an acute coronary artery occlusion model (7). However, Mergner et al. (8) investigated epidural analgesia combined with general anesthesia in a swine model with a tight coronary artery stenosis. Distal to the coronary stenosis was a moderate decrease in regional myocardial function and a severe reduction in blood flow. The epidural analgesia reaching the level of T1 was added to an animal which already had a decreased blood pressure and sympathetic tone from the isoflurane/fentanyl anesthesia. No correction of the reduced blood pressure was done in this study. Stenseth et al. (9) investigated the cardiovascular and metabolic effects of T1-T12 epidural block in 18 patients receiving chronic beta-adrenergic blocker medication and scheduled for aortocoronary bypass surgery. Thoracic epidural analgesia induced a moderate decrease in mean arterial pressure, coronary perfusion pressure, free fatty acids and myocardial consumption of free fatty acids. Blomberg et al. (10,11) also found no cardiac effects after a T1-T8 or T1-T6 block in beta-adrenergic blocked patients with ischemic heart disease. Christensen et al. (12) evaluated myocardial ischemic events by Holter monitoring of ST-segment depression in 14 patients with angina pectoris given spinal analgesia for minor surgery. Ephedrine in doses of 5 mg was given, if rapid infusion of saline did not improve the arterial pressure.The first ischemic event occurred at a mean of 338 minutes after spinal analgesia, and not in association with the onset of block, with the decrease in mean arterial pressure after spinal analgesia or with the administration of ephedrine. This could be explained by increased cardiac pre- and afterload, probably further aggravated by the volume load. 1. Baron JF, Coriat P, Mundler O, et al. Left ventricular global and regional function during lumbar epidural anesthesia in patients with and without angina pectoris: influence of volume loading. Anesthesiology 1987;66:621-7. 2. Diebel LN, Lange MP, Schneider F, et al. Cardiopulmonary complications after major surgery: a role for epidural analgesia. Surgery 1987;102:660-6. 3. Yeager MP, Glass DD, Neff RK, Brinck-Johnson T. Epidural anesthesia and analgesia in high-risk surgical patients. Anesthesiology 1987;66:729-36. 4. Her C, Kizelshteyr G, Walker V, et al. Combined epidural and general anesthesia for abdominal aortic surgery. J Cardiothorac Anesth 1990;4:552-7. 5. Heusch G, Deussen A, Thamer V. Cardiac sympathetic nerve activity and progressive vasoconstriction distal to coronary stenoses: feed-back aggravation of myocardial ischemia. J Auton Nerv Syst 1985;13:311-26. 6. Davis RF, DeBoer LWV, Maroko PR. Thoracic epidural anesthesia reduces myocardial infarct size after coronary artery occlusion in dogs. Anesth Analg 1986;65:711-7. 7. Vik-Mo H, Ottesen S, Renck H. Cardiac effects of thoracic epidural analgesia before and during acute coronary artery occlusion in open-chest dogs. Scand J Clin Lab Invest 1978;38:737-46. 8. Mergner GW, Stolte AL, Frame WB, Lim HJ. Combined epidural analgesia and general anesthesia induce ischemia distal to a severe coronary artery stenosis in swine. Anesth Analg 1994;78:37-45. 9. Stenseth R, Berg EM, Bjella L, Christensen O, Levang OW, Gisvold SE. The influence of thoracic epidural analgesia alone and in combination with general anesthesia on cardiovascular function and myocardial metabolism in patients receiving beta-adrenergic blockers. Anesth Analg 1993;77:463-8. 10. Blomberg S, Emanuelsson H, Kvist H, et al. Effects of thoracic epidural anesthesia on coronary arteries and arterioles in patients with coronary artery disease. Anesthesiology 1990;73:840-7. 11. Blomberg S, Emanuelsson H, Ricksten SE. Thoracic epidural anesthesia and central hemodynamics in patients with unstable angina pectoris. Anesth Analg 1989;69:558-62. 12. Christensen EF, Sogaard P, Egebo K, Bach LF, Riis J. Myocardial ischemia and spinal analgesia in patients with angina pectoris. Br J Anaesth 1993;71:472-5.

Cord ischemia and preemptive analgesia

Breckwoldt et al. (1) investigated the effect of intrathecal tetracaine on the neurological sequelae of spinal cord ischemia and reperfusion with aortic occlusion in rabbits. They found that intrathecal tetracaine significantly and dramatically abrogated the neurological injury secondary to spinal cord ischemia and reperfusion after aortic occlusion at 30 minutes. Peripheral tissue injury provokes two kinds of modification in the responsiveness of the nervous system: peripheral sensitization and central sensitization. The optimal form of pain treatment may be one that is applied both pre-, intra-, and postoperatively to preempt the establishment of pain hypersensitivity during and after surgery. Woolf and Chong (2) in their review of preemptive analgesia concluded that "although evolution has conserved sensitization in humans, the capacity to inflict `controlled injury` during surgery has clearly not been anticipated". 1. Breckwoldt WL, Genco CM, Connolly RJ, Cleveland RJ, Diehl JT. Spinal cord protection during aortic occlusion: Efficacy of intrathecal tetracaine. Am Thorac Surg 1991;51:959-63. 2. Woolf CJ, Chong MS. Preemptive analgesia - treating postoperative pain by preventing the establishment of central sensitization. Anesth analg 1993;77:362-79.

CSEA for Cesarean section

An increasing number of parturients wish to be awake during cesarean section (1) and opt for regional rather than general anesthesia. Spinal block is a simple technique which requires a small dose of local anesthetic to provide surgical anesthesia (1,2) with rapid, intense and reliable block without missed segments (1,3), greater muscle relaxation (1) and minimal risk of drug toxicity to the mother as well as to the fetus (3). For these reasons it has been proposed as the anesthetic method of choice for emergent cesarean section (4). Visceral pain is a poorly localized, dull and deep pain which is often accompanied by nausea, vomiting and sweating. Instead of pain, some patients describe it as a feeling of heaviness, pressure, tightness and/or squeezing. Alahuhta et al. (5) compared the incidence of visceral pain in 46 patients undergoing elective cesarean section under spinal or epidural anesthesia with 0.5% bupivacaine. Visceral pain occurred in 12/23 patients in the spinal group and in 13/23 patients in the epidural group. Rawal et al. (1) used the combined spinal-epidural anesthesia in 15 parturients scheduled for cesarean section. With the patients in the sitting position they injected 1.5-2 ml of 0.5% (7.5-10 mg) hyperbaric bupivacaine through the spinal needle to achieve an S5-T8-9 block. After withdrawing the spinal needle, the epidural needle was rotated and an epidural catheter introduced through it. After aspiration for blood or spinal fluid, 0.5-1 ml saline was injected in the epidural catheter to test its patency. 15-20 min after the spinal injection, 0.5% plain bupivacaine 1.5-2 ml per unblocked segment were injected till a T4-5 level was reached. The combined mean total dose of bupivacaine was 40.24.24 mg. It means that only 5-7 ml of 0.5% bupivacaine injected through the epidural catheter were needed to rise the anesthetic level from T8-9, reached by the previous spinal injection, to T3-4 achieved by the epidural augmentation. Riley et al. (6) compared the spinal versus epidural anesthesia for cesarean section in relation to time efficiency. They have found that patients who received epidural anesthesia had significantly longer total operating room times than those who received spinal anesthesia (101 20 vs 83 16 min). This was caused by longer times spent in the operating room until surgical incision (46 11 vs 296 min). Supplemental intraoperative intravenous analgesics and anxiolytics were required more often in the epidural group (38%) than in the spinal group (17%). Vucevic and Russell (7) compared 12 ml 0.125% plain bupivacaine with 3 ml 0.5% plain bupivacaine for cesarean section in 40 women using the combined spinal-epidural technique. The initial spread was greater with the 12 ml solution but within 5 min of placing the women in the supine tilted (right hip up) position, there were no differences in the levels of sensory blockade. The study also showed that the 12 ml solution resulted in more intensive blockade as there was less need for extradural anesthesia in this group than in the 3 ml group. Parturients receiving 15 mg of spinal hyperbaric bupivacaine for cesarean delivery developed a higher mean level and longer duration of sensory analgesia than those receiving 12 mg (8). Fan et al. (9) examined four regimens of combined spinal-epidural anesthesia in 80 parturients for cesarean section: 1. 2.5 mg bupivacaine 0.5% intrathecally combined with 22.24.6 ml of lidocaine 2% epidurally. This combination provided insufficient muscle relaxation. 2. 5 mg of bupivacaine 0.5% - spinally with 10.1 2.0 ml of lidocaine 2% epidurally resulted in satisfactory anesthesia with rapid onset and minimum side effects. 3. Spinal 7.5 mg of bupivacaine 0.5% . 4. Spinal 10 mg of bupivacaine 0.5%. Anesthesia in these groups (7.5 mg and 10 mg bupivacaine 0.5%) was mostly due to the spinal block. Their conclusion was that the combined spinal-epidural technique, using 5 mg of bupivacaine and with sufficient epidural lidocaine to reach a T4 level, had the advantages of both spinal and epidural anesthesia with few of the complications of either. Ciccozzi et al. (10) evaluated the combined spinal-epidural anesthesia by the needle-through-needle technique in 40 parturients (20 in the sitting position and 20 in the left lateral position). Supine position after the spinal injection was achieved in 7.54.3 min in the sitting position group and in 7.7 4.9 min in the left lateral group. One patient (5%) in each group received a single shot spinal because of technical difficulties in the epidural catheter placement. Five patients (25%) of the left lateral group showed poor spinal analgesia and then required epidural supplementation. Mok and Tzeng (11) demonstated that 2 mg epidural morphine combined with 30 mg ketoralac IM provided a better pain relief after cesarean section than using the 2 mg epidural morphine alone. Swami et al. (12) studied the effect on the blood pressure of a spinal dose of 7.5 mg vs 12.5 mg hyperbaric bupivacaine in 90 parturients for cesarean section. Using the combined spinal-epidural technique, 23% of the 7.5 mg group needed an epidural top-up, while none in the 12.5 mg group. Hypotension occurred in 40% of the 12.5 mg and only in 22% of the 7.5 mg hyperbaric bupivacaine spinal injection. Dickson and Jenkins (13) assessed the efficacy of a bolus dose of bupivacaine 0.5% 10 ml following an infusion of 0.1% for extension of epidural blockade for emergency cesarean section. In only 11 patients out of 18 was the analgesic block of labour successfully converted to a block adequate for cesarean section using 10 ml bupivacaine 0.5%. Five patients required an additional top-up (range 3-10 ml). A general anesthetic was necessary in two patients with blocks which had initially appeared to be adequate. Westbrook et al. (14) induced combined spinal-epidural anesthesia in the lateral position in 150 women presenting for cesarean delivery. They saw CSF after the first pass of the spinal needle through epidural needle in only 86%-92% of the time. 1. Rawal N, Schollin J, Wesstrom G. Epidural versus combined epidural block for cesarean section. Acta Anaesthesiol Scand 1988;32:61-6 2. Covino BG. Rationale for spinal anesthesia. International Anesthesiology Clinics 1989;27:8-12 3. Hunt CO. Spinal anesthesia for obstetrics. International Anesthesiology Clinics 1989;27:26-30 4. Marx GF, Lughx WM, Cohen S. Fetal-neonatal status following Caesarean section for fetal distress. Br J Anaesth 1984;56:1009-12 5. Alahuhta S, Kangas-Saarela T, Hollmen AI, Edstrom HH. Visceral pain during caesarean section under spinal and epidural anaesthesia with bupivacaine. Acta Anaesthesiol Scand 1990;34:95-98 6. Riley ET, Cohen SE, Macario A, Desai JB, Ratner EF. Spinal versus epidural anesthesia for cesarean section: A comparison of time efficiency, costs, charges, and complications. Anesth Analg 1995;80:709-12 7. Vucevic M, Russell IF. Spinal anaesthesia for Caesarean section: 0.125% plain bupivacaine 12 ml compared with 0.5% plain bupivacaine 3 ml. Br J Anaesth 1992;68:590-595 8. De Simone CA, Leighton BL, Norris MC. Spinal anesthesia for cesarean delivery: A comparison of two doses of hyperbaric bupivacaine. Reg Anesth 1995;20:90-94 9. Fan SZ, Susetio L, Wang YP, Cheng YJ, Liu CC. Low dose of intrathecal hyperbaric bupivacaine combined with epidural lidocaine for cesarean section - a balance block technique. Anesth Analg 1994;78:474-7 10. Ciccozzi A, Iovinelli G, Varrassi G. Effects of posture on the spread of local anesthetics in CSEA for Caesarean delivery. Reg Anesth 1995;20:S74 11. Mok MS, Tzeng JI. Intramuscular ketoralac enhances the analgesic effect of low dose epidural morphine. Anesth Analg 1993;76:S269 12. Swami A, McHale S, Abbott P, Morgan B. Low dose spinal anesthesia for cesarean section using combined spinal-epidural (CSE) technique. Anesth Analg 1993;76:S423 13. Dickson MAS, Jenkins J. Extension of epidural blockade for emergency Caesarean section. Anaesthesia 1994;94:636-638 14. Westbrook JL, Donald F, Carrie LES. An evaluation of a combined spinal/epidural needle set utilising a 26-gauge pencil point spinal needle for Caesarean section. Anaesthesia 1992;47:990-2

Corning

The first epidural anesthesia done by Corning, a New York city neurologist, in 1885 was a "walking" epidural. He injected twice 2 ml of a 3% solution of the hydrochlorate of cocaine into the epidural space of a man "addicted to sexual abuse". While standing with eyes closed, the man experienced some dizziness, but no incoordination or motor impairment was discernible in his gait. He left the office an hour or more after the injection and seemed "none worse for the experience" (1). 1. Marx GF. The first spinal anesthesia: Who deserves the laurels? Reg Anesth 1994;19:429-430

Bier

August Bier (1), on August 24, 1898, asked his assistant, Dr. Hilderbrandt, "to perform a lumbar puncture on me", 8 days after he first performed it on a 34-year-old patient for excision of a tuberculous capsule at the ankle joint. Bier wrote that he did not feel any discomfort "except for a quick flash of pain in one leg at the moment that the needle penetrated the meninges". Unfortunately, the experiment was not successful because of an error (the syringe did not fit the needle tightly... and consequently some CSF ran out and most of the cocaine was lost). No sensory loss ensued. Dr. Hilderbrandt immediately offered to submit himself to the experiment, which was successful. Both of them "went to eat after the experiments were performed on our bodies. We had no physical discomfort, we ate, drank wine, and smoked several cigars". However, next morning, after a one hour morning stroll Bier felt slight headache which increased in intensity during the course of the day. Nine days after the puncture, all the symptoms disappeared. After 3 more days, "I was able to go on a train trip without discomfort and was fit enough to participate in a strenuous 8 day hunting trip in the mountains". 1. Bier AKG, von Esmarch JFA. Versuche uber Cocainisirung des Ruckenmarkes. Dtsch Z Chir 1899;51:361-369

A new look at the lumbar extradural space pressure

The answer to the questions: Why does not the Macintosh balloon indicator deflate, or why the hanging drop technique is unreliable was given by Shah (1): The epidural space pressure is influenced by many factors. It is raised by jugular venous compression, ventilation with carbon dioxide and positive end-expiratory pressure (PEEP). The lumbar extradural pressure is increased rapidly with stimuli known to increase CSF pressure. However, the next question is what happens in the "normal" condition (without jugular venous compression or CO2 inhalation, etc.)? There is a wave pressure, which is the lumbar CSF wave pressure transmitted to the epidural space. On that subject Shah quoted an article by Hirai et al (2) published in 1982:"The arterial pressure wave in the spinal CSF originates from the choroid plexus... The pulsatile vibration of the brain parenchyma derived from the blood flow in the cerebral arteries may have enough energy to generate the spinal CSF pulse. The amplitude of the pulse wave varies directly with intracranial pressure". This citation is not exactly true in the light of an investigation published by Urayama (3). He performed system analysis on 16 adult mongrel dogs to determine the origin of the lumbar cerebrospinal fluid pulse wave. The descending thoracic aorta was occluded to evaluate the effects of the spinal arterial pulsations, and the thoracic aorta and inferior vena cava were simultaneously occluded to evaluate the effects of the spinal venous pulsations. It was concluded that, in the first harmonic wave, the components of the lumbar cerebrospinal fluid pulse wave are as follows: spinal arterial pulsations - 39.4%; spinal vascular (arteries and veins) pulsations - 77%; venous pulsations in the spinal canal - 37.6%; and the intracranial pressure pulse wave transmitted through the spinal canal from the intracranial space to the lumbar level - 23%. So, from this investigation we can learn that 77% of the lumbar cerebrospinal fluid pulse wave which is directly transmitted to the extradural space as an extradural pressure wave is originated in the vascular system (arteries and veins), and not in the brain . So, any rise in the blood pressure, which is not an infrequent observation during epidural needle insertion, can give a concomitant rise in the extradural pressure with the loss of the "negative" pressure in the extradural space and "unreliable" hanging drop and Macintosh balloon indicator techniques. 1. Shah JL. Positive lumbar extradural space pressure. Br J Anaesth 1994;73:309-314. 2. Hirai O, Handa H, Ishikawa M. Intracranial pressure pulse waveform: considerations about its origin and methods of estimating intracranial pressure dynamics. Brain Nerve (Tokyo) 1982;34:1059-1065. 3. Urayama K. Origin of lumbar cerebrospinal fluid pulse wave. Spine 1994;19:441-445

