A Comparative Study of Intravenous Clonidine and Dexmedetomidine on Characteristics of Bupivacaine Spinal Anesthesia

Background: Spinal anesthesia with bupivacaine is administered routinely for lower abdominal and lower limb surgeries. The ensuing nerve block is sufficient to ensure patient’s well being, while motor block facilitates the surgeon’s work. In patients receiving spinal anaesthesia, with local anesthetic agents like bupivacaine, the addition of another drug as adjuvant prolongs the analgesia. The present study is designed to study the effect of dexmedetomidine (D) and Clonidine (C) on the duration of motor and sensory block as well as postoperative analgesia by intrathecal bupivacaine in patients undergoing lower limb orthopedic surgery. Subjects and Methods: This study was carried out on 90 patients in the age group of 18 to 50 years, belonging to the American Society of Anesthesiologists(ASA) physical status I and II presenting for lower limb orthopedic surgery were included in the study. Patients were divided randomly into 3 groups. Group D received 1μg kg-1of dexmedetomidine, group C received 2 μg kg-1 of clonidine and group NS Control group received an equivalent amount of normal saline. Results: From the current study we observed that single dose of 1 μg kg-1 dexmedetomidine over 20 minutes started 20 minutes after spinal block and a single dose of 2 μg kg-1 Clonidine resulted in a significant prolongation of time to two-segment regression, postoperative analgesia,  sensory block and motor block with the maintenance of hemodynamic parameters. Intravenous dexmedetomidine was more effective than Clonidine at the prolongation of time to two-segment regression, postoperative analgesia, sensory block and motor block of spinal anesthesia with 0.5% hyperbaric bupivacaine. Conclusion:  Dexmedetomidine (1μg kg-1) in comparison to Clonidine (2 μg kg-1) and placebo is far more effective in the motor blockade, sensory blockade and duration of postoperative analgesia.