The effect of local infiltration with morphine before carpal tunnel release

We compared the effect of infiltration with a mixture of 1 per cent lidocaine and two milligrams of morphine in twenty-five patients who were to be managed with a carpal tunnel release with the effect of infiltration with 1 per cent lidocaine only in a second group of twenty-five patients who were to have such a release. In both groups, the injection was administered after inflation of the tourniquet. During the procedure, the patients' movement and vocalization of discomfort did not differ substantially between the groups. However, in the immediate postoperative period, the patients who had received morphine indicated a significantly higher score (on a visual-analog scale) for peak intraoperative pain than did the patients who had received lidocaine only (2.44 +/- 1.73 points compared with 1.32 +/- 1.22 points; p = 0.01). The numbers of patients who had pain in the recovery room, the numbers of patients who received analgesics in the recovery room, and the scores for pain at the time of discharge were similar for the two groups. The score for pain on the first postoperative day was more than 4 points for seven patients who had received morphine, whereas no patient who had received lidocaine only had a score of more than 4 points (p = 0.01); however, the amount of analgesics taken at home was similar for the two groups. Postoperative complications, which included hypotension, fainting, weakness, and chest pain, occurred in eight patients (32 per cent) who had received morphine and in none who had received lidocaine only (p < 0.01).