Using routine prophylactic ondansetron on the Cardiac Intensive Care Unit to prevent post-operative nausea and vomiting following enhanced recovery cardiac surgery
Timothy AC Snow, Anne Campbell & Sibtain Anwar
Department of Perioperative Medicine, Barts Heart Centre, St Bartholomew's Hospital, West Smithfield, London, EC1A 7BE
Minimising post-operative nausea and vomiting (PONV) is a key component of enhanced recovery. These pathways aim to improve patient experience whilst enabling efficient health care resource utilisation including reducing Cardiac Intensive Care Unit (CICU) length of stay. Traditional scoring systems suggest cardiac surgery is low risk, however, previous studies and our own CICU audit indicate that the incidence of PONV is high. This study assessed whether routine administration of ondansetron would reduce the incidence of PONV in the enhanced recovery patient.
We performed a sequential 2 week prospective cohort study at our single centre tertiary referral CICU. For the first week, enhanced recovery patients underwent surgery as standard per the surgeon and anaesthetists preference which excludes routine anti-emetic prophylaxis. Following closure patients were transferred to the intensive care on a propofol infusion. Baseline data collected on arrival included age, PONV risk factors (sex, previous PONV, smoking status and intra-operative opiates), operation type, duration of anaesthesia and bypass, PCA type and use of an intra-operative propofol infusion. Once haemodynamics, clotting and temperature were optimised, sedation was stopped, the patient allowed to wake and extubated once following commands. For the first 24hours of admission, data was collected on time until extubation, presence of 1st episode of nausea or vomiting, time from extubation until symptoms and rescue anti-emetic given.
The following week, patients underwent the same standard of intra-operative management however, following admission to the ICU, they were given 4mg IV ondansetron once their temperature was above 36oC and they were ready for sedation to be weaned. They were followed for the next 24hrs as above.
In the control group, 12/18 (67%) patients suffered nausea of which 8 (44% total/67% of those with nausea) also suffered vomiting. In the ondansetron group, 6/19 (32%) suffered nausea and 4 (21%/66%) vomiting. The odds ratio reduction for nausea was 4.33 (CI 1.09-17.17, p=0.04) and for vomiting 2.39 (CI 0.56-10.22, p=0.24), a relative risk reduction of 53%. Time between extubation and symptom onset increased from 305±261 to 585±115 minutes (p=0.02). There were no significant inter-group differences in patient demographics or intra-operative variables. Ondansetron 4mg IV was used as rescue anti-emetic.
This pilot study has shown the potential effectiveness of the addition of pre-extubation ondansetron in reducing PONV following fast-track cardiac surgery. The incidence of nausea was reduced and the time for symptom onset was prolonged.
Our study supports previous evidence of an increased risk of PONV following cardiac surgery (up to 67% according to literature from the last 15years) despite changes in anaesthetic practice such as propofol infusions. CICU management has the potential to improve this.
Despite a 4hour delay between ondansetron administration and extubation, the anti-emetic effect extended beyond the standard minimal dosing interval. Routine prophylaxis may therefore protect against PONV but not that caused by opiate PCA.
Limitations of the study include its use of a week by week allocation rather than randomisation, some differences in total anaesthetic duration and the consequences of PONV were not measured.
Administration of ondansetron as part of a fast-track post-cardiac surgery pathway is feasible and may reduce the incidence of PONV. This needs to be validated in larger patient numbers as part of a prospective, well-controlled study.
Conflict of interest: None declared
Funding: None requested