[Efficacy of axillary approach brachial plexus blocking by ultrasound-guided four points via one-puncture technique].

Objective: To investigate the clinical effects and safety of the technique of axillary approach brachial plexus blocking by ultrasound-guided four points via one-puncture.

Methods: Eighty patients scheduled for elective operation were randomly divided into 2 equal groups to undergo axillary approach brachial plexus blocking by ultrasound-guided four points via one-puncture technique (Group U) or nerve stimulator-guided brachial plexus blocking (Group N). The main branches of brachial plexus (radial, median, ulnar, and musculocutaneous nerves) were localized by ultrasound-guided or nerve stimulator-guided techniques. In Group U 8 ml of mixed anesthetic solution containing isovolumetric 0.75% ropivacaine and 2% lidocaine was injected into the 4 main branches of brachial plexus, with a total volume of 32 ml. The ultrasonic manifestations of the brachial plexus and its surrounding tissues were observed. The values of diameter and depth of the 4 nerves and the distance of the musculocutaneous nerve to the midpoint of axillary artery were measured. The manipulation time, onset time, maintaining time, efficacy of blocking, and incidence of complication were recorded.

Results: The manipulation time of Group U was 5.2 +/- 2.1 min, significantly shorter than that of Group N (14.6 +/- 3.2 min, P = 0.000), The onset times of the median, radial, and ulnar nerves of Group U were 3.3 +/- 1.9 min, 3.0 +/- 1.7 min, and 3.4 +/- 1.9 min respectively, all significantly shorter than those of Group N (4.6 +/- 2.0 min, 7.3 +/- 7.4 min, and 6.4 +/- 6.1 min respectively, P < 0.01 or P < 0.05). The anesthetic success rate of Group U was 100%, significantly higher than that of Group N (77.5%, P = 0.005). The rate of accidental puncture to blood vessel of Group U was 0, significantly lower than that of Group N (40%, P = 0.000).

Conclusion: With significantly higher anesthetic success rate, shorter manipulation time and onset time, and lower complication rate, the technique of axillary approach brachial plexus blocking by ultrasound-guided four points via one-puncture is a safe and reliable blocking method in comparison with the nerve stimulator-guided method.