Comparison of subhypnotic doses of thiopentone vs propofol on the incidence of postoperative nausea and vomiting following middle ear surgery.

Background: Middle ear surgery is associated with a high incidence of emetic sequelae and propofol has been reported to have antiemetic activity in subhypnotic doses.

Methods: In a double-blind, randomized study, the patients received either thiopentone 1.0 mg.kg-1 (n = 26) or 0.5 mg.kg-1 propofol (n = 26) at the end of middle ear surgery under isoflurane-N2O-fentanyl-vecuronium anaesthesia. Trained nurses, unaware of the group assignment, assessed postoperative nausea, retching and vomiting up to 24 h after the end of anaesthesia. Droperidol 10 micrograms.kg-1 was used as a "rescue" antiemetic.

Results: The main result was that the patient in the propofol group did not suffer from retching and vomiting (R&V) during the first 6 h, whereas these symptoms occurred in 46% (P < 0.001) of the patients in the thiopentone group. The patients in the propofol group needed significantly less droperidol during the first 24 h (mean number of doses 0.39 +/- 0.57 (SD)) than the patients in the thiopentone group (1.35 +/- 1.47, P < 0.005). Treatment with propofol was a predictor for lowered incidence of R&V, as well as male gender and negative history of motion sickness.

Conclusion: Propofol at a subhypnotic dose of 0.5 mg.kg-1 provides prophylaxis against retching and vomiting for the first 6 h postoperatively after middle ear surgery. The incidence of nausea was not reduced by propofol.