Adjuvant dexamethasone with bupivacaine prolongs the duration of interscalene block: a prospective randomized trial

Purpose To identify the effects of adding two different doses of dexamethasone on the duration and quality of interscalene block in patients undergoing shoulder surgery in ambulatory surgery settings. Methods The study design was reviewed and approved by the University at Buffalo Institutional Review Board for Human Subjects. After obtaining informed consent, a total of 90 patients undergoing shoulder surgery using interscalene block with 0.5% bupivacaine (40 mL) were assigned randomly to one of three groups: control patients, “Group C,” who received no additive; low dose, “Group L,” who received additional dexamethasone 4 mg; and high dose, “Group H,” who received dexamethasone 8 mg in addition to 0.5% bupivacaine. Postoperative analgesia was assessed using the numeric rating scores of pain and the postoperative consumption of acetaminophen 325 mg + hydrocodone 7.5 mg tablets. Analysis was by intention to treat. Statistical significance was tested using a two-way analysis of variance and a nonparametric analysis of variance for consumption of analgesics. Results Four patients were excluded from the study due to either a failed block or inadequate follow-up. The duration of analgesia was significantly prolonged in both Group L (21.6 ± 2.4 h) and Group H (25.2 ± 1.9 h) compared with Group C (13.3 ± 1.0 h) ( p