Comparative Study of Anaesthetic Properties of Bupivacaine Alone And A Combination of Dexamethasone And Bupivacaine, for Interscalene Brachial Plexus Block, in Upper Limb Surgery

Background: Peripheral nerve blocks are used as the sole anaesthetic technique to facilitate painless surgery supplemented with monitored anaesthesia care. People have tried mixing local anaesthetic with adjuvant drugs in an attempt to prolong analgesia duration. Aims of this study is to determine the effects of dexamethasone, when added to bupivacaine on the onset, duration of sensory blockade, motor blockade and evaluated its side effects during interscalene brachial plexus block . Method : It was a randomized, double blind, interventional type, hospital based controlled study. 60 patients were randomized into two groups. In control group bupivacaine 140 mg (28 ml of 0.5 % solution) + 2 ml normal saline. In dexamethasone group bupivacaine 140 mg (28 ml of 0.5 % solution) + dexamethasone 8mg (2 ml of 4mg/ml of solution). The primary outcome was the time to first analgesic requested in post-anaesthesia care unit . Numerical variables were compared by the student’s t-test or mann-whitney U-test, depending on the distribution. Result: Dexamethasone significantly prolonged the duration of analgesia . The duration of analgesia with bupivacaine was [mean ± SD] 395+47.25 (min) and with dexamethasone and bupivacaine was 718+57.14 (min). There was significant difference between the postoperative VAS scores of the two groups at the time period of 6 hrs and 12 hrs postoperatively. In 18 hrs. and 24 hrs, there was also significant difference in onset of sensory blockade [dexamethasone(9.67 +1.12min) vs bupivacaine(12.72+1.39 min.),P vale 0.00] but there was no significant difference in onset motor and duration of motor blockade. Conclusion: Dexamethasone when added to 0.5% bupivacaine in interscalene brachial plexus block in shoulder and arm surgeries,there was in early onset and prolongation of sensory analgesia and provides better postoperative analgesia.