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

Not Applicable

Completed

Brief Summary: 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.

Detailed Description: 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

Recruitment & Eligibility

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

Arm && Interventions

Group	Intervention	Description
Saline	Saline	2 mL IV Normal Saline at time of discontinuation of Propofol Infusion
Ondansetron	Ondansetron	Ondansetron 4mg IV at time of discontinuation of Propofol Infusion

Primary Outcome Measures

Name	Time	Method
Occurrence of Post-operative Nausea and Vomiting (PONV)	First 24 hours post-extubation	Measured by asking the patient hourly to assess their post operative nausea and vomiting using a 10-point verbal Likert rating scale.

Secondary Outcome Measures

Name	Time	Method
Time to first dose of rescue PONV medication	First 24 hours post-extubation	Time of administration of first dose of rescue post-operative nausea and vomiting medication
Dose of any Rescue PONV medication	First 24 hours post-extubation	Dose of administered rescue post-operative nausea and vomiting medication after extubation.
Time to first report of nausea or first vomit post-operatively	First 24 hours post-extubation	Time to first report of any nausea or vomiting after extubation post-operatively.
Incidence of Rescue PONV medication administration	First 24 hours post-extubation	How many participants received rescue post-operative nausea and vomiting medication post-extubation after surgery.
Incidence of Post-operative nausea without vomiting	First 24 hours post-extubation	Nurses both asked patients' for a nausea severity rating and recorded any vomiting hourly.
Severity Post-operative nausea without vomiting	First 24 hours post-extubation	Severity of post-operative nausea without vomiting based on a 10-point likert scale, recorded hourly.
Incidence of ventricular arrhythmias	first 24 hours post-extubation	Any sustained Ventricular Arrhythmias (i.e. lasting greater than 30 seconds)