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Possible reasons for failed conversion of epidural analgesia into anaesthesia
- Niraj Sinha (21 July 2009)
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Conversion of epidural labour analgesia to anaesthesia for CS
- Parag Shastri, Venkatesh Annam, Ishwinder Suri (1 April 2009)
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Conversion of epidural labour analgesia to anaesthesia for Caesarean section
- James M Shannon, [ Patrick Thornton], [Heather Loane] [Jessica Tyler] [Roanne Preston] (22 January 2009)
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Labour epidural analgesia to epidural anaesthesia for emergency caesarean sections
- Stephen H. Halpern (22 January 2009)
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Labour epidural analgesia to epidural anaesthesia for emergency caesarean sections
- Pavan K Bangalore Chandrashekara Raju (17 January 2009)
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Niraj Sinha Corniche Hospital, Abu Dhabi, UAE
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Dear Editor The study of Halpern (1) made an interesting read. As resident anaesthetists some of us have used cocktail of local anaesthetics viz mixture of 10 ml of 0.5% bupivacaine and 2% lignocaine each for epidural anaesthesia in emergency situation. It may not be safe to mix drugs; clinically they don’t give a better block. At the same time lower concentration of single local anaesthetic might succeed. Once I accidentally injected 0.25% of bupivacaine rather than 0.5% into epidural catheter for conversion into anaesthesia and still the block was dense enough for caesarean section to be completed. A research which allows epidural injection of lower concentration of local anaesthetic is needed to know if it is possible to use the same. Lack of correlation between BMI and successful conversion is surprising since obese parturients are difficult to operate on, need more pushing and pulling during operation and often report discomfort. Orbach- Zinger (2) have concluded that obese patients are at higher risk of failure. The intra abdominal stimulus being carried by unblocked parasympathetic and phrenic nerve fibres is known (3) . Anxiolysis helps..! Though there is concern of low Apgar scores if midazolam is used before delivery, in clinical practice low dose (1-2 mg) doesn’t look to be problematic. References: 1.Halpern SH, Soliman A et al. Conversion of epidural labour analgesia to anaesthesia for caesarean section: A prospective study of the incidence and determinants of failure. Br J Anaesth 2009; 102:240-3 2. Orbach-Zinger S, Friedman L, Avramovich A, et al. Risk factors for failure to extend labor epidural analgesia to epidural anesthesia for cesarean section. Acta Anaesthesiol Scand (2006) 50:1014–8 3. Fettes PDW, Jansson JR, Wildsmith JAW. Failed spinal anaesthesia: mechanisms, management, and prevention. Br J Anaesth 2009; 102: 739-48 Conflict of Interest:None declared |
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Parag Shastri, Locum Consultant Anaesthetist University Hospital Coventry & Warwickshire, Venkatesh Annam, Ishwinder Suri
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Dear Editor, We read the article by Halpern et al(1) with great interest. It is very encouraging to read that guidelines of Royal College of Anaesthetists on incidence of general anaesthesia in parturients with a labour epidural in situ should not be more than 3% is achievable. We conducted a very similar audit in Warwick hospital in 2007 over a period of six months where we looked at the practice of conversion of labour epidural for emergency Caesarian section. Our conversion rate was 3% (2/70). However we found a very high rate of conversion to spinal anaesthesia (17%, 12/70). A detailed case notes review revealed that more than half of these conversions to spinal anaesthesia were merely due to anaesthetists’ lack of confidence on otherwise non- problematic labour epidurals and no attempts were made either to assess the block or to top up. We also found that documentation of reasons for conversions was inadequate. It is very important to document the reasons for conversion to avoid any potential future litigation risk. We recommend that this should be a regular part of audit activity for all obstetric units as there are quality and teaching issues involved. References: 1.Halpern SH, Soliman A et al. Conversion of epidural labour analgesia to anaesthesia for caesarean section: A prospective study of the incidence and determinants of failure. Br J Anaesth 2009; 102:240-3 Conflict of Interest:None declared |
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James M Shannon BC Women's Hospital, Vancouver, [ Patrick Thornton], [Heather Loane] [Jessica Tyler] [Roanne Preston]
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Editor- We read with interest the article by Halpern et al1, in which the authors prospectively analyzed parturients who had epidural analgesia for labour and subsequently required Caesarean delivery. The authors suggest that maternal height and more clinician top-ups predict “block failure”- epidural analgesia which cannot be extended to anaesthesia for Cesarean section Their data appear to indicate that mean maternal height of 167cm as opposed to 163cm predicted failure. This would not reflect our current practice, and indeed the results of previous studies quoted by the authors. Lee et al 2 identified epidural vs. combined spinal epidural and > 2 “breakthrough pains” in their retrospective analysis, while Orbach- Zinger et al 3 showed that younger parturients with higher BMIs and higher gestational weeks may be more likely to require conversion to general anaesthesia. Having identified a novel result which appears statistically significant, the authors do not expand on its clinical significance and on how it relates to previously accepted teaching. In analyzing supplementation of regional anaesthesia, or conversion to general anaesthesia, the significance of individual factors is limited. Practitioners may supplement regional techniques with intravenous narcotic or sedative for a number of reasons. Psychological factors, language barrier and physician attitudes may play a far more significant role than previously described. Patients may be subjected to inappropriate levels of discomfort because of unwillingness to convert to general anaesthesia due to safety concerns. We agree with the authors that early recognition of epidural analgesia which is inadequate, as well as multimodal testing to ensure adequacy of block height and surgical anaesthesia are important to prevent untimely conversion to general anaesthesia, with all its inherent risks. We feel, however, that the significance of patient height may be misleading. References 1. Halpern S. H, Soliman A, Yee J, Angle P, Ioscovich A Conversion of epidural labour analgesia to anaesthesia for Caesarean section: a prospective study of the incidence and determinants of failure Br J Anaesth (2009) 102 (2): 240-3 2. Lee SY, Lew E, Lim Y, Sia A. Failed epidural ‘ top-ups’ for emergency cesarean sections: incidence and risk factors. Reg Anesth Pain Med 2007; 32 (Suppl) 7 3. Orbach-Zinger S, Friedman L, Avramovich A, Ilgiaeva N, Orvieto R, Sulkes J, Eidelman LA Risk factors for failure to extend labor epidural analgesia to epidural anesthesia for Cesarean section Acta Anaesthesiol Scand 2006;50:1014 -1018 Conflict of Interest:None declared |
