A COMPARATIVE CLINICAL STUDY OF INTRATHECAL DEXMEDETOMIDINE 5 mu g AND INTRATHECAL FENTANYL 25 mu g AS AN ADJUVANT WITH 0.5% HYPERBARIC BUPIVACAINE 12.5 mg IN ELECTIVE LOWER LIMB SURGERIES

BACKGROUND Various adjuvants are being used with local anaesthetics intrathecally for prolongation of intraoperative and postoperative analgesia. Dexmedetomidine, the highly selective alpha-2 adrenergic agonist is a new neuraxial adjuvant gaining popularity. Fentanyl is commonly used as an opioid adjuvant to local anaesthetic for spinal anaesthesia. AIM The purpose of this study was to compare the onset, duration of sensory and motor block, haemodynamic effects, postoperative analgesia and adverse effects of dexmedetomidine and fentanyl used intrathecally with hyperbaric 0.5% bupivacaine for spinal anaesthesia. METHODOLOGY The study was conducted in prospective, double-blind manner. It included 90 American Society of Anaesthesiology (ASA) class I and II patients undergoing lower limb surgery under spinal anaesthesia. The patients were randomly allocated into three groups (30 patients each). Group C received 12.5 mg hyperbaric bupivacaine (2.5 mL) with normal saline (0. 5mL), group F received 12.5 mg bupivacaine (2.5 mL) with 25 mu g fentanyl (0.5 mL) and group D received 12.5 mg bupivacaine (2.5 mL) plus 5 mu g dexmedetomidine (0.5 mL). The onset time to reach peak sensory and motor level, the regression time of sensory and motor block, haemodynamic changes and side effects were studied. RESULTS Patients in Group D had significantly longer duration of sensory and motor block than patients in Group C and F. The mean time of two segment sensory block regression was 95.8 +/- 21 min in Group C, 130.5 +/- 17 in Group D, 131 +/- 22 in Group F (P<0.0001). The duration of motor block was 226 +/- 24.1, 626.5 +/- 48.5, 391.5 +/- 30.0 in Group C, D, and F respectively (P<0.0001). The onset time to reach maximum level of sensory block and modified Bromage 3 motor block were not significantly different between the groups. Dexmedetomidine group showed significantly less and delayed requirement of rescue analgesic. CONCLUSION Intrathecal dexmedetomidine is associated with prolonged motor and sensory block, haemodynamic stability and reduced demand of rescue analgesics as compared to fentanyl or lone bupivacaine.