M. Tramer et al., PROPOFOL ANESTHESIA AND POSTOPERATIVE NAUSEA AND VOMITING - QUANTITATIVE SYSTEMATIC REVIEW OF RANDOMIZED CONTROLLED-STUDIES, British Journal of Anaesthesia, 78(3), 1997, pp. 247-255
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.