Effect of intravenous dexmedetomidine on duration of spinal anaesthesia with hyperbaric bupivacaine - A comparative study

Introduction and Objectives: Sub Arachnoid Block is one of the commonly used anaesthetic technique for lower limb surgeries, the duration and quality of block can be prolonged using several adjuvants. The objective of this study was to assess the quality, duration of block and time required for supplemental analgesia in patients undergoing lower limb surgeries. Materials and Methods: Fifty ASA class I and II patients scheduled for lower limb surgeries, received Subarachnoid block with 15 mg hyperbaric bupivacaine or 15 mg hyperbaric bupivacaine plus intravenous dexmedetomidine 0.5microgm/kg body weight in 10ml saline as bolus dose prior to Sub Arachnoid Block. Outcome measures included onset and duration of sensory and motor block and duration of analgesia. Results: Duration of sensory block (p=0.0001), duration of motor block (p=0.0001) and duration of analgesia (p=0.0001) was significantly longer in dexmedetomidine group than the patients who received Subarachnoid block with 15 mg Bupivacaine alone. A significant decrease in heart rate, systolic blood pressure and mean arterial pressure was noted in dexmedetomidine group. Conclusion: Intravenous dexmedetomidine in a single dose of 0.5?g/kg, administered over a period of 10 minutes prior to sub arachnoid block, prolongs the duration of sensory and motor blockade with arousable sedation, without any respiratory depression.