Do not rotate the epidural needle

The epidural needle rotation in CSEA using the needle-through-needle technique was first suggested in 1988 by Rawal et al. (1). However, Dr. Rawal abandoned this technique of epidural needle rotation (2) because he was convinced that "180 rotation of the epidural needle may cause dural tear". Nickalls and Dennison (3) found that the distance the spinal needle has to be advanced past the end of the Tuohy needle to just puncture the dura ranges from 0.3 to 1.05 cm. Joshi and McCarroll (4) described two sets of needle-through-needle techniques to perform the combined spinal-epidural anesthesia. They were concerned to find cerebrospinal fluid in the Tuohy needle after removal of the spinal needle. Carter et al. (5) abandoned this technique of epidural needle rotation because it increased the chance of inadvertent dural puncture by a factor of 5.6: there was also a 16.6% incidence of the epidural catheter protruding through the hole made previously by the spinal needle. Meiklejohn (6) found that "postmortem dura mater demonstrated that rotation of the epidural needle significantly decreases the force required to puncture the dura". He concluded that "once the needle has been inserted into the epidural space... it should not be moved for any reason other than to remove it". 1. Rawal N, Schollin J, Wesstrom G. Epidural versus combined spinal epidural block for cesarean section. Acta Anaesthesiol Scand 1988;32:61-6 2. Rawal N. Combined spinal-epidural needle (CSEN) for the combined spinal-epidural block - reply. Acta Anaesthesiol Scand 1989;33:618 3. Nickalls RWD, Dennison B. A modification of the combined spinal and epidural technique. Anaesthesia 1984;39:935 4. Joshi GP, McCarroll SM. Combined spinal-epidural anesthesia using needle-through-needle technique. Anesthesiology 1993;78:406-7 5. Carter LC, Popat MT, Wallace DH. Epidural needle rotation and inadvertent dural puncture with catheter. Anaesthesia 1992;47:447-8 6. Meiklejohn BH. The effect of rotation of an epidural needle. Anaesthesia 1987;42:1180-2

Epidural rostral augmentation of spinal anesthesia

Suzuki et al. (1) found that spinal puncture with a 26G spinal needle, with no spinal anesthetic injection, immediately before epidural injection of 18 ml 2% mepivacaine resulted in rapid caudal spread of analgesia as compared to an epidural anesthesia alone. They attributed it to the flow of local anesthetic into the subarachnoid space through the perforation produced by the spinal needle. Dobson et al. (2) reported of a sudden asystole 70 min after intrathecal injection of 2.75 ml hyperbaric bupivacaine 0.5% in a patient whose cardiac output was being monitored. After successful resuscitation , the height of the block was judged to be T4. According to the authors of the report, monitoring should continue for at least 90 min after induction of spinal anesthesia. Bodily et al. (3) warned that changes in position can alter the spread of sensory blockade for at least 1 hr after the intrathecal injection of a hypobaric solution. They showed that 8 ml lidocaine 0.5% (baricity 0.99850.0003, 25C) produced effective spinal anesthesia for perirectal surgery in the jack-knife position. Dermatomal levels remained low (T11-L5) while the patients were in the head-down position during surgery, but rose two to six dermatomes if the patient`s head was elevated after surgery. Fast rate of injection (0.5 ml/sec) of 5 ml 0.3% bupivacaine into the subarachnoid space results in a higher maximum sensory level than slow rate injection (0.02 ml/sec) (4). Serpell et al. (5) recorded intrathecal pressure after instillation of saline boluses into the epidural space in adult ewes. Mean baseline CSF pressure was 28.55.5 mmHg. Five ml saline boluses (1 ml/sec) were injected at 5-minute intervals until CSF pressure exceeded 100 mmHg. Initially, a rapid increase in CSF pressure accompanied each saline bolus with a gradual return to baseline. Up to a cumulative volume of 20 ml (range 5-60), the mean value of peak CSF pressure was 5312 mmHg and the resting pressure would return to baseline. After a cumulative injection volume of 50.539.5 ml (range 15-115) saline, the resting pressure progressively rose to 64.1 17.4 mmHg to coincide with a peak CSF pressure exceeding 100 mmHg, indicating that the compliance of the spinal space had been compromised. Radiographic contrast injected into the caudal sheath revealed that initial decompression occurred via leakage into the large sacral root foramina and sheaths. Dell and Orlikowski (6) described a 26-year-old patient who received 45 ml of bupivacaine 0.25% (including a 3 ml of bupivacaine 0.5% as a test dose) within 3 hours of labour analgesia. One hour after the last dose of epidural bupivacaine, with the patient in the left lateral position, 2.5 ml of hyperbaric bupivacaine 0.5% was injected through a 25 gauge Whitacre needle into the subarachnoid space for cesarean section, because the epidural sensory block was patchy. Two minutes later, there was profound motor block of the lower limbs. At 5 min she developed paresthesias and weakness in the upper limbs and experienced difficulty in breathing. At 8 min she complained of nasal stuffiness and her trachea was intubated following rapid sequence induction of general anesthesia. The reduced CSF volume following epidural injection of a relatively large volume (45 ml) was suggested as an explanation for this high spinal anesthesia following 2.5 ml hyperbaric bupivacaine spinal injection. D`Angelo et al. (7) found a rapid cephalad spread of intrathecal sufentanil 10 g combined with 12 ml epidural saline injection for labor analgesia. However, they have "blamed" this phenomenon only on the opioid pharmacokinetics and not the epidural saline rostral augmentation of intrathecal sufentanil. Barclay et al. (8) showed that compression of the vena cava by an abdominal binder decreases the volume of the subarachnoid space and heightens the level of spinal anesthesia. Furst and Reisner (9) described two cases of high spinal anesthesia following failed epidural blockade. They found its incidence to be 11% versus fewer than 1% in patients undergoing spinal anesthesia alone. In light of these findings, they changed their practice by reducing the dose of spinal bupivacaine by 20% in those patients in whom epidural anesthesia has proved inadequate. They also perform the spinal block in the sitting position, allowing it to "set" for 60-90 seconds prior to placing the patient supine. Gamil (10) reported a case of a parturient for cesarean section who received spinal anesthesia with 2.5 ml of 0.5% heavy bupivacaine in the sitting position. The patient was maintained in this position whilst an epidural catheter was sited in a cephalad direction. It took 15 min. Before threading the epidural catheter, the epidural space was primed with 20 ml of saline. Then the patient positioned for surgery, supported under the shoulders by three pillows. 75 min from the insertion of the spinal, at the end of surgery, 50 ml of saline was injected to the epidural space as prophylaxis against headache. 5 min later the block extended from L1 to T1. The injection of a relatively small amount of 0.5% bupivacaine into the extradural space after a subarachnoid injection of a standard dose of bupivacaine results in rapid extension of the block (11,12). Several hypotheses have been advanced to explain this enhancement of the subarachnoid block. These include leakage of extradural bupivacaine into the subarachnoid space via the hole created by the subarachnoid puncture, the existence of a "subclinical" analgesia at a higher level which is enhanced and becomes evident by perineural or transdural spread of the extradural solution, or the continuing spread of the initial subarachnoid injection independent of the extradural injection (11-14). Blumgart et al. (15) found that the mechanism of extension of spinal anesthesia by extradural injection of local anesthetics is largely a volume effect. Using extradural saline 10 ml and extradural bupivacaine 0.5% 10 ml - the extension of the block was found to be similar in the saline or the bupivacaine groups and significantly faster than the group which received no extradural injection after spinal injection of 1.6-1.8 ml of 0.5% hyperbaric bupivacaine. 1. Suzuki N, Koyanemaru M, Onizuka S, Takasaki M. Dural puncture with a 26-gauge spinal needle affects epidural anesthesia. Reg Anesth 1995;20:S118 2. Dobson PMS, Caldicott LD, Gerrish SP. Delayed asystole during spinal anaesthesia for transurethral resection of the prostate. Eur J Anaesth 1993;10:41-43 3. Bodily MN, Carpenter RL, Owens BD. Lidocaine 0.5% spinal anaesthesia: A hypobaric solution for short-stay perirectal surgery. Can J Anaesth 1992;39:770-773 4. Horlocker TT, Wedel DJ, Wilson PR. Effect of injection rate on sensory level and duration of hypobaric bupivacaine spinal anesthesia for total hip arthroplasty. Anesth Analg 1994;79:773-7 5. Serpell MG, Coombs DW, Colburn RW, Deheo JA, Twitchell BB. Intrathecal pressure recordings due to instillation in the epidural space. International Monitor on Regional Anaesthesia 1993;52 6. Dell RG, Orlikowski CEP. Unexpectedly high spinal anaesthesia following failed extradural anaesthesia for caesarean section. Anaesthesia 1993;48:641 7. D`Angelo R, Anderson MT, Philip J, Eisenach JC. Intrathecal sufentanil compared to epidural bupivacaine for labor analgesia. Anesthesiology 1994;80:1209-1215 8. Barclay DL, Renegar OJ, Nelson EW. The influence of inferior vena cava compression on the level of spinal anesthesia. Am J Obstet Gynecol 1968;101:792-800 9. Furst SR, Reisner LS. Risk of high spinal anesthesia following failed epidural block for cesarean delivery. J Clin Anesth 1995;7:71-74 10. Gamil M. Combined spinal/epidural anaesthesia for caesarean section. Anaesthesia 1994;49:545-6 11. Carrie LES. Epidural versus combined spinal epidural block for Caesarean section. Acta Anaesthesiol Scand 1988;32:595-596 12. Rawal N, Schollin J, Wesstrom G. Epidural versus combined spinal epidural block for Caesarean section. Acta Anaesthesiol Scand 1988;32:61-66 13. Rawal N. Single segment combined subarachnoid and epidural block for Caesarean section. Can Anaesth Soc J 1986;33:254-255 14. Bromage PR. Mechanism of action of extradural anaesthesia. Br J Anaesth 1975;47:199-212 15. Blumgart CH, Ryall D, Dennison B, Thompson-Hill LM. Mechanism of extension of spinal anaesthesia by extradural injection of local anaesthetic. Br J Anaesth 1992;69:457-460

Metallic particles in the needle-through-needle technique

The Tuohy needle was not originally intended to be an introducer for a spinal needle. Tuohy (1) in 1944, used a needle with a curved Huber tip for continuous spinal anesthesia, and Curbelo (2) in 1949, adapted this needle for continuous epidural block. Coates (3) and Mumtaz et al. (4) were the first to publish the possibility of inserting a long spinal needle through a Tuohy epidural needle. They encountered only two potential hazards, "possible passage of the epidural catheter through the hole in the dura mater and the possibility of subarachnoid effects from epidurally injected drugs by passage through the hole in the dura". Evans (5) applied for a patent for this instrument a year later. The long spinal needles have been available in the British market since 1985 (6). The forward end of the spinal needle is inclined at an angle of about 30 to its length when it projects by about 10 mm from the forward end of the epidural needle (5). At that inclination the spinal needle scratches the inner surface of the epidural needle tip when moving forward and backward. This friction must cause metallic microparticles. Spectral analysis of the 18-gauge epidural needle (Portex) at 20 KV (7) revealed 18.960.28% chromium and 68.75 0.82% iron. The other components were: nickel, 9.350.57%; manganese, 1.85 0.07%; silicone, 0.670.16%; and molybdenum, 0.31 0.23%. For example, nickel implanted in rats produced a necrotic, abcesslike reaction (8). In the clinical setting, an epidural catheter is pushed through the shaft after the spinal needle is withdrawn, so the microparticles produced by the friction between the two needles can be pushed forward by the force exerted to insert the catheter into the epidural space. 1. Tuohy EB. Continuous spinal anesthesia: Its usefulness and technique involved. Anesthesiology 1944;5:142-143 2. Curbelo MM. Continuous peridural segmental anesthesia by means of a ureteral catheter. Curr Res Anesth Analg 1949; 28:13 3. Coates MB. Combined subarachnoid and epidural techniques. Anaesthesia 1982;37:89-90 4. Mumtaz MH, Daz M, Kuz M. Another single space technique for orthopaedic surgery. Anaesthesia 1982;37:90 5. Evans JM. Instrument for epidural and spinal anaesthesia: UK patent application, 1983: GB 2124503A 6. Desira WR. A special needle for combined subarachnoid and epidural block. Anaesthesia 1984;39:308 7. Kumar B, Messahel FM. Evaluation of epidural needles. Acta Anaesthesiol Scand 1987;31:96-99 8. Wigle RL. The reaction of copper and other projectile metals in body tissues. J Trauma 1992;33:14-18

Superselective spinal anesthesia

Veneziani et al. (1) described a technique of superselective spinal anesthesia for the surgical treatment of saphenectomy. The block has been performed at L2-3 with the patients laying in omolateral decubitus with respect to surgical side and injecting slowly 1% hyperbaric bupivacaine 0.5-0.6 ml and maintaining such a position for about 10-15 minutes. The 24G Sprotte spinal needle was used with an incidence of only 0.4% postspinal headache. 1. Veneziani A, Santagostino G, Matera D, Tulli G. Superselective spinal anaesthesia for the surgical treatment of saphenectomy. Acta Anaesthesiol Scand 1995;39:A430

CSEA in uncommon disease

Cherng et al. (1) described a case report of combined spinal and epidural anesthesia for abdominal hysterectomy in a 34-year-old woman with myotonic dystrophy. Patients with myotonic dystrophy have a high risk of anesthetic complications, and the anesthetic technique should aim to prevent any stimulation (chemical, mechanical or thermal), and avoid any drugs that would induce uncontrollable muscular contraction (myotonic crisis) (2). 1. Cherng YG, Wang YP, Liu CC, Shi JJ, Huang SC. Combined spinal and epidural anesthesia for abdominal hysterectomy in a patient with myotonic dystrophy. Reg Anesth 1994;19:69-72 2. Paterson RA, Tousignant M, Skene DS. Caesarean section for twins in a patient with myotonic dystrophy. Can Anaesth Soc J 1985;32:418-421

CSEA for laparoscopic operations

Ciofolo et al. (1) evaluated the respiratory effects of laparoscopy under epidural anesthesia in seven female patients scheduled for a gamete intrafallopian transfer procedure. No significant changes in the ventilatory variables were observed in the Trendelenburg position. In contrast, CO2 insufflation significantly increased minute ventilation (from 9.11.0 L/min to 11.8 2.6 L/min) and respiratory rate (from 16.91.9 breaths/min to 23.1 3.3 breaths/min), whereas CO2 output remained unchanged. PaCO2 remained constant throughout the study. They concluded that epidural anesthesia may be a safe alternative to general anesthesia for outpatient laparoscopy, as it is not associated with ventilatory depression. Epidural analgesia for minilaparotomy cholecystectomy improves pain relief in the immediate postoperative period, compared to intramuscular morphine (2). Reduction of the surgical stress response can be achieved by two techniques: One is to reduce the degree of tissue trauma and thereby the injury response using the "minimal invasive surgery concept"; the other is "stress-free anesthesia and surgery" providing effective pain relief, including afferent neural block (3,4), together with block of various humoral mediator cascade systems (arachidonic cascade metabolites, cytokines, etc.) as well as a maintenance of nutritional status by provision of unspecific nutrients (glutamine, arginine) or growth factors (growth hormone, etc.) (5). 1. Ciofolo MJ, Clergue F, Seebacher J, Lefebvre G, Viars P. Ventilatory effects of laparoscopy under epidural anesthesia. Anesth Analg 1990;70:357-61 2. Dahl JB, Hjortso N-C, Stage JG, Hansen BL, Moiniche S, Damgaard B, Kehlet H. Effects of combined perioperative epidural bupivacaine and morphine, ibuprofen, and incisional bupivacaine on postoperative pain, pulmonary, and endocrine-metabolic function after minilaparotomy cholecystectomy. Reg Anesth 1994;19:199-205 3. Kehlet H. Modification of responses to surgery and anesthesia by neural blockade: Clinical implications. In:Cousins MJ, Bridenbaugh PO, eds. Neural blockade in clinical anesthesia and management of pain. Philadelphia, Lippincott, 1987:145-188 4. Kehlet H. General vs regional anesthesia. In: Rogers MC, Tinker JH, Covino EG, Longnecker DE (eds.). Principles and practice of anesthesiology. St Louis, C.V. Mosby, 1993:1218-1234 5. Kehlet H. Postoperative pain relief. A look from the other side. Reg Anesth 1994;19:369-377

Postoperative epidural analgesia

Albert Schweitzer said that "pain is a more terrible lord of mankind than even death itself". Bonica (1) wrote that "acute and chronic pain afflicts millions upon millions of persons annually, and in many patients with chronic pain and a significant percentage of those with acute pain, it is inadequately relieved". In the 1980s, surveys of patients` subjective well-being revealed an incidence of moderate or severe pain after surgery of 31-75% (2,3). De Leon-Casasola et al. (4) compared the effect on postoperative myocardial ischemia of epidural versus intravenous patient-controlled analgesia. 198 patients received either technique for 5-7 days postoperatively. Patients in the epidural group had a lower incidence of tachycardia (14% vs. 65%), ischemia (5% vs. 17%), and infarction - 0% vs. 20% of patients with ischemia in the intravenous patient-controlled analgesia group. Postoperative ileus is an undesirable response to injury and is predominantly caused by an increase in inhibitory afferent sympathetic activity (5). Postoperative continuous epidural analgesia may improve gastrointestinal motility and reduce ileus (6-9). Early oral feeding reduced the risk of septic complications (10). The positive effect of epidural local anesthetic analgesic techniques on gastrointestinal paralysis may facilitate early oral nutrition as well as reducing fatigue and convalescence. 1. Bonica J.J. History of pain concepts and pain therapy. Mt Sinai J Med 1991;58:191-202 2. Kuhn S, Cooke K, Collins M, Jones JM, Mucklow JC. Perceptions of pain relief after surgery. Br Med J 1990;300:1687-1690 3. Owen H, McMillan V, Royowski D. Postoperative pain therapy: A survey of patients` expectations and their experiences. Pain 1990;41:303-307 4. De Leon Casasola OA, Lema MJ, Karabella D, Harrison P. Postoperative myocardial ischemia: Epidural versus intravenous patient-controlled analgesia. Reg Anesth 1995;20:105-112 5. Wattwill M. Postoperative pain relief in gastrointestinal motility. Acta Chir Scand 1988;550(Suppl):140-145 6. Bredtmann RD, Herden RN, Teichmann W, Moecke HP, Kniesel B, Batdgen R, Tecklenburg A. Epidural analgesia in colonic surgery: Results of a randomized prospective study. Br J Surg 1990;77:638-642 7. Sheinin B, Asantila R, Orku R. The effect of bupivacaine on pain and bowel function after colonic surgery. Acta Anaesthesiol Scand 1987;31:161-164 8. Ahn H, Bronge A, Johansson K, Ygge H, Lindhargen J. Effect of continuous postoperative epidural analgesia on intestinal motility. Br J Surg 1988;75:1176-1178 9. Wattwill M, Thoren T, Hennerdal S, Garvill J-E. Epidural analgesia with bupivacaine reduces postoperative paralytic ileus after hysterectomy. Anesth Analg 1989;68:353-358 10. Moore FA, Philiciano DV, Andrassy REJ, McArdle AH, Booth FVM, Morgenstein-Wargnen TB, Kellum JM, Welling RE, Moore EE. Early enteral feeding, compared with parenteral, reduces postoperative septic complications: The results of a meta-analysis. Ann Surg 1992;216:172-183

