Efficacy of fentanyl combined with bupivacaine and morphine for spinal anesthesia during cesarean section: A double-blind randomized controlled trial

ObjectiveAdequate anesthesia is necessary during cesarean section. We aimed to study the efficacy and safety of different doses of fentanyl combined with 10 mg bupivacaine and 0.1 mg morphine for spinal anesthesia during elective cesarean section.MethodThis double-blind randomized controlled trial enrolled pregnant women undergoing elective cesarean section between April 2019 and June 2021. Eligible women (n = 180) were randomized into six groups (C (control), F1, F2, F3, F4, or F5; n = 30 each) based on different doses of fentanyl (0, 5, 10, 15, 20, and 25 µg, respectively) for spinal anesthesia. Each patient also received 0.1 mg morphine and 10 mg bupivacaine.ResultSensory and motor blocks, muscle relaxation, pain intensity, intraoperative hemodynamics (every 5 min starting from the initial intrathecal injection), and adverse events were recorded. Compared with group C, groups F2-F5 had a faster onset of sensory block (p < 0.001), and groups F1-F5 had a faster onset of motor block (p = 0.015). During surgery, diastolic blood pressure levels in groups F4 and F5 were lower than those in group C between 5 and 20 min after anesthesia initiation (p < 0.05). Heart rates in group F5 were significantly higher than those in group C at 5 and 15 min of anesthesia initiation (p = 0.016 and 0.008, respectively). Groups F4 and F5 required a higher dose of phenylephrine to prevent hypotension than group C (p = 0.027). There were no significant differences in muscle relaxation, postoperative analgesia, and adverse events among the groups.ConclusionIntrathecal fentanyl administration at doses of 10-15 μg combined with 10 mg bupivacaine and 0.1 mg morphine provides rapid and satisfactory analgesia without additional adverse events during elective cesarean section.This clinical trial was registered with the Chinese Clinical Registry (ChiCTR1900021721, https://www.chictr.org.cn/showproj.html?proj=35939).