- Email: [email protected]
General anesthesia is unacceptable for elective cesarean section
212 22. Carvalho B, Cohen SE, Lipman SS, Fuller A, Mathusamy AD, Macario A. Patient preferences for anesthesia outcomes associated with cesarean delivery. Anesth Analg 2005;101:1182–97. 23. Cohen SE, Subak LL, Brose WG, Halpern J. Analgesia after cesarean delivery: patient evaluations and costs of five opioid techniques. Reg Anesth 1991;16:141–9. 24. Harrison DM, Sinatra R, Morgese L, Chung JH. Epidural narcotic and patient-controlled analgesia for post-cesarean section pain relief. Anesthesiology 1988;68:454–7. 25. Yarnell RW, Polis T, Reid GN, Murphy IL, Penning JP. Patientcontrolled analgesia with epidural meperidine after elective cesarean section. Reg Anesth 1992;17:329–33. 26. Cohen SE, Woods WA. The role of epidural morphine in the postcesarean patient: efficacy and effects on bonding. Anesthesiology 1983;58:500–4. 27. Roseag OP, Lui ACP, Cicutti NJ, Bragg PR, Crossan M, Krepski B. Peri-operative multi-modal pain therapy for caesarean section: analgesia and fitness for discharge. Can J Anaesth 1997;44:803–9. 28. Nikolajsen L, Sorensen HC, Jensen TS, Kehlet H. Chronic pain following caesarean section. Acta Anaesthesiol Scand 2004;48: 111–6. 29. Eisenach JC, Pan PH, Smiley R, Lavand’homme P, Landau R, Houle TT. Severity of acute pain after childbirth, but not type of delivery, predicts persistent pain and postpartum depression. Pain 2008;140:87–94. 30. Clark SL, Belfort MA, Dildy GA, Herbst MA, Meyers JA, Hankins GD. Maternal death in the 21st century: causes, prevention, and relationship to cesarean delivery. Am J Obstet Gynecol 2008;199:36 e1–5. 31. Lewis G, editor. Confidential enquiry into maternal and child health (CEMACH). Saving mothers’ lives: reviewing materal deaths to make motherhood safer – 2003–2005. London: CEMACH; 2007. 32. Rodgers A, Walker N, Schug S, et al. Reduction of postoperative mortality and morbidity with epidural or spinal anaesthesia: results from overview of randomised trials. BMJ 2000;321: 1493. 33. Roderick P, Ferris G, Wilson K, et al. Towards evidence-based guidelines for the prevention of venous thromboembolism:
Controversies
34.
35.
36.
37. 38.
39. 40.
41.
42.
43.
systematic reviews of mechanical methods, oral anticoagulation, dextran and regional anaesthesia as thromboprophylaxis. Health Technol Assess 2005;9:iii–iv, ix–x, 1–78. Brandsborg B, Nikolajsen L, Hansen CT, Kehlet H, Jensen TS. Risk factors for chronic pain after hysterectomy: a nationwide questionnaire and database study. Anesthesiology 2007;106: 1003–12. Reynolds F, Seed PT. Anaesthesia for caesarean section and neonatal acid-base status: a meta-analysis. Anaesthesia 2005;60: 636–53. Lee A, Ngan Kee WD, Gin T. A quantitative, systematic review of randomized controlled trials of ephedrine versus phenylephrine for the management of hypotension during spinal anesthesia for cesarean delivery. Anesth Analg 2002;94:920–6. Lie B, Juul J. Effect of epidural vs. general anesthesia on breastfeeding. Acta Obstet Gynecol Scand 1988;67:207–9. Camann W. Labor analgesia and breast feeding: avoid parenteral narcotics and provide lactation support. Int J Obstet Anesth 2007;16:199–201. Thomson AJ, Webb DJ, Maxwell SR, Grant IS. Oxygen therapy in acute medical care. BMJ 2002;324:1406–7. Tan A, Schulze A, O’Donnell CP, Davis PG. Air versus oxygen for resuscitation of infants at birth. Cochrane Database Syst Rev 2005:CD002273. Khaw KS, Wang CC, Ngan Kee WD, Pang CP, Rogers MS. Effects of high inspired oxygen fraction during elective caesarean section under spinal anaesthesia on maternal and fetal oxygenation and lipid peroxidation. Br J Anaesth 2002;88:18–23. Perouansky M. General anesthetics and long-term neurotoxicity. Modern anesthetics: handbook of experimental pharmacology. Berlin: Springer; 2008. p. 143–57. Mellon RD, Simone AF, Rappaport BA. Use of anesthetic agents in neonates and young children. Anesth Analg 2007;104:509–20.
0959-289X/$ - see front matter
c 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijoa.2009.10.002
Opposer: Felicity Reynolds St Thomas’ Hospital, London, UK
I would not for one moment deny that regional anesthesia is superior to general anesthesia for elective cesarean section. It is not only preferable as an experience for the mother who wishes to witness the birth of her baby and to share the experience with her partner, it is also safer in many respects. But this does not imply that general anesthesia is unacceptable. Such an idea must be a hangover from times when techniques were used that would, today, certainly be regarded as unacceptable. They were, by modern standards, downright dangerous and are largely responsible for creating a climate of fear around general anesthesia in obstetrics.