Unilateral spinal anesthesia

Using the needle-through-needle technique in 80 patients for cesarean section Fan et al. (1) noted the occurrence of a unilateral spinal block with the hyperbaric 0.5% bupivacaine, "because keeping the patient in the lateral position was necessary to accomplish the epidural procedure". 1. Fan SZ, Susetio L, Wang YP, Cheng YJ, Liu CC. Low dose of intrathecal hyperbaric bupivacaine combined with epidural lidocaine for cesarean section - a balance block technique. Anesth Analg 1994;78:474-7

CSEA for abdominal operations

Guedj et al. (1) compared between spinal anesthesia and combined spinal-epidural anesthesia (CSEA) in 63 patients undergoing gynecological surgery. Spinal anesthesia (n=34) was carried out in the L3-4 interspace with the patients sitting using 15 mg of hyperbaric 0.5% bupivacaine with adrenaline. In the CSEA group (n=29) an epidural catheter was inserted through the L2-3 interspace and the spinal anesthesia in the L3-4 interspace, while the patients were sitting. In the CSEA group, excellent analgesia was obtained in all patients. In the spinal group, general anesthesia was required in 3 patients (8.8%), as anesthesia only reached the T12 level in 2 cases, and as surgery lasted longer than the spinal in the third one. Moiniche et al. (2) described a case of colonic resection with early discharge after combined subarachnoid - epidural analgesia, preoperative glucocorticoids, and early postoperative mobilization and feeding in a 59-year-old pulmonary high-risk woman. They have introduced an epidural catheter between T9-10 and a spinal catheter between L3-4. During the operation the patient was fully awake. At one time during intestinal traction, visceral pain was treated vith intravenous 100 g fentanyl. Surgery lasted for 70 minutes. The spinal catheter was removed at the end of surgery, while the epidural catheter provided postoperative analgesia for 72 hours. Luchetti et al. (3) used the combined spinal-epidural anesthesia in 20 patients undergoing surgery for hernioplasty, saphenectomy, hemorroidectomy and varicocelectomy. The subarachnoid injection consisted of hyperbaric bupivacaine 1% 1 ml and the epidural catheter injection - bupivacaine 0.5% 3 ml + fentanyl 50 g. Analgesia was excellent in 17 patients and good in 3. No patient needed further analgesic medication intraoperatively. Mihic and Abram (4) compared five groups of patients undergoing abdominal hysterectomy with or without appendicectomy with regional anesthesia. Two hundred patients were divided as follows: Group 1 - spinal anesthesia with hyperbaric 0.5% bupivacaine; Group 2 - as group 1 with the addition of 0.06 mg of IV buprenorphine and 2.5 mg of IV midazolam; Group 3 - epidural block with 0.75% bupivacaine; Group 4 - as group 3 with the addition of epidural morphine 1%; Group 5 - combined spinal-epidural block (as in groups 1 and 4). No case of unsuccessful blockade occurred in the combined spinal-epidural anesthesia, compared to 3-4 cases of failed block in the other groups. Four patients whose analgesia was considered to be unsuccessful had to be intubated to obtain satisfactory surgical conditions. The combination of subarachnoid and epidural block provided the best analgesia. 1. Guedj P, Eldor J, Gozal Y. Conventional spinal block versus combined spinal-epidural anaesthesia for lower abdominal surgery. Ann Fr Anesth Reanim 1992;11:399-404 2. Moiniche S, Dahl JB, Rosenberg J, Kehlet H. Colonic resection with early discharge after combined subarachnoid-epidural analgesia, preoperative glucocorticoids, and early postoperative mobilization and feeding in a pulmonary high-risk patient. Reg Anesth 1994;19:352-356 3. Luchetti M, Palomba R, Liardo A, Bardari G, Sica G. Combined spinal-epidural anaesthesia (CSEA) is effective and safe for minor general surgery. Int Monitor Reg Anaesth 1994;A97 4. Mihic DN, Abram SE. Optimal regional anaesthesia for abdominal hysterectomy: Combined subarachnoid and epidural block compared with other regional techniques. Eur J Anaesthesiol 1993;10:297-301

CSEA for thoracic operations

Kowalewski et al. (1) reported on the use of spinal anesthesia with hyperbaric bupivacaine (20-30 mg) and/or lidocaine (150 mg) with morphine (0.5-1 mg) combined with general anesthesia with alfentanil 97 22 g/Kg and midazolam 0.040.02 mg/Kg supplemented with a muscle relaxant and maintained with isoflurane (0.25-0.5%) in oxygen in 18 patients for coronary artery bypass surgery (CABG). They suggested that general anesthesia combined with spinal anesthesia may be an effective technique for CABG. Very low concentrations of inhalational agents are required to maintain unconsciousness during high spinal anesthesia (2). Epidural anesthesia attenuates the endocrine-metabolic responses to surgical stress (3), reduces intestinal paralysis (4,5) and decreases perioperative morbidity (6,7). Thoracic epidural anesthesia decreases heart rate, mean arterial pressure, cardiac output and left ventricular contractility (8,9). Dopamine effectively counters cardiovascular depression during thoracic epidural anesthesia (10,11). Dopamine effectively and dose-dependently counters cardiovascular depression induced by the anesthetic technique of combining isoflurane and thoracic epidural anesthesia (12). Animals` experiments demonstrated that spinal cord section (13) or its cooling at the T1 level (14) resulted in behavioral and electrophysiological evidence of sleep. Subarachnoid bupivacaine blockade decreased the hypnotic dose of thiopental from 3.40 0.68 mg/Kg to 2.170.48 mg/Kg. The ED50 value of midazolam also decreased with bupivacaine blockade, from 0.23 mg/Kg to 0.06 mg/Kg. It was suggested that the reduction in hypnotic requirements was due to the decrease in afferent input induced by spinal anesthesia (15). Extension of the segmental block to involve the cardioaccelerator fibers (above T4) is commonly advanced as a reason to explain the bradycardia that may accompany epidural analgesia (16), however, central volume depletion may have a greater cardioinhibitory vasodepressor influence (16,17). 1. Kowalewski RJ, MacAdams CL, Eagle CJ, Archer DP, Bharadwaj B. Anaesthesia for coronary artery bypass surgery supplemented with subarachnoid bupivacaine and morphine: a report of 18 cases. Can J Anaesth 1994;41:1189-95 2. Greene NM, Brull SJ. Physiology of spinal anesthesia. 4th ed. Baltimore: Williams & Wilkins, 1993:61-8 3. Kehlet H. Modification of responses to surgery by neural blockade: clinical implications. In: Cousins MJ, Bridenbaugh PO, eds. Neural bloclkade. Philadelphia: JB Lippincott, 1988:145-188 4. Scheinin B, Asantila R, Orko R. The effect of bupivacaine and morphine on pain and bowel function after colonic surgery. Acta Anaesthesiol Scand 1987;31:161-164 5. Ahn H, Bronge A, Johansson K, Ygge H, Lindhagen J. Effect of continuous postoperative epidural analgesia on intestinal motility. Br J Surg 1988;75:1176-1178 6. Yeager MP, Glass DD, Neff RK, Brinck-Johnson T. Epidural anesthesia and analgesia in high-risk surgical patients. Anesthesiology 1987;66:729-736 7. Scott NB, Kehlet H. Regional anaesthesia and surgical morbidity. Br J Surg 1988;75:299-304 8. Reiz S, Nath S, Ponten E, Friedman A, Backlund U, Olsson B, Rais O. Effects of thoracic epidural block and the beta-1-adrenoreceptor agonist prenalterol on the cardiovascular response to infrarenal aortic cross-clamping in man. Acta Anaesthesiol Scand 1979;23:395-403 9. McLean APH, Mulligan GW, Otton P, MacLean LD. Hemodynamic alterations associated with epidural anesthesia. Surgery 1967;62:79-87 10. Lundberg J, Biber B, Henriksson BA, Martner J, Raner C, Werner O, Winso O. Effects of thoracic epidural anesthesia and adrenoreceptor blockade on the cardiovascular response to dopamine in dog. Acta Anaesthesiol Scand 1991;35:359-365 11. Lundberg J, Norgren L, Thomson D, Werner O. Hemodynamic effects of dopamine during thoracic epidural analgesia in man. Anesthesiology 1987;66:641-646 12. Raner C, Biber B, Lundberg J, Martner J, Winso O. Cardiovascular depression by isoflurane and concomitant thoracic epidural anesthesia is reversed by dopamine. Acta Anaesthesiol Scand 1994;38:136-143 13. Ho T, Wang YR, Lin TAN, Chang YF. Predominance of electrocortical sleep patterns in the "encephale isole" cat and new evidence for a sleep center. Physiol Bohemosloven 1960;9:85-92 14. Oreshchuk FA. The development of sleep on local cooling of the spinal cord. Fiziol Z (Moscow) 1960;46:1230-5 15. Tverskoy M, Shagal M, Finger J, Kissin I. Subarachnoid bupivacaine blockade decreases midazolam and thiopental hypnotic requirements. J Clin Anesth 1994;6:487-490 16. Bromage PR. Physiology and pharmacology of epidural anesthesia. Anesthesiology 1967;28:592-608 17. Arndt JO, Hock A, Stanton Hicks M, Stuhmeier KD. Peridural anesthesia and the distribution of blood in supine humans. Anesthesiology 1985;63:616-623

Anesthetic risk factors

In a survey among 1,152 Australian and New Zealand anesthetists Kitching et al. (1) evaluated the percentage of anesthetists who warn patients before operation about "material risks" like death, neurological injury, awareness, failed intubation, failed block, seizures, etc. Only 1-9% have discussed and documented these items to their patients. 55% discussed but not documented the subject of failed block compared to 2% - for failed intubation. 36-97% did not discuss these matters at all pre-operatively. 1. Kitching A, Love J, Donnan G. Mishap or negligence. Br J Anaesth 1995;74:110-111


Medico-legal aspects of CSEA

Reports of cauda equina syndrome associated with micro-bore spinal catheter use, resulted in their removal from clinical practice in the USA (1). Finucane (2) in an editorial on the dosage dilemma of spinal anesthesia for cesarean delivery wrote that "the era of the microcatheter technique was short lived... The combined spinal-epidural technique is an excellent alternative and addresses many of the issues raised. One does not have to commit to a large initial subarachnoid dose of local anesthetic, supplementation may be administered epidurally, and opioids may be administered in this fashion for postoperative pain relief". 1. FDA Safety Alert; 29.5.92 2. Finucane BT. Spinal anesthesia for cesarean section: The dosage dilemma. Reg Anesth 1995;20:87-89

Spinal opioid pruritus and emesis

Larger doses of spinal morphine result in a greater incidence of pruritus (1). Knudsen and Lisander (2) decreased the incidence of emesis post subarachnoid morphine from 58% to 17% by 20 mg metoclopramide given intramuscularly before and after the surgery. Combined use of intrathecal sufentanil and bupivacaine can reduce the incidence of pruritus due to the sole use of intrathecal sufentanil for labor analgesia. Abouleish et al. (3) used spinal injection of bupivacaine 2.5 mg and sufentanil 10 g in the combined spinal-epidural analgesia (CSEA) and found an incidence of 21%. However, D`Angelo et al. (4) used only intrathecal sufentanil 10 g in CSEA with an incidence of pruritus of 84%. 1. Fuller JG, McMorland GH, Douglas MJ, Palmer L. Epidural morphine for analgesia after caesarean section: A report of 4880 patients. Can J Anaesth 1990;37:636-40 2. Knudsen K, Lisander B. Metoclopramide decreases emesis after spinal anesthesia supplemented with subarachnoid morphine. Reg Anesth 1994;19:390-394 3. Abouleish A, Abouleish E, Camann W. Combined spinal-epidural analgesia in advanced labour. Can J Anaesth 1994;41:575-8 4. D`Angelo R, Anderson MT, Philip J, Eisenach JC. Intrathecal sufentanil compared to epidural bupivacaine for labor analgesia. Anesthesiology 1994;80:1208-1215

Endocrine responses to spinal or epidural anesthesia

The endocrine response measured by plasma cortisol and glucose levels was not abolished by thoracic epidural etidocaine (1). Studies have failed to dampen the endocrine metabolic response to surgical trauma by thoracic epidural anesthesia unless this has been combined with spinal anesthesia (2). 1. Dahl JB, Rosenberg J, Kehlet H. Effect of thoracic epidural etidocaine 1.5% on somatosensory evoked potentials, cortisol and glucose during cholecystectomy. Acta Anaesthesiol Scand 1992;36:378-382 2. Dahl JB, Rosenberg J, Dirkes WE, Mogensen T, Kehlet H. Prevention of postoperative pain by balanced analgesia. Br J Anaesth 1990;64:518-520

Epidural unilateral blockade

The incidence of unilateral blockade in continuous lumbar epidural anesthesia is 5.9% (1). There have been four etiologic factors described for the development of unilateral epidural blockade (2-9):1. Slow injection of small volumes, patient position, and baricity of local anesthetic solution may cause anesthetic solutions to pool on the lower side during injection; 2. A congenital median epidural septum or acquired midline adhesion may act as a diffusion barrier; 3. The epidural catheter tip may pass through an intervertebral foramen resulting in production of a unilateral paravertebral block; 4. The epidural catheter tip may be in the anterior epidural space resulting in longitudinal and ipsilateral transverse spread of local anesthetics, instead of circumferential spread around the dura. Unilateral epidural block is more common in women receiving repeat epidurals (6.6% vs. 18.3%) (10). Crawford (11) reported an incidence of two cases of inadequate epidural block (one unilateral block; one missed segment) in 17 women who received epidural analgesia after a blood patch. In a further woman the sensory level could not be extended above T10 for cesarean section. 1. Asato F, Hirakawa N, Oda M, Iyatomi I, Nagasawa I, Katekawa Y, Totoki T. A median epidural septum is not a common cause of unilateral epidural blockade. Anesth Analg 1990;71:427-9 2. Singh A. Unilateral epidural analgesia. Anaesthesia 1967;22:147-9 3. Shanks CA. Four cases of unilateral epidural analgesia. Br J Anaesth 1968;40:999-1002 4. Usubiaga JE, Dos Reis A, Usubiaga LE. Epidural misplacement of catheters and mechanisms of unilateral block. Anesthesiology 1970;32:158-61 5. Bozeman PM, Chandra P. Unilateral analgesia following epidural and subarachnoid block. Anesthesiology 1980;52:356-7 6. De Rosayro AM. A case of unilateral analgesia following epidural and subarachnoid block revisited. Anesthesiology 1981;55:478 7. Bailey PW. Median epidural septum and multiple cannulation. Anaesthesia 1986;41:881-2 8. Nunn G, Mackinnon RP. Two unilateral epidural blocks. Anaesthesia 1986;41:439-40 9. Hehre FW, Sayig JM, Lowman RM. Etiologic aspects of failure of continuous lumbar peridural anesthesia. Anesth Analg 1960;39:511-7 10. Withington DE, Weeks SK. Repeat epidural analgesia and unilateral block. Can J Anaesth 1994;41:568-71 11. Crawford SJ. Epidural blood patch. Anaesthesia 1985;40:381

