[Clinical experimental studies of postoperative infusion analgesia]

30 postoperative patients, who had undergone abdominal gynaecological surgery with standard general anaesthesia were randomly divided into three groups and received, in the recovery ward, a continuous infusion of either pentazocine, piritramid, or ketamine. The patients rated their pain on a 15 cm pain analogue score. Group I pentazocine: Mean dosage on the day of operation 0.12 mg/kg/h, 0.1 mg/kg/h on the first and only 0.07 mg/kg/h on the second postoperative day. Pentazocine blood levels were on average 50 micrograms/l. Group II piritramid: Mean dosage on the day of operation 0.038 mg/kg/h, 0.024 mg/kg/h on the first and 0.019 mg/kg/h on the second postoperative day. Blood levels of piritramid were not determined because there is no satisfactory assay available. Group III ketamine: mean dosage on the day of operation 0.32 mg/kg/h, 0.28 mg/kg/h on the first and 0.29 mg/kg/h on the second postoperative day. Ketamine blood levels lay between 120 and 180 micrograms/l. The three analgesics did not cause any important haemodynamic or respiratory side effects. Pentazocine and piritramid were the most effective analgesics, ketamine was the least effective with a high incidence of side effects.