Differential axillary nerve block for hand or forearm soft-tissue surgery

Purpose: This study determined the effective concentration of ropivacaine required to produce the type of differential block known as sensory block with mobilization, for adequate analgesia after forearm or hand soft tissue surgery by axillary brachial plexus block. Methods: Forty-four patients were enrolled, and ultrasound-guided axillary nerve block with nerve stimulation was achieved using 16 mL of ropivacaine in total. Postoperative analgesia and sensory/motor function, side effects, the use of rescue analgesics, and the patient satisfaction score were evaluated 24 h after surgery. The effective concentration of nerve block was calculated by probit analysis. Results: Eighteen patients achieved differential block and were sufficiently satisfied with the block, which was significantly better than the patient satisfaction obtained with incomplete differential block. The maximum effective concentration of 6 mL of ropivacaine needed for differential block was calculated as 0.1285 %, which meant that 71 % of the patients experienced both sensory block and maintenance of motor function. Conclusion: This analysis showed that 16 ml of 0.1285 % ropivacaine is suitable for achieving differential block in ultrasound-guided axillary nerve block for hand and forearm surgery.