Exploration of the optimal programmed intermittent epidural bolus volume with the dural puncture epidural technique for labour analgesia: a biased-coin up-and-down sequential allocation study.

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To determine the optimal programmed intermittent epidural bolus (PIEB) volume for providing effective analgesia in 90% of patients (EV90) during the first stage of labour using the dural puncture epidural (DPE) technique to initiate labour analgesia. We conducted a biased-coin up-and-down sequential allocation study. We included 40 nulliparous women requiring epidural labour analgesia. We used a 25G Whitacre spinal needle to puncture the dural mater and then administered a loading dose of 12mL of ropivacaine 0.1% and sufentanil 0.3μg·mL-1. Subsequently, the PIEB pump delivered boluses with an identical solution at a fixed 40-min interval, starting 1hr after epidural initiation. The bolus volume for the first patient was 7mL and was adjusted for subsequent patients according to the study protocol (bolus volume, 7-12mL). The primary endpoint was effective analgesia, indicated by no need for patient-controlled or manual boluses within 6hr after analgesia initiation or until complete cervical dilation, whichever came first. Outcome evaluators assessed the patients' pain ratings, Bromage scores, sensory blockade level, and maternal blood pressure hourly. Using the truncated Dixon and Mood method, the estimated EV90 was 9.2mL (95% confidence interval [CI], 8.5 to 9.9) whereas the isotonic regression method yielded a value of 8.8mL (95% CI, 8.6 to 9.8). None of the patients experienced a motor block. Two patients experienced hypotension without the need for vasopressors. The estimated PIEB EV90 for ropivacaine 0.1% and sufentanil 0.3μg·mL-1 approached 9mL when DPE was combined with a fixed 40-min interval. ChiCTR.org.cn ( ChiCTR2300067281 ); first submitted 3 January 2023.