Evaluation of postoperative analgesic efficacy of dexmedetomidine as adjuvant with ropivacaine in ultrasound guided adductor canal block in patients undergoing unilateral Total Knee Replacement

Abstract

The aim of anaesthesia in Total knee replacement (TKR) is to provide adequate analgesia and early ambulation. The recent success of adductor canal block in providing post-operative analgesia and achieving early ambulation has evoked interest in studying the effects of local anaesthetic agents and various adjuvants.This study was a randomized three arm parallel group comparative study conducted in a tertiary care center in India on 135 patients undergoing unilateral total knee replacement under spinal anaesthesia. After completion of the surgery, the adductor canal block was performed with ultrasound guidance at mid-thigh level in all three groups. In group A, 20 ml 0.375% ropivacaine was only used but in group B and C Dexmedetomidine was added to ropivacaine (total volume of 20 ml; 0.375%) at a dose of 0.25 µg/kg and 0.50 µg/kg respectively. The primary outcome of the study was to compare duration of analgesia after the adductor canal block. Duration to rescue analgesia (in hours) was significantly longer [Group A: 15.71±4.87; Group B: 16.44±6.21; Group C: 19.78±5.57 (p=0.014)] and total opioid (24 hours tramadol needed in mg) consumption [Group A: 60.00±13.94; Group B: 52.22±18.80; Group C: 33.33±13.95 (p=0.033)] was significantly lower in Group C. NRS scores both at movement and rest were significantly lesser in Group C at 18 and 24 hours timepoints. Patient satisfaction was significantly higher in Group C with 46.67% patient reporting better than expected peri-operative experience (p=0.022).The addition of dexmedetomidine, 0.5 µg/kg to 0.375% ropivacaine in adductor canal block results in longer duration of analgesia, less 24 hours opioid consumption, better motor strength and better patient satisfaction without any adverse effect after unilateral total knee replacement surgery.