[Comparison between 1.5% lidocaine with adrenaline and 1.5% plain mepivacaine in axillary brachial plexus block]

To evaluate the distribution of sensory blockade, the onset time and the duration of the axillary plexus block obtained after the administration of 40 mL of 1.5% lignocaine with adrenaline or 40 mL of plain 1.5% mepivacaine.

Prospective, randomised, comparative, double blind study.

One hundred and fifty five patients undergoing hand surgery were randomised into two groups: in group L, 73 patients were given 1.5% lignocaine with 1/200,000 adrenaline and in group M, 82 patients received 1.5% mepivacaine. The entire volume was injected on the first evoked motor activity obtained for a current less than 0.5 mA. Sensory and motor block of each of the four major nerves of the hand and forearm were assessed using light touch and motor strength respectively. The block was considered complete when all nerves were anaesthetised (median, radial, musculocutaneous and ulnar).

The percentage of complete sensitive blockade was 22% in group L and 24% in group M. Complete motor blockade was respectively 27% in group L and 40% in group M. The median time required to obtain a complete sensory blockade was 18 min for both group. The median time required to obtain a complete motor blockade was 17 min in-group L and 16 min in-group M. The duration of the sensory blockade was not different for both groups (i.e., 255 +/- 76 min versus 231 +/- 70 min in group L and M respectively. The duration of the motor blockade was longer in group L compared to group M (199 +/- 64 min versus 231 +/- 74 min respectively, p < 0.05).

Following axillary plexus block, 1.5% mepivacaine improves neither the extension nor the duration of sensory blockade achieved by 1.5% lignocaine with adrenaline.