Safe, reliable, and timely conversion of epidural analgesia to cesarean delivery anesthesia can be among the most challenging aspects of obstetric anesthesia practice. It is also one of the most important. When conversion fails, the risks of anesthesia-related complications escalate. Spinal anesthesia injected after failed conversion to cesarean delivery anesthesia risks high neuraxial blockade.1 Unplanned conversion to general anesthesia risks failed airway management, which remains a serious safety concern despite decades of improvements in equipment and management protocols.2 Beyond ensuring maternal safety, successful conversion enhances experience of care. Unplanned cesarean delivery in labor can be traumatic; the added stress of operative delay, intraoperative pain, or unplanned conversion to general anesthesia can make the experience of care even worse.
In the current issue of Anesthesia and Analgesia, a focused review by Mankowitz et al3 surveys the literature to identify risk factors for failure to extend epidural labor analgesia to cesarean delivery anesthesia and evidence-based strategies to improve the rate of successful conversion to cesarean delivery anesthesia. The authors are to be congratulated for providing an evidence-based and clinically practical review on an important topic in obstetric anesthesiology.
Three major risk factors are consistently associated with failed epidural conversion: care provided by a nonobstetric anesthesiologist, increased boluses during labor as a result of pain, and urgency of cesarean delivery. Clinical strategies to mitigate these risks are provided here.
Obstetric anesthesiologists facilitate high rates of successful conversion from epidural analgesia to cesarean delivery anesthesia.3 Differences in anesthetic technique may partially explain these high rates of success. For example, obstetric anesthesiologists are more likely to withdraw an epidural catheter to improve anesthetic block quality.4 However, we believe a complete explanation lies beyond clinical technique; obstetric anesthesiologists focus more intensely on analgesic quality before cesarean delivery is declared. Active management of labor analgesia is a care philosophy in which the anesthesiologist integrates information about block quality, progress of labor, maternal and fetal well-being, and maternal and obstetric decision-making to optimize block quality and density before a decision for cesarean delivery is declared. Active management of labor analgesia enhances conversion to epidural anesthesia (ie, limiting use of general anesthesia), but it also targets improved experience of care, which is emerging as an important quality measure for obstetric anesthesia.5
Obstetric anesthesiologists may be more likely to work in hospitals that ensure dedicated staffing for the labor and delivery unit. Free from duties outside of the unit, dedicated staff are best able to maintain ongoing communication with the obstetric team, to provide active management of labor analgesia, and to identify those women most likely to require cesarean delivery. Dedicated staffing also ensures immediate availability for emergency cesarean delivery. Despite its many benefits, dedicated staffing may only be practical in a minority of delivery units with sufficient volume to support the service. According to the Centers for Medicare and Medicaid Services medical direction rules, even a high-volume labor epidural service is not considered an anesthetizing location; this reduces the incentive for many practices to provide dedicated coverage.
Breakthrough pain that requires clinician-administered bolus dosing during labor is an important risk factor for failed conversion of epidural analgesia to anesthesia. Analgesic dosing requirements and breakthrough pain have also been associated with dysfunctional labor and cesarean delivery,6 so prompt diagnosis of the cause of breakthrough pain, targeted treatment, and timely replacement will help facilitate safe conversion if it is needed. In a retrospective review of cesarean delivery cases at Brigham and Women’s Hospital from 2000 to 2005, the low rate of cesarean delivery requiring general anesthesia was partially attributed to aggressive replacement of epidural catheters providing suboptimal labor analgesia.7
Labor analgesia infusion pump technology may also play a role. Although a meta-analysis of studies comparing continuous epidural infusion with programmed intermittent epidural bolus (PIEB) did not find a difference between the need for clinician-administered boluses or time to first bolus request administered between groups,8 PIEB combined with patient-controlled epidural analgesia is an emerging strategy to reduce the time needed to troubleshoot epidural analgesia. A clinical impact study comparing continuous epidural infusion and PIEB, each with patient-controlled epidural analgesia, found that the patients with PIEB required 36% fewer rescue clinician boluses.9 This could reduce time spent administering boluses and troubleshooting epidural analgesia.
When failed epidural analgesia has been diagnosed and replacement is needed, a combined spinal epidural (CSE) technique provides multiple benefits. In our clinical experience, the speed of onset and density of spinal analgesia offer a welcome respite for women who have experienced unexpected breakthrough pain. Furthermore, subsequent epidural analgesia is highly likely to be successful as long as spontaneous return of cerebrospinal fluid is observed with spinal needle placement.10,11 The Brigham and Women’s report could only find one instance of failure of a CSE requiring general anesthesia during 2000 to 2005.7 Additionally, the CSE itself may facilitate progress of labor for women with dysfunctional labor patterns.12,13
Lastly, the authors identified urgency of cesarean delivery as a risk for failed conversion to cesarean delivery anesthesia. Active management of labor analgesia and early interventions to extend the epidural blockade may reduce this risk. In a retrospective review of emergent cesarean deliveries, the decision to delivery interval was not different between general anesthesia compared with bolusing the epidural catheter, and both were shorter than spinal anesthesia.14 However, epidural anesthesia was only administered to those women whose catheters provided high-quality labor analgesia, further emphasizing the importance of close monitoring of labor epidural catheters.14 Conversion of epidural analgesia to cesarean delivery anesthesia may begin in the labor room once the patient has consented to cesarean delivery.3 A small bolus before patient transport (ie, 5 mL) followed by another bolus on arrival in the operating room can accelerate the anesthetic induction. Then on the operating table, a quick assessment for the surgical level, and reassessment of maternal and fetal status, allows the clinician to discern whether the block is ascending and to decide whether to continue induction of epidural anesthesia or to select an alternate technique. (Mankowitz et al3 includes a brief review of alternate anesthetic techniques.) A well-tested epidural catheter and judicious block extension mitigate the risk of unintended high neuraxial blockade or hypotension during transport; any such risk should be balanced against the risk of emergency general anesthesia if block extension is delayed.
