ABSTRACT: To assess differences in the brachial plexus block in 2 groups who received the same dose of levobupivacaine: 1 group received a small volume of solution at high concentration and the other group received a large volume in solution at low concentration.
A prospective, randomized clinical trial enrolling 69 patients scheduled for wrist and/or hand surgery with a brachial plexus block with levobupivacaine in the humeral canal. Nerve stimulation was used to locate a response from the 4 terminal nerves in the brachial plexus. In the group receiving a larger volume, 10 mL of a solution of levobupivacaine at a concentration of 0.375% was used for each nerve. In the high concentration group receiving a smaller volume, levobupivacaine was used at a concentration of 0.75% in 5 mL for each nerve. Sensory latency was assessed by the pin prick technique. Motor block, the success rate (percentage), and duration of sensory and motor blockades were also evaluated.
The full sensory block was significantly more efficacious in the large volume group than in the high concentration group (85.3% vs 51.6%, P = 0.003). A full motor block was reached in a small percentage of patients in both groups. There were no significant differences in latency or duration of block.
The success rate was lower in the group receiving the smaller volume at a higher concentration. It is advisable to administer local anesthetics in larger volumes at lower concentrations to improve block quality. Latency and duration were similar in both groups.
Revista espanola de anestesiologia y reanimacion 12/2005; 52(9):529-35.