Dose-dependency of dexamethasone on the analgesic effect of interscalene block for arthroscopic shoulder surgery using ropivacaine 0.5% A randomised controlled trial

BACKGROUNDDexamethasone prolongs the duration of single-shot interscalene brachial plexus block (SISB). However, dose-dependency of dexamethasone as an adjuvant for SISB remains insufficiently understood.OBJECTIVEThe objective of this study is to evaluate the effect of different doses of dexamethasone on the duration of SISB using ropivacaine 0.5%.DESIGNA randomised, double-blind controlled trial.SETTINGSingle university tertiary care centre.PATIENTSOne hundred and forty-four patients scheduled for elective arthroscopic shoulder surgery were allocated randomly to one of four groups.INTERVENTIONSPatients received 12ml of ropivacaine 0.5% in 0.9% saline (control group), or containing dexamethasone 2.5, 5.0 or 7.5mg for SISB.MAIN OUTCOME MEASURESThe primary endpoint was the time to the first analgesic request. Pain scores and adverse effects were also assessed up to 48h postoperatively.RESULTSInclusion of dexamethasone 2.5, 5.0 and 7.5mg resulted in significant (P<0.001) increases in time to the first analgesic request by factors of 1.6, 2.2 and 1.8, respectively. The percentages of patients not requiring analgesics in the first 48h postoperatively with dexamethasone 0.0, 2.5, 5.0 and 7.5mg were 3, 22, 39 and 33%, respectively (P<0.001). There were no significant effects on pain scores or incidences of adverse effects.CONCLUSIONDexamethasone demonstrated significant beneficial dose-dependent effects on duration to the first analgesic request, the number of patients not requiring analgesics and analgesic use in the first 48h after SISB for arthroscopic shoulder surgery. There were no significant effects on pain scores or incidences of adverse effects.TRIAL REGISTRATIONthe trial was registered with the Clinical Trial Registry of Korea: https://cris.nih.go.kr/cris/index.jsp. Identifier: KCT0001078