The role of combined spinal epidural analgesia for labour: is there still a question?

Abstract

HEN combined spinal epidural (CSE) analgesia was introduced as a technique for labour analgesia, two distinct camps of opinion quickly emerged amongst anesthesiologists practicing obstetrical anesthesia: those who believe benefits of CSE are advantageous to every woman requesting a labour epidural; and those who believe the benefits over a standard epidural do not justify the intentional “invasion” of the dura nor the side effects. Efficacy has been well proven by a plethora of CSE studies, but safety remains a concern for many. In this issue of the Journal, Rofaeel et al. 1 report on a CSE study, examining hyperbaric bupivacaine vs isobaric bupivacaine. The study finds that when added to intrathecal (IT) sufentanil 2.5 µg, isobaric bupivacaine 2.5 mg, the standard dose which many anesthesiologists use, provides better analgesia within the first ten minutes post injection, compared to a 2.5-mg dose of hyperbaric bupivacaine. This difference disappears by 20 min post injection. The far more important finding of the study is that the incidence of sustained fetal bradycardia, defined as fetal heart rate 60 sec, was 33% in the isobaric group vs 10% in the hyperbaric group. This result is both statistically and clinically significant. While initial reports on CSE showed a high incidence of fetal bradycardia, more contemporary prospective studies, including those by Wong et al. 2 in 2005 and Van de Velde et al. 3 in 2004, report an incidence of prolonged decelerations varying between 3.9%–12%. None of the fetal bradycardias reported in Rofaeel’s study resulted in emergency obstetrical intervention, but perhaps this is a high cost to pay for a difference of ten minutes to attainment of excellent analgesia. One might conclude from this study that IT isobaric bupivacaine should no longer be used. But, it raises a more important issue: are the benefits of CSE over a standard epidural for labour analgesia enough to justify this risk of fetal harm? As a provider of CSE labour analgesia, I have established my own set of exclusion criteria based on interpretation of the literature. For instance, like the authors of this study, I do not use the technique when there is a poor fetal heart trace, nor when I wish to know the epidural catheter is functioning unequivocally at the time of insertion. I also use CSE for those who may gain the most benefit: women in advanced labour and those in extreme pain. However, given the incidence of fetal bradycardia observed in both groups of Rofaeel’s study, perhaps it is time to reassess whether CSE should continue to have a role in labour analgesia. Today, the purported benefits of CSE are: faster onset of analgesia, superior analgesia in late labour, better subsequent functioning of the epidural catheter, and higher patient satisfaction. It has been well-proven that when compared to dilute epidural solutions, CSE offers no advantage in terms of obstetrical intervention, nor any difference in the ability to be mobile. 4 The usually quoted disadvantages include: fetal bradycardia; unknown reliability of epidural catheter function; risk of central nervous system infection and respiratory depression; and significant pruritus. Risks of hypotension and post-dural puncture headache have been shown to be no different than with epidural analgesia. 4