Evaluating effect of intravenous dexmedetomidine on hyperbaric bupivacaine spinal anesthesia
Abstract
Background & Aims: Intravenous dexmedetomidine is being increasingly used in perioperative setting including as an adjunct to local anesthetic in various regional techniques with an intent to either improve the block quality, increase the duration of block or to provide sedation and patient comfort during the periblock period. Intravenous dexmedetomidine when used just before or after spinal anesthesia has many desirable effects such as adequate sedation and patient comfort, longer sensory-motor blockade, prolonged postoperative analgesia and reduced post-anesthesia shivering. We aimed to study the effect of intravenous dexmedetomidine on spinal anesthesia with hyperbaric 0.5% bupivacaine.
Methodology: One hundred American Society of Anesthesiologists (ASA) physical status I and II patients undergoing orthopaedic surgeries under spinal anesthesia were randomized into two groups of 50 each. After giving spinal anesthesia with 3.5 ml of 0.5% hyperbaric bupivacaine, patients in Group D received a loading dose of 1 μg/kg of dexmedetomidine intravenously by infusion pump over 10 min followed by a maintenance dose of 0.5 μg/kg/h till the end of surgery, whereas patients in Group C received an equivalent quantity of normal saline. The two-dermatome pinprick sensory regression time, duration of the motor block, Ramsay sedation score (RSS), duration of analgesia and side effects of dexmedetomidine were assessed.
Results: The time taken for regression of sensory block to S1 dermatome and Bromage 0 motor block was increased significantly by addition of dexmedetomidine. Time to first requirement of analgesic in postoperative period was more in Group D compared to Group C. Sedation was more in patients of Group D compared to Group C (P < 0.001).
Conclusion: Intravenous dexmedetomidine significantly prolongs the duration of sensory and motor block of bupivacaine spinal anesthesia. The incidence of bradycardia is significantly higher when intravenous dexmedetomidine is used as an adjuvant to bupivacaine spinal anesthesia. Dexmedetomidine provides excellent intraoperative sedation and postoperative analgesia.
