Discussion
The main finding from this RCT is that epidural extension initiated with a DPE has an approximately 3-minute faster onset time to cesarean anesthesia than a standard epidural and a more favorable quality of epidural blockade (18.6% risk reduction) for cesarean delivery. We believe these results are clinically meaningful and relevant for patients requiring emergent cesarean delivery under epidural extension anesthesia. A recent study by Palmer et alAlthough our study demonstrates clear evidence of benefit in women requiring elective cesarean delivery, studies examining labor analgesia have reported inconsistent findings. StudiesThese contradictory results may be due to methodological heterogeneity. The mechanisms determining flux of local anesthetics through the meninges and the hole created by the dural puncture are complex and have not yet been fully elucidated.The physicochemical properties of the local anesthetic may also be an important determinant of transmeningeal diffusion. Chloroprocaine is mostly ionized at physiological pH with an inherently slow diffusion rate. Our study indicates that the flow of chloroprocaine may have been promoted through the dural puncture owing to the rapid administration of a relatively large mass of drug.The differences in umbilical cord base excess between the groups warrant further study, as do the differences in Apgar scores, although they were not significant. This study was underpowered for these outcomes, and the clinical relevance of such findings is questionable because umbilical artery and vein pH values were within normal limits.