How Much Dexamethasone Is Required to Prolong Analgesic Duration After Interscalene Block?

Low doses of IV dexamethasone (4 and 10 mg) were demonstrated to prolong the analgesic duration of interscalene block significantly, in a prospective double-blind randomized placebo-controlled study [Clinical Trials Registration.gov (NCT02412657)].

The study analyzed data for 69 patients undergoing elective arthroscopic shoulder surgery under regional anesthesia with a single-shot interscalene block (0.5% ropivacaine 20 mL).

The authors defined 3 groups: (1) addition of dexamethasone 4 mg (D4); (2) dexamethasone 10 mg (D10); or (3) a placebo [normal saline (NS)]. The treatments and placebo were given intravenously at the time of block completion.

Median duration of analgesia before request for additional medication differed between the 3 groups [D4, 19.7 (16.9-23.3) hours; D10, 19.1 (11.5-22.8) hours; and NS, 11.8 (9.3-14.0) hours; P = .001]. Statistical significance was determined for D4 and D10 compared with placebo but not for D4 compared with D10.

The authors concluded that low doses of IV dexamethasone (4 and 10 mg) significantly prolong the analgesic duration of interscalene block. (See Chalifoux F, Colin F, St-Pierre P, et al. Low dose intravenous dexamethasone (4 mg and 10 mg) significantly prolongs the analgesic duration of single-shot interscalene block after arthroscopic shoulder surgery: a prospective randomized placebo-controlled study [published online ahead of print January 3, 2017]. Can J Anaesth. doi:10.1007/s12630-016-0796-6.)