Historical perspective Yes, techniques long abandoned would nowadays be regarded as unacceptable. When in 1961 I first anestheAccepted October 2009 E-mail address: [email protected]
tized obstetric patients, cesarean section was rare, and most patients needed our services for forceps delivery, retained placenta, vaginal delivery of the after-coming head or the second twin. For breech or second twin one was usually presented with a woman already in the lithotomy position, and a certain urgency. The received procedure was to give ‘‘a quick whiff’’ of cyclopropane – wonderfully swift and effective! For the rest, slightly more conventional general anesthesia was the norm, although cricoids pressure, first described only in 1961,1 came into general use later. To avoid aspiration of gastric contents, we were taught to induce patients either in the steep head-up position, in the hope that refluxed gastric contents would not rise up as far as the pharynx, or in the left lateral head-down position, so that gastric contents would trickle out of the mouth and not be inhaled. In the first six months of training we were told not to attempt intubation if on our own, as we might find it difficult, but rather to use mask
Controversies
213 aspiration
Failed intubation ↓ Maintain cricoid pressure ↓ Head down left side ↓ O2 + IPPV + aspirate pharynx
other
50 45
Number of deaths
40 35 30 25 20 15 10 5 0 53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 1
4
Middle year of triennium
Fig. 1 Maternal deaths due to anesthesia from 1952-1984 in England and Wales, and from 1985-2005 in the UK. The subgroup ‘aspiration’ refers to death due to aspiration of gastric contents. Data derived from all reports on confidential enquiries into maternal deaths from 1952-4 to 2003-5.
anesthesia with ether. For maintenance of anesthesia there was no calibrated vaporizer, no mechanical ventilator, no automated blood pressure machine, no pulse oximeter, no capnography to detect esophageal intubation, no etc. etc. Now that was unacceptable. It was in this climate that maternal deaths from general anesthesia soared.2 Detailed audit of maternal deaths in the UK since 1952 showed that initially the main cause of anesthetic death was aspiration of gastric contents (Fig. 1), but the advice that all mothers should be intubated merely added death from failed intubation to the numbers. Moreover the advent of cricoids pressure apparently did little to help.
Things ain’t what they used to be But all that has changed. Equipment and techniques have improved. Anesthesia in general, and airway management in particular, have become immeasurably safer in recent years, thanks to a number of crucial advances. Failed intubation drill: A situation culminating in maternal death, in which a series of progressively more senior anesthesiologists would queue up to attempt to intubate, while cricoid pressure was obsessively maintained, led Michael Tunstall to describe the first failed intubation drill in 1976 (Fig. 2).3 More elaborate versions have since been described,4 and the problem has been further refined into difficulty with laryngoscopy, with intubation and with ventilation. All schemes provide a framework for calm planned action to avert loss of life. Aids to airway establishment: The bougie is a simple but invaluable tool that has been around a long time; it is still probably the most important aid to difficult intubation, though sometimes overlooked. The esophageal gastric tube airway was one of the first gadgets used
obstruction persists? ↓ release cricoid ↓ obstruction persists ↓ awaken ↓
no obstruction
↓
bag and mask aspirate stomach
inhalational anesthesia
consider regional
Fig. 2 Graphic representation of the failed intubation drill described by Tunstall in 1976.3
to overcome difficult intubation,5 but has since been superseded by the laryngeal mask airway, with all its current modifications and developments, one of the great life-savers of our time. There is fiberoptic intubation, and simulator training to teach this and failed intubation drills in general; there are now more gadgets and techniques than I have even heard of. I have to say: ‘‘What more do you want?’’ Aids to airway assessment: The Mallampati score was described in 1985,6 and since then many other signs to predict difficult intubation have been established, including short neck or restricted head and neck movement, obesity, protruding maxillary teeth, receding mandible, poor mouth opening, facial edema and swollen tongue.7–9 Examination of combinations of these factors can go a long way to predicting difficult laryngoscopy, though sensitivity and selectivity vary with operator skill. It must be remembered that we are concerned with elective cesarean section. There is all the time in the world to assess the airway and assemble the necessary gadgets and skilled help if problems are anticipated. Other factors in the decline of aspiration as a cause of death: In addition cricoid pressure, antacid prophylaxis, most importantly ranitidine, and starvation during labor (not to mention the decline in the use of general anesthesia) may all have contributed to the improved outcome evident in Fig. 1, but improvement there has certainly been.
Indications for general anesthesia for elective cesarean section Despite the rise in popularity of spinal anesthesia, general anesthesia may be needed for a small but irreducible number of elective cesarean sections:10
214
Controversies
In the presence of infection. Though the danger of neuraxial anesthesia in the presence of systemic and distant infection appears to be slight, local skin infection is still considered a contraindication. Certainly neuraxial infection is one of the most important complications of neuraxial anesthesia.11 In the presence of coagulopathy. Patients for elective cesarean section may be encountered with conditions such as Von Willebrand disease and idiopathic thrombocytopenia.10 In the presence of skeletal abnormality. Those with severe scoliosis not only pose a problem for neuraxial block insertion, they are often unable to breath spontaneously when lying flat, so general anesthesia may be preferable on all counts.12 A tethered cord may be damaged not only by a spinal needle, but also by an attempted epidural insertion, and therefore should, if recognized, be an absolute contraindication to neuraxial anesthesia.13 When the mother insists on being asleep. Admittedly this becomes a rarity once regional anesthesia is estab-
Table 1 section
Indications for general anesthesia for cesarean Tsen et al. 199810
Total number of general anesthetics (percent of all cesarean sections)
538 (4.5%)
Indication n (percent of general Need for speed Obstetrician’s request Failed neuraxial block Maternal request Maternal condition
anesthetics) 269 (50%)
Table 2
59 (11%) 28 (5.2%) 182 (34%)
McDonnell et al. 200815 1095 (7.6%)
471 321 272 260 502
(43%) (29%) (25%) (24%) (46%)
lished in any population, but it still occurs.10 Overpersuading a reluctant mother to remain awake is a potential cause of post traumatic stress disorder and litigation. I myself encountered several cases in my medical negligence practice. When regional anesthesia fails. Even in well-regulated circles this still arises occasionally. Regional anesthesia may fail because of haste, ineptitude or skeletal deformity. Although failure is commoner in emergency cases, conversion to general anesthesia is still needed in about 0.5-1% of elective cesarean deliveries.10,14,15 Several teams have examined why general anesthesia is still given; the indications for general anesthesia derived from two surveys, one from a single center of excellence,10 one multicenter,16 are summarized in Table 1. True the indication most frequently cited, the need for speed, is not applicable to the present argument, but failed regional, maternal request and maternal condition may well apply to elective surgery. In the survey from Boston,10 maternal conditions cited that were applicable to elective cesarean section were neurologic (6), coagulopathy (18), infection (25), bad back (14), allergy to local anesthetic (1) and repeat cesarean section (6). Even in the best regulated centers general anesthesia is still needed from time to time, so how can we maintain that it is unacceptable?
