Is there a dose response of dexamethasone as adjuvant for supraclavicular brachial plexus nerve block? A prospective randomized double-blinded clinical study.

ABSTRACT

STUDY OBJECTIVE: The study objective is to examine the analgesic effect of 3 doses of dexamethasone in combination with low concentration local anesthetics to determine the lowest effective dose of dexamethasone for use as an adjuvant in supraclavicular brachial plexus nerve block. DESIGN: The design is a prospective randomized double-blinded clinical study. SETTING: The setting is an academic medical center. PATIENTS The patients are 89 adult patients scheduled for shoulder arthroscopy. INTERVENTIONS: All patients were randomly assigned into 1 of 4 treatment groups (i) bupivacaine, 0.25% 30 mL; (ii) bupivacaine, 0.25% 30 mL with 1-mg preservative-free dexamethasone; (iii) bupivacaine, 0.25% 30 mL with 2-mg preservative-free dexamethasone; and (iv) bupivacaine, 0.25% 30 mL with 4-mg preservative-free dexamethasone. All patients received ultrasound-guided supraclavicular brachial plexus nerve blocks and general anesthesia. MEASUREMENTS The measurements are the duration of analgesia and motor block. MAIN RESULTS: The median analgesia duration of supraclavicular brachial plexus nerve block with 0.25% bupivacaine was 12.1 hours; and 1-, 2-, or 4-mg dexamethasone significantly prolonged the analgesia duration to 22.3, 23.3, and 21.2 hours, respectively (P = .0105). Dexamethasone also significantly extended the duration of motor nerve block in a similar trend (P = .0247). CONCLUSION: Low-dose dexamethasone (1-2 mg) prolongs analgesia duration and motor blockade to the similar extent as 4-mg dexamethasone when added to 0.25% bupivacaine for supraclavicular brachial plexus nerve block.