Effect of Intrathecal Fentanyl on subarachnoid block with 0.5% hyperbaric bupivacaine

Background and objectives: Subarachnoid block is most versatile regional block commonly employed for infraumbilical surgeries. The use of neuroaxial opioids has gained widespread popularity as they potentiate the analgesia produced by local anesthetics. Hence the present study was undertaken to evaluate the effects of intrathecally administered fentanyl (25mcg) on the characteristics of hyperbaric bupivacaine induced subarachnoid block and adverse effects of fentanyl. Methods: In this prospective randomized study eighty ASA grade I and II patients scheduled for elective gynecological surgeries were assigned to receive either 3ml of 0.5% hyperbaric bupivacaine with0.5ml of CSF (Group I) or 3ml of 0.5%hyperbaric bupivacaine and 0.5ml of fentanyl(25mcg,Group II).Vital signs, sensory , motor block and side effects were observed every 1minute for first 30minutes , at 10 minutes for an hour and at every 30minutes till recovery. Results: Onset of sensory and motor block was comparable in both groups. Two segment regression and the duration of analgesia was significantly prolonged in group II i.e.134.12±10.81 and 207±17.57 minutes respectively compared to group I i.e-89.85±10.98 and 192.12±21.04minutes respectively. Intraoperatively 75% [30] of patients in group I needed sedation and 10 %( 4) patients had to be administered GA, however none required supplementation in group II, which was statistically highly significant. There was no significant statistical difference in the incidence of side effects in both the groups. Conclusion: This study confirmed that addition of fentanyl (25mcg) to 0.5% hyperbaric bupivacaine for spinal anesthesia would markedly improve the quality of intraoperative analgesia with minimal side effects.