Complications My opponent has ably described the many and serious complications of general anesthesia, and I would not deny them. These complications have, however, become rarer in recent years (see below, under Maternal mortality) and cannot be presumed to render general anesthesia unacceptable. Moreover, the elective situation offers plenty of time to take a thorough history and consider
Litigation in obstetric anesthesia USA Closed Claims Chadwick 1996 Regional
Maternal death Maternal brain damage Newborn death Newborn brain damage Aspiration Nerve damage Pain/awareness Headache Back pain Emotional distress Drug errors Other (not specified) Totals
31 17 16 51 2 38 36 61 36 23
311
16
General 52 14 8 28 18 5 0 2 0 8
135
UK NHS Litigation 17
Ashpole 200818
Ross 2003 Regional 10 9 5 19 1 17 13 22 16 9
121
General 37 21 8 24 11 4 1 1 0 7
114
Regional
General
0
4
13 51
0 21
4
0
10 12
1 0
90
26
Controversies
215
options, to examine the airway and prepare all the equipment that may be held in readiness to secure it. I must also point out that regional anesthesia is far from perfect; it may produce complications that range from tiresome to life-threatening. We can ignore the dangers of the large doses of local anesthetic that are needed for epidural anesthesia, as not applicable to elective surgery, but even spinal anesthesia may be associated with hypotension, nausea, pruritus, intraoperative pain, headache, cranial nerve palsy, nerve root damage, conus damage, meningitis and, probably worst of all, cauda equine syndrome due to neurotoxicity. Surely not the blameless paragon my opponent might imply! Litigation: Table 2 shows that the numbers of malpractice suits in the US17,18 and cases of litigation in the UK19 related to regional anesthesia in obstetrics outnumber those related to general anesthesia. True, more serious cases involve general anesthesia, and the denominators are greater for neuraxial blockade. Nevertheless mothers seem more inclined to resent their care when they have been conscious than when they have been asleep. Imperfect neuraxial anesthesia is far commoner than awareness during general anesthesia. The latter, moreover, is readily amenable to the use of a correct technique. It is regrettable that anesthesiologists have thought it necessary to skimp on dosages in general anesthesia for fear of anesthetizing the baby. Neonatal sedation from maternal general anesthesia is short-lived and reversible (see below: What about the baby?). It is far more important to achieve complete maternal anesthesia and to reduce maternal stress, which is damaging to the fetus. Maternal mortality: A lower mortality rate with neuraxial than with general anesthesia is often cited as a reason to favor the former. In 1997 Hawkins et al.
demonstrated an increasing fatality rate with general anesthesia and an increasing risk of death with general compared with neuraxial anesthesia.20 The situation has, however, greatly improved since then (Fig. 3).20,21 Between 1985-1990 and 1997-2002 the risk ratio declined from 16.7 to 1.7. To discover specifically about elective cesarean section, however, it is necessary to turn to UK data. Though the cesarean section rate has increased about 10-fold in the 54 years of continuous data collection, the death rate has declined (Fig. 4). Only a minority of those deaths were due to anesthesia, and many anesthetic deaths in the early years were not associated with cesarean section (Fig. 5). When, in addition, one eliminates emergency cesarean sections, the 450 400
total deaths associated with cesarean section
350
deaths per 100 000 cesarean sections
300 250 200 150 100 50 0 53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 1
Middle year of each triennium
Fig. 4 Deaths and death rate associated with cesarean section from 1952-1984 in England and Wales, and from 1985-2005 in the UK. Death rates are missing in some of the later years for which the total numbers of operations are unknown. Data derived from all reports on confidential enquiries into maternal deaths from 1952-4 to 2003-5.
all anesthetic
Fatality rate per million anesthetics (Risk ratio)
4
CS anesthetic
elective GA only
50 45 general
regional
relative risk
40
35
35
30
30
25
25 20
20
15
15
10
10
5 0
5
53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 1
4
Middle year of each triennium
0 79-84
85-90
91-96
97-02
Year
Fig. 3 Fatality rates for general and neuraxial anesthesia and the relative risk of general compared to neuraxial anesthesia in the US, as reported in six-yearly tranches by Hawkins et al.20,21
Fig. 5 Deaths due to anesthesia, deaths due to anesthesia for cesarean (CS anesthetic) section and deaths due to general anesthesia for elective cesarean section (elective GA only) from 1952-1984 in England and Wales, and from 1985-2005 in the UK. Data derived from all reports on confidential enquiries into maternal deaths from 1952-4 to 2003-5.
216
Controversies
numbers become very small. Reviewing data relating to the last 21 years, a period when there were 15 377 009 births, there were 34 death directly attributed to anesthesia, nineteen of which followed general anesthesia for cesarean delivery, but in only three of these was the operation elective.2,22 During this time one might estimate that about 300,000 elective cesarean sections had been conducted under general anesthesia.14 Not a colossal slaughter.
