Comparison of clonidine and fentanyl as adjuvant in femoro-sciatic nerve block for postoperative analgesia – A prospective randomized controlled trial

Abstract

Introduction: Arthroscopic anterior cruciate ligament reconstruction (ACLR) is associated with moderate-to-severe postoperative pain which may delay hospital discharge as well as physiotherapy resulting in poor outcome. The aim of our study was to compare the effect of clonidine or fentanyl as adjuvant to bupivacaine in femoro-sciatic nerve block (FSNB) on the duration of pain-free period and requirement of rescue analgesic postoperatively. Materials and Methods: Sixty adult patients undergoing ACLR of the knee joint received subarachnoid block as anesthesia for surgery and FSNB for postoperative analgesia. Patients in Group C (control group) received 40 ml of 0.25% isobaric bupivacaine (20 ml in femoral and sciatic block each), whereas Group F (fentanyl group) received fentanyl (1 μg/kg) and Group CL (clonidine group) received clonidine (1 μg/kg) with 40 ml of 0.25% isobaric bupivacaine. The duration of pain-free period, rescue analgesic consumption, postoperative pain score, sedation levels and adverse effects were monitored along with hemodynamic parameters for 24 h postoperatively. Results: The patients in the clonidine group had longer pain-free period (10.06 ± 3.62 h) as compared to the fentanyl group (7.94 ± 3.62 h) and control group (4.59 ± 1.20 h) (P < 0.001). Postoperative pain scores were higher in the control group at the 4th, 8th, and 12th h and comparable between the fentanyl and clonidine groups. The total amount of rescue analgesic requirement was less in the clonidine group (71.25 ± 16.77 mg) than the fentanyl group (86.25 ± 36.71 mg) and control group (161.20 ± 50.34 mg) (P < 0.001). No clinically significant adverse effects were observed in any group. Conclusion: Clonidine as an adjuvant to bupivacaine in FSNB provides better postoperative analgesia compared to fentanyl by significantly prolonging the pain-free period and decreasing rescue analgesic requirement in postoperative period without any untoward side effect.