PROPOFOL ANESTHESIA AND POSTOPERATIVE NAUSEA AND VOMITING - QUANTITATIVE SYSTEMATIC REVIEW OF RANDOMIZED CONTROLLED-STUDIES

We have analysed randomized controlled studies which reported the inci dence of postoperative nausea and vomiting (PONV) after propofol anaes thesia compared with other anaesthetics (control). Cumulative data of early (0-6 h) and late (0-48 h) PONV were recorded as occurrence or no n-occurrence of nausea or vomiting. Combined odds ratio and number-nee ded-to-treat were calculated for propofol as an induction or maintenan ce regimen, early or late outcomes, and different emetic events. This was performed for all control event rates and within a range of 20-60% control event rates. We analysed 84 studies involving 6069 patients. The effect of propofol on PONV was dependent mainly on the method of a dministration, time of measurement and range of control event rates. W hen all studies were included the number-needed-to-treat to prevent PO NV with propofol was more than 9 when used for induction of anaesthesi a and at best 6 when used for maintenance. Within the 20-60% control e vent rate range, best results were achieved with propofol maintenance to prevent early PONV: the number-needed-to-treat to prevent early nau sea was 4.7 (95% confidence interval 3.8-6.3), vomiting 4.9 (4-6.1) an d any emetic event 4.9 (3.7-7.1). Within the 20-60% control event rate , of five patients treated with propofol for maintenance of anaesthesi a, one will not vomit or be nauseated in the immediate postoperative p eriod who would otherwise have vomited or been nauseated. This may be clinically relevant. In all other situations the difference between pr opofol and control may have reached statistical significance but was o f doubtful clinical relevance. Treatment efficacy should be establishe d within a defined range of control event rates for meaningful estimat es of efficacy and for comparisons.