What about the baby? It is often supposed that, as spinal anesthesia has many advantages for the mother, it must be best for the baby. Seven studies have found that general anesthesia reduces the one-minute Apgar score, but by five minutes these studies found no significant difference in Apgar score between regional and general anesthesia.23 Moreover, many more studies have shown no significant difference at 1 or 5 minutes (all cited in reference 23). The baby readily recovers or can be resuscitated from even pro-
(a) Adams Datta Dyer Matorras Gokpinar Hodgson Kolatat Wallace Kavak Petropoulos Ratcliffe Abboud Krishnan Combined -0.15
-0.1
-0.05
0
0.05
0.1
Difference in pH
← Favours GA ←
(b)
longed general anesthesia, as we know from experience with the EXIT procedure. Moreover, meta-analysis of acid-base data shows that general anesthesia is associated with significantly better umbilical artery pH and base deficit than is spinal anesthesia (Fig. 6a and b) This analysis relies mainly on randomized trials, most of which were conducted in elective surgery. It cannot therefore be justified to claim that spinal anesthesia is better for the baby. In this respect general anesthesia must be considered thoroughly acceptable, if not highly respectable! My opponent cites the dangers of hyperoxia and of neurotoxicity to the neonate. Hyperoxia is surely not a problem created by the use of general anesthesia per se. The danger of neurotoxicity to the developing brain (accelerated apoptosis) is not one I would lose any sleep over. Let us start worrying about that if any such damage is ever actually demonstrated in human babies.
Conclusions General anesthesia is needed if regional anesthesia fails, is impossible or contraindicated. It is ill-advised, therefore, to imply to a mother that it is unacceptable. Moreover, if general anesthesia is acceptable in emergencies and in sick obstetric patients, it must be all the more acceptable in elective surgery, which is both safer and happens in office hours, often in the presence of a more experienced anesthesiologist. The elective situation offers plenty of time to take a thorough history and examine the airway, to consider options and prepare specialized equipment. Regional anesthesia has its own complications and often provokes litigation. Techniques, equipment and outcome of general anesthesia have improved to an extent that it is now much safer than it once was. There is no evidence of lasting detriment to the baby, just the reverse. The following scenario is therefore unacceptable:
Dyer Matorras Gokpinar Kolatat
You simply cannot say:
Ratcliffe
“We will give you a spinal because it is safest and best. General anesthesia is unacceptable.”
Abboud Krishnan
Combined -2
0
2
4
Favours GA →
Fig. 6 Meta-analysis of (a) umbilical artery pH values and (b) base deficit, from trials comparing spinal with general anesthesia. Data from Reynolds and Seed (2005).23
Controversies Twenty minutes later……
“Now we are going to give you a general anesthetic.”
Of course we need to keep our options open and affirm that general anesthesia for elective cesarean section is perfectly acceptable.
References 1. Sellick BA. Cricoid pressure to control regurgitation of stomach contents during induction of anaesthesia. Lancet 1961;2(7199): 404–6. 2. Morris S, Harmer M, Reynolds F. The impact of regional anaesthesia on maternal mortality. In: Reynolds F, editor. Regional analgesia in obstetrics. London: Springer; 2000. p. 347–56. 3. Tunstall ME. Failed intubation drill. Anaesthesia 1976;31:850. 4. Harmer M. Difficult and failed intubation in obstetrics. Int J Obstet Anesth 1997;6:25–31. 5. Tunstall ME, Geddes C. ‘‘Failed intubation’’ in obstetric anaesthesia. An indication for use of the ‘‘Oesophageal gastric tube airway’’. Br J Anaesth 1984;56:659–61. 6. Mallampati SR, Gatt SP, Gugino LD et al. A clinical sign to predict difficult tracheal intubation: a prospective study. Can Anaesth Soc J 1985;32:429–34. 7. Wilson ME, Spiegelhalter D, Robertson JA, Lesser P. Predicting difficult intubation. Br J Anaesth 1988;61:211–6. 8. Rocke DA, Murray WB, Rout CC, Gouws E. Relative risk analysis of factors associated with difficult intubation in obstetric anesthesia. Anesthesiology 1992;77:67–73. 9. Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normal patients: a metaanalysis of bedside screening test performance. Anesthesiology 2005;103:429–37.
217 10. Tsen LC, Pitner R, Camann WR. General anesthesia for cesarean section at a tertiary care hospital 1990–1995: indications and implications. Int J Obstet Anesth 1998;7:147–52. 11. Lee LA, Posner KL, Domino KB, Caplan RA, Cheney FW. Injuries associated with regional anesthesia in the 1980s and 1990s. Anesthesiology 2004;101:143–52. 12. Reynolds F. Peripheral Neuropathy. In: Gambling DR, Douglas R, McKay R, editors. Obstetric Anesthesia and Uncommon Disorders. 2nd ed. Philadelphia: WB Saunders; 2008. p. 215–27. 13. Reynolds F. Litigation in obstetric regional anaesthesia. In: Van Zurdert A, editor. Highlights in Pain Therapy and Regional Anaesthesia V. Barcelona: Publicidad Permanyer; 1996. p. 39–43. 14. Shibli KU, Russell IF. A survey of anaesthetic techniques used for caesarean section in the UK in 1997. Int J Obstet Anesth 2000;9:160–7. 15. Reide PJW, Durbridge J, Yentis SM. Conversion from regional to general anaesthesia for emergency and elective caesarean section. Int J Obstet Anesth 2008;17:S32. 16. McDonnell NJ, Paech MJ, Clavisi OM, Scott KL and the ANZCA Trials Group. Difficult and failed intubation in obstetric anaesthesia: an observational study of airway management and complications associated with general anaesthesia for caesarean section. Int J Obstet Anesth 2008;17. 17. Chadwick HS. An analysis of obstetric anesthesia cases from the American Society of Anesthesiologist closed claims project database. Int J Obstet Anesth 1996;5:258–63. 18. Ross BK. ASA closed claims in obstetrics: lessons learnt. Anesthesiol Clin N Am 2003;21:183–97. 19. Ashpole K, Yentis SM, Scott S, Mihai R, Cook TM. NHS litigation authority claims associated with caesarean sections. Int J Obstet Anesth 2008;17:52. 20. Hawkins JL, Koonin LM, Palmer SK, Gibbs CP. Anesthesiarelated deaths during obstetric delivery in the United States, 1979– 1990. Anesthesiology 1997;86:277–84. 21. Hawkins JL, Chang J, Palmer SK, Callahan WM, Gibbs CP. Anesthesia-related maternal mortality in the United States, 1997– 2002. Presented an the annual meeting of SOAP in Chicago; 2008: A10. 22. Lewis, G (ed) 2007. The Confidential Enquiry into Maternal and Child Health (CEMACH). Saving Mothers’ Lives: reviewing maternal deaths to make motherhood safer – 2003-2005. The Seventh Report on Confidential Enquiries into Maternal Deaths in the United Kingdom. London: CEMACH. 23. Reynolds F, Seed PT. Anaesthesia for caesarean section and neonatal acid-base status: a meta-analysis. Anaesthesia 2005;60: 636–53. 0959-289X/$ - see front matter c 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijoa.2009.10.003
Controversies
34.
