Efficacy of fentanyl combined with bupivacaine and morphine for cesarean section -- A double-blinded randomized controlled trial

Adequate anesthesia is necessary during the cesarean delivery. We studied the anesthesia efficacy and safety of different doses of fentanyl combined with 10 mg bupivacaine and 0.1 mg morphine for elective cesarean section. We performed a double-blinded, randomized, and controlled trial in pregnant women undergoing elective cesarean delivery between April 2019 and June 2021. Eligible women were randomized into groups C, F1, F2, F3, F4, or F5 based on different doses of fentanyl (0, 5, 10, 15, 20, or 25 µg, respectively) during the spinal anesthesia. Each woman also received 0.1 mg morphine and 10 mg bupivacaine. Sensory and motor blocks, muscle relaxation, pain intensity, intraoperative hemodynamics (every 5 min from the intrathecal injection), and adverse events were recorded and compared. Our study included a total of 180 women, with 30 women in each group. Compared with group C, group F2–5 had a faster onset of sensory block (P < 0.001) and group F1–5 had a faster onset of motor block (P = 0.015). During the surgery, diastolic blood pressures in groups F4 and F5 were lower than those in group C between 5 and 20 min after the anesthesia initiation (P < 0.05). Heart rate in group F5 was significantly higher than those in group C at 5 and 15 min after the anesthesia initiation (P = 0.016 and 0.008), respectively. Group F4 and F5 required a higher dose of phenylephrine to prevent hypotension than group C (P = 0.027). There was no significant difference in muscle relaxation, postoperative analgesia, and adverse events among these groups. Intrathecal fentanyl administration at the doses of 10–15µg combined with 10 mg bupivacaine and 0.1 mg morphine could provide rapid and satisfactory analgesia without additional adverse events during elective cesarean delivery.