Different effects on postoperative nausea and vomiting of various antiemetic strategies

I. Grigoropoulou, T. Zervou, N. Zafiris, T. Fountoulaki, S. Kontoyiannopoulou, K. Papilas, N. Palgimesi. Piraeus General Hospital, Greece

Background and Goal of study

Postoperative nausea and vomiting (PONV) are frequent causes of morbidity following operations under general anaesthesia, but none of the currently used prophylactic regimens is entirely successful.

The aim of this study was to record the incidence of PONV in our department and to evaluate the antiemetic efficacy of various antiemetic drugs, as droperidol, tropisetron, ondasetron and their combinations.

Materials and Methods

238 patients, ASA I-III, who underwent surgery under general anaesthesia were studied. Preoperatively patients’ data and history of PONV following previous anaesthetics were recorded. Five minutes before induction in anaesthesia, the patients received a single IV dose of one of the following antiemetic regimens: tropisetron 5 mg (T group), ondasetron 4 mg (O group), droperidol 1.25 mg and tropisetron 5 mg (D+T group), droperidol 1.25 mg and ondasetron 4 mg (D+O group), placebo (no antiemetic, P group).

In the first 24 h postoperatively (up to 30 min following extubation, 8 h, and 24 h postoperatively) the patients were evaluated by the same blinded nurse anaesthetist for nausea and vomiting, number of vomiting episodes and the use of rescue drugs.

Results

The patients’ age range was 16-84 yrs, 55% were ASA I, 26% ASA II, 13% ASA III, and 52% were female. For the immediate postoperative PONV, we have complete records for 222 patients. The overall PONV incidence was 9.9%. In group T (n=62) 6.5% of the patients experienced PONV, 5.9% in group O (n=34), 1.7% in group D+T (n=58), while 16.7% in group D+O (n=42) and 30.8% in P group (n=26). Statistical analysis (SPSS 7.5) with x² test yields p<0.005 for the exact 2-tailed test, and the adjusted standardized residuals give significantly greater incidence of PONV in the P group, and significantly less PONV in the D+T group. Similar results were obtained with the data for PONV in 8 and 24 h, except that the greater incidence of PONV in the D+O group reaches statistical significance in 24 h.

However, we have not prospectively controlled any confounding factors, such as the induction agent etc. So, although there are other statistically significant results as well, we did not pursue them any further.

Conclusion

In our study, there is evidence that the combination of droperidol with tropisetron offers more efficacious antiemetic prophylaxis than tropisetron alone, but the administration of droperidol with ondasetron is not advantageous over ondasetron alone. However, we are aware of the limitations of this study and would not attempt to interpret these findings further, awaiting the results of a current randomized double blind control trial in our department.