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Stephen H. Halpern Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto Canada
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Re: Letter to the editor by Drs Bangalore P.K. and Chandrashekara R. Thank you for your interest in our article(1). Your points concerning the relative safety of general and regional anesthesia are well taken. We did not mean to imply that one was safer than the other (that was not the intent of the study), rather that general anaesthesia may, in this context, be taken as a marker or surrogate outcome for quality of care. Clearly individual patient factors are more important. Regarding your specific points: The reasons for general anaesthesia among the 15 patients who had insufficient analgesia intraoperatively were heterogeneous. All the patients had a sufficient height of block at the beginning of the surgery as measured either by cold or pinprick. However, some patients complained of visceral pain either before or after delivery. In these cases, more local anaesthetic, intravenous opioids and/or general anaesthesia would be administered according to the clinical situation and the wishes of the parturient. We do not have data on the number of “trial of forceps” are included in the sample. The supplemental sedation was given for a variety of reasons including analgesia, control of shivering and anxiolysis. These were often administered at the request of the patient. Your point regarding maternal height is interesting. It appears that maternal height may be a factor (text books aside). Clearly more data is necessary. Finally, thank you for pointing out the typographical error. On reviewing the data, the number of staff procedures was 353. We counted a procedure as done by staff when a fellow and staff were both involved. Reference 1) Halpern SH, Soliman A, Yee J, Angle P, and Ioscovich A. Conversion of epidural labour analgesia to anaesthesia for Caesarean section: a prospective study of the incidence and determinants of failure. Br. J. Anaesth. 2009; 102: 240-3. Conflict of Interest:None declared |
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Pavan K Bangalore Chandrashekara Raju, Anaesthetic Registrar NHS Tayside
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I read with interest the article written by Dr S. H. Halpern et al., regarding the conversion of epidural labour analgesia to anaesthesia for caesarean section [1]. I completely agree that early recognition of failing labour epidural can reduce the number of general anaesthetics (GA) for caesarean sections (CS). There is evidence that regional anaesthesia (RA) is safer than GA for CS [2][3][4]. However, a recent Cochrane review said that there is no evidence to show RA is superior to GA in terms of major maternal or neonatal outcomes [5]. As I read the article, I thought of a few points which I have mentioned below. 15 patients had GA due to intra-operative insufficient analgesia. Does this mean that they had patchy block or was the height of the block not achieved or any other reason? An extra top up of local anaesthetic via the epidural catheter intra-operatively might have decreased the chances of a GA. Was this considered before deciding to give a GA to the patient? Did any patient initially come for a trial of forceps and then was eventually converted to CS, as this could have affected the level of the block due to the time spent on trial or inadequate amount of local anaesthetic as a top up for CS but adequate for a trial. 14 patients had sedation to supplement epidural anaesthesia. Most of them had fentanyl, 1 had morphine and 5 of them had multiple drugs. Does this mean that they received these opioids due to insufficient intra- operative analgesia? Maternal height was one of the independent variable to predict the block failure. Several textbooks on anaesthesia and studies in the past mention that patients' height does not influence the level of the block except in extremely short or extremely tall patients [6], [7]. Is the height really an independent variable predicting the block failure? Finally, in table 1, CS done by staff (373) and fellow (148) add up to 521 patients instead of 501 as mentioned elsewhere. Does this mean that 20 patients had CS in the presence of both fellow and staff or is it just a printing error? References: 1. S. H. Halpern, A. Soliman, J. Yee, P. Angle, and A. Ioscovich. Conversion of epidural labour analgesia to anaesthesia for Caesarean section: a prospective study of the incidence and determinants of failure. BJA. 2009; 102: 240-243 2.Confidential Enquiry into Maternal and Child Health. Why mothers die 2000–2002. RCOG Press,London 2004. 3. Shibli KU, Russell IF. A survey of anaesthetic techniques used for caesarean section in the UK in 1997. Int J Obstet Anesth 2000;9(3):160–167. 4.Hawkins JL, Koonin LM, Palmer SK, Gibbs CP. Anesthesia related deaths during obstetric delivery in the United States,1979–1990. Anesthesiology 1997; 86: 277–84. 5.Afolabi BB, Lesi AFE, Merah NA. Regional versus general anaesthesia for caesarean section. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD004350. DOI: 10.1002/14651858.CD004350.pub2 6. Factors Affecting the Distribution of Neural Blockade by Local Anesthetics in Epidural Anesthesia and a Comparison of Lumbar Versus Thoracic Epidural Anesthesia. Visser et al. Anesth Analg.2008; 107: 708- 721. 7. J. Duggan, G. M. R. Bowler, J. H. Mcclure, and J. A. W. Wildsmith. Extradural block with bupivacaine: influence of dose, volume, concentration and patient characteristics BJA, september 1988; 61: 324 – 331 Conflict of Interest:None declared |
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