Effect of ketamine as an adjuvant in ultrasound-guided supraclavicular brachial plexus block: A double-blind randomized clinical trial study

BACKGROUND: Supraclavicular brachial plexus block is one of the most effective anesthetic procedures in operations for the upper extremity. Ketamine has been reported to enhance the analgesic effects of local anesthetics. We have conducted this study to assess whether coadministration of ketamine can prolong the local analgesic effect of lidocaine in the supraclavicular brachial plexus block for patients undergoing elective upper extremity surgery. MATERIALS AND METHODS: Sixty adult patients undergoing elective surgery of the elbow, forearm, wrist or hand were randomly allocated in two groups of 30 patients each. Group 1 (ketamine group) received 5 mg/kg lidocaine 1.5% plus 2 mg/kg ketamine, Group 2 (control group) received 5 mg/kg lidocaine 1.5% and saline. The outcome measures included severity of pain by using visual analog scale (VAS, 0 = no pain 10 cm = the most severe pain), time of first request for analgesia, and total dose of postoperative opioid administration. The data was analyzed using the χ(2) test, student's t-test, Kaplan-Meier survival analysis, and Multivariate analysis tests. RESULTS: Patients in the control group had a higher VAS than patients who received ketamine, at all time points during the first 24 hours after surgery (all P < 0.05). The time of first request for analgesia in the ketamine group was significantly more than in the control group (8.93 ± 1.0 vs. 7.30 ± 1.9, respectively, P < 0.001). CONCLUSION: The addition of ketamine to lidocaine in the ultrasound-guided brachial plexus block could decrease the postoperative pain and need for analgesic. Therefore, it could be considered as an option in the brachial plexus block to enhance the analgesic action of lidocaine.