Combined spinal-epidural anesthesia: The anesthesia of choice

In 1992 (1) only 6.6% of patients operated in 17 European countries received epidural or spinal opioid analgesia. 89.2% received epidural opioids, while 10.8% intrathecal opioids (ratio 8:1). In a recent review on regional anesthesia and analgesia for same-day surgery in adults Wurm (2) stated that "regional anesthesia continuous to remain under-utilized for same-day surgery. Reasons for this include uncertainty of success, prolonged preparation time, and special skills required by the anesthesiologist". Lyons et al. (3) found a "demonstrable lack of enthusiasm for the sequential separate punctures amongst women who had previous experience of regional anesthesia for caesarean section. An additional skin breech, while seeming trivial in itself, may have had a greater impact on patient acceptance". There is a considerable variation in the frequency with which regional anesthesia is used. A review of 6,000 patients at the Royal Adelaide Hospital revealed that only 3% received regional anesthesia (4). In contrast, in a review of 1-year prospective analysis (5), the Hospital for Special Surgery in New York City used regional anesthesia in 89% of their orthopedic outpatient population. The incidence of spinal anesthesia in an orthopedic institute in Firenze increased from 22% in 1989 to 42% in 1993 (6). However, the incidence of epidural anesthesia decreased from 20% to 4% during that period. The overall incidence of regional anesthesia (spinal and epidural) increased only in 2%. This was due to the introduction of the 25G Quincke needle in 1990, and the blunting needles in 1993 (Sprotte 24G; and Whitacre 25, 27G).The selective spinal anesthetic technique also contributed to this increase in spinal anesthesia. Valia et al. (7) evaluated patient attitudes towards regional anesthesia in Valencia, Spain. The following advantages during surgery under regional anesthesia were referred to by 82.7% of patients: possibility of speaking with relatives during the immediate postoperative period (72.7%), the maintaining of consciousness during surgery (71.8%) and the absence of pain during the immediate postoperative interval (37.3%). Carson et al. (8) compared the use of spinal anesthesia with that of general anesthesia in 100 young adults (aged 18-45 years) scheduled for lower body minor surgery. The spinal anesthesia group took longer than the general anesthesia group for surgical readiness (130.6 vs. 9 0.5 min), but much less time in recovery (57.73.1 vs. 72.5 3.6 min). Spinal anesthesia patients were quicker to drink fluids (3.40.3 vs. 5.1 0.7 hr), required less narcotic analgesia (0.6 1 vs. 1.20.2 intramuscular injections) and had a lower incidence of vomiting (0.20.09 vs. 1.070.34). In a survey performed at the 1993 meeting of the Society for Obstetric Anesthesia and Perinatology (SOAP), 52% of the conference attendees reported using spinal anesthesia as their technique of choice for elective cesarean delivery (9). Regional anesthesia offers safe, effective and cheap anesthesia when performed by trained personnel. The Kilimanjaro Christian Medical Center in Tanzania (10) produces its own lidocaine and crystalloid intravenous fluids. Volatile and intravenous anesthetic agents are often unavailable and considered expensive. Supplies of oxygen are also unreliable. Hence, spinal and epidural anesthesia are frequently performed for lower abdominal and lower extremity procedures. Patients in Canada and Scotland were asked to complete a pre-operative questionnaire examining their desire for information relating to anesthesia. Details of dangerous complications of anesthesia and surgery were consistently rated of low priority, with high priority going to postoperative landmarks such as eating and drinking. Both countries rated meeting the anesthetist before surgery as the highest priority of all (11). In the second edition of Principles and Practice of Obstetric Analgesia and Anesthesia edited by Bonica and McDonald (12) and published in 1995, there are 1,344 pages. The chapter on epidural analgesia and anesthesia contains 127 pages. That on subarachnoid block - 26 pages. On subarachnoid/epidural combination there is only half a page with only 2 references in the chapter on cesarean section. So, the new combined spinal-epidural anesthesia and analgesia gained only 0.03% of the space in a book published in 1995 on the practice of obstetric analgesia and anesthesia. This is really not its present, neither its future... Rawal (13) mailed a questionnaire in April 1993 to 105 European anesthesiologists in 5-10 hospitals from each of the 17 European countries. Data requested was for 1992. A total of 102 (96.2%) completed questionnaires. Except for Ireland, combined spinal-epidural anesthesia was used in every participating country. It was used in 53% of participating hospitals. During 1992, 835,986 in-patient surgical procedures were performed in the participating European hospitals, 141,444 (17%) of those procedures were performed under central blocks (epidural,spinal, combined spinal-epidural). A total of 5,348 combined spinal-epidural blocks were performed during 1992, which constitutes only 4% of the central blocks (spinal - 56%; epidural - 40%; combined spinal-epidural - 4%). The commonest indication for combined spinal-epidural block was hip replacement surgery (28.2%) followed by hysterectomy (19%), knee surgery (14.4%), cesarean section (14%), emergency cesarean section (13%), femur fracture in elderly patients (7.2%) and prostatectomy (5.6%). Special combined spinal-epidural sets were used by 31% respondents; the remaining used their own combinations of epidural needles and extra long spinal needles. 1. Rawal N. Epidural and intrathecal opioids for postoperative pain management in Europe - A 17-nation survey. ASRA Annual Meeting 1995:45 2. Wurm WH. Regional anesthesia and analgesia for same-day surgery in adults. Current Opinion in Anaesthesiology 1994;7:436-440 3. Lyons G, Macdonald R, Mikl B. Combined epidural/spinal anaesthesia for Caesarean section: Through the needle or in separate spaces? Anaesthesia 1992;47:199-201 4. Osborne GA, Rudkin GE. Outcome after day-care surgery in a major teaching hospital. Anaesth Intensive Care 1993;21:822-827 5. Urmey WF, Stanton J, Sharrock NE. Initial one-year experience of a 97.3% regional anesthesia ambulatory surgery center. Reg Anesth 1993;18:69 6. Florio R, Sassu B, Cianciullo A. Selective spinal technique and atraumatic needles increase the incidence of spinal anesthesia. Acta Anaesthesiol Scand 1995;39:A432 7. Valia JC, De Andres J, Gil A, Bolinches R. Analysis of patient attitudes towards regional anaesthesia. Int Monitor Reg Anaesth 1993:57 8. Carson D, McLead G, Serpell M, Bannister J. Minor surgery for young adults: general or spinal anaesthesia? Int Monitor Reg Anaesth 1993:51 9. Riley ET, Cohen SE, Macario A, Desai JB, Ratner EF. Spinal versus epidural anesthesia for cesarean section: A comparison of time efficiency, costs, charges, and complications. Anesth Analg 1995;80:709-12 10. Smith J, Egan E. Regional anaesthesia in a developing country. Int Monitor Reg Anaesth 1993:57 11. Lonsdale M, Hutchison GL. Patient`s desire for information about anaesthesia: Scottish and Canadian Attitudes. Anaesthesia 1991;46:410-412 12. Bonica JJ, McDonald JS, eds. Principles and practice of obstetric analgesia and anesthesia. 2nd ed, Williams & Wilkins, 1995 13. Rawal N. European trends in the use of combined spinal epidural technique - A 17-nation survey. Reg Anesth 1995;20(Suppl):162

Epidural catheter strength

A 10 cm segment of four epidural catheters to be tested was suspended vertically from a stand, and weights were hung from it until it broke to investigate the comparative strengths of 19 gauge epidural catheters. The concord - Portex`s weight at break was 2,04267 gm while that of Kendall - 1,674 67 gm, Arrow (Flex Tip Plus with spiral wire reinforcement) - 1,37016 gm and Becton-Dickinson only 1,284149 gm were needed for its breakage. 1. Blum S, Sosis M. An investigation of the comparative strengths of 19 gauge epidural catheters. Reg Anesth 1995;20(Suppl):157

Epidural catheter paresthesias

Rolbin et al. (1) reported a 24-44% incidence of transient paresthesias during epidural catheter insertion. Juneja et al. (2) compared the incidence of transient paresthesias among three types of epidural catheters. The Flex Tip Plus (19 gauge; open tip; Arrow) produced only 2.16% paresthesias, while the 20 gauge Copolymer Bullet tip (Kendall) - 15.16%, and the 20 gauge Polymide, open tip, Perifix (Braun) - 32.24%. It was concluded that the softer tip epidural catheters like Flex Tip Plus (Arrow) were least likely to cause transient paresthesias during epidural catheter placement. Spriggs et al. (3) compared between Arrow`s wire reinforced epidural catheter (Flex Tip Plus; 19 gauge; open tip) and Braun`s Perifix (18 gauge; open tip). They found that the wire reinforced catheter was inferior than the Perifix in its inability of insertion (8/50 vs. 0/51) and the incidence of catheter related transient paresthesias (5/42 vs. 0/51). Huhtala et al. (4) examined the incidence of transient radicular irritation after spinal anesthesia with hyperbaric 5% lidocaine compared to 0.5% hyperbaric bupivacaine and 0.5% plain bupivacaine. 10.2% of patients anesthetized with hyperbaric lidocaine complained of radicular irritation compared to 1% of patients anesthetized with hyperbaric bupivacaine and none of the patients in the plain bupivacaine group. 1. Rolbin SH, Hew E, Olgilvie G. A comparison of two types of epidural catheters. Can J Anaesth 1987;34:459-461 2. Juneja M, Kargas GA, Miller DL, Perry EA, Gupta B, Garcia E, Pajel V, Botic Z, Rigor B. Comparison of epidural catheter`s induced paresthesias in parturients. Reg Anesth 1995;20(Suppl):152 3. Spriggs LE, Vasdev GM, Leicht CH. Clinical evaluation of wire impregnated epidural catheters with standard epidural catheters for labor analgesia. Reg Anesth 1995;20(Suppl):154 4. Huhtala J, Tarkkila P, Tuominen M. Transient radicular irritation after spinal anaesthesia with hyperbaric 5% lidocaine. Acta Anaesthesiol Scand 1995;39:A426

CSEA and anticoagulation

Intraoperative anticoagulation with heparin appears relatively safe if epidural catheters are inserted prior to anticoagulation (1,2). 1. De Angelis J. Hazards of subdural and epidural anesthesia during anticoagulant therapy: A case report and review. Anesth Analg 1972;51:676-679 2. Odoom JA, Sih IL. Epidural analgesia and anticoagulant therapy. Experience with one thousand cases of continuous epidurals. Anaesthesia 1983;38:254-259


Combined spinal-epidural analgesia in labor

Pain during the first stage of labor is attributed to uterine contractions that contribute to dilation of the lower uterine segment and cervix. During this stage, neural transmission of painful sensation to the neuroaxis travels via sympathetic fibers that enter at the 10th, 11th, and 12th thoracic and 1st lumbar spinal segments (1). These fibers synapse with ascending and descending fibers in the dorsal horn of the spinal cord. As labor progresses to the second stage, additional pain is produced by stretching and distention of the vagina and perineum. This pain is more somatic in nature and is conveyed by the pudendal nerve that arises from 2nd, 3rd, and 4th sacral nerves (2). Interactive computer questioning of 218 delegates at the meeting of the Society for Obstetric Anesthesiology and Perinatology in 1993 revealed that only 4.2% clinicians did not add opioids to bupivacaine for epidural analgesia in labour. Fentanyl and sufentanil were chosen by 97% (3). In the UK, 30% of 272 obstetric units surveyed by Davies et al. (4) stated that they used opioids in routine epidural analgesia for normal labor, but only when an infusion technique was employed. Scott et al. (5) in 1980, first reported the use in labor of "single-shot" intrathecal morphine. Abouleish et al. (6) suggested that the use of combined spinal-epidural analgesia in labor "avoids the requirement for setting up infusion devices, tubing, and solutions routinely used for continuous epidural infusion techniques" since all of their patients delivered with only the original intrathecal dose, or a small amount of epidural local anesthetic as a supplemental bolus. Columb et al. (7) found that the minimum local analgesic concentration of epidural bupivacaine in labor is 0.065%. Breen et al. (8) compared two regimes of epidural anesthesia for labor in ambulatory parturients: epidural fentanyl bolus of 75 g diluted to 15 ml with normal saline with an epidural infusion of fentanyl 2.5 g/ml at 15 ml/hr vs. epidural bolus of bupivacaine 0.04% 15 ml, epinephrine 1.7 g/ml and fentanyl 1.7 g/ml, following by an infusion of this combination at 15 ml/hr. Patients experiencing inadequate analgesia at any time were given one 10 ml bolus of the study drug. Any patient not made sufficiently comfortable by the study drug, including the additional 10 ml bolus, was given 10 ml of bupivacaine 0.125% with fentanyl 150 g added, followed by an infusion of bupivacaine 0.125% with fentanyl 2 g/ml. 48% in the bupivacaine-epinephrine-fentanyl group and 79% in the fentanyl group needed these bolus augmentations. Justins et al. (9) first published in 1982 the use of fentanyl-bupivacaine mixtures for epidural analgesia in labor. Since the continuous infusion epidural analgesia needs supplementary top-ups in many cases it should be termed more accurately a continuous infusion - intermittent bolus epidural analgesia. However, intermittent low-dose epidural injections every approximately 90 minutes will avoid the need for the patient to be connected to an infusion set, and on the other hand will allow the "walking epidural" due to the low dose injections at equal times, without waiting for the analgesic effect to wear off. Enever et al. (10) believed that "infusions rather than intermittent technique... are safer and more effective". However, in their study of epidural infusion of diamorphine with bupivacaine in labor 63.2% - 66.8% required top-up injections of bupivacaine during the epidural catheter infusion technique. Wlodarski et al. (11) found that adding 250 g nalbuphine to a 10 g sufentanyl in 1 ml saline mixture for the spinal injection in the combined spinal-epidural analgesia for labor reduced significantly the incidence of pruritus: 62% in the sufentanyl group compared to only 20% in the sufentanyl-nalbuphine group. Using an extradural mixture, in labor, of 0.1% bupivacaine with fentanyl 30 g in 15 ml, the initial test dose of 0.5% bupivacaine 3 ml is unnecessary, as the single bolus of 15 ml of the extradural mixture serves equally to detect accidental subarachnoid injection without producing a total spinal block (12). It is the total amount of local anesthetic drug which determines the extent of a subarachnoid block and not its volume (13). Ewen et al. (14) have been shown in parturient women that analgesia obtained by infusing 0.25% bupivacaine 8 ml/hr is inferior to that obtained by giving the same mass of drug as 0.07% bupivacaine 25 ml/hr. Eddleston et al. (15) found no advantage to either mother or fetus in using an extradural infusion of 0.125% bupivacaine compared with intermittent injections of 0.25% bupivacaine. In the intermittent group, the majority of fetal decelerations (73.8%) were recorded as transient, whereas in the infusion group 61.1% of episodes lasted in excess of 10 min. Silva and Popat (16) described a 34-year-old parturient with Harrington rods in whom they have done a combined spinal-epidural analgesia for labor. Using the needle-through-needle technique they injected 1 ml 0.25% bupivacaine and 25 g fentanyl through the spinal needle. The epidural catheter was not tested after insertion. Two hours after the spinal injection the patient requested a top up. 15 ml 0.1% bupivacaine with 2 g/ml fentanyl were injected epidurally without success. Further 10 ml of 2% lidocaine 1:200,000 epinephrine injected epidurally produced a dense motor block in both legs but did not reduce the pain. Another combined spinal-epidural procedure was done at the same interspace and a similar spinal dose of bupivacaine and fentanyl again resulted in excellent pain relief for two hours. Because of a high breech with cervical dilatation of 9 cm the patient needed a cesarean section. However, she declined regional anesthesia and had a cesarean delivery under general anesthesia. Sufentanil 5, 10 and 15 g and fentanyl 25, 37.5 and 50 g as intrathecal solutions for labor analgesia were compared in 36 parturients using the combined spinal-epidural analgesia. Duration of analgesia or pruritus were not affected by drug dosage, but rather by drug choice. Both the duration of analgesia and pruritus were longer for sufentanil than for fentanyl (17). In a review of analgesia for labor Crowhurst (3) stated that "with the advent of `pencil-point` spinal needles, the simpler technique of subarachnoid blockade will almost certainly continue to supplant other methods, especially for late first stage and second stage labour". Joos et al. (18) used a combined spinal-epidural analgesia technique in 620 parturients. The spinal injection consisted of 1 mg 0.5% bupivacaine, 25 g adrenaline,and 5 g sufentanil. When pain returned bolus doses of 10 ml saline containing 12.5 mg bupivacaine 0.125%, 12.5 g adrenaline and 12.5 g sufentanil were injected. Spinal analgesia was perfect in 94%. The mean duration of the spinal analgesia was 134 min. All parturients were able to move perfectly both legs. Transient pruritus occurred in 48% of women, drowsiness in 12%. The postspinal headache rate was 0.8%. The injections were made by a 16G Tuohy epidural needle and a 29G 113 mm Quincke spinal needle inserted through it. Caldwell et al. (2) used the combined spinal-epidural analgesia in 26 parturients. Subarachnoid injection consisted of morphine 0.25 mg with fentanyl 25 g. In cases where additional analgesia was requested, epidural analgesia was initiated with 10 ml of bupivacaine 0.25%, followed by an infusion of bupivacaine 0.125%, with fentanyl 1 g/ml. 76% of patients requested additional epidural analgesia. Side effects were nausea and vomiting (50%) and pruritus (50%). One patient developed postdural puncture headache, following unintentional dural puncture with the 18 gauge Tuohy needle. Bonica and McDonald (19) referred to their double-catheter technique (lumbar epidural catheter and caudal catheter) as "the ultimate in analgesia/anesthesia for labor and vaginal delivery, and is often referred to by anesthesiologists as the `Rolls Royce` of obstetric analgesia and anesthesia". In comparison, the combined spinal-epidural analgesia and anesthesia is the "Mercedes Benz"... Hill et al. (20) compared the efficacy of intrathecal 250 g alfentanil and 400 g diamorphine in combination with 0.5 ml of 0.5% bupivacaine (2.5 mg) in the combined spinal-epidural analgesia in labor. If labour continued beyond the duration of the subarachnoid block analgesia was maintained with a top-up of 15 ml of 0.125% bupivacaine followed by an infusion of 0.125% bupivacaine at 8 ml/hr. Abdominal analgesia was inadequate in 8% in the alfentanil group and in 44% in the diamorphine group. Sympathetic block occurred in 20% of the alfentanil group and none of the diamorphine group. 32% of the women in the alfentanil group were unable to walk after 20 min due to motor block. Transient fetal bradycardia was seen in 20% of the alfentanil group and none of the diamorphine group. Pruritus was common in both groups (over 90%). Arkoosh et al. (21) compared the subarachnoid injection of fentanyl 2.5 g with morphine 0.25 mg to sufentanil 10 g with morphine 0.25 mg for labor analgesia using the combined spinal-epidural analgesia. Both fentanyl and morphine and sufentanil and morphine provided adequate labor analgesia for about 2 hours. However, patients who received sufentanil experienced more severe pruritus. Norris et al. (22) compared epidural versus combined spinal-epidural (CSE) technique for maternal pain relief during labor in 1022 laboring parturients. 9.6% of the women chose not to receive neuroaxial labor analgesia; 38% chose epidural while 52.4% received combined spinal-epidural analgesia. The CSE was done by a long spinal needle (27G Whitacre or 24G Sprotte) passed through a 18G epidural needle. After withdrawing the spinal needle the epidural needle was rotated cephalad and a 20G epidural catheter inserted through it. In 94.4% of the CSE group the epidural and subarachnoid spaces were successfully identified. In 4.9% of them no CSF was obtained and only epidural analgesia was induced. There was an incidence of 0.2% of the epidural catheter entering subarachnoid space after dural puncture with a 24G Sprotte spinal needle. In 0.8% an accidental dural puncture occurred while rotating the epidural needle. 1. Shnider SM, Levinson G, Ralston DH. Regional anesthesia for labor and delivery. In: SM Shnider, G. Levinson, eds. Anesthesia for obstetrics, 3rd ed., Baltimore, Williams & Wilkins, 1987, p.135 2. Caldwell LE, Rosen MA, Shnider SM. Subarachnoid morphine and fentanyl for labor analgesia: Efficacy and adverse effects. Reg Anesth 1994;19:2-8 3. Crowhurst JA. Analgesia for labour. Curr Opin Anaesthesiol 1994;7:224-228 4. Davies M, Harrison J, Ryan T. Current practice of epidural analgesia during normal labour. A survey of maternity units in the United Kingdom. Anaesthesia 1993;48:63-65 5. Scott PV, Bowen FE, Cartwright P, Mohan Rao BC, Deeley D, Wotherspoon HG, Sumrein IMA. Intrathecal morphine as sole analgesia during labour. Br Med J 1980;278:351-353 6. Abouleish A, Abouleish E, Camann W. Combined spinal-epidural analgesia in advanced labour. Can J Anaesth 1994;41:575-578 7. Columb MO, Lyons G, Vail A. Estimation of the minimum local analgesia concentration (MLAC) of epidural bupivacaine hydrochloride in labour. International Monitor on Regional Anaesthesia 1994;A89 8. Breen TW, Shapiro T, Glass B, Foster-Payne D, Oriol NE. Epidural anesthesia for labor in an ambulatory patient. Anesth Analg 1993;77:919-924 9. Justino DM, Francis D, Houlton PG, Reynolds F. A controlled trial of extradural fentanyl in labour. Br J Anaesth 1982;54:409-414 10. Enever GR, Noble HA, Kolditz D, Valentine S, Thomas TA. Epidural infusion of diamorphine with bupivacaine in labour: A comparison with fentanyl and bupivacaine. Anaesthesia 1991;46:169-173 11. Wlodarski JC, Tanck EN, Newman LM, Ivankovich AD. Nalbuphine added to intrathecal sufentanyl ameliorates the pruritus in laboring patients. Anesth Analg 1994;78:S483 12. Morgan BM, Kadim MY. Mobile regional analgesia in labour. Br J Obstet Gynaecol 1994;101:839-841 13. Van Zundert AA, Wolf AM, Vaes L, Soetens M. High volume spinal anesthesia with bupivacaine 0.125% for cesarean section. Anesthesiology 1988;69:998-1003 14. Ewen A, McLeod DD, MacLeod DM, Campbell A, Tunstall ME. Continuous infusion epidural analgesia in obstetrics. A comparison of 0.08% and 0.25% bupivacaine. Anaesthesia 1986;41:143-147 15. Eddleston JM, Maresh M, Horsman EL, Young H, Lacey P, Anderton J. Comparison of the maternal and fetal effects associated with intermittent or continuous infusion of extradural analgesia. Br J Anaesth 1992;69:154-158 16. Silva TSS, Popat MT. Combined spinal-epidural anesthesia in parturient with Harrington rods. Reg Anesth 1994;19:360 17. Gaiser R, Adams H, Cheek TG, Gutsche BB. Comparison of three different doses of intrathecal fentanyl and sufentanyl for labor analgesia. ASRA Annual Meeting 1995;75 18. Joos S, Servais R, Van Steenberge A. Sequential spinal-epidural analgesia for pain relief during labour. International Monitor on Regional Anaesthesia 1994;A88 19. Bonica JJ, McDonald JS. Epidural analgesia and anesthesia. In: Bonica JJ, McDonald JS. eds. Principles and Practice of Obstetric Analgesia. 2nd ed., Williams & Williams, 1995, p.442 20. Hill DA, McAuley DM, Clarke RSJ. Randomised double blind comparison of intrathecal alfentanil or diamorphine with bupivacaine in a single space, needle through needle, combined spinal-epidural for analgesia in labour. International Monitor on Regional Anaesthesia 1994;A94 21. Arkoosh VA, Sharkey SJ, Norris MC, Isaacson W, Honet JE, Leighton BL. Subarachnoid labor analgesia: Fentanyl and morphine versus fentanyl and morphine. Reg Anesth 1994;19:243-246 22. Norris MC, Grieco WM, Borkowski M, Leighton BL, Arkoosh VA, Huffnagle HJ, Huffnagle S. Complications of labor analgesia: epidural versus combined spinal epidural techniques. Anesth Analg 1994;79:529-537

