[Ondansetron versus droperidol. Postoperative treatment against nausea and vomiting. Comparison of action, adverse effects and acceptance by gynecologic inpatients].

INTRODUCTION: Ondansetron is more effective than a placebo in treating postoperative nausea and vomiting (PONV), but it has not been proved to be superior to established antiemetics for prophylaxis or therapy. We compared ondansetron vs droperidol for the treatment of PONV.

METHODS: Our prospective, randomized double-blind study was performed between 15 October 1992 and July 1993; it included 271 gynaecological ASA I-III inpatients who had been operated on under general anaesthesia with intubation. Patients were excluded if: there was no informed consent; it was an ambulatory or emergency operation; the patient was pregnant or breast feeding; allergies were being treated with antihistamines; drug addiction was present or convulsions or Parkinson's disease; any pre- or intraoperative antiemetic medication had been administered. All patients wishing an antiemetic and/or suffering from at least one emetic episode during the first 24 h postoperatively received either 8 mg ondansetron or 1.25 mg droperidol from identical 4 ml ampoules intravenously. The verbal nausea score (1 = none, 2 = mild, 3 = moderate, 4 = severe) was recorded every 30 min for 4 h, then before and 2 h after each antiemetic dose. All emetic episodes and the interval between administration and effect were also noted. Patients were interviewed 36-48 h postoperatively on subjective effects, side-effects and individual acceptance. After oral premedication with diazepam, anaesthesia was induced with thiopental, in a few cases with etomidate or propofol. Relaxation was achieved with pancuronium or atracurium and, when indicated, with succinylcholine. Muscular relaxation was antagonized with neostigmine and glycopyrrolate. Gastric content was aspirated once after intubation. Anaesthesia was maintained with nitrous oxide/oxygen, enflurane, halothane or isoflurane and fentanyl up to 0.3 mg. Statistical evaluation was performed by the unpaired Student's t-test and the Mann-Whitney U test. Categoric variables were examined by the chi 2 test. Significance was defined as P < 0.05.

RESULTS: Of 271 patients, 100 (37%) experienced PONV. The groups were statistically comparable with respect to demographic data, type and duration of operation, emesis record, perioperative uterotonic medication. Twenty patients in the ondansetron group and 27 in the droperidol group received the first antiemetic within 2 h, the other patients up to 17 h after extubation. Nausea scores and emetic episodes were identical before antiemetic medication. The reduction of these parameters after medication was similar. Complete response over 6 h was 60% in the ondansetron and 68% in the droperidol group. In both groups the first medication failed in 4 cases during the initial 2 h. Twenty of the ondansetron and 16 of the droperidol patients needed a second dose; among these 2 and 4, respectively, a third ampoule. No rescue medication was necessary over 24 h and a mean of 1.4 ampoules was administered in both groups. Onset and quality of emetic action were identical in both groups. It was not possible to evaluate 25 interviews due to linguistic or amnestic problems. Multiple side-effects were noted frequently. Injection pain was reported significantly more often in the droperidol, pruritus in the ondansetron group. Ninety-three percent of the ondansetron and 85% of the droperidol patients opted for the same drug for future PONV treatment.

CONCLUSIONS: Ondansetron (8 mg) and droperidol (1.25 mg) proved to be equally effective when used as a postoperative antiemetic. Both drugs showed similar side-effects. Due to differences in methods it was difficult to compare our results to those obtained in other studies.