Optimal programmed intermittent epidural bolus volume for dural puncture epidural labor analgesia in patients with gestational hypertension: a biased-coin up-and-down sequential allocation trial

Background This study aimed to evaluate the effective programmed intermittent epidural bolus (PIEB) volume and the efficacy of dural puncture epidural (DPE) for labor analgesia in patients with gestational hypertension (GH). Methods Fifty primiparous women with GH, aged 22–40 years and classified as American Society of Anesthesiologists physical status II, scheduled for DPE labor analgesia were included. A biased-coin up-and-down sequential method was used to determine bolus volumes (7–12 mL). The first patient received 7 mL, with subsequent adjustments based on the need for rescue analgesia within 6 h of initiation or full cervical dilation. The truncated Dixon and Mood method and isotonic regression analysis were employed to calculate the 90% effective PIEB volume (EV90) and 95% confidence interval (CI). Recorded parameters included maximum sensory and motor blockade scores, mean arterial pressure, adverse events, and neonatal outcomes (umbilical artery pH, Apgar scores at 1 and 5 min). Results The EV90 was 9.82 (95% CI: 9.41–10.23) mL using the truncated Dixon and Mood method and 9.95 (95% CI: 9.52–10.38) mL using isotonic regression. The incidence of sensory blockade ≥T6 increased with higher volumes: 0% (7–9 mL), 13.33% (10 mL), 25.00% (11 mL), and 60.00% (12 mL). In the 12 mL group, one case of Bromage grade 1 motor blockade (recovered within 6 h), one of fetal bradycardia (resolved after maternal repositioning), and two cases of hypotension not requiring treatment were observed. No significant intergroup differences were detected in the duration of the first or second stage of labor or in the use of antihypertensive medications ( p > 0.05). Conclusion For patients with GH receiving DPE with PIEB (40-min interval; 0.08% ropivacaine + 0.3 μg/mL sufentanil), the EV90 was 9.89 mL. This regimen significantly reduced the risk of excessive sensory block and hypotension while ensuring effective analgesia. Clinical trial registration www.chictr.org.cn , identifier ChiCTR2500099107.