Perineural Low-Dose Dexamethasone Prolongs Interscalene Block Analgesia With Bupivacaine Compared With Systemic...

Perineural dexamethasone and intravenous (IV) dexamethasone have been shown to prolong peripheral nerve block duration. The effects of perineural and IV dexamethasone have only been compared at doses of 4 mg or greater. This triple-blind, randomized trial examined the effect of 1 mg IV versus perineural dexamethasone on interscalene block (ISB) analgesia duration.

Patients undergoing ambulatory shoulder arthroscopy received an ultrasound-guided ISB with 15 mL bupivacaine 0.5% and 1 mg preservative-free dexamethasone that was administered perineurally (PeriD) or IV (IVDex). All patients received IV ketorolac and were discharged on naproxen 500 mg 2 times a day plus oxycodone/acetaminophen as needed. Peripheral nerve block duration, pain, opioid consumption, and block satisfaction were assessed via telephone follow-ups.

There were 63 PeriD patients and 62 IVDex patients who completed the primary outcome follow-up. The median time until analgesia from the ISB completely wore off was 3.5 hours (95% confidence interval, 1.0-6.0 hours) longer in the PeriD versus IVDex groups; P = 0.007). Time until the pain relief from the ISB began to wear off was also longer in the PeriD versus IVDex group (5.5 hours [95% confidence interval, 2.1-9.0 hours]; P = 0.002). Other secondary outcomes, including opioid consumption, satisfaction, and pain scores, were not different between groups.

In patients undergoing shoulder arthroscopy, low-dose perineural dexamethasone (1 mg) in combination with 15 mL of 0.5% bupivacaine prolonged the median time until pain relief from the ISB completely wore off compared with 1 mg IV dexamethasone. However, the degree of prolongation was smaller than the a priori-defined minimal clinically meaningful difference of 5 hours.

This study was registered at Clinicaltrials.gov, identifier NCT02506660.