Prophylactic Ondansetron in Post-op Cardiac Surgery Patients to Prevent Post-operative Nausea and Vomiting

Prophylactic Ondansetron in Post-op Cardiac Surgery Patients to Prevent Post-operative Nausea and Vomiting

A Double-blinded, Randomized Control Trial of Prophylactic Ondansetron in a Post-operative Cardiac Surgery Population for Post-operative Nausea and Vomiting

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.

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

Normal saline is salt water and is acting as a placebo in this study. A placebo is an inactive substance that looks identical to the test drug, but it contains no therapeutic ingredient.

Measured by asking the patient hourly to assess their post operative nausea and vomiting using a 10-point verbal Likert rating scale.

How many participants received rescue post-operative nausea and vomiting medication post-extubation after surgery.

Severity of post-operative nausea without vomiting based on a 10-point likert scale, recorded hourly.

Inclusion Criteria: Elective (outpatient) and urgent (inpatient) cardiac surgery procedures requiring cardiopulmonary bypass, including: Coronary artery bypass grafting (CABG) Valve surgery (ie. repair and/or replacement) CABG and valve surgery Exclusion Criteria: Undergoing 'off-pump' CABG (not involving the cardiopulmonary bypass machine) With a contraindication to the study drug - including but not limited to congenital Long QT Syndrome, allergy to ondansetron, or a history of migraines Unable to understand the consent process, either due to language limitations or cognitive limitations if a translator or substitute decision maker is not available Receiving heart transplants, ventricular assist devices or on extra-corporeal membrane oxygenation (ECMO) Intubated for more than 12 hours post-operatively With a known history of PONV Sedated with dexmedatomine instead of propofol

Wang EHZ, Sunderland S, Edwards NY, Chima NS, Yarnold CH, Schwarz SKW, Coley MA. A Single Prophylactic Dose of Ondansetron Given at Cessation of Postoperative Propofol Sedation Decreases Postoperative Nausea and Vomiting in Cardiac Surgery Patients: A Randomized Controlled Trial. Anesth Analg. 2020 Oct;131(4):1164-1172. doi: 10.1213/ANE.0000000000004730.