Comparison of the Ketamine-Lidocaine and Fentanyl-Lidocaine in Postoperative Analgesia in Axillary Block in Upper Limb Fractures By Ultrasound Guidance.

Background: Regional anesthesia provides safe anesthesia for upper extremity surgery. Axillary plexus block approach for hand and forearm surgery is commonly used. The use of adjuvants in combination with local anesthetics for peripheral nerve blocks enhances the quality and duration of anesthesia and postoperative analgesia.

Methods: This double-blind clinical trial was performed on 60 patients who were candidates for the surgery of upper extremity fractures with ASA I and II classes. The patients were randomly divided into two equal groups (n = 30). The intervention group 1 received 4 mg/kg lidocaine 1% and 50 µg fentanyl and the intervention group 2 received 4 mg/kg lidocaine 1% and 30 mg ketamine during the axillary block. After the necessary monitoring, a pinprick test was performed to evaluate sensory block, and a three-point scale test for the motor block was performed for median, ulnar, radial and musculocutaneous nerves. The duration of postoperative analgesia, the time of the first request for a painkiller, and the amount of opioid received were compared in the two groups.

Results: Onset of sensory and motor block was shorter in the fentanyl group but did not differ significantly. The sensory and motor block length was slightly higher in the fentanyl group, but no significant difference was observed. The severity of pain (VAS) and the mean of received opioid (pethidine) were significantly lower in the fentanyl group 24 hours after the surgery (P < 0.0001). The duration of postoperative analgesia and the time of the first request for painkiller were longer in the fentanyl group, but there was no significant difference.

Conclusions: The severity of pain and analgesic intake in the fentanyl group decreased significantly. Therefore, fentanyl is a better drug than ketamine for using as an adjuvant in the axillary block.