Conclusions: Spinal Anesthesia (SA: hyperbaric bupivacaine 9mg + fentanyl 15mcg) increased the success rate and reduced pain for both primary and re-attempts of External Cephalic Version (ECV), whereas IV Anesthesia (IVA) using remifentanil infusion (0.1mcg/kg/min) only reduced the pain. There was no significant increase in the incidence of fetal bradycardia or emergency CS, with ECV performed under anaesthetic interventions. Relaxation of the abdominal muscles from SA appears to underlie the improved outcomes for ECV.
Editor’s key points: There is no consensus on best anaesthetic technique for external cephalic version (ECV). In this study, success at ECV was higher using spinal anaesthesia compared with remifentanil infusion or no intervention. Pain was also reduced in the remifentanil group but success at ECV was no different to the no intervention group. The effect of spinal anaesthesia in ECV may relate to relaxation of the abdominal musculature.
It is both effective and cost-effective to utilize spinal anesthesia to perform ECV in term, nulliparous women with breech fetuses. Translation of this potentially impactful approach into broad obstetric practice should be undertaken.
Six RCTs met criteria for study inclusion. Regional anesthesia was associated with a higher external cephalic version success rate compared to intravenous or no analgesia (59.7% vs. 37.6%; pooled RR 1.58, 95% confidence interval [CI] 1.29-1.93). This significant association persisted when the data was stratified by type of regional anesthesia (spinal vs. epidural). The number needed to treat with regional anesthesia to achieve one additional successful ECV was 5. There was no evidence of statistical heterogeneity (p=0.32, I2=14.9%) or publication bias (Harbord test p=0.78). There was no statistically significant difference in the risk of cesarean delivery comparing regional anesthesia to intravenous or no analgesia (48.4% vs. 59.3%; pooled RR 0.80, 95% CI 0.55-1.17). Adverse events were rare and not significantly different between the two groups.
Neuraxial Anesthesia (NA) for External Cephalic Version (ECV) increased the risk of emergent cesarean delivery (CD) without impacting ECV success. These findings differ from previous randomized controlled trials (RCTs). The increased risk and decreased success of our ECVs compared to ECVs performed in the context of RCTs could be explained by patient selection, variation in operator experience or technique, or variation in anesthetic management. Future studies should further evaluate the risk of NA for ECV in true practice scenarios outside of RCTs.
Results: A total of 240 subjects were enrolled, and 239 received the intervention. External cephalic version was successful in 123 (51.5%) of 239 patients. Compared with bupivacaine 2.5 mg, the odds (99% CI) for a successful version were 1.0 (0.4 to 2.6), 1.0 (0.4 to 2.7), and 0.9 (0.4 to 2.4) for bupivacaine 5.0, 7.5, and 10.0 mg, respectively (P = 0.99). There were no differences in the cesarean delivery rate (P = 0.76) or indication for cesarean delivery (P = 0.82). Time to discharge was increased 60 min (16 to 116 min) with bupivacaine 7.5 mg or higher as compared with 2.5 mg (P = 0.004).
Conclusions: A dose of intrathecal bupivacaine greater than 2.5 mg does not lead to an additional increase in external cephalic procedural success or a reduction in cesarean delivery.
A is adapted, with permission, from Purdon et al:Electroencephalogram signatures of loss and recovery of consciousness from propofol. Proc Natl Acad Sci U S A 2013; 110:E1142–51; and C is adapted, with permission, from Lewis et al. Rapid fragmentation of neuronal networks at the onset of propofol-induced unconsciousness. Proc Natl Acad Sci U S A2012; 109:E3377–86. Adaptations are themselves works protected by copyright. In order to publish this adaptation, authorization has been obtained both from the owner of the copyright of the original work and from the owner of copyright of the translation or adaptation.
(A) At low doses, ketamine blocks preferentially the actions of glutamate N-methyl-d-aspartate receptors on γ-aminobutyric acid (GABA)ergic inhibitory interneurons in the cortex and subcortical sites such as the thalamus, hippocampus, and the limbic system. The antinociceptive effect of ketamine is due in part to its blockade of glutamate release from peripheral afferent (PAF) neurons in the dorsal root ganglia (DRG) at their synapses on to projection neurons (PNs) in the spinal cord. (B) Spectrogram showing the beta-gamma oscillations in the electroencephalogram of a 61-yr-old woman who received ketamine administered in 30 mg and 20 mg doses (green arrows) for a vacuum dressing change. Blocking the inhibitory action of the interneurons in cortical and subcortical circuits helps explain why ketamine produces beta oscillations as its electroencephalogram signature. (C) Ten-second electroencephalogram trace recorded at minute 5 from the spectrogram in B. A is reproduced, with permission, from Brown, Purdon, and Van Dort: General anesthesia and altered states of arousal: A systems neuroscience analysis. Annu Rev Neurosci. 2011;324:601–28. B and C were adapted from Purdon and Brown, Clinical Electroencephalography for the Anesthesiologist (2014), with permission, from the Partners Healthcare Office of Continuing Professional Development.69 Adaptations are themselves works protected by copyright. In order to publish this adaptation, authorization has been obtained both from the owner of the copyright of the original work and from the owner of copyright of the translation or adaptation.
For the inhaled ether-derived anesthetics such as sevoflurane, isoflurane, and desflurane, we observed that, with the exception of the theta oscillations that appear around 1 MAC and beyond, their electroencephalogram patterns during maintenance and emergence closely resemble those seen in propofol. Nitrous oxide is known to be associated with increased beta and gamma oscillations and likely decreased slow-delta oscillations. However, we demonstrated that nitrous oxide also produces profound slow-delta oscillations during the transition from an inhaled ether anesthetic.