Management of the parturient presenting for intrapartum caesarean delivery (IPCD) with an epidural catheter in situ is a common challenge for the obstetric anaesthetist.1,2 Epidural top up (ETU) has been associated with conversion rates to general anaesthesia of up to 21%.2 Risk factors include an increased number of boluses during labour and enhanced urgency for caesarean delivery.3 Spinal anaesthesia may be considered instead of ETU when there is doubt about the quality of epidural labour analgesia (ELA).1 However, this course of action may be rejected because of concern for a high spinal block,2 which may prompt clinicians to proceed with a suboptimal epidural catheter. Although we recently demonstrated the efficacy and safety of routinely performing spinal anaesthesia for all patients presenting for IPCD following ELA,4 this practice remains controversial. Indeed, an unknown number of women in our study might have received successful ETU. Therefore, at present, we use ETU for all IPCDs when the quality of the block is confirmed. However, given the reassuring results of our previous study, we perform spinal anaesthesia when inadequate ELA is suspected. We reviewed a cohort of 96 consecutive parturients presenting for IPCD with an epidural catheter in situ managed as such, to assess the overall failure rate of neuraxial anaesthesia in this group.
Our Institutional Review Board approved this study and waived the requirements for written informed consent (Amphia Advisory Committee on Medical Research in Humans, approval issued 31 October 2017 by Miss Els Biemans). The first author has maintained a data base of all parturients for whom he provided both ELA and surgical anaesthesia for IPCD since June 2010. Women presenting for Category 1 IPCD, that is immediate threat to the life of the mother or the foetus, were not included.
Epidural analgesia commenced on maternal request, independent of cervical dilation. A bolus dose of 12 to 18 ml of bupivacaine 1.25 mg ml−1 with sufentanil 1 μg ml−1 was given and a continuous infusion of the same solution was started. Nursing staff customised epidural infusion rates within a range of 8 to 14 ml h−1, and administered bolus doses of 6 ml on request of the mother, to a maximum of once every 30 min.
Upon arrival for IPCD in the operating room holding area, all patients were asked about the quality of their ELA. When ELA had been satisfactory, an initial epidural injection of 10 ml was administered in the holding area, consisting of lidocaine 18 mg ml−1, sufentanil 0.5 μg ml−1 and adrenaline 5 μg ml−1. When block height had not reached the T6 level after 10 min, another 5 to 10 ml was given. When ELA had not been completely satisfactory, or had required repeated bolus doses, the epidural catheter was removed and spinal anaesthesia was performed at the L3 to L4 or L2 to L3 interspace using 1.8 ml of bupivacaine 0.5% with glucose and 0.7 ml of sufentanil 5 μg ml−1.
Our results after 96 consecutive parturients show that the overall incidence of conversion to general anaesthesia due to insufficient neuraxial anaesthesia (ETU and spinal anaesthesia combined) was 1% (Table 1). This is much lower than the 5% conversion rate to general anaesthesia for nonelective caesarean delivery as stated in the guidelines for acceptable rates for neuraxial anaesthesia.5 To realise this low failure rate, we administered spinal anaesthesia rather than ETU in 15% of parturients.
We believe the favourable overall success rate in our series is due to the low threshold to choose spinal anaesthesia for IPCD when there is doubt about the quality of ELA. We also believe that spinal anaesthesia for IPCD following ELA suffers from an undeserved reputation of high spinal blocks, based on a number of case reports published in the early 1990s.2 Most, but not all of the patients in these reports received spinal anaesthesia following failed ETU. In contrast, we found no difference in the incidence of high or total spinal block between a group of 126 women receiving spinal anaesthesia following ELA without prior ETU compared with a control group receiving spinal anaesthesia only for IPCD.4 Indeed, high spinal block occurs more frequently when spinal anaesthesia is administered after unsuccessful ETU, than when spinal anaesthesia is performed following ELA without ETU.6 In addition, administration of spinal anaesthesia within 30 min of an ETU dose is associated with increased risk of failure.7 Furthermore, a considerable portion of reported high neuraxial blocks for IPCD occur after ETU only.6 Therefore, we believe that avoiding the situation where spinal anaesthesia is administered following failed top up with a large volume of epidural local anaesthetic ensures effective and safe neuraxial anaesthesia.
We have applied statistical analysis to our patient data to avoid the possibility that these parameters affected the choice of anaesthetic technique. Although our study was neither designed nor specifically powered to detect differences in other outcome variables, we found statistically significant differences in the use of phenylephrine and Apgar scores. Because of the small size of the spinal anaesthesia group, and the fact that all low Apgar scores in this group occurred in children who had been diagnosed with foetal distress during delivery, this difference should be interpreted with caution.
The current study may be criticised for several reasons. During the study period, we did not employ patient controlled epidural analgesia. However, all parturients could request epidural boluses during labour. Furthermore, the assessment of quality of ELA may have been subjective. Given the circumstances, it is difficult to obtain objective measures of efficacy of ELA, such as pain scores or block height.
Clearly, our results should be tested in prospective trials to assess the efficacy and safety of this practice. As long as randomised clinical trials are lacking, we believe there is value in case series like ours.
In conclusion, our series demonstrates that when ETU is used only when previous ELA was satisfactory, and spinal anaesthesia is performed instead of ETU when it was not, excellent overall success rates of neuraxial anaesthesia for IPCD following ELA can be achieved.
Acknowledgements relating to this article
Assistance with the letter: the authors thank Dr Philip Bolton and Dr Frank O’Connor for reviewing the article.
Financial support and sponsorship: none.
Conflicts of interest: none.
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