35.
36.
37. 38.
39. 40.
41.
42.
43.
systematic reviews of mechanical methods, oral anticoagulation, dextran and regional anaesthesia as thromboprophylaxis. Health Technol Assess 2005;9:iii–iv, ix–x, 1–78. Brandsborg B, Nikolajsen L, Hansen CT, Kehlet H, Jensen TS. Risk factors for chronic pain after hysterectomy: a nationwide questionnaire and database study. Anesthesiology 2007;106: 1003–12. Reynolds F, Seed PT. Anaesthesia for caesarean section and neonatal acid-base status: a meta-analysis. Anaesthesia 2005;60: 636–53. Lee A, Ngan Kee WD, Gin T. A quantitative, systematic review of randomized controlled trials of ephedrine versus phenylephrine for the management of hypotension during spinal anesthesia for cesarean delivery. Anesth Analg 2002;94:920–6. Lie B, Juul J. Effect of epidural vs. general anesthesia on breastfeeding. Acta Obstet Gynecol Scand 1988;67:207–9. Camann W. Labor analgesia and breast feeding: avoid parenteral narcotics and provide lactation support. Int J Obstet Anesth 2007;16:199–201. Thomson AJ, Webb DJ, Maxwell SR, Grant IS. Oxygen therapy in acute medical care. BMJ 2002;324:1406–7. Tan A, Schulze A, O’Donnell CP, Davis PG. Air versus oxygen for resuscitation of infants at birth. Cochrane Database Syst Rev 2005:CD002273. Khaw KS, Wang CC, Ngan Kee WD, Pang CP, Rogers MS. Effects of high inspired oxygen fraction during elective caesarean section under spinal anaesthesia on maternal and fetal oxygenation and lipid peroxidation. Br J Anaesth 2002;88:18–23. Perouansky M. General anesthetics and long-term neurotoxicity. Modern anesthetics: handbook of experimental pharmacology. Berlin: Springer; 2008. p. 143–57. Mellon RD, Simone AF, Rappaport BA. Use of anesthetic agents in neonates and young children. Anesth Analg 2007;104:509–20.
0959-289X/$ - see front matter
c 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijoa.2009.10.002
Opposer: Felicity Reynolds St Thomas’ Hospital, London, UK
I would not for one moment deny that regional anesthesia is superior to general anesthesia for elective cesarean section. It is not only preferable as an experience for the mother who wishes to witness the birth of her baby and to share the experience with her partner, it is also safer in many respects. But this does not imply that general anesthesia is unacceptable. Such an idea must be a hangover from times when techniques were used that would, today, certainly be regarded as unacceptable. They were, by modern standards, downright dangerous and are largely responsible for creating a climate of fear around general anesthesia in obstetrics.
Historical perspective Yes, techniques long abandoned would nowadays be regarded as unacceptable. When in 1961 I first anestheAccepted October 2009 E-mail address: [email protected]
tized obstetric patients, cesarean section was rare, and most patients needed our services for forceps delivery, retained placenta, vaginal delivery of the after-coming head or the second twin. For breech or second twin one was usually presented with a woman already in the lithotomy position, and a certain urgency. The received procedure was to give ‘‘a quick whiff’’ of cyclopropane – wonderfully swift and effective! For the rest, slightly more conventional general anesthesia was the norm, although cricoids pressure, first described only in 1961,1 came into general use later. To avoid aspiration of gastric contents, we were taught to induce patients either in the steep head-up position, in the hope that refluxed gastric contents would not rise up as far as the pharynx, or in the left lateral head-down position, so that gastric contents would trickle out of the mouth and not be inhaled. In the first six months of training we were told not to attempt intubation if on our own, as we might find it difficult, but rather to use mask
Controversies
213 aspiration
Failed intubation ↓ Maintain cricoid pressure ↓ Head down left side ↓ O2 + IPPV + aspirate pharynx
other
50 45
Number of deaths
40 35 30 25 20 15 10 5 0 53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 1
4
Middle year of triennium
Fig. 1 Maternal deaths due to anesthesia from 1952-1984 in England and Wales, and from 1985-2005 in the UK. The subgroup ‘aspiration’ refers to death due to aspiration of gastric contents. Data derived from all reports on confidential enquiries into maternal deaths from 1952-4 to 2003-5.
anesthesia with ether. For maintenance of anesthesia there was no calibrated vaporizer, no mechanical ventilator, no automated blood pressure machine, no pulse oximeter, no capnography to detect esophageal intubation, no etc. etc. Now that was unacceptable. It was in this climate that maternal deaths from general anesthesia soared.2 Detailed audit of maternal deaths in the UK since 1952 showed that initially the main cause of anesthetic death was aspiration of gastric contents (Fig. 1), but the advice that all mothers should be intubated merely added death from failed intubation to the numbers. Moreover the advent of cricoids pressure apparently did little to help.
