A double-blind randomized control trial to compare the effect of varying doses of intrathecal fentanyl on clinical efficacy and side effects in parturients undergoing cesarean section

Background and Aims: It is a common practice to add intrathecal lipophilic opioids to local anesthetics to improve the quality of subarachnoid block. This study was designed to find a dose of intrathecal fentanyl, which can improve the quality of surgical anesthesia with minimal side effects in parturients undergoing cesarean section under spinal anesthesia with intrathecal bupivacaine. Material and Methods: In a prospective randomized double-blind study, 243 parturients undergoing cesarean section under spinal anesthesia were randomly allocated to receive 10, 15, or 25 μg of intrathecal fentanyl with 10 mg of 0.5% hyperbaric bupivacaine. Patients were assessed for clinical efficacy by measuring pain score, need for rescue analgesia, conversion to general anesthesia, and complaints of inadequacy of surgical anesthesia by the surgeon. The side effects assessed were pruritus, nausea, vomiting, dizziness, and decrease in saturation and respiratory rate. In addition, neonatal APGAR score, patients' hemodynamics, need for vasopressors, onset and duration of sensory, and motor block were measured. Results: Patients receiving 25 μg of fentanyl had a significantly higher incidence of pruritus, nausea, and dizziness in addition to a significantly prolonged sensory and motor block (P < 0.001). All patients in three groups had adequate surgical anesthesia with no statistically significant difference in the onset of block, quality of surgical anesthesia, pain scores, neonatal APGAR score, hemodynamic variables, and need for vasopressor. Conclusion: For patients undergoing cesarean section, 10 or 15 μg of intrathecal fentanyl with 10 mg of bupivacaine provided adequate surgical anesthesia and analgesia with minimal side effects.