The choice of epidural anesthetic solution can also impact the time required to prepare for cesarean delivery. In a meta-analysis reviewing studies evaluating solutions to extend labor epidural analgesia to emergency cesarean delivery anesthesia, the fastest onset solution for bolusing for cesarean delivery anesthesia was 2% lidocaine with epinephrine and fentanyl.15 Although there were not enough studies to evaluate sodium bicarbonate, it also appeared to reduce onset time.15 Based on this information, the solution of 2% lidocaine with epinephrine, fentanyl, and bicarbonate may be an excellent choice for preparing for surgical anesthesia when fast onset is desired.15 Although none of the studies utilizing 3% 2-chloroprocaine met inclusion criteria for the systematic review, it may also provide a rapid-onset anesthetic for cesarean delivery anesthesia. However, the benefits of rapid onset must be weighed against the potential decreased efficacy of subsequent epidural opioids.
In summary, prevention appears to be the key to avoiding a failed conversion from epidural analgesia to cesarean delivery anesthesia. By providing active management of labor epidural analgesia with prompt replacement of poorly functioning catheters, successful conversion to epidural anesthesia is more likely to occur. Close communication with the obstetric team allows anesthesia providers to optimize block density in preparation for cesarean delivery and to initiate conversion to epidural anesthesia as early as possible. A fast-onset solution such as 2% lidocaine with epinephrine, fentanyl, and sodium bicarbonate is most likely to provide a timely surgical level. When it comes to optimizing birth outcomes, obstetrics and obstetric anesthesia have a lot in common. Watchful, active preventive management on labor and delivery can make all the difference.
Name: Melissa E. Bauer, DO.
Contribution: This author helped write the manuscript.
Name: Jill M. Mhyre, MD.
Contribution: This author helped write the manuscript.
This manuscript was handled by: Jean-Francois Pittet, MD.
1. D’Angelo R, Smiley RM, Riley ET, Segal S. Serious complications related to obstetric anesthesia: the serious complication repository project of the Society for Obstetric Anesthesia and Perinatology. Anesthesiology. 2014;120:15051512.
2. Kinsella SM, Winton AL, Mushambi MC, et al. Failed tracheal intubation during obstetric general anaesthesia: a literature review. Int J Obstet Anesth. 2015;24:356374.
3. Mankowitz SKW, Gonzalez Fiol A, Smiley R. Failure to extend epidural labor analgesia for cesarean delivery anesthesia: a focused review. Anesth Analg. 2016;123:11741180.
4. Campbell DC, Tran T. Conversion of epidural labour analgesia to epidural anesthesia for intrapartum cesarean delivery. Can J Anaesth. 2009;56:1926.
5. Barnett SF, Alagar RK, Grocott MP, Giannaris S, Dick JR, Moonesinghe SR. Patient-satisfaction measures in anesthesia: qualitative systematic review. Anesthesiology. 2013;119:452478.
6. Hess PE, Pratt SD, Soni AK, Sarna MC, Oriol NE. An association between severe labor pain and cesarean delivery. Anesth Analg. 2000;90:881886.
7. Palanisamy A, Mitani AA, Tsen LC. General anesthesia for cesarean delivery at a tertiary care hospital from 2000 to 2005: a retrospective analysis and 10-year update. Int J Obstet Anesth. 2011;20:1016.
8. George RB, Allen TK, Habib AS. Intermittent epidural bolus compared with continuous epidural infusions for labor analgesia: a systematic review and meta-analysis. Anesth Analg. 2013;116:133144.
9. McKenzie CP, Cobb B, Riley ET, Carvalho B. Programmed intermittent epidural boluses for maintenance of labor analgesia: an impact study. Int J Obstet Anesth. 2016;26:3238.
10. Booth JM, Pan JC, Ross VH, Russell GB, Harris LC, Pan PH. Combined Spinal epidural technique for labor analgesia does not delay recognition of epidural catheter failures: a single-center retrospective cohort survival analysis. Anesthesiology. 2016.
11. Grondin LS, Nelson K, Ross V, Aponte O, Lee S, Pan PH. Success of spinal and epidural labor analgesia: comparison of loss of resistance technique using air versus saline in combined spinal-epidural labor analgesia technique. Anesthesiology. 2009;111:165172.
12. Wong CA, Scavone BM, Peaceman AM, et al. The risk of cesarean delivery with neuraxial analgesia given early versus late in labor. N Engl J Med. 2005;352:655665.
13. Tsen LC, Thue B, Datta S, Segal S. Is combined spinal-epidural analgesia associated with more rapid cervical dilation in nulliparous patients when compared with conventional epidural analgesia? Anesthesiology. 1999;91:920925.
14. Popham P, Buettner A, Mendola M. Anaesthesia for emergency caesarean section, 2000-2004, at the Royal Women’s Hospital, Melbourne. Anaesth Intensive Care. 2007;35:7479.
15. Hillyard SG, Bate TE, Corcoran TB, Paech MJ, O’Sullivan G. Extending epidural analgesia for emergency caesarean section: a meta-analysis. Br J Anaesth. 2011;107:668678.