Morphine as an adjuvant to local anesthetics in axillary brachial plexus block in forearm and hand surgery

Background
The axillary brachial plexus block is a popular nerve block for forearm, wrist, and hand surgery. The use of local anesthetic peripheral nerve blocks for surgical anesthesia and postoperative pain management has increased significantly with the advent of ultrasound-guided techniques. The discovery of peripheral opioid receptors led to the clinical application of adding opioids to local anesthetics for peripheral nerve blocks. This study is done to evaluate effect of morphine on onset, duration, and quality of analgesia when added to local anesthetics in axillary brachial plexus block and to detect any complications that occurred with this technique.
Patients and methods
In this prospective controlled clinical trial, 60 adult patients aged 18–60 years scheduled for orthopedic surgery of the forearm and hand with axillary brachial plexus block were selected and randomly allocated to two groups. Placebo group received 24 ml bupivacaine 0.5%, and morphine group received 24 ml bupivacaine 0.5%+5 mg morphine. The onset and duration of sensory and motor blocks, duration of analgesia, and adverse events (such as nausea and pruritus) during perioperative period were recorded.
Results
Onset of touch and pain block was faster in morphine group, with values of 0.016 and 0.025, respectively. Onset of motor block was similar in the two groups. Duration of touch block was longer in morphine group, with value of 0.022. Duration of motor block showed no change between the two groups. Duration of analgesia was longer in the morphine group, with value of 0.001, with lower consumption of analgesia. No complications were recorded perioperatively.
Conclusion
We concluded that morphine provide better postoperative analgesia when injected with local anesthetics in ultrasound-guided axillary brachial plexus block without an increase in the frequency of complications.