Patient-controlled analgesia with piritramid for the treatment of postoperative pain.

Patient-controlled analgesia (PCA, intravenous self-application of narcotics) was studied during the early postoperative period. Subjects were 40 ASA I-III patients recovering from elective major and minor surgery (20 each having undergone abdominal or orthopedic operations). Whenever the patients required pain relief, piritramid demand doses of 2.0 mg were given via the hand-button of a microprocessor-controlled injection pump (On-Demand Analgesia Computer, ODAC). Hourly maximum dose was set to 15 mg with a pump refractory time of 1 minute between valid demands. A continuous low-dose piritramid infusion (0.24 mg/h) was additionally administered in order to prevent catheter obstruction. Duration of the PCA period was 19.7 +/- 6.5 hours (mean +/- SD). During this time, 17.1 +/- 13.8 demands per patient were recorded resulting in mean individual piritramid consumptions of 30.4 +/- 28.1 micrograms/kg/h. Self-administration was characterized by considerable intra- and interindividual variability. Following abdominal surgery, slightly more piritramid was needed compared with orthopedic patients, although less pain relief was achieved in the former group. The same proved to be true for a comparison between the sexes, males requiring significantly more piritramide for less pain relief than females (p = 0.05). Over-all efficacy and patient acceptance proved to be excellent. Effectiveness of PCA was judged superior by about 73% of patients when compared with previously experienced conventional postoperative analgesia. Side effects (sweating, nausea, emesis) occurred in about 20% but were usually of minor intensity. No serious circulatory or respiratory problems were observed during the PCA period. Patient-controlled analgesia is discussed as a promising concept for the treatment of acute pain and for clinical pain research.