Effects of Intrathecal Dexmedetomidine as an Adjuvant to Hyperbaric Bupivacaine for Spinal Anaesthesia in Adults Undergoing Elective Infra-umbilical Surgery.

INTRODUCTION: Various adjuvants to local anaesthetic are used to improve quality and duration of spinal anaesthesia. Dexmedetomidine, a novel alpha-2 adrenergic agonist, has been proposed to augment local anaesthetic effects. This study aims to investigate effects of intrathecal Dexmedetomidine on duration of analgesia and duration of sensory block during spinal anaesthesia.

METHODS: In this randomized double-blind study 38 patients were allocated into each of two groups. Otherwise healthy patients (18 to 75 years) scheduled for inguinal hernia repair or vaginal hysterectomy were included. For spinal anaesthesia, Group A received 2.5 ml hyperbaric Bupivacaine 0.5%, whereas Group B received five micrograms intrathecal Dexmedetomidine in addition. Characteristics of sensory and motor blocks, duration of analgesia, analgesic requirements, and side effects were studied for 24 hours. Student's t-test for quantitative variables and Chi- squared test for qualitative variables were used for statistical analysis.

RESULTS: Duration of analgesia was prolonged in Group B (326 min ±91) as compared to 217 min ±98 in Group A (P value <0.05). Sensory and motor block durations were significantly prolonged in Group B. Time taken to reach significant peak sensory block level was earlier in Group B. Significant reductions in incidence of visceral pain, shivering and analgesic requirements were observed in Dexmedetomidine group, without increased need of medications for altered hemodynamic parameters.

CONCLUSIONS: Dexmedetomidine as an intrathecal adjuvant to hyperbaric Bupivacaine in spinal anaesthesia prolongs duration of analgesia and sensory block with minimal adverse effects.