Dexamethasone Versus Ketamine in the Interscalene Block in Patients Undergoing Arthroscopic Shoulder Surgery: A Randomized Double-Blinded Study

Abstract

Objective: Arthroscopic shoulder surgery (ASS) is often followed by severe pain. Interscalene brachial plexus block (ISB) was used to relieve such pain. The aim of the study was to compare the effect of adding either dexamethasone or ketamine to ISB on time to the fi rst request for analgesia.

Methods: Sixty patients scheduled for ASS were enrolled in this study. Before induction of general anaesthesia, patients were randomly allocated to two groups; in Group D, patients received ISB with bupivacaine 0.3%, 5 mL lidocaine 2% plus 8 mg dexamethasone. Whereas in Group K, patients received ISB with bupivacaine 0.3%, 5 mL lidocaine 2% plus 50 mg ketamine. Time to the fi rst administration of supplemental analgesic postoperative was our primary concern. Secondary outcomes included pain score, patient satisfaction, and side effects of either block or drugs. Student's t-test was utilized for comparison between the two groups. Chi-square test was used to test the association between categorical variables.

Results: Time to the first request of analgesia was statistically significantly longer in Group D when compared to Group K. The onset of sensory and motor blocks, number of patients requiring rescue analgesia and patient satisfaction showed no difference between the two groups. Pain score in Group K, compared to Group D, was statistically signifi cant less early postoperatively.

Conclusions: We conclude that addition of dexamethasone to local anesthetic in ISB for patients undergoing ASS resulted in longer time elapsed to the first request of analgesia when compared with ketamine. Pain score in the early postoperative period was statistically improved in ketamine group, but this might be of no clinical signifi cance, when compared with dexamethasone.

Keywords: arthroscopic shoulder surgery; dexamethasone; interscalene; ketamine.