Dose-Related Comparative Clinical Evaluation of Fentanyl as An Adjuvant To Hyperbaric Bupivacaine In Intrathecal Neuraxial Block

Abstract

Background: Fentanyl is commonly used as an adjuvant to hyperbaric bupivacaine in spinal anesthesia to enhance analgesia and prolong the duration of the block. However, the optimal dose that maximizes benefits while minimizing side effects remains uncertain.

Methods: In this randomized, double-blind clinical trial, 120 patients undergoing lower limb surgeries under spinal anesthesia were allocated into four groups (n=30 each). Group A received 12.5 mg hyperbaric bupivacaine with 10 µg fentanyl; Group B received bupivacaine with 20 µg fentanyl; Group C received bupivacaine with 25 µg fentanyl; and Group D (control) received bupivacaine with saline. Onset and duration of sensory and motor block, hemodynamic parameters, and adverse effects were recorded.

Results: Groups B and C showed significantly faster onset and prolonged duration of sensory and motor block compared to Groups A and D (p < 0.05). The incidence of pruritus was higher in Group C (p < 0.05). Hemodynamic parameters remained stable across all groups.

Conclusion: Adding 20 µg fentanyl to hyperbaric bupivacaine enhances spinal anesthesia quality without significant adverse effects. Higher doses increase side effects like pruritus without substantial additional benefits.