Comparison of Dexmedetomidine and Fentanyl Added to Levobupivacaine in USG-guided Axillary Block for Upper Limb Surgeries: A Randomised Double-blinded Controlled Study

Abstract

Introduction: Apart from general anaesthesia, brachial plexus block by the axillary approach is one of the reliable sole anaesthetic techniques for patients undergoing upper limb surgeries. In this study, levobupivacaine was chosen due to fewer adverse effects compared to Bupivacaine, and fewer studies were available for the axillary approach to brachial plexus block. Adjuvants were added to hasten the onset and also to prolong their analgesic effect. Aim: To compare the effect of Dexmedetomidine (D) 0.5 mcg/kg and Fentanyl (F) 0.5 mcg/kg when added to 0.5% Levobupivacaine (L) as an adjuvant in brachial plexus block by the axillary approach for upper limb surgeries. Materials and Methods: A randomised double-blind controlled study was carried out at the Department of Anaesthesiology, Sree Balaji Medical College, BIHER, Chennai, Tamil Nadu, India from January 2020 to October 2021 on 60 American Society of Anaesthesiologists (ASA) I and II patients of either sex posted for various types of upper limb surgeries. Subjects were divided into two equal groups by computer-generated randomisation. Group A received 0.5% levobupivacaine and dexmedetomidine 0.5 mcg/kg, and Group B received 0.5% levobupivacaine and Fentanyl 0.5 mcg/kg. Both patients and the evaluator were unaware of the type of adjuvants added to the local anaesthetic. The onset time, duration of sensory and Motor blockade were recorded. Haemodynamic variables and duration of analgesia were recorded for 24 hours postoperatively. The Mann-Whitney U test demonstrated variations in the onset and duration of sensory and motor blocks. Adverse effects, including nausea, vomiting, and hypotension, exhibited significant differences according to Fisher’s-exact test. Results: Age and weight distributions were comparable between groups (mean age: Group A=45.20 years, Group B=44.80 years; mean weight: Group A=74.13 kg, Group B=74.43 kg). Group A exhibited faster sensory and motor block onset times (sensory: Group A=6.20 minutes, Group B=8.63 minutes; motor: Group A=8.27 minutes, Group B=10.00 minutes), longer block durations (sensory: Group A=11.63 hours, Group B=9.53 hours; motor: Group A=9.67 hours, Group B=8.20 hours), and required the first rescue analgesic (Group A=12.57 hours, Group B=10.27 hours) compared to Group B (p<0.05). Similarly, the mean time for the first rescue analgesia for patients among these two groups was also statistically significant (p<0.05). Conclusion: The addition of 0.5 mcg/kg dexmedetomidine to 0.5% levobupivacaine in axillary block was more effective in prolonging the duration of blockade and providing adequate intraoperative analgesia when compared to 0.5 mcg/kg fentanyl with 0.5% levobupivacaine, without producing any adverse events.