Post-operative nausea and vomiting (PONV) is a significant source of morbidity for patients undergoing general anesthesia, and in particular, patients undergoing cardiac anesthesia. Despite its common occurrence, literature on PONV prophylaxis in the cardiac surgical population is limited relative to other surgical populations.~A rational approach to preventing PONV would be to administer prophylaxis prior to extubation once post-operative sedation has ceased. This timing of administration would be more standardized across patients, as duration of surgery and time of extubation after surgery can vary considerably, rendering plasma levels of PONV prophylaxis agents highly variable across patients.~At St. Paul's Hospital, PONV prophylaxis has not been a routine part of cardiac anesthesia care. Furthermore, there are no standardized guidelines, and practice varies between care providers. Following surgery, patients recover from anesthesia and are extubated in the cardiac surgery ICU (CSICU). They are usually sedated on a propofol infusion for one to four hours after surgery until they are ready for extubation. When PONV occurs, the first line drug for treatment is ondansetron 4 mg. The investigators therefore propose the use of a single, prophylactic dose of ondansetron (4 mg IV), given at the time of propofol cessation. A randomized, double blinded placebo controlled model will be utilized
To evaluate the effectiveness of a prophylactic dose of ondansetron in decreasing the incidence of post-operative nausea and vomiting in cardiac surgery patients after cessation of post-operative sedation. In patients who have undergone open heart surgery, a single prophylactic dose of ondansetron 4 mg IV given at the time of discontinuing propofol sedation will result in a 50% reduction of the rate of post-operative nausea and vomiting in the first 24 post-operative hours compared to placebo.