Success rate of neuraxial anesthesia for cesarean section following epidural labor analgesia using a low treshold to spinal anesthesia: A case series of 96 consecutive parturients
Management of the parturient presenting for intrapartum cesarean section (CS) following epidural labor analgesia (ELA) is a common challenge. Indeed, the matter has spawned several practice advisories.1-3 Epidural top up (ETU) has been associated with failure rates requiring conversion to general anesthesia (GA) up to 21%.2 Risk factors include an increased number of boluses and enhanced urgency for CS.2 Spinal anesthesia (SA) for patients presenting for CS following ELA remains controversial, mostly because of concern about high spinal block.2,3 However, given the reassuring results of our previous study,4 we believe a low threshold should be applied to perform de novo SA instead of ETU when inadequate ELA is suspected. We present a case series of 96 consecutive parturients managed in such a manner, to assess the overall failure rate of neuraxial anesthesia in this situation.
Our Institutional Review Board approved the study and waived the requirements for written informed consent. The first author has maintained a data base of all parturients under his care presenting for intrapartum CS following ELA since 2010. ELA was commenced on maternal request, starting with a bolus dose of bupivacaine and sufentanil, followed by continuous infusion and nurse administered boluses on request. Upon arrival for CS at the operating room, all patients were queried about the quality of their ELA. When satisfactory (85%), i.e. without additional bolus doses, or only few, but effective bolus doses, ETU was administered using lidocaine, sufentanil and adrenaline. When not satisfactory, or when repeated bolus doses were requested (15%), the epidural catheter was removed and SA was performed using bupivacaine and sufentanil. Surgery was started when block levels reached T6. Overall conversion rate to GA was 1% (one woman in the ETU group). No high blocks were recorded. Vasopressor use was higher in the SA group.
Discussion & Conclusion
While there is no conclusive evidence to support a particular management strategy to provide adequate and safe neuraxial anesthesia for parturients presenting for CS following ELA, tradition dictates the epidural catheter in situ be topped up. However, we believe SA for CS following labour ELA may be underused when there are predictive signs that the epidural catheter may fail to produce adequate surgical anesthesia. This may, in part, explain the disappointing failure rates of ETU for CS. Our conversion rate to GA of 1% in this series is much lower than the 3% allowed for non-elective CS in the guidelines by the Royal College of Anaesthetists. To realize this low failure rate, we administered SA instead of ETU in 15% of parturients. In conclusion, while some authors have advocated4 and others have opposed3 liberal use of SA following ELA, our series demonstrates that when SA is considered with a low threshold when ELA was unsatisfactory, excellent success rates for neuraxial anesthesia for intrapartum CS can be achieved.