Volatile anaesthetics may be the main cause of early but not delayed
postoperative vomiting: a randomized controlled trial of factorial design.
Author(s): Apfel CC, Kranke P, Katz MH, Goepfert C, Papenfuss T, Rauch S, Heineck R, Greim
CA, Roewer N.
Affiliation(s): Department of Anaesthesiology, Julius-Maximilians-University of Wuerzburg,
Germany.
Publication date & source: 2002, Br J Anaesth. , 88(5):659-68
BACKGROUND: Despite intensive research, the main causes of postoperative nausea
and vomiting (PONV) remain unclear. We sought to quantify the relative importance
of operative, anaesthetic and patient-specific risk factors to the development of
PONV.
METHODS: We conducted a randomized controlled trial of 1180 children and adults
at high risk for PONV scheduled for elective surgery. Using a five-way factorial
design, we randomly assigned subjects by gender who were undergoing specific
operative procedures, to receive various combinations of anaesthetics, opioids,
and prophylactic antiemetics.
RESULTS: Of the 1180 patients, 355 (30.1% 95% CI (27.5-32.7%)) had at least one
episode of postoperative vomiting (PV) within 24 h post-anaesthesia. In the early
postoperative period (0-2 h), the leading risk factor for vomiting was the use of
volatile anaesthetics, with similar odds ratios (OR (95% CI)) being found for
isoflurane (19.8 (7.7-51.2)), enflurane (16.1 (6.2-41.8)) and sevoflurane (14.5
(5.6-37.4)). A dose-response relationship was present for the use of volatile
anaesthetics. In contrast, no dose response existed for propofol anaesthesia. In
the delayed postoperative period (2-24 h), the main predictors were being a child
(5.7 (3.0-10.9)), PONV in the early period (3.4 (2.4-4.7)) and the use of
postoperative opioids (2.5 (1.7-3.7)). The influence of the antiemetics was
considerably smaller and did not interact with anaesthetic or surgical variables.
CONCLUSION: Volatile anaesthetics were the leading cause of early postoperative
vomiting. The pro-emetic effect was larger than other risk factors. In patients
at high risk for PONV, it would therefore make better sense to avoid inhalational
anaesthesia rather than simply to add an antiemetic, which may still be needed to
prevent or treat delayed vomiting.
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