Combined spinal-epidural anesthesia for orthopedic operations

In some hospitals the combined spinal-epidural anesthesia is the method of choice in all surgical interventions of the lower extremities. For example, in the Endo-Clinic in Hamburg, since 1989 till 1994 there were over 13,602 cases of combined spinal-epidural anesthesia (1). Urmey et al. (2) compared the use of 40, 60 or 80 mg isobaric lidocaine 2% injected subarachnoidally in the needle-through-needle technique for ambulatory knee arthroscopy in 90 patients aged 18-60 years. 24.5% of patients required separate spinal injections due to inadequate protrusion length of the 120 mm 27G Whitacre spinal needle through the 3 inch Weiss epidural needle. Seven patients required epidural reinforcement doses intraoperatively. Motor recovery onset was at 82.320.3 minutes in the 40 mg lidocaine 2% group, 108.2 25.6 - in the 60 mg and 122.825 in the 80 mg spinal injection. 1. Schleinzer W, Hook D, Reibold JP, Schmalz B. Combined spinal/epidural anaesthesia (CSE) - An appropriate procedure. Acta Anaesthesiol Scand 1995;39:A424 2. Urmey WF, Stanton J, Sharrock NE. Combined spinal-epidural (CSE) technique to assess dose-response of isobaric lidocaine spinal anesthesia. Anesth Analg 1993;76:S441

Combined end-multiple lateral holes (CEMLH) epidural catheter

Most of the epidural catheters used in the USA are of the single terminal hole, while most of those used in the UK are of the three lateral holes with a blunted end (1). A new epidural catheter was designed which is claimed to combine the benefits of these two different types of catheters: Combined end-multiple lateral holes epidural catheter (CEMLH). Curbelo (2) in 1947 was the first to use an epidural catheter for epidural anesthesia. It was of the end hole type. Lee (3) in 1962 described an epidural catheter which its "tip is non-patent and smooth, to facilitate insertion, solution enters the space from a small opening 1 cm from the tip". Skinner (4) in 1966 described another epidural catheter with "the tip of the cannula...is blunt...and has a hole in its end. There is a second hole, 3 mm from the distal end". He said that "with the hole in this position, kinking is impossible with the stresses involved in normal use". Collier and Gatt (5) described an epidural catheter, with a closed end and three holes spaced at approximately 2, 3 and 4 mm from the smooth closed tip. They suggested that the close spacings of the holes will eliminate the complication of multicompartment block (epidural, spinal or intravenous), as seen with earlier multihole epidural catheters. The CEMLH epidural catheter has 7 holes within its 1.5 cm head: One at the tip; the first 3 lateral holes are arranged circumferentially at 1 mm from each other; the other 3 holes have a 4 mm distance from one to the other. All the holes are within the 1.5 cm from the tip. The area of the 6 lateral holes is the same , so the anesthetic solution stream is the same from each hole, depending on the correct pressure elicited upon the syringe plunger. While introducing the epidural catheter for 3 cm into the epidural space there is a proximal 1.5 cm with 7 holes and a distal 1.5 cm which is "blind". The epidural catheter (CEMLH) has the following possible claimed advantages: The end hole can recognize an intravascular or intrathecal insertion of the epidural catheter tip, which a blunted tip cannot, but an open-end catheter can; The six lateral holes spaced at 1.5 cm from the tip allow anesthetic solution injection into the epidural space in case that the end hole or one of the lateral holes is obstructed by a blood clot or tissue; The chance that all the 7 holes will be blocked is six times less than the one open-end hole and 4 times less than the three lateral holes closed-end catheter; The CEMLH epidural catheter gives a better distribution of the anesthetic solution due to its 7 holes, avoiding a partial block; The CEMLH epidural catheter also afford the use of a lesser amount of anesthetic solution to achieve an anesthetic level than the present used catheters, due to its even distribution, without preferrence to any side; Because of its small end hole the CEMLH catheter will give less paresthesias than the bigger end hole catheter. The terminal hole catheter elicits more paresthesias than the rounded closed end side hole catheter (6). Michael et al. (7) compared between the open-end (single hole) and closed-end (three lateral holes) epidural catheters. They found that the open-end catheters "caused an unacceptably high incidence of unsatisfactory sensory blockade". Collier and Gatt (5) also found the incidence of unsatisfactory blocks with terminal hole catheter to be "unacceptably High" (32%) when compared with the three lateral holes catheter (12%). Ward et al. (8) found that the pressure elicited upon a lateral double-orifice epidural catheter (orifices 180 degrees opposed 5 mm and 12 mm from the closed end tip) is important whether it will exit fluid from the proximal or the distal holes. In order to achieve injection through the two holes at the same time they needed to exceed the pressure of 900 torr. With a pressure of 700 torr, ejection was only from the proximal port. If one of the three lateral holes epidural catheter is obstructed the injection through the catheter can miss this direction and result in partial block. If the end hole epidural catheter is obstructed you need to replace it. Just to remind us: Before Lee (3) described in 1962 his prepackaged epidural catheter anesthetists had employed polyvinyl chloride tubing and nylon infant`s ureteric catheters and cut it by themselves. Lee himself said that his epidural catheter "will also withstand autoclaving several times without deterioration". It seems that we have already passed the point of epidural catheter autoclaving. However, other problems confronting us: Inadvertent intrathecal or intravascular insertion; partial blockade; unreliability of the present used epidural catheters with need to supplement it by a prior anesthetic solution injected through the epidural needle, etc. 1. Collier CB, Gatt SP. Epidural catheter for obstetrics: Terminal hole or lateral eyes? Reg Anesth 1994;19:378-385 2. Curbelo MM. Continuous peridural segmental anesthesia by means of an ureteral catheter. Anesth Analg 1949;28:13-23 3. Lee JA. A new catheter for continuous extradural analgesia. Anaesthesia 1962;17:248-250 4. Skinner BS. A new epidural cannula. Can Anaesth Soc J 1966;13:622-623 5. Collier CB, Gatt SP. A new epidural catheter: Closer eyes for safety? Anaesthesia 1993;48:803-806 6. Segal S, Eappen S, Datta S. Comparison of single-orifice and multi-orifice epidural catheters for labor analgesia and cesarean delivery. ASRA Annual Meeting 1995:149 7. Michael S, Richmond MN, Birks RJS. A comparison between open-end (single hole) and closed-end (three lateral holes) epidural catheters. Anaesthesia 1989;44:578-580 8. Ward CF, Osborne R, Benumof JL, Saidman LJ. A hazard of double-orifice epidural catheters. Anesthesiology 1978;48:362-364

Double-hole pencil-point spinal needle

Greene (1) described in 1926 a needle with a point that is "round, tapering, and sharp". This was the result of experiments made by him during 1923 (2) and his experience since then that brought him to the conclusion that "postpuncture headache is caused by trauma to the spinal dura sufficient to result in excessive leakage of cerebrospinal fluid to the point at which the brain is left without a water cushion". His experiments demonstrated that a greater trauma was produced by the use of a needle with a blunt cutting point than by a needle of the same caliber with a point rounded, tapering and sharp. He found also that it was possible to pass a small sharp, round, tapering pointed instrument between the fibers of a spinal dural sac, suspended and filled with water, without cutting any of them. He performed 215 consecutive punctures with his needle, with a headache incidence of two in the series. In many instances the puncture was done during the noon hour, and the patient resumed his work for the remainder of the day... Kirschner (3) in 1931 described a needle for spinal anesthesia with an opening in the shaft just proximal to the beveled closed end. Such a needle was recommended to aid in the more accurate control of the duration and extent of anesthesia, since it could be manipulated to permit the injection of solution in the stream flowing parallel to the long axis of the spinal fluid column rather than against the side of the canal opposite puncture. Hart and Whitacre (4) described in 1951 their pencil-point spinal needle, known since as the Whitacre needle. Sprotte, Schedel and Pajunk (5) in 1987 modified the Whitacre needle, known since as the Sprotte needle. The FDA approves only the use of the pencil-point spinal needle in the needle-through-needle or the Eldor needle techniques for the combined spinal-epidural anesthesia. However, the long orifice of 24 gauge Sprotte spinal needles may result in failed spinal anesthetics when they are used, since this length exceeds the 1 mm thickness of human lumbar dura (6). Sprotte has modified this device by reducing the length of the orifice. Sosis et al. (6) compared in vitro the 1.8 mm long laterally placed orifice of the original version of the Sprotte spinal needle with the 1.0 mm long new Sprotte needle. They found that the flow of water through the needle was not reduced after the orifice length was reduced by 44%. Lipov et al.(7) examined whether the window design of Sprotte pencil point needles leads to deformation under lateral or axial loading conditions. They examined the 22- and 24-gauge Sprotte, 22- and 25-gauge Whitacre and 22- and 25-gauge Quincke needles. The force needed to bend the Sprotte needles was less than needed for the Whitacre and Quincke needles of similar size when lateral or axial pressure was applied. Examination of the needle tips demonstrated that the Sprotte needles were most likely to bend at the needle window, while the Quincke and Whitacre needles deformed at the point of clamping. They concluded that the Sprotte needles have an inherent design weakness to lateral and axial pressure, which may result in a greater number of needle tip deformations upon needle insertion. The nature of this deformation may result in difficulty in needle withdrawal and possibly fracture of the needle tip. A new pencil-point spinal needle is described: It is named double-hole pencil-point (DHPP) spinal needle, and is composed of a blunt ogival tip and two circular holes opposing each other just proximal to the tip. The area of the two holes is almost the same as of the single hole Sprotte needle`s area, which enables more rapid CSF reflux. The anesthetic solution injection spreads through both holes. There is a possible advantage of a more diffuse anesthetic distribution and less anesthetic solution dosage. The DHPP spinal needle allows anesthetic solution injection when one of the holes is obstructed by a tissue fragment, through the opposite hole. Using the DHPP spinal needle is like inserting two Whitacre needles in the same interspace, from the point of view of the hole`s area. There is a possibility to avoid the risk of needle deformation due to bending at the window, as it is the case with the Sprotte needle. In this respect it is more like the Whitacre needle. However, unlike the Whitacre needle there is a possibility of a two times rapid CSF reflux, because of a double orifice area. There is also a possibility for a more even distribution of the anesthetic solution through the opposite holes of the DHPP spinal needle as compared to the Whitacre or Sprotte one-sided orifice spinal needles. On account of that there is a possibilty to reduce the anesthetic solution dosage with less untoward effects due to a larger spinal anesthetic dose needed in the Whitacre or Sprotte spinal needles. 1. Greene HM. Lumbar puncture and the prevention of postpuncture headache. JAMA 1926;86:391-392 2. Greene HM. A technic to reduce the incidence of headache following lumbar puncture in ambulatory patients with a plea for more frequent examinations of the cerebrospinal fluids. Northwest Med 1923;22:240 3. Kirschner M. Versuche zur Herstellung einer gurtelformigen Spinal-anasthesie. Arch Klin Chir 1931;167:755-760 4. Hart JR, Whitacre RJ. Pencil-point needle in prevention of postspinal headache. JAMA 1951;147:657-658 5. Sprotte G, Schedel R, Pajunk H. Eine atraumatische Universalkanule fur einzeitige Regionalanaesthesien. Reg Anaesth 1987;10:104-108 6. Sosis MB, Braverman B, Toppses A. An in vitro evaluation of the new shorter orifice Sprotte spinal needle. Anesth Analg 1994;78:S410 7. Lipov EG, Sosis MB, McCarthy RJ, Ivankovich AD. Does the design of the Sprotte spinal needle reduce the force needed to deform the tip? J Clin Anesth 1994;6:411-413

