Improvement in postoperative pain control by combined use of intravenous dexamethasone with intravenous dexmedetomidine after interscalene brachial plexus block for arthroscopic shoulder surgery A randomised controlled trial

OBJECTIVES We evaluated the difference in time to first rescue analgesic request between patients receiving co-administered intravenous dexamethasone and dexmedetomidine and patients receiving intravenous dexamethasone alone after single-shot ISBPB for arthroscopic shoulder surgery. DESIGN A randomised controlled study. SETTING A single tertiary care centre, study period from August 2017 to January 2018. PATIENTS Sixty-six patients undergoing arthroscopic shoulder surgery with ISBPB with 15 ml of 0.5% ropivacaine with 1: 200 000 epinephrine. INTERVENTIONS We randomly assigned the patients to one of three groups: intravenous 0.9% saline (control), intravenous dexamethasone 0.11 mg kg^-1 (D1 group), or co-administered intravenous dexamethasone 0.11 mg kg^-1 and intravenous dexmedetomidine 1.0 mg kg^-1 (D2 group). MAIN OUTCOME MEASURES The primary outcome was the time to first rescue analgesic request. RESULTS The median [interquartile range] time to first rescue analgesic request was significantly longer for the D2 group (66.3 h [23.3 to 72]) than the D1 (17.4 h [14.9 to 36], P ¼ 0.002) and control (10.9 h [10.1 to 12.2], P < 0.001) groups. The D1 and D2 groups both had reduced pain scores, reduced postoperative opioid consumption, less sleep disruption and improved patient satisfaction compared with the control group. There were no significant elevations in blood glucose concentrations in patients receiving dexamethasone (D1 and D2 groups) compared with the control group at postoperative day 1. CONCLUSION Co-administration of intravenous dexamethasone (0.11 mg kg^-1) with dexmedetomidine (1.0 mg kg^-1) significantly prolonged the time to first rescue analgesic request after single-shot ISBPB in patients undergoing arthroscopic shoulder surgery.