[Comparison of dosage relations of prilocaine and bupivacaine for axillary plexus anesthesia].

The effects of 40 ml of prilocaine 1% compared to 30 ml prilocaine 1% added to 10 ml bupivacaine 0.5% and 20 ml prilocaine 1% added to 20 ml bupivacaine 0.5% after injection into the brachial plexus sheath were evaluated. In a prospective study, 90 patients who underwent surgery on the upper limb were randomly allocated to one of these three groups. In each group 15 patients were treated using nerve stimulation with an immobile needle and 15 using a plexus catheter. We assessed the sensory and motor blockade of the appropriate nerves every 5 minutes after injection for a period of 45 minutes (pin-prick testing or strength of the appropriate muscles). Postoperatively the patients documented the strength of their pain on a score of 0 to 10 four hours, six hours and 24 hours after injection. There were no differences in onset time between the groups, the operation normally starting after about 30 minutes. Compared to other nerves, blockade of the musculocutaneous nerve was delayed and not as complete. The quality of the blockade of the radial nerve was not worse than that of the ulnar and median nerve. Eighty-four patients were operated on in regional anaesthesia, 74 patients without supplementary measures. There were no differences in postoperative pain between the two different techniques. Significant differences, however, were found between the three drug groups: Patients given 40 ml of prilocaine 1% documented pain (0.75) 4 hours after injection; the other two groups reported nearly none. Six hours after injection the patients who had received 40 ml of prilocaine 1% had significantly more pain (2.25) than patients who had received 30 ml of prilocaine 1% plus 10 ml of bupivacaine 0.5% (0.96); patients who had received 20 ml of prilocaine 1% plus 20 ml of bupivacaine 0.5% had nearly no pain (0.19). We can conclude that mixing of prilocaine 1% with bupivacaine 0.5% is a useful way to achieve adequate duration of anaesthesia and to reduce postoperative pain without extending onset times for axillary plexus block. Postoperative application of analgetics can often be avoided completely.