Epidural catheter test dose in the combined spinal-epidural anesthesia

The epidural test dose was first recommended by Dogliotti (1) in 1933. He suggested a small volume of local anesthetic through the epidural needle to insure that a subarachnoid placement had not occurred prior to injecting the full epidural dose. Scott (2) in 1988 wrote in an editorial that "many anaesthetists do not use (epidural test dose) unless they have serious doubts on the correct position of the needle or catheter". Brown (3) in the 4th edition of Miller`s textbook Anesthesia wrote that "in spite of an adequately positioned catheter during first use of local anesthetic, each subsequent injection should be preceded by aspiration and an epidural test dose, since catheter migration into vessels and subarachnoid or subdural spaces does occur." Moore (4) in his handbook on regional block advocates the use of "2 cc of the local anesthetic solution" to be injected "at the rate of 1 cc per 6 to 8 seconds" as an epidural catheter test dose. An epidural test dose is considered mandatory (5). Albright (6) suggested that the test dose should consist of 3 ml 0.5% bupivacaine with 1:200,000 epinephrine. This kind of test dose should be adequate to detect intravascular placement as it produces a rapid increase in pulse rate. This test dose is also adequate to detect a subarachnoid injection because a significant motor or sensory block will occur within 5 minutes. Some authors recommend that every top-up should be preceded by a test dose or given in fractions (6,7). Crawford (8) in his review of 27,000 lumbar epidural blocks concluded that "the requirements for safety are that all top ups are given in divided doses, with an interval of approximately 5 minutes between the two increments." The epidural catheter test dose consists of either 1 ml of hyperbaric lidocaine with adrenaline or 2 ml of 0.5% bupivacaine with adrenaline (9). A volume of 1.5 ml has also been recommended (10). The epidural catheter test dose is a must maneuver, because as Moore (11) said on the epidural needle, none of us has "an eye on the end of the needle", neither on the end of the catheter introduced through that needle. Soresi (12) was the first to describe the combined spinal-epidural anesthesia in 1937.He called it "episubdural anesthesia" and thought it is "the safest procedure giving perfect surgical anesthesia, ideal relaxation and eliminating practically all postoperative pain and distress". Soresi first injected 7-8 ml of 20 centigrams novocain into the epidural space and then insert the spinal needle further into the spinal space and injected there 2 ml of 10-15 centigrams novocain. These 7-8 ml injected into the epidural space can be looked now as the first "test dose" in the combined spinal-epidural technique. He recommended "to inject only 7 to 8 cc of fluid in the epidural space because large amounts of fluid will make the pressure in the epidural space positive. This increased pressure being contrary to natural conditions is the reason for the troubles noticed in the ordinary epidural anesthesia". Soresi also stated that "to make episubdural anesthesia safer the anesthesiologist must be absolutely certain of the position of the needle". Rawal (13) injected into the subarachnoid space 1.5-2 ml 0.5% hyperbaric bupivacaine through a 26-27G spinal needle in 24 parturients scheduled for cesarean section. Fifteen minutes later he injected fractional doses of 5 ml 0.5% bupivacaine through the epidural catheter (range: 5-10 ml). Myint et al. (14) published the first case report of cardiorespiratory arrest following combined spinal-epidural anesthesia. Using the needle-through-needle technique in a 31-year-old parturient scheduled for cesarean section they injected into the spinal space 2 ml 0.5% bupivacaine in 8% dextrose through 24G Sprotte needle. Then they rotated the epidural needle 180 and introduced an epidural catheter with three lateral holes into the epidural space. They made an aspiration test which was negative for blood or CSF. Then they made a test dose of 2 ml 0.5% bupivacaine with adrenaline 1:200,000 given through the epidural catheter. A few minutes later the patient complained of some numbness in her fingers, but her hand grip was strong and she was able to breathe deeply and strongly on request. Upper limit of sensory block was T4 bilaterally. At the end of the operation they have given 2.5 mg of diamorphine in 5 ml of 0.25% bupivacaine through the epidural catheter for postoperative analgesia. Forty minutes later she complained of difficulty in breathing which developed rapidly to respiratory and cardiac arrest. Resuscitation started with endotracheal intubation, adrenaline 1 mg and atropine 0.6 mg i.v. Then she received two doses of naloxone 0.4 mg i.v. The patient started breathing and regained consciousness within 2 min of the first administration of intravenous naloxone. Her recovery was complete with no neurological deficit. She also did not develop a postspinal headache. Due to the masking of the epidural test dose by the previous spinal anesthetic injection Myint et al. could not appreciate correctly the patient`s complaint of "some numbness in her fingers". If it would occur at the first place, i.e., the epidural catheter test dose injected before the spinal anesthetic injection, their suspicion would certainly be of an intravascular or subarachnoid inadvertent placement of the epidural catheter or one of its three lateral holes. Their inability to recognize it was caused by the technique of the needle-through-needle in which you need first to inject the anesthetic solution into the spinal space and then to insert the epidural catheter into the epidural space. Thoren et al.(15) used the combined spinal-epidural technique in 21 parturients scheduled for cesarean section. Hyperbaric bupivacaine 0.5% was injected intrathecally. Additional bupivacaine was injected through the epidural catheter in fractionated doses. After an initial "test dose" of 2 ml 0.5% bupivacaine, an additional 2 ml per unblocked segment was given through the epidural catheter until a T4 level was achieved. Kumar (16) observed that when an epidural catheter is threaded after a spinal block was performed in the needle-through-needle technique, "a minute quantity of clear, or slightly red-tinged fluid sometimes comes back through the catheter". The source of this minute quantity of fluid is either CSF or local anesthetic agent. He advocated an aspiration test before giving the epidural medication to extend the spinal block. Spinal dura mater thickness at the lumbar region is 0.5 mm (17). Using magnetic resonance imaging (MRI) in 39 patients Westbrook et al. (18) found that the depth of the extradural space at the level of T12 is 0.83 0.195 cm. There are many reports of failed aspiration tests for both subarachnoid and intravascular epidural catheter placement (19-21). Aspiration test through an epidural needle was suspected as a cause for dural puncture. In eight of 31 patients (25.8%) aspiration produced CSF flow. It was not possible to say whether the aspiration caused puncture of the dura or just revealed it, but "the suspicion remains that aspiration of a Tuohy needle may cause dural puncture by increasing the transdural pressure gradient" (22). In the first 1,000 epidural cases reported by Crawford (23), of 71 dural taps, nine were with the catheter. In his second series of 1,000, Crawford reported 33 dural taps, four of which were caused by the catheter (24). Epidural catheter migration has been shown to be relatively common, occurring in approximately one-third of the patients in one study (25). Hogan (26) suggested another mechanism for the "migration" of an epidural catheter: the membrane which separates the lateral epidural spaces from the anterior venous confluence ruptures, allowing local anesthetic to pour from the epidural space into the circulation. Another mechanism of epidural catheter "migration" is rupture of subdural bleb of local anesthetic into the CSF (27). The incidence of epidural needle/catheter unintentional dural puncture range from 2.5% (28) to 0.6% (29) and even 0.26% (30). Recognized intravascular placement or migration of an epidural catheter occurs in 5.2% of obstetric epidural anesthetics (31). Chadwick et al. (32) reviewed the malpractice claims filed against anesthesiologists in USA in 1985. There were 190 claims for care involving obstetric anesthesia (OB) and 1,351 of claims not involving obstetric anesthesia cases. Sixty five percent (124) of the OB claims were associated with regional anesthesia. Of the 17 claims for newborn brain injury attributed to an anesthetic cause, 13 had regional anesthesia as the primary technique. Of the 13 associated with regional anesthesia, 9 involved a convulsion, 8 of which appeared due to intravascular local anesthetic injection. Convulsions were much more common in the OB claims (10%). Eighteen of 19 convulsions occurred in patients having epidural anesthesia. Seventeen of the convulsions appeared to be due to local anesthetic toxic reactions. In 10 of these cases, epinephrine containing test doses were not used; in 7 others, data were not sufficient to determine if epinephrine-containing test doses were used or not. The local anesthesia used in 15 cases was bupivacaine, and in 2 other cases was not specified. Two of the convulsions appeared to be eclamptic. Eighty three percent of the convulsions resulted in neurologic injury or death to the mother, newborn, or both. Dain et al. (43) in 1987 distinguished in their review on the epidural test dose in obstetrics between "what is medically safe and what is legally safe. The authors have the impression that in order to be `legally safe` one must perform a test dose". In conclusion, it seems that the needle-through-needle technique for the combined spinal-epidural anesthesia has an inherent risk because of its inability to perform properly the epidural catheter test dosing. This can result in intravascular or subarachnoid local anesthetic or opioid inadvertent injections. Using the Eldor needle technique for the combined spinal-epidural anesthesia the epidural catheter can be inserted before the spinal local anesthetic is injected, allowing a proper epidural catheter test dosing, as it is done in a regular epidural anesthesia. The comparison between these two techniques (the needle-through-needle and the Eldor needle) makes the Eldor needle technique safer from the epidural catheter test dose point of view. 1. Dogliotti AM. Segmental peridural anesthesia. Am J Surg 1933;20:107-18 2. Scott DB. Test doses in extradural block. Br J Anaesth 1988;61:129-130 3. Brown DL. Spinal, epidural, and caudal anesthesia. In: Anesthesia, Miller RD (ed.); Churchill Livingstone; 4th ed.; 1994;p.1525 4. Moore DC. Regional block. Charles C. Thomas; 4th ed.; 1981;p.433 5. Shnider SM, Levinson G. Anesthesia for cesarian section. In: Anesthesia for obstetrics; 2nd ed.; Shnider SM, Levinson G (eds.); Baltimore: Williams and Wilkins; 1987; p.161 6. Galloon S. Test doses in extradural analgesia. Br J Anaesth 1978;50:304 7. Rees GAD, Rosen M. Test-dose in extradural analgesia. Br J Anaesth 1979;51:70-71 8. Crawford JS. Some maternal complications of epidural analgesia for labour. Anaesthesia 1985;40:1219-1225 9. Moore DC, Batra MS. The components of an effective test dose prior to epidural block. Anesthesiology 1981;55:693-6 10. Kumar CM, Dennison B, Panchal HI. Epidural test dose. Anaesthesia 1985;40:1023 11. Moore DC. Accidental dural puncture - who has an eye on the end of a needle. Anaesth Intensive Care 1986;14:208 12. Soresi AL. Episubdural anesthesia. Anesth Analg 1937;16:306-10 13. Rawal N. Single segment combined subarachnoid and epidural block for caesarean section. Can Anaesth Soc J 1986;33:254-5 14. Myint Y, Bailey PW, Milne BR. Cardiorespiratory arrest following combined spinal epidural anaesthesia for caesarean section. Anaesthesia 1993;48:684-686 15. Thoren T, Holmstrom B, Rawal N, Schollin J, Lindeberg S, Skeppner G. Sequential combined spinal epidural block versus spinal block for cesarean section: Effects on maternal hypotension and neurobehavioral function of the newborn. Anesth Analg 1994;78:1087-92 16. Kumar CM. More on combined subarachnoid and epidural techniques. Anaesthesia 1986;41:90-91 17. Cheng PA. The anatomical and clinical aspects of epidural anesthesia. Part 1. Anesth Analg 1963;42:398-406 18. Westbrook JL, Renowden SA, Carrie LES. Study of the anatomy of the extradural region using magnetic resonance imaging. Br J Anaesth 1993;71:495-498 19. Ravindran RS, Bond UK, Tasch MD, Gupta CD, Luerssen TG. Prolonged neural blockade following regional analgesia with 2-chloroprocaine. Anesth Analg 1980;59:447-51 20. Reisner LS, Hochman BN, Plumer MH. Persistent neurologic deficit and adhesive arachnoiditis following intrathecal 2-chloroprocaine injection. Anesth Analg 1980;59:452-4 21. Moore DC, Spierdijik J, Vankleef LD, Coleman RL, Love GF. Chloroprocaine neurotoxicity: four additional cases. Anesth Analg 1982;61:155-9 22. Hollway TE, Telford RJ. Observations on deliberate dural puncture with a Tuohy needle: depth measurements. Anaesthesia 1991;46:722-724 23. Crawford JS. Lumbar epidural block in labour: A clinical analysis. Br J Anaesth 1972;44:66-74 24. Crawford JS. The second thousand epidural blocks in obstetric hospital prctice. Br J Anaesth 1972;44:1277-1287 25. Bishton IM, Martin PH, Vernon JM, Liu WH. Factors influencing epidural catheter migration. Anaesthesia 1992;47:610-2 26. Hogan QH. "Migration" of an epidural catheter? Anesth Analg 1993;76:910-911 27. Reynolds F, Speedy HM. The subdural space: the third space to go astray. Anaesthesia 1990;45:120-3 28. Dawkins CJM. An analysis of the complications of extradural and caudal block. Anaesthesia 1969;24:554 29. Tanaka K, Watanabe R, Harada T, Dan K. Extensive application of epidural anesthesia and analgesia in a university hospital: incidence of complications related to technique. Reg Anesth 1993;18:34-38 30. Macdonald R. Unintentional dural puncture. Anaesthesia 1988;43:705 31. Kenepp NB, Gutsche BB. Inadvertent intravascular injections during lumbar epidural anesthesia. Anesthesiology 1981;54:172-173 32. Chadwick HS, Posner K, Caplan RA, Ward RJ, Cheney FW. A comparison of obstetric and nonobstetric anesthesia malpractice claims. Anesthesiology 1991;74:242-249 33. Dain SL, Rolbin SH, Hew EM. The epidural test dose in obstetrics; is it necessary? Can J Anaesth 1987;34:601-5

Spinal and epidural opioid analgesia

Epidural bolus injection of opioid, morphine and fentanyl, can produce good analgesia in doses of 2-4 mg and 0.1-0.2 mg, respectively (1). In animal studies, it has been demonstrated that intrathecal or epidural coadministration of opioid and local anesthetics produced synergistic analgesia (2-5). The use of continuous epidural opioid infusions may obviate the need for redosing, but it may obligate the patient to receive more opioid than is required (6) and increase the risk of respiratory depression (7). Drug dose is the important determinant of efficacy, rather than concentration or volume (8). Torda et al. (9) found that in patients who had undergone major abdominal surgery, analgesia after thoracic extradural injection of fentanyl 50 g did not differ significantly from analgesia after 0.5% bupivacaine 10 ml, or the fentanyl-bupivacaine mixtures. Bupivacaine alone caused a greater decrease in arterial pressure and a higher incidence of hypotension than fentanyl or the fentanyl-bupivacaine mixtures. Badner et al. (10,11) reported that after abdominal, thoracic or knee replacement surgery, there was no advantage in using a mixture of 0.1% bupivacaine with fentanyl 10 g/ml compared with fentanyl alone by continuous extradural infusion. Rudolph Matas (12), on November 10, 1899, was the first in the U.S. to apply the subarachnoid anesthesia. Matas may have been the first to inject morphine into the subarachnoid space (13). Moreno et al. (14) described three patients treated by CSF rechange after total spinal block caused by mistaken overdosage of local anesthetic in the subarachnoid space (two after epidural and one after paravertebral blocks). In all three patients clinical features of total spinal block appeared with severe hypotension, respiratory depression and loss of consciousness. After crystalloid perfusion and epinephrine administration, CSF rechange was performed. A 22G spinal needle was introduced in a cervical space in two patients and in a lumbar space in one patient. Repeated removal of 5 ml of CSF was followed by replacement of an equal volume of saline solution up to a volume of 50 ml. In less than 5 minutes all three patients recovered normal blood tension, spontaneous respiration and consciousness, while spontaneous movements of the four limbs were achieved between 20-30 minutes. The method was also used for the treatment of subarachnoid morphine overdose (15). Addition of 20 g of fentanyl to plain lidocaine 5% in dextrose (50 mg) spinal anesthesia improve duration of sensory anesthesia without prolonging recovery of motor function or time to micturition (16). Sosis et al. (17) have shown that staphylococcus aureus and candida albicans continue to survive 51 hr after inoculation of fentanyl/bupivacaine mixtures. The fraction of the lumbar epidural dose found in CSF after epidural sufentanil 75 g, diluted in 10 ml saline, was 2.7%. The time to peak CSF sufentanil concentration was 0.760.50 hr in the lumbar area and 2.11.4 hr in the thoracic area (18). The availability to CSF of epidural morphine is 2% and of epidural pethidine - 10% (19). Spinal anesthesia has been achieved with meperidine as a sole agent (20). Meperidine has also been used for spinal analgesia during labor and delivery (21) because it provides sensory anesthesia with a weak motor block (22). 1. De Castro J, Meynadier J, Zenz M. Regional opioid analgesia. Dordrecht: Kluwer Academic Publishers, 1991, p. 198-200 2. Akerman B, Arwestrom E, Post C. Local anesthetics potentiate spinal morphine antinociception. Anesth Analg 1988;67:943-948 3. Penning JP, Yaksh TL. Interaction of intrathecal morphine with bupivacaine and lidocaine in the rat. Anesthesiology 1992;77:1186-1200 4. Maves TJ, Gebhart GF. Antinociceptive synergy between intrathecal morphine and lidocaine during visceral and somatic nociception in the rat. Anesthesiology 1992;76:91-99 5. Kaneko M, Saito Y, Kirihara Y, Kosaka Y. Effects of epidural morphine and lidocaine on somatic and visceral pain. Neuroscience Abstracts 1991;17:294 6. Marlowe S, Engstrom R, White PF. Epidural patient-controlled analgesia (PCA): an alternative to continuous epidural infusions. Pain 1989;37:97-101 7. Boudreault D, Brasseur L, Samii K, Lemoing J. Comparison of continuous epidural bupivacaine infusion plus either continuous epidural infusion or patient-controlled epidural injection of fentanyl for postoperative analgesia. Anesth Analg 1991;73:132-137 8. Laveaux MMD, Hasenbos MAWM, Harbers JBM, Liem T. Thoracic epidural bupivacaine plus sufentanyl: High concentration/low volume versus low concentration/high volume. Regional Anaesthesia 1993;18:39-43 9. Torda TA, Hann P, Mills G, DeLeon G, Persman D. Comparison of extradural fentanyl, bupivacaine and two fentanyl-bupivacaine mixtures for pain relief after abdominal surgery. Br J Anaesth 1995;74:35-40 10. Badner NH, Komar WE. Bupivacaine 0.1% does not improve postoperative epidural fentanyl analgesia after abdominal or thoracic surgery. Can Anaesth Soc J 1992;39:330-336 11. Badner NH, Reimer EJ, Komar WE, Moote CA. Low-dose bupivacaine does not improve postoperative epidural fentanyl analgesia in orthopedic patients. Anesth Analg 1991;72:337-341 12. Matas R. Local and regional anesthesia with cocaine and other analgesic drugs, including the subarachnoid method, as applied in general surgical practice. Phil Med J 1900;6:820-843 13. Vandam LD. On the origins of intrathecal anesthesia. International Anesthesiology Clinics 1989;27:2-7 14. Moreno LA, Sinche M, Balust J, Izquierdo E, De Jose Mana B, Sala X, Galard JJ, Nalda MA. Total spinal block (TSB) treated by means of cerebrospinal fluid rechange (CSFR). International Monitor on Regional Anesthesia 1993;68 15. Kaiser KG, Bainton CR. Treatment of intrathecal morphine overdose by aspiration of cerebrospinal fluid. Anesth Analg 1987;66:475-477 16. Liu S, Carpenter RL, Neal JM, Pollock JE, Gerancher JC. Effects of addition of 20 g of fentanyl to lidocaine spinal anesthesia. Reg Anesth 1995;20:S112 17. Sosis M, Braverman B, Ivankovich A. Growth of Candida albicans and staphylococcus aureus in Fentanyl/Bupivacaine mixtures for epidural administration. Society of Obstetric Anesthesia and Perinatology (SOAP), 25th Annual Meeting, 1993:92 18. Hansdottir V, Woestenborghs R, Nordberg G. The cerebrospinal fluid and plasma pharmacokinetics of sufentanil after thoracic or lumbar epidural administration. Anesth Analg 1995;80:724-729 19. Nordberg G, Hansdottir V, Bondesson U, Boreus LO, Mellstrand T, Hedner T. CSF and plasma pharmacokinetics of pethidine and norpethidine in man after epidural and intrathecal administration of pethidine. Eur J Clin Pharmacol 1988;34:625-631 20. Famewo CE, Naguib M. Spinal anaesthesia with meperidine as the sole agent. Can Anaesth Soc J 1985;5:533-537 21. Swayze C, Sherman JH, Walker EB. Efficacy of subarachnoid meperidine for labor analgesia. Reg Anesth 1991;16:309-313 22. Sangarlankarn S, Klaewtanong V, Jonglerttrakool P, Khankaew V. Meperidine as a sole anesthetic agent: A comparison with lidocaine-glucose. Anesth Analg 1987;66:235-240


