Ondansetron prevents postoperative emesis in male outpatients. S3A-379 Study Group.

Study Objectives: To determine (1) the efficacy and safety of ondansetron in the prevention of postoperative nausea and vomiting (PONV) in male outpatients; (2) prognostic factors for PONV in male outpatients; and (3) patients' perceptions of the debilitating effects of PONV in the ambulatory surgery setting.

Design: Prospective, randomized, stratified, double-blind study.

Setting: Multicenter-24 medical centers.

Patients: 468 ASA physical status I and II males at least 12 years of age scheduled for general anesthesia.

Interventions: All patients received intravenous ondansetron 4 mg or placebo prior to undergoing general balanced (opioid) anesthesia.

Measurements And Main Results: In the postanesthesia care unit (PACU), the number of emetic episodes, vital signs, adverse events, and nausea assessments were recorded by a blinded observer. After discharge, and until the end of the 24-hour study period, patients completed a diary that collected emetic episodes, adverse events, nausea, and pharmacoeconomic data. There were no differences in patient demographics or safety profiles between groups. The number of patients with no emesis and no nausea during the 24-hour study period was significantly greater (p < 0.05) with ondansetron 4 mg compared with placebo. Prognostic factors for an increased likelihood of developing PONV in males included a history of motion sickness or previous PONV, patients undergoing nonorthopedic procedures, and surgeries lasting longer than one hour. Finally, 38% of patients experiencing PONV perceived PONV to be as, or more debilitating than, the aftereffects of surgery itself.

Conclusions: Ondansetron 4 mg was more effective than placebo in preventing PONV in male outpatients. Males at potential risk for developing PONV include: (1) those with a history of motion sickness and/or PONV; (2) patients undergoing nonorthopedic procedures; and (3) procedures lasting longer than one hour. Such patients may benefit from receipt of a prophylactic antiemetic. Postoperative nausea and vomiting has a debilitating effect that can be differentiated by patients from the effects of surgery itself.