Background: Single-injection interscalene blocks for shoulder surgery are effective but time-limited. Adjuncts such as dexamethasone may help. This study tested the hypothesis that adding dexamethasone significantly prolongs the duration of ropivacaine and bupivacaine analgesia, and that the effect differs between the two local anesthetics.
Methods: At 3 centers in the Cleveland Clinic, 218 patients undergoing shoulder procedures with interscalene blocks were randomized to 4 groups: 30 ml ropivacaine or bupivacaine 0.5% with or without dexamethasone 8mg. The primary outcome was time to first analgesic request. Kaplan-Meier curves and Cox proportional hazard models were used to compare groups.
Results: Dexamethasone significantly prolonged analgesia from both ropivacaine (Kaplan-Meier curve estimated median [interquartile range] 11.8 [9.7, 13.8] versus 22.2 [18.0, 28.6] hours) and bupivacaine (14.8 [11.8, 18.1] and 22.4 [20.5, 29.3] hours). This effect was stronger in ropivacaine than bupivacaine.
Conclusions: Dexamethasone prolongs analgesia from blocks using ropivacaine or bupivacaine, with the effect stronger with ropivacaine.