The choice of the anesthesiologists

Gantt et al. (1) evaluated whether anesthesiologists will still prefer spinal or epidural anesthesia over general anesthesia after they will experience these regional techniques. Twelve anesthesiologists underwent two procedures (spinal and epidural anesthesia) on the same day. All but one anesthesiologist (91.6%) did not change their preference for regional over general anesthesia. In a survey among 558 Canadian surgeons they have been asked which anesthesia they would choose for themselves for a hernia repair. The results were: local - 38%; general - 30%; epidural - 15%; spinal - 10%; other - 6% (2). The choice was somewhat surprising, because surgeons rarely perform local anesthesia on patients for hernia repair. It was also interesting to note that the the method of anesthesia selected by the surgeons for themselves was not necessarily the method they would choose for their patients. 1. Gantt R, Beardsley D, Lindsey J, Setzer V, Stevens RA. Subjective preferences of twelve anesthesiologists undergoing two major neuroaxial blockades: spinal and epidural. Anesthesiology 1994;81:A990 2. Klassen N, Grace M, Finucane BT. Surgeons` attitudes towards regional anesthesia: a Canadian perspective. ASRA Annual Meeting 1995;107

Epidural catheter malposition

In a survey (1) conducted in 218 obstetric units in the UK in 1993, 99% of the units resited the epidural catheter following an inadvertent dural tap. One percent inserted the epidural catheter into the subarachnoid space to provide continuous spinal analgesia. There are many reports of failed aspiration tests for both subarachnoid and intravascular catheter placement (2-4). Epidural catheter test dose is a must maneuver, because as Moore (5) said on the epidural needle, none of us has "an eye on the end of the needle", neither on the end of the catheter introduced through that needle. The incidence of inadvertent epidural catheter intravascular cannulation range from 5.6% (6) to 4.8% (7) and even 0.67% (8). Brown (9), in the 4th edition of Miller`s Anesthesia wrote that "in spite of an adequately positioned catheter during first use of local anesthetic, each subsequent injection should be preceded by aspiration and an epidural test dose, since catheter migration into vessels and subarachnoid or subdural spaces does occur". Campbell et al. (10) evaluated the spinal injection of 2.5 mg bupivacaine, 10 g sufentanil and 10 g sufentanil plus 2.5 mg bupivacaine in 52 nulliparous patients using the needle-through-needle technique in the combined spinal-epidural anesthesia. After spinal anesthetic injection the 25G spinal needle was removed and the 20G epidural catheter inserted but not tested. CSF was not obtained in 7.7% (4/52) of the patients who subsequently had a functioning epidural catheter. 4.2% (2/48) of the epidural catheters required replacement. Rathmell et al. (11) evaluated in 8 healthy volunteers whether premedication with nalbuphine 0.15 mg/Kg IV has an effect on the ability to detect auditory or taste symptoms of IV local anesthetic injection (1.5 mg/Kg 2% chloroprocaine). They found that nalbuphine sedation does not interfere with the detection of intravascular epidural catheters when 2% chloroprocaine is used as a test dose. Cantelo and Walsh (12) described a case in which an epidural catheter was inserted at the T12-L1 interspace after an inadvertent dural puncture occurred at the L1-2 interspace. Aspiration tests revealed 0.2-0.3 ml of CSF, which leaked from the subarachnoid space into the epidural space. Failure to detect inadvertent intravenous injection of a local anesthetic with epinephrine can result in cardiac arrest (13) during general anesthesia. In the elderly (14,15) or in patients with -adrenergic blockade (16), systolic blood pressure changes were reported to be more reliable than heart rate changes. Tanaka et al. (17) gave 3 ml of 1.5% lidocaine with epinephrine (1:200,000) IV to 15 patients anesthetized with 1% end-tidal isoflurane and nitrous oxide. 5 of 15 patients developed heart rate increments smaller than 20 beats/min. However, all patients exhibited systolic blood pressure increases more than 15 mmHg. They concluded that the systolic blood pressure criterion should be used to diagnose suspected intravascular migration of the epidural catheter during combined spinal-epidural anesthesia. Crawford (18) in his review of 27,000 lumbar epidural blocks concluded that "the requirements for safety are that all top ups are given in divided dose, with an interval of approximately 5 minutes between two increments". The inadvertent intravenous administration of local anesthetic during "epidural" injection was classified by Crawford as a "potentially life threatening complication" (18). Scott and Hibbard (19) collated 108 nonfatal complications from more than 500,000 obstetric epidurals in the UK from 1982 to 1986 inclusive. One out of three cardiac arrests and 21 convulsions were associated with inadvertent intravascular injection. Michels et al. (20) found that the use of 1 mg/Kg lignocaine as a test dose would result in a significantly higher sensitivity of subjective symptoms for detecting intravascular injection than the use of 0.5 mg/Kg (95% vs. 50%). The incidence of epidural needle/catheter unintentional dural puncture range from 2.5% (21) to 0.6% (8) and even 0.26% (22). 1. Sajjad T, Ryan TDR. Current management of inadvertent dural taps occurring during the siting of epidurals for pain relief in labour: A survey of maternity units in the United Kingdom. Anaesthesia 1995;50:156-161 2. Ravindran RS, Bond UK, Tasch MD, Gupta CD, Luerssen TG. Prolonged neural blockade following regional analgesia with 2-chloroprocaine. Anesth Analg 1980;59:447-51 3. Reisner LS, Hochman BN, Plumer MH. Persistent neurologic deficit and adhesive arachnoiditis following intrathecal 2-chloroprocaine injection. Anesth Analg 1980;59:452-4 4. Moore DC, Spierdijik J, Vankleef JD, Coleman RL, Love GF. Chloroprocaine neurotoxicity: four additional cases. Anesth Analg 1982;61:155-9 5. Moore DC. Accidental dural puncture - who has an eye on the end of a needle. Anaesth Intensive Care 1986;14:208 6. Jaucot J. Paramedian approach of the peridural space in obstetrics. Acta Anaesthesiol Belg 1986;37:187 7. Kenepp NB, Gutsche BB. Inadvertent intravascular injections during lumbar epidural anesthesia. Anesthesiology 1981;54:172-173 8. Tanaka K, Watanabe R, Harada T, Dan K. Extensive application of epidural anesthesia and analgesia in a university hospital: incidence of complications related to technique. Reg Anesth 1993;18:34-38 9. Brown DL. Spinal, epidural, and caudal anesthesia. In: Anesthesia; Miller RD (ed.); Churchill Livingstone; 4th ed.; 1994;p.1525 10. Campbell DC, Camann WR, Datta S. Combined spinal-epidural for labor analgesia: Comparison of intrathecal sufentanil vs bupivacaine vs sufentanil plus bupivacaine. Anesthesiology 1994;81:A1145 11. Rathmell JP, Viscomi CM, Roth J, Aladjem E, Williams J. Detection of intravascular epidural catheters using 2-chloroprocaine injection: influence of dose and nalbuphine premedication. Anesthesiology 1994;81:A971 12. Cantelo RA, Walsh GR. Aspiration of cerebrospinal fluid - not always a dural tap. Anaesthesia 1993;48:452 13. Marx GF. Cardiotoxicity of local anesthetics - the plot thickens. Anesthesiology 1984;60:3-5 14. Kahn RL, Quinn TJ. Blood pressure, not heart rate, as a marker of intravascular injection of epinephrine in an epidural test dose. Reg Anesth 1991;16:292-5 15. Vestal RE, Wood AJJ, Shand DG. Reduced -adrenoceptor sensitivity in the elderly. Clin Pharmacol Ther 1979;26:181-6 16. Guinard JP, Mulroy MF, Carpenter RL, Knopes KD. Test doses: optimal epinephrine content with and without acute beta-adrenergic blockade. Anesthesiology 1990;73:386-92 17. Tanaka M, Yamamoto S, Ashimura H, Iwai M, Matsumiya N. Efficacy of an epidural test dose in adult patients anesthetized with isoflurane: Lidocaine containing 15 g epinephrine reliably increases arterial blood pressure, but not heart rate. Anesth Analg 1995;80:310-4 18. Crawford JS. Some maternal complications of epidural analgesia for labour. Anaesthesia 1985;40:1219-1225 19. Scott DB, Hibbard BM. Serious non-fatal complications associated with extradural block in obstetric practice. Br J Anaesth 1991;64:537-41 20. Michels AMJ, Lyons G, Hopkins PM. Lignocaine test dose to detect intravenous injection. Anaesthesia 1995;50:211-213 21. Dawkins CJM. An analysis of the complications of extradural and caudal block. Anaesthesia 1969;24:554-563 22. Macdonald R. Unintentional dural puncture. Anaesthesia 1988;43:705

Woolley and Roe case

On October 13, 1947, two incidents occurred which resulted in one of the most famous of all medicolegal actions as far as the speciality of anesthesia was concerned. Two patients, Cecil Roe and Albert Woolley who were on the same operative list for relatively minor surgical procedures, developed permanent, painful, spastic paraparesis following spinal anesthesia with hypobaric 1:1500 cinchocaine (nupercaine; dibucaine) administered by the same anesthetist. Both patients sued the hospital and the anesthetist and the case came to court in October 1953 and lasted 11 days. This case had a profound effect on the practice of spinal anesthesia, as anesthetists were fearful of producing permanent neurological damage and the technique, in the UK, was probably retarded by 20-25 years (1). Noble and Murray (2) in a review of 78,746 spinal anesthetics in Canada, found no permanent neurological sequelae. Similarly, Moore and Bridenbaugh (3) surveyed 12,386 and Dripps and Vandam (4) - 10,098 spinal anesthetics, and did not find evidence of permanent neurological deficits. In an editorial published in 1975 on spinal anesthesia Scott and Thorburn (5) wrote that "it has been virtually ignored in the last 20 years for several reasons, including the introduction of muscle relaxants. Since the Woolley and Roe cases, reported in 1954, in which two patients developed painful and permanent paraplegia following spinal anaesthesia, the use of the technique in the United Kingdom has been confined to a few enthusiasts". 1. Morgan M. The Woolley and Roe case. Anaesthesia 1995;50:162-173 2. Noble AB, Murray JJ. A review of the complications of spinal anaesthesia with experience in Canadian teaching hospitals from 1959-1969. Can Anaesth Soc J 1971;18:5-????? 3. Moore DC, Bridenbaugh LD, Bagdi PA, et al. Present status of spinal (subarachnoid) and epidural (peridural) block: a comparison of the two technics. Anesth Analg 1968;47:40-9 4. Dripps RD, Vandam LD. Long term follow-up of patients who received 10,098 spinal anesthetics. JAMA 1954;156:1486-1491 5. Scott DB, Thorburn JT. Spinal anaesthesia. Br J Anaesth 1975;47:421-2

Anesthetic costs

US cost of local anesthetic drugs are much cheaper than those of general anesthetics. For example, bupivacaine 0.5% 30 ml - $1.24; lidocaine 1% 30 ml - $0.35; fentanyl 100 g - 0.30 compared to midazolam 5 mg - $7.27; atracurium 100 mg - $39.17; propofol 200 mg - $9.63. Inhalational anesthetics also cost much more: Isoflurane 100 ml -$70.75; halothane 250 ml - $14.89 (1). For total hip or knee replacement, the anesthesia related drug costs for a spinal anesthetic are approximately one half that for a general anesthetic (2). 1. Cooper JO. The relative costs of anesthesia drugs in New Zealand versus the United States. Anesth Analg 1995;80:850-851 2. Bowe EA, Brill VL, Baysinger CL, Brown KL, Longston GM, Chillag KJ. Anesthesia drug costs for total joint replacement: Spinal versus general anesthesia. ASRA Annual Meeting 1995;21

From the skin to the spinal-epidural spaces

The distribution of distance from the skin to the epidural space in obstetric patients (n=2,123) was: < 3 cm - 0.3%; 3 to < 4 cm - 15%; 4 to < 5 cm - 47.3%; 5 to < 6 cm - 28.6%; 6 to < 7 cm - 6.9%; 7 to < 8 cm - 1.4%; and > 8 cm - 0.5% (1). Barbara l. Leighton (2) described her model for initial instruction in epidural catheterization technique... the banana. The banana represents the skin, subcutaneous tissue and the ligamentum flavum. "An average banana can be used for 30 attempts before it becomes mushy". Unripe bananas need less frequent replacement. In addition, an average banana`s width (3 cm) is only slightly less than the distance from the skin to the epidural space in the average patient (4 cm) (3). This model does not represent the vertebrae; however, bony anatomy can be learned from a skeleton. The mean value of the distance from skin to the epidural space in term parturients is influenced by the patient`s position during epidural needle placement. It is 4.44 0.82 cm in the sitting position and 5.03 1.05 cm in the lateral position (1). Spinal dura mater thickness at the lumbar region is 0.5 mm (4). Using magnetic resonance imaging (MRI) of 39 patients Westbrook et al. (5) found that the depth of the extradural space at the level of T12 is 0.830.195 cm. Cerebrospinal fluid is formed at the rate of 400 ml/day (6). The average adult has a total of 120 to 150 ml of fluid, of which only 20 to 35 ml are in the spinal portion of the subarachnoid space. In parturients, this volume in the spinal canal is decreased (7). Valsalva (8), in 1682, was the first to remark on the CSF when he cut open the spine of a dog and noticed the liquid "which in all its aspects resembles that which is found in the joints". Meme et al. (9) using an epiduroscope could visualize the pulsation of the dura synchronized to heart rate. The human dura mater shows its fibers neither longitudinally nor parallel directed. It has thin collagen fibers and thick elastic ones with wavy characteristics, grouped in ribbons or sheets (10). 1. Hamza J, Smida M, Benhamou D, Cohen SE. Parturient`s posture during epidural puncture affects the distance from skin to epidural space. J Clin Anesth 1995;7:1-4 2. Leighton BL. A greengrocer`s model of the epidural space. Anesthesiology 1989;70:368-9 3. Cousins MJ. Epidural neural blockade. In: Neural blockade in clinical anesthesia and management of pain. Cousins MJ, Bridenbaugh PO (eds.); Philadelphia; JB Lippincott, 1980:pp. 184-5 4. Cheng PA. The anatomical and clinical aspects of epidural anesthesia. Part 1. Anesth Analg 1963;42;398-406 5. Westbrook JL, Renowden SA, Carrie LES. Study of the anatomy of the extradural region using magnetic resonance imaging. Br J Anaesth 1993;71:495-498 6. Franksson C, Gordh R. Headache after spinal anesthesia and a technic for lessening its frequency. Acta Chir Scand 1946;94:443-454 7. McDonald JS, Mandalfino DA. Subarachnoid block. In: Bonica JJ, McDonald JS, eds. Principles and practice of obstetric analgesia and anesthesia. 2nd ed., Williams & Wilkins, 1995;pp.479-480 8. Viets HR. Domenico Cotugno: his description of the cerebrospinal fluid. Bull Inst Hist Med 1935;3:701-720 9. Meme E, Amici M, Ricci L, Merletti F. Epidural space: anatomical living view. International Monitor on Regional Anaesthesia 1993;96 10. Reina MA, Lopez A, Escriu MN, Del Cano MC, Cascales MR, Delgado MP. Structure of human duramater by a scanning electron microscopy. International monitor on Regional Anaesthesia 1994;A71

