Intravenous Dexamethasone for Prolongation of Analgesia Following Supraclavicular Brachial Plexus Block for Shoulder Arthroscopy: A Randomized Controlled Study
The optimal dose of intravenous (IV) dexamethasone for prolongation of analgesia from supraclavicular blocks in shoulder surgery has yet to be delineated (1-4). Many studies comparing IV to perineural dexamethasone have shown analgesic equivalence. Thus, this triple-blinded study aims to clarify the analgesic duration provided by supraclavicular blocks when supplemented with varying doses of IV dexamethasone and to clarify the effect of IV dexamethasone on blood glucose levels during and after arthroscopic surgery.
Materials and Methods
140 patients scheduled for ambulatory shoulder arthroscopy with supraclavicular blocks (30-40cc of 50:50 mixture 1.5% Mepivacaine:0.5% Bupivacaine) and sedation, were randomized into four groups to receive 0mg, 4mg, 6mg, or 8mg of IV dexamethasone.
The primary outcome was the analgesic duration defined as the time from block placement until the patient reported time that analgesia from the block completely wore off.
Patient characteristics are reported (Table 1). The median time until pain relief from the block completely wore off was 17.4 hours for the 0mg group, 22.7 hours for the 4mg group, 20.2 hours for the 6mg group and 19.8 hours for the 8mg group (Figures 1 and 2). Mean blood glucose levels for the 0mg, 4mg, 6mg and 8mg groups were 101.6 ± 20.2mg/dl, 124.5 ± 30.7mg/dl, 110.1 ± 22.8mg/dl, and 110.0 ± 27.1mg/dl at two hours after dexamethasone administration (Figure 3). Postoperatively, one patient in the 8mg group developed a psoriatic rash at the site of a previously healed spider bite.
There was no significant difference in block duration between any of the doses of IV dexamethasone and placebo. However, in a post-hoc analysis of the pooled dexamethasone groups, dexamethasone mildly increased the duration of analgesia compared to the saline group (20h vs. 17h, p=0.02). Patients in all groups reported excellent satisfaction with their analgesia.