Background: For emergent intrapartum cesarean delivery (CD), the literature does not support the use of any particular local anesthetic solution to extend epidural analgesia to cesarean anesthesia. We hypothesized that 3% chloroprocaine (CP) would be noninferior to a mixture of 2% lidocaine, 150 µg of epinephrine, 2 mL of 8.4% bicarbonate, and 100 µg of fentanyl (LEBF) in terms of onset time to surgical anesthesia.
Methods: In this single-center randomized noninferiority trial, adult healthy women undergoing CD were randomly assigned to epidural anesthesia with either CP or LEBF. Sensory blockade (pinprick) to T10 was established before operating room (OR) entry for elective CD. On arrival to the OR, participants received the epidural study medications in a standardized manner to simulate the conversion of "epidural labor analgesia to surgical anesthesia." The primary outcome was the time to loss of touch sensation at the T7 level. A noninferiority margin was set at 3 minutes. The secondary outcome was the need for intraoperative analgesia supplementation.
Results: In total, 70 women were enrolled in the study. The mean onset time to achieve a bilateral sensory block to touch at the T7 dermatome level was 655 (standard deviation [SD] = 258) seconds for group CP and 558 (269) seconds for group LEBF, a difference in means of 97 seconds (90% confidence interval [CI], SD = -10.6 to 204; P = .10 for noninferiority). The upper limit of the 90% CI for the mean difference exceeded the prespecified 3-minute noninferiority margin. There was no meaningful difference in the requirement for intraoperative analgesia between the 2 groups.
Conclusion: Both anesthetic solutions have a rapid onset of anesthesia when used to extend low-dose epidural sensory block to surgical anesthesia. Data from the current study provide insufficient evidence to confirm that CP is noninferior to LEBF for rapid epidural extension anesthesia for CD, and further research is required to determine noninferiority.
Trial registration: ClinicalTrials.gov NCT03414359.
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