[Optimal dose of local anesthetic mixture in ultrasound-guided infraclavicular brachial plexus block via coracoid approach: analysis of 160 cases].

OBJECTIVE: To investigate the optimal dose of local anesthetic mixture in ultrasound-guided infraclavicular brachial plexus block via coracoid approach.

METHODS: 160 patients scheduled for surgery of the hand or forearm were randomly divided into 4 equal groups (Groups A, B, C, and D). To receive 8, 7, 6, or 5 ml of anesthetic mixture of 0.75% ropivacaine and 2% lidocaine for radial nerve, axillary nerve, median nerve, ulnar nerve, median cutaneous nerve of arm, median antebrachial cutaneous nerve, and lateral antebrachial cutaneous nerve respectively ultrasound-guided infraclavicular brachial plexus block via coracoid approach. The time for anesthesia taking effect, anesthesia maintenance time, and quality of sensory block were observed.

RESULTS: Anesthesia took effect about 4 minutes after injection in these 4 groups without significant differences among then (all P > 0.05). The good analgesic effect rates of Groups A, B, and C were all 100%, all significantly higher than that of Group D (87.5%, P = 0.027). The block maintenance times of Groups A, B, and C were (377 +/- 111) min, (369 +/- 135) min, and (351 +/- 112) min respectively, all significantly longer than that of Group D [(296 +/- 101) min, P = 0.024]. No anesthesia-related complication was found in these 4 groups.

CONCLUSION: Ultrasound-guided infraclavicular brachial plexus block via coracoid approach can reduce the volume of local anesthetic mixture. The dose of 6 ml local anesthetic mixture for each nerve fascicle, totally 18 ml, provides good analgesic effect and does not seem to affect the time for anesthesia taking effect.