Myint case

Myint et al. (1) published the first case report of cardiorespiratory arrest following combined spinal-epidural anesthesia. using the needle-through-needle technique in a 31 year old parturient scheduled for cesarean section they injected 2 ml 0.5% bupivacaine in 8% dextrose through 24G Sprotte needle into the spinal space. Then they rotated the epidural needle 180 and introduced an epidural catheter with three lateral holes into the epidural space. They made an aspiration test which was negative for blood or CSF. Then they made a test dose of 2 ml 0.5% bupivacaine with adrenaline 1:200,000 given through the epidural catheter. A few minutes later the patient complained of some numbness in her fingers, but her hand grip was strong and she was able to breath deeply and strongly on request. Upper limit of sensory block was T4 bilaterally. At the end of the operation they have given 2.5 mg of diamorphine in 5 ml of 0.25% bupivacaine through the epidural catheter for postoperative analgesia. Forty minutes later she complained of difficulty in breathing which developed rapidly to respiratory and cardiac arrest. Resuscitation started with endotracheal intubation, adrenaline 1 mg and atropine 0.6 mg IV. Then she received two doses of naloxone 0.4 mg IV. She started breathing and regained consciousness within 2 min of the first administration of intravenous naloxone. The patient recovered completely with no neurological deficit and did not develop a postspinal headache. Due to the masking of the epidural test dose by the previous spinal anesthetic injection Myint et al. could not appreciate correctly the patient`s complaint of "some numbness in her fingers". If it occurred at the first place, i.e., the epidural catheter test dose before the spinal anesthetic injection, their suspicion would certainly be of an intravascular or subarachnoid inadvertent placement of the epidural catheter or one of its 3 lateral holes. Their inability to recognize it is blamed upon the technique of the needle-through-needle in which you have first to inject the anesthetic solution into the spinal space and then to insert the epidural catheter into the epidural space. It is in contrast to the Eldor needle technique in which the epidural catheter is first inserted allowing a proper test dose, and then the spinal anesthetic is injected through the spinal needle introduced through its spinal conduit. 1. Myint Y, Bailey PW, Milne BR. Cardiorespiratory arrest following combined spinal epidural anaesthesia for caesarean section. Anaesthesia 1993;48:684-686

Spinal needles

Slow flowback of CSF through 25 and 26-gauge spinal needles may, particularly in inexperienced hands, lead to repeated unrecognized dural puncture and this may contribute to post dural puncture headache. In 1968, Brandus (1) examined 22G spinal needles and identified tissue fragments ("cores") in 75% of needles in which the stylet was not removed and CSF not seen. The cores (skin or epidural threads) were absent when CSF was identified and local anesthetic injected. Campbell et al. (2) compared the coring effect between the 25G Quincke and 25G Whitacre spinal needles. Tissue fragments were identified in 80% of the Quincke needles compared to 41% of the Whitacre needles in which the stylet was not removed and CSF not seen, and in one of the 25G Quincke needles in which CSF was identified and local anesthetic injected. All tissue fragments were fat tissue. Westbrook et al. (3) compared the force required for dural puncture with different spinal needles and subsequent leakage of cerebrospinal fluid using an in vitro model of a bovine dura. They found that the pencil-point needles required significantly more force to pierce the dura than the Quincke needle of the same external diameter. For example, using the B-D 25G Quincke needle the puncture was 0.040.01 Kg force, while using the B-D Whitacre needle it was three times more - 0.120.02 Kg force. The CSF flow through the Quincke needle was almost twice than that of the Whitacre needle (8.30.9 vs 4.30.9). This lesser leak of CSF of the pencil-point needle compared to the Quincke needle, confirms its superiority in reducing the incidence of post dural puncture headache. In a meta-analysis of 450 articles published from January 1966 till December 1993 Halpern and Preston (4) found a reduction in the incidence of postdural puncture headache when noncutting spinal needles rather than cutting needles were used and when a small spinal needle was used compared with a large needle of the same type. There was no difference in the incidence of failure of spinal anesthesia or the incidence of back pain between the noncutting and the cutting spinal needles. Garcia et al. (5) found a significantly higher unsuccessful dural puncture or inadequate sensory block while using 27G Whitacre needle as compared to 25G Whitacre needle (10% vs 2%). Anderson et al. (6) used either 25G Whitacre or 27G Quincke spinal needles to induce combined spinal-epidural labor analgesia. They were able to obtain CSF in only 28 of 37 patients (75.6%) when using the Whitacre needle but in all of 13 patients in whom they used the Quincke-point needle. McLeod et al. (7) described two 25G Whitacre needles which tips resembled "concorde nose" after it struck bone while introduced at the L3-4 interspace. Using the needle-through-needle technique Pedraza et al. (8) found that after dural puncture with 26G Whitacre spinal needle there were 0.11 ml CSF refluxed through the epidural needle within 2 minutes, while with the 24G Sprotte needle there were 0.30 ml of CSF. Using the needle-through-needle technique Joshi and McCarroll (9) encountered difficulties to feel the spinal needle puncturing the dura. "This could be due to the fact that the spinal needle has to brush the curved bevel of the Tuohy needle". Turner and Shaw (10) found an increased incidence of paresthesias (16.6%) while using the long Whitacre spinal needles through the epidural needles in the combined spinal epidural anesthesia for cesarean section. They postulated its long nose cone as an explanation ("before cerebrospinal fluid is evident, these needles have to be passed further through the dura"). Injection of local anesthetics at the first appearance of fluid at the hubs of spinal needles with long orifices (Sprotte, Quincke, Diamond point) may result in failed spinal anesthesia due to leakage into the epidural space. In that regard the shorter orifice spinal needle (Whitacre) is preferred (11). Failed or incomplete spinal block with Sprotte needles varies between 1.6% and 11.5% (12,13). This could possibly be related to the larger length of the orifice compared to the dura. Since the thickness of the dura is from 0.5 to almost 2.0 mm (14), and the length of the orifice of 22 gauge Sprotte needle is 2 mm and that of the 24 gauge Sprotte is 1.4 mm, it is possible that CSF aspiration can occur while, on injection, some of the local anesthetic escapes through that part of the orifice outside the dura (15). Coring of the epidermis by a spinal needle with tissue deposition and proliferation in the subarachnoid space is a presumed etiology for iatrogenic intraspinal epidermoid tumors. These tumors have been reported as a late complication of lumbar puncture (16,1). 1. Brandus V. The spinal needle as a carrier of foreign material. Can Anaesth Soc J 1968;15:197-201 2. Campbell DC, Douglas J, Taylor G. Do the newer spinal needles reduce "coring"? Anesthesiology 1993;79:A478 3. Westbrook JL, Uncles DR, Sitzman BT, Carrie LES. Comparison of the force required for dural puncture with different spinal needles and subsequent leakage of cerebrospinal fluid. Anesth Analg 1994;79:769-72 4. Halpern S, Preston R. Postdural puncture headache and spinal needle design. Anesthesiology 1994;81:1376-1383 5. Garcia J, Arilla MC, Sierra P, Castillo J, Pares N, Escolano F, Castano J. Spinal anaesthesia with 25G and 27G Whitacre spinal needles in patients under 60 years of age. International Monitor on Regional Anaesthesia 1993;23 6. Anderson M, D`Angelo R, Philip J, Hood DD, Eisenach JC. Intrathecal sufentanil compared to epidural bupivacaine for labor analgesia. Anesthesiology 1993;79:A970 7. McLeod GA, Carson D, Bannister J. "Concorde nose" in Whitacre spinal needles. Br J Anaesth 1993;70:593 8. Pedraza I, Riobo MI, Alvarez J. Collection of CSF using a combined spinal epidural needle as an indication of a duramater hole spinal puncture. International Monitor on Regional Anaesthesia 1994;A96 9. Joshi GP, McCarroll SM. Evaluation of combined spinal-epidural anesthesia using two different techniques. Reg Anesth 1994;19:169-174 10. Turner MA, Shaw M. Atraumatic spinal needles. Anaesthesia 1993;48:452 11. Sayeed YG, Sosis MB, Braverman B, Ivankovich AD. An in vitro investigation of the relationship between spinal needle design and failed spinal anesthetics. Reg Anesth 1993;18:S85 12. Brettner J, Wresch KP, Klose R. Does a pencil-shaped spinal needle offer advantages for spinal anesthesia? Reg Anaesth 1990;13:124-128 13. Crone LL, Vogel W. Failed spinal anesthesia with the Sprotte needle. Anesthesiology 1991;75:717 14. Dittman M, Schafer HG, Ulrich J, Bond-Taylor W. Anatomical re-evaluation of lumbar dura mater with regard to postspinal headache: Effect of dural puncture. Anaesthesia 1988;43:635-7 15. Ackerman W, Cases-Cristobal V, Juneja M, Rigor BM. Sprotte needle for caesarean section. Anaesthesia 1991;46:230 16. Gardner DJ, O`Gorman AM, Blundell JE. Interspinal epidermoid tumor: late complication of lumbar puncture. Can Med J 1987;141:233-235

Meningitis post combined spinal-epidural anesthesia

Harding et al. (1) reported on two cases of meningitis which developed after combined spinal-extradural procedures for obstetric analgesia. The first case was thought to be caused by aseptic or chemical meningitis and the second was a case of bacterial meningitis in a patient who also received an extradural blood patch. 1. Harding SA, Collis RE, Morgan BM. Meningitis after combined spinal-extradural anaesthesia in obstetrics. Br J Anaesth 1994;73:545-547

Preemptive analgesia and combined spinal-epidural anesthesia

Shir et al. (1) compared three groups of patients undergoing radical prostatectomy with general, epidural or combined epidural and general anesthesia. Preemptive analgesia was observed only with epidural anesthesia, because this type of anesthesia allows for even minor discomfort to be noticed and treated during surgery. They concluded that "complete intraoperative blockade of afferent signals to the CNS is fundamental in decreasing postoperative pain". 1. Shir Y, Raja SN, Frank SM. The effect of epidural versus general anesthesia on postoperative pain and analgesic requirements in patients undergoing radical prostatectomy. Anesthesiology 1994;80:49-56

Sympathetic innervation and CSEA

Sympathetic innervation to the sinoatrial node exits from the spinal cord between T1 and T4 (1,2). Sympathetic block below these segments results in arterial and venous vasodilation in the lower extremities and reflex compensatory increased sympathetic activity above the block (1). Blocks reaching the T1-4 segments would then interrupt the sympathetic flow to the heart. Parasympathetic innervation to the heart, on the other hand, originates in the brainstem, travels via the vagus nerve and should not be blocked, even during high levels of spinal anesthesia (1). The adrenal medulla, which is the only known source of plasma epinephrine, receives its sympathetic innervation from preganglionic fibers having their cell bodies in spinal segments T6 through L2 (3). For many years, anesthesiologists have assumed that, when local anesthetic is given to produce a sensory or motor block, blockade of preganglionic sympathetic fibers would be present (4). In vivo investigations of spinal (5,6) and epidural (7,8) anesthesia have concluded that sympathetic denervation is present during sensory and motor centroneuraxis block and that the level of sympathetic block exceeds the level of sensory block by at least two dermatome segments. However, these conclusions are based on a loss of cold sensation (5,9), an increase in skin temperature (6) or thermography (4). However, studies evaluating sympathetic blockade by monitoring skin conductance responses (10,11) have reported that spinal anesthesia (upper level of sensory analgesia T4-T6) produced an incomplete sympathectomy of the lower extremity. Stevens et al. (12) evaluated ten subjects who underwent both spinal and epidural anesthesia with plain lidocaine on the same day with complete recovery between blocks. Before and 30 min after local anesthetic injection, a cold pressor test (immersion of an hand up to the wrist into an ice-water bucket (4C) for 120 sec) was performed. Conduction block attenuated the increase in response to cold pressor test only in mean arterial pressure (spinal and epidural) and cardiac index (spinal only). Neither spinal nor epidural anesthesia blocked the increase in heart rate, norepinephrine or epinephrine to cold pressor test. Despite a more complete motor block during spinal anesthesia, spinal anesthesia did not produce a more complete sympathectomy than epidural anesthesia. The myocardium and the coronary vasculature are densely innervated by sympathetic fibers. Sympathetic tone in the coronary circulation both at rest and during exercise may improve the matching of coronary blood flow and myocardial oxygen demand (13). In patients with coronary artery disease, however, there is evidence for a nonbeneficial sympathetic influence as this matching capability is disturbed during sympathetic stimulation (14-18). In patients with severe coronary artery disease, cardiac sympathetic block with high thoracic epidural anesthesia increases coronary artery stenotic diameter at rest (15), improves global as well as regional left ventricular wall motility, and increases left ventricular ejection fraction during exercise stress tests (19). Furthermore, in patients with severe coronary artery disease and unstable angina refractory to maximal medical therapy, thoracic epidural anesthesia offers efficient pain relief (20), and decreases determinants of myocardial oxygen demand - heart rate, preload and afterload during myocardial ischemia (14). It also seems to "stabilize" patients with unstable angina (20,21). Thoracic epidural anesthesia may beneficially affect the collateral flow during ischemia. It was observed by Klassen et al. (22) that thoracic epidural anesthesia reduced the coronary vascular resistance 20%-25% for collateral flow into the ischemic myocardium. 1. Greene NM. Physiology of spinal anesthesia. 3rd ed. Baltimore: Williams & Wilkins, 1981 2. Lefkowitz RJ, Hoffman BB, Taylor P. Neurohumoral transmission: the autonomic and somatic motor nervous system. In: Gilman AG, Rall TW, Nies AS, Taylor P, eds. Goodman and Gilman`s The Pharmacologic basis of therapeutics. 8th ed. New York: Pergamon Press, 1990:84-121 3. Bonica JJ. Autonomic innervation of the viscera in relation to nerve block. Anesthesiology 1968;29:793-813 4. Greene NM, Brull SJ. Physiology of spinal anesthesia. 4th ed. Baltimore, Williams and Wilkins, 1993, pp. 21-40 5. Greene NM. The area of differential spinal block during spinal anesthesia with hyperbaric tetracaine. Anesthesiology 1958;19:45-50 6. Chamberlain DP, Chamberlain BDL. Changes in skin temperature of the trunk and their relationship to sympathetic blockade during spinal anesthesia. Anesthesiology 1986;65:139-145 7. Brull SJ, Greene NM. Zones of differential sensory block during extradural anaesthesia. Br J Anaesth 1991;66:651-655 8. Hopf HB, Weissbach B, Peters J. High segmental thoracic epidural anesthesia diminishes sympathetic outflow to the legs despite restriction of sensory block to the upper thorax. Anesthesiology 1990;73:882-889 9. Gibbons JD. Non-parametric methods for quantitative analysis. 2nd ed. Columbus, American, 1988 10. Bengtsson M, Loefstroem JB, Malmqvist LA. Skin conductance responses during spinal anesthesia. Acta Anaesthesiol Scand 1985;29:67-71 11. Malmqvist LA, Bengtsson M, Bjoernsson G, Jordfeldt L, Loefstroem JB. Sympathetic activity and hemodynamic variables during spinal analgesia in man. Acta Anaesthesiol Scand 1987;31:467-473 12. Stevens RA, Beardsley D, White JL, Kao TC, Gantt R, Holman S. Does spinal anesthesia result in a more complete sympathetic block than that from epidural anesthesia? Anesthesiology 1995;82:877-883 13. feigl E. Coronary physiology. Physiol Rev 1983;63:1-205 14. Blomberg S, Emanuelsson H, Ricksten S-E. Thoracic epidural anesthesia and central hemodynamics in patients with unstable angina pectoris. Anesth Analg 1989;69:558-62 15. Blomberg S, Emanuelsson H, Kvist H, Lamm C, Ponten J, Waagstein F, Ricksten SE. Effects of thoracic epidural anesthesia on coronary arteries and arterioles in patients with coronary artery disease. Anesthesiology 1990;73:840-7 16. Chierchia S, Lazzari M, Simonetti I, Maseri A. Hemodynamic monitoring in angina at rest. Herz 1980;5:189-98 17. Heusch G, Deussen A. The effects of cardiac sympathetic nerve stimulation on perfusion of stenotic coronary arteries in the dog. Cir Res 1983;53:8-15 18. Heusch G, Deussen A, Thamer V. Cardiac sympathetic nerve activity and progressive vasoconstriction distal to coronary stenoses: feed-back aggravation of myocardial ischemia. J Auton Nerv Syst 1985;13:311-26 19. Kock M, Blomberg S, Emanuelsson H, Lomsky M, Stromblad SO, Ricksten SE. Thoracic epidural anesthesia improves global and regional left ventricular function during stress-induced myocardial ischemia in patients with coronary artery disease. Anesth Analg 1990;71:625-30 20. Blomberg S, Curelaru I, Emanuelsson H, et al. Thoracic epidural anaesthesia in patients with unstable angina pectoris. Eur Heart J 1989;10:437-44 21. Blomberg SG. Long-term home self-treatment with high thoracic epidural anesthesia in patients with severe coronary artery disease. Anesth Analg 1994;79:413-21 22. Klassen G, Bramwell R, Bromage P, Zborowska-Sluis D. Effect of acute sympathectomy by epidural anesthesia on the canine coronary circulation. Anesthesiology 1980;52:8-15

The politics of anesthesiology

Bridenbaugh (1) in his 1994 Gaston Labat Award Lecture recalled "visiting our congressman in the late 1980`s when we were fighting against legislation that proposed the radiology, anesthesiology, and pathology specialities should be reimbursed by the hospital and not our patients. In spite of our rational and logical protests, the congressman reminded us that our groups had little impact on the voting public. His comment was `All of your group`s patients are either in the dark, asleep, or dead`". 1. Bridenbaugh PO. Anesthesiology and pain management: Medical practice or perception. Reg Anesth 1994;19:301-306

Preconclusion

John Selden was an English historian, jurist, antiquary and statesman. He lived between 1584 and 1654. In 1689 was published a collection of his sayings entitled: Table talk. One of them is as follows: "Preachers say, Do as I say, not as I do. But if the physician had the same disease upon him that I have, and he should bid me do one thing, and himself do quite another, could I believe him?"

Conclusion

"We shape the architecture of our buildings and then they shape us" (Winston Churchill).
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