Things ain’t what they used to be But all that has changed. Equipment and techniques have improved. Anesthesia in general, and airway management in particular, have become immeasurably safer in recent years, thanks to a number of crucial advances. Failed intubation drill: A situation culminating in maternal death, in which a series of progressively more senior anesthesiologists would queue up to attempt to intubate, while cricoid pressure was obsessively maintained, led Michael Tunstall to describe the first failed intubation drill in 1976 (Fig. 2).3 More elaborate versions have since been described,4 and the problem has been further refined into difficulty with laryngoscopy, with intubation and with ventilation. All schemes provide a framework for calm planned action to avert loss of life. Aids to airway establishment: The bougie is a simple but invaluable tool that has been around a long time; it is still probably the most important aid to difficult intubation, though sometimes overlooked. The esophageal gastric tube airway was one of the first gadgets used
obstruction persists? ↓ release cricoid ↓ obstruction persists ↓ awaken ↓
no obstruction
↓
bag and mask aspirate stomach
inhalational anesthesia
consider regional
Fig. 2 Graphic representation of the failed intubation drill described by Tunstall in 1976.3
to overcome difficult intubation,5 but has since been superseded by the laryngeal mask airway, with all its current modifications and developments, one of the great life-savers of our time. There is fiberoptic intubation, and simulator training to teach this and failed intubation drills in general; there are now more gadgets and techniques than I have even heard of. I have to say: ‘‘What more do you want?’’ Aids to airway assessment: The Mallampati score was described in 1985,6 and since then many other signs to predict difficult intubation have been established, including short neck or restricted head and neck movement, obesity, protruding maxillary teeth, receding mandible, poor mouth opening, facial edema and swollen tongue.7–9 Examination of combinations of these factors can go a long way to predicting difficult laryngoscopy, though sensitivity and selectivity vary with operator skill. It must be remembered that we are concerned with elective cesarean section. There is all the time in the world to assess the airway and assemble the necessary gadgets and skilled help if problems are anticipated. Other factors in the decline of aspiration as a cause of death: In addition cricoid pressure, antacid prophylaxis, most importantly ranitidine, and starvation during labor (not to mention the decline in the use of general anesthesia) may all have contributed to the improved outcome evident in Fig. 1, but improvement there has certainly been.
Indications for general anesthesia for elective cesarean section Despite the rise in popularity of spinal anesthesia, general anesthesia may be needed for a small but irreducible number of elective cesarean sections:10
214
Controversies
In the presence of infection. Though the danger of neuraxial anesthesia in the presence of systemic and distant infection appears to be slight, local skin infection is still considered a contraindication. Certainly neuraxial infection is one of the most important complications of neuraxial anesthesia.11 In the presence of coagulopathy. Patients for elective cesarean section may be encountered with conditions such as Von Willebrand disease and idiopathic thrombocytopenia.10 In the presence of skeletal abnormality. Those with severe scoliosis not only pose a problem for neuraxial block insertion, they are often unable to breath spontaneously when lying flat, so general anesthesia may be preferable on all counts.12 A tethered cord may be damaged not only by a spinal needle, but also by an attempted epidural insertion, and therefore should, if recognized, be an absolute contraindication to neuraxial anesthesia.13 When the mother insists on being asleep. Admittedly this becomes a rarity once regional anesthesia is estab-
Table 1 section
Indications for general anesthesia for cesarean Tsen et al. 199810
Total number of general anesthetics (percent of all cesarean sections)
538 (4.5%)
Indication n (percent of general Need for speed Obstetrician’s request Failed neuraxial block Maternal request Maternal condition
anesthetics) 269 (50%)
Table 2
59 (11%) 28 (5.2%) 182 (34%)
McDonnell et al. 200815 1095 (7.6%)
471 321 272 260 502
(43%) (29%) (25%) (24%) (46%)
lished in any population, but it still occurs.10 Overpersuading a reluctant mother to remain awake is a potential cause of post traumatic stress disorder and litigation. I myself encountered several cases in my medical negligence practice. When regional anesthesia fails. Even in well-regulated circles this still arises occasionally. Regional anesthesia may fail because of haste, ineptitude or skeletal deformity. Although failure is commoner in emergency cases, conversion to general anesthesia is still needed in about 0.5-1% of elective cesarean deliveries.10,14,15 Several teams have examined why general anesthesia is still given; the indications for general anesthesia derived from two surveys, one from a single center of excellence,10 one multicenter,16 are summarized in Table 1. True the indication most frequently cited, the need for speed, is not applicable to the present argument, but failed regional, maternal request and maternal condition may well apply to elective surgery. In the survey from Boston,10 maternal conditions cited that were applicable to elective cesarean section were neurologic (6), coagulopathy (18), infection (25), bad back (14), allergy to local anesthetic (1) and repeat cesarean section (6). Even in the best regulated centers general anesthesia is still needed from time to time, so how can we maintain that it is unacceptable?
