Comparison of onset of action of Intrathecal Clonidine vs Intrathecal Fentanyl as an adjuvant with hyperbaric Bupivacaine and Bupivacaine alone under spinal anesthesia for lower limb orthopedic surgeries

Abstract

Background: Adjuvants are added to a local anesthetic solution to prolong the duration of analgesia. There is a paucity of studies comparing the onset of action of adjuvants like Clonidine and Fentanyl. In this study, the time of onset of action of intrathecal clonidine and intrathecal fentanyl as adjuvants to bupivacaine and bupivacaine alone were compared in the subarachnoid block for lower limb orthopedic surgeries. Materials and Methods: 90 adult patients posted for orthopedic surgery of the lower limb were divided into three equal groups of 30 each. Group A being the control group was given hyperbaric Bupivacaine(3ml) +0.5ml of Normal saline, Group B was given Intrathecal hyperbaric Bupivacaine (3 ml) +30 μg Clonidine and Group C was given Intrathecal hyperbaric Bupivacaine (3 ml) + Fentanyl 25 μg. The primary objective was to compare the time of onset of block and duration of analgesia. The secondary outcomes were the duration of sensory and motor block, duration of analgesia, hemodynamic parameters, and side effects. Results: The time of onset of the sensory blockade was 4.83 ± 0.64, 1.72 ± 1.47, and 3.4 ± 1.43 mins in groups A, B, and C respectively. The time of onset of the motor blockade as estimated by the time to reach level 2 on the Bromage scale, was 6.07 ± 0.55, 2.38 ± 1.32, and 5.06 ± 1.28 mins in groups A, B, and C respectively. The duration of postoperative analgesia was prolonged in the Clonidine group compared to the Fentanyl group. Conclusion: The study reveals that the time of onset of action of sensory and motor block was faster and the duration of analgesia was prolonged with adjuvants like Clonidine when compared to Fentanyl when added to Bupivacaine.