[Effect of the peridural methadone concentration in postoperative analgesia].

The analgesic characteristics of 3 to 6 mg epidural methadone administered in two different concentrations for postoperative analgesia have been compared in two homogeneous groups of patients submitted to surgical procedures on trunk or legs. Methadone was given at a concentration of 0.1% in group I (70 patients) and diluted in 10 ml saline in group II (35 patients). Methadone doses were calculated on the basis of age and weight of the patient and the performed surgical procedure. Mean latency for analgesia was 25 +/- 11 min in group I and 28 +/- 13 min in group II. The duration of the analgesia was significantly longer (p less than 0.01) in group I (9.7 +/- 5.6 h) than in group II (5.7 +/- 2.4 h). Side effects were not frequent and without clinical significance in both groups. Epidural methadone is an effective method for postoperative pain relief. Drug concentration modifies the duration of the analgesia and concentration of 0.1% gives better results than more diluted preparations.