Complications My opponent has ably described the many and serious complications of general anesthesia, and I would not deny them. These complications have, however, become rarer in recent years (see below, under Maternal mortality) and cannot be presumed to render general anesthesia unacceptable. Moreover, the elective situation offers plenty of time to take a thorough history and consider
Litigation in obstetric anesthesia USA Closed Claims Chadwick 1996 Regional
Maternal death Maternal brain damage Newborn death Newborn brain damage Aspiration Nerve damage Pain/awareness Headache Back pain Emotional distress Drug errors Other (not specified) Totals
31 17 16 51 2 38 36 61 36 23
311
16
General 52 14 8 28 18 5 0 2 0 8
135
UK NHS Litigation 17
Ashpole 200818
Ross 2003 Regional 10 9 5 19 1 17 13 22 16 9
121
General 37 21 8 24 11 4 1 1 0 7
114
Regional
General
0
4
13 51
0 21
4
0
10 12
1 0
90
26
Controversies
215
options, to examine the airway and prepare all the equipment that may be held in readiness to secure it. I must also point out that regional anesthesia is far from perfect; it may produce complications that range from tiresome to life-threatening. We can ignore the dangers of the large doses of local anesthetic that are needed for epidural anesthesia, as not applicable to elective surgery, but even spinal anesthesia may be associated with hypotension, nausea, pruritus, intraoperative pain, headache, cranial nerve palsy, nerve root damage, conus damage, meningitis and, probably worst of all, cauda equine syndrome due to neurotoxicity. Surely not the blameless paragon my opponent might imply! Litigation: Table 2 shows that the numbers of malpractice suits in the US17,18 and cases of litigation in the UK19 related to regional anesthesia in obstetrics outnumber those related to general anesthesia. True, more serious cases involve general anesthesia, and the denominators are greater for neuraxial blockade. Nevertheless mothers seem more inclined to resent their care when they have been conscious than when they have been asleep. Imperfect neuraxial anesthesia is far commoner than awareness during general anesthesia. The latter, moreover, is readily amenable to the use of a correct technique. It is regrettable that anesthesiologists have thought it necessary to skimp on dosages in general anesthesia for fear of anesthetizing the baby. Neonatal sedation from maternal general anesthesia is short-lived and reversible (see below: What about the baby?). It is far more important to achieve complete maternal anesthesia and to reduce maternal stress, which is damaging to the fetus. Maternal mortality: A lower mortality rate with neuraxial than with general anesthesia is often cited as a reason to favor the former. In 1997 Hawkins et al.
demonstrated an increasing fatality rate with general anesthesia and an increasing risk of death with general compared with neuraxial anesthesia.20 The situation has, however, greatly improved since then (Fig. 3).20,21 Between 1985-1990 and 1997-2002 the risk ratio declined from 16.7 to 1.7. To discover specifically about elective cesarean section, however, it is necessary to turn to UK data. Though the cesarean section rate has increased about 10-fold in the 54 years of continuous data collection, the death rate has declined (Fig. 4). Only a minority of those deaths were due to anesthesia, and many anesthetic deaths in the early years were not associated with cesarean section (Fig. 5). When, in addition, one eliminates emergency cesarean sections, the 450 400
total deaths associated with cesarean section
350
deaths per 100 000 cesarean sections
300 250 200 150 100 50 0 53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 1
Middle year of each triennium
Fig. 4 Deaths and death rate associated with cesarean section from 1952-1984 in England and Wales, and from 1985-2005 in the UK. Death rates are missing in some of the later years for which the total numbers of operations are unknown. Data derived from all reports on confidential enquiries into maternal deaths from 1952-4 to 2003-5.
all anesthetic
Fatality rate per million anesthetics (Risk ratio)
4
CS anesthetic
elective GA only
50 45 general
regional
relative risk
40
35
35
30
30
25
25 20
20
15
15
10
10
5 0
5
53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 1
4
Middle year of each triennium
0 79-84
85-90
91-96
97-02
Year
Fig. 3 Fatality rates for general and neuraxial anesthesia and the relative risk of general compared to neuraxial anesthesia in the US, as reported in six-yearly tranches by Hawkins et al.20,21
Fig. 5 Deaths due to anesthesia, deaths due to anesthesia for cesarean (CS anesthetic) section and deaths due to general anesthesia for elective cesarean section (elective GA only) from 1952-1984 in England and Wales, and from 1985-2005 in the UK. Data derived from all reports on confidential enquiries into maternal deaths from 1952-4 to 2003-5.
216
Controversies
numbers become very small. Reviewing data relating to the last 21 years, a period when there were 15 377 009 births, there were 34 death directly attributed to anesthesia, nineteen of which followed general anesthesia for cesarean delivery, but in only three of these was the operation elective.2,22 During this time one might estimate that about 300,000 elective cesarean sections had been conducted under general anesthesia.14 Not a colossal slaughter.
What about the baby? It is often supposed that, as spinal anesthesia has many advantages for the mother, it must be best for the baby. Seven studies have found that general anesthesia reduces the one-minute Apgar score, but by five minutes these studies found no significant difference in Apgar score between regional and general anesthesia.23 Moreover, many more studies have shown no significant difference at 1 or 5 minutes (all cited in reference 23). The baby readily recovers or can be resuscitated from even pro-
(a) Adams Datta Dyer Matorras Gokpinar Hodgson Kolatat Wallace Kavak Petropoulos Ratcliffe Abboud Krishnan Combined -0.15
-0.1
-0.05
0
0.05
0.1
Difference in pH
← Favours GA ←
(b)
longed general anesthesia, as we know from experience with the EXIT procedure. Moreover, meta-analysis of acid-base data shows that general anesthesia is associated with significantly better umbilical artery pH and base deficit than is spinal anesthesia (Fig. 6a and b) This analysis relies mainly on randomized trials, most of which were conducted in elective surgery. It cannot therefore be justified to claim that spinal anesthesia is better for the baby. In this respect general anesthesia must be considered thoroughly acceptable, if not highly respectable! My opponent cites the dangers of hyperoxia and of neurotoxicity to the neonate. Hyperoxia is surely not a problem created by the use of general anesthesia per se. The danger of neurotoxicity to the developing brain (accelerated apoptosis) is not one I would lose any sleep over. Let us start worrying about that if any such damage is ever actually demonstrated in human babies.
Conclusions General anesthesia is needed if regional anesthesia fails, is impossible or contraindicated. It is ill-advised, therefore, to imply to a mother that it is unacceptable. Moreover, if general anesthesia is acceptable in emergencies and in sick obstetric patients, it must be all the more acceptable in elective surgery, which is both safer and happens in office hours, often in the presence of a more experienced anesthesiologist. The elective situation offers plenty of time to take a thorough history and examine the airway, to consider options and prepare specialized equipment. Regional anesthesia has its own complications and often provokes litigation. Techniques, equipment and outcome of general anesthesia have improved to an extent that it is now much safer than it once was. There is no evidence of lasting detriment to the baby, just the reverse. The following scenario is therefore unacceptable:
Dyer Matorras Gokpinar Kolatat
You simply cannot say:
Ratcliffe
“We will give you a spinal because it is safest and best. General anesthesia is unacceptable.”
Abboud Krishnan
Combined -2
0
2
4
Favours GA →
Fig. 6 Meta-analysis of (a) umbilical artery pH values and (b) base deficit, from trials comparing spinal with general anesthesia. Data from Reynolds and Seed (2005).23
Controversies Twenty minutes later……
“Now we are going to give you a general anesthetic.”
Of course we need to keep our options open and affirm that general anesthesia for elective cesarean section is perfectly acceptable.
References 1. Sellick BA. Cricoid pressure to control regurgitation of stomach contents during induction of anaesthesia. Lancet 1961;2(7199): 404–6. 2. Morris S, Harmer M, Reynolds F. The impact of regional anaesthesia on maternal mortality. In: Reynolds F, editor. Regional analgesia in obstetrics. London: Springer; 2000. p. 347–56. 3. Tunstall ME. Failed intubation drill. Anaesthesia 1976;31:850. 4. Harmer M. Difficult and failed intubation in obstetrics. Int J Obstet Anesth 1997;6:25–31. 5. Tunstall ME, Geddes C. ‘‘Failed intubation’’ in obstetric anaesthesia. An indication for use of the ‘‘Oesophageal gastric tube airway’’. Br J Anaesth 1984;56:659–61. 6. Mallampati SR, Gatt SP, Gugino LD et al. A clinical sign to predict difficult tracheal intubation: a prospective study. Can Anaesth Soc J 1985;32:429–34. 7. Wilson ME, Spiegelhalter D, Robertson JA, Lesser P. Predicting difficult intubation. Br J Anaesth 1988;61:211–6. 8. Rocke DA, Murray WB, Rout CC, Gouws E. Relative risk analysis of factors associated with difficult intubation in obstetric anesthesia. Anesthesiology 1992;77:67–73. 9. Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normal patients: a metaanalysis of bedside screening test performance. Anesthesiology 2005;103:429–37.
217 10. Tsen LC, Pitner R, Camann WR. General anesthesia for cesarean section at a tertiary care hospital 1990–1995: indications and implications. Int J Obstet Anesth 1998;7:147–52. 11. Lee LA, Posner KL, Domino KB, Caplan RA, Cheney FW. Injuries associated with regional anesthesia in the 1980s and 1990s. Anesthesiology 2004;101:143–52. 12. Reynolds F. Peripheral Neuropathy. In: Gambling DR, Douglas R, McKay R, editors. Obstetric Anesthesia and Uncommon Disorders. 2nd ed. Philadelphia: WB Saunders; 2008. p. 215–27. 13. Reynolds F. Litigation in obstetric regional anaesthesia. In: Van Zurdert A, editor. Highlights in Pain Therapy and Regional Anaesthesia V. Barcelona: Publicidad Permanyer; 1996. p. 39–43. 14. Shibli KU, Russell IF. A survey of anaesthetic techniques used for caesarean section in the UK in 1997. Int J Obstet Anesth 2000;9:160–7. 15. Reide PJW, Durbridge J, Yentis SM. Conversion from regional to general anaesthesia for emergency and elective caesarean section. Int J Obstet Anesth 2008;17:S32. 16. McDonnell NJ, Paech MJ, Clavisi OM, Scott KL and the ANZCA Trials Group. Difficult and failed intubation in obstetric anaesthesia: an observational study of airway management and complications associated with general anaesthesia for caesarean section. Int J Obstet Anesth 2008;17. 17. Chadwick HS. An analysis of obstetric anesthesia cases from the American Society of Anesthesiologist closed claims project database. Int J Obstet Anesth 1996;5:258–63. 18. Ross BK. ASA closed claims in obstetrics: lessons learnt. Anesthesiol Clin N Am 2003;21:183–97. 19. Ashpole K, Yentis SM, Scott S, Mihai R, Cook TM. NHS litigation authority claims associated with caesarean sections. Int J Obstet Anesth 2008;17:52. 20. Hawkins JL, Koonin LM, Palmer SK, Gibbs CP. Anesthesiarelated deaths during obstetric delivery in the United States, 1979– 1990. Anesthesiology 1997;86:277–84. 21. Hawkins JL, Chang J, Palmer SK, Callahan WM, Gibbs CP. Anesthesia-related maternal mortality in the United States, 1997– 2002. Presented an the annual meeting of SOAP in Chicago; 2008: A10. 22. Lewis, G (ed) 2007. The Confidential Enquiry into Maternal and Child Health (CEMACH). Saving Mothers’ Lives: reviewing maternal deaths to make motherhood safer – 2003-2005. The Seventh Report on Confidential Enquiries into Maternal Deaths in the United Kingdom. London: CEMACH. 23. Reynolds F, Seed PT. Anaesthesia for caesarean section and neonatal acid-base status: a meta-analysis. Anaesthesia 2005;60: 636–53. 0959-289X/$ - see front matter c 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijoa.2009.10.003