Elsevier

Heart & Lung

Volume 43, Issue 6, November–December 2014, Pages 550-554
Heart & Lung

Care of Patients in Acute and Critical Care Settings
Post-operative nausea and vomiting in the cardiac surgery population: Who is at risk?

https://doi.org/10.1016/j.hrtlng.2014.07.002Get rights and content

Abstract

Objectives

Post-operative nausea and vomiting (PONV) is a common and distressing complication following cardiac surgery. Therefore, our primary objective was to explore the predictors of severe PONV in the cardiac surgery population.

Methods

A retrospective study was completed on cardiac surgery patients (N = 150). A modified preoperative PONV risk assessment tool was utilized to identify patients at high and low risk for PONV.

Results

54% of the high-risk group versus 13% of the low-risk group experienced ≥2 nausea events in the early post-operative period (p < 0.0001). The high-risk group had a uniquely elevated and sustained number of PONV events post-operatively. History of PONV (p = 0.03) and female gender (p = 0.01) emerged as significant predictors of any nausea event.

Conclusions

A specific PONV risk assessment tool may be useful for predicting those at highest risk following cardiac surgery. Further research is required to identify strategies to reduce PONV.

Introduction

Post-operative nausea and vomiting (PONV) is one of the most frequently reported complications following anesthesia and surgery. Despite advances in anesthesia practice and anti-emetic therapies, the overall incidence of PONV has remained relatively unchanged over the past four decades.1, 2, 3, 4, 5, 6, 7, 8, 9 While the incidence of PONV is 20–30% in the general surgery population, PONV rates in the cardiac surgery population are reportedly as high as 42–71%.10, 11, 12, 13, 14, 15 The higher incidence of PONV in cardiac surgery patients may be related to factors such as the duration of the anesthesia, the post-operative pain and anxiety often associated with this procedure, and the consequent utilization of opiate analgesics.11, 14, 16, 17 However, accurate and reliable tools to predict PONV in this population have not been established.

PONV can have a significant impact on patient morbidity, which, in turn affects patient satisfaction, hospital length of stay, and overall health care costs. For example, PONV may result in complications such as aspiration pneumonia, dehydration, and electrolyte imbalance.2, 18, 19 Patients experiencing PONV may also have inadequate absorption of per os medications (e.g., beta blockers, diuretics, analgesics), which, in turn may lead to complications such as increased rates of peri-operative dysrhythmias, fluid volume overload, and uncontrolled pain.20 In a prospective study of gastrointestinal (GI) symptoms in cardiac surgery patients (N = 122), Grap et al10 found that nausea was the most distressing GI symptom reported during patients' hospital stay. Furthermore, PONV may impact on the patient's willingness and ability to participate effectively in their post-operative recovery (e.g., ambulating, deep breathing and coughing, dietary and fluid intake). This, in turn can lead to further post-operative complications, such as pulmonary infections and renal dysfunction. In addition to pain, vomiting and retching can also cause significant mechanical complications for the cardiac surgery patient, including stress on the new graft sites and dehiscence of the sternal incision.21

Although PONV symptoms generally occur and resolve in the early post-operative period, cardiac surgery patients reportedly experience persistent GI symptoms for 4–6 weeks post-surgery.7 Therefore, PONV has implications not only for immediate peri-operative outcomes, but also for post-discharge quality of life, cardiac rehabilitation attendance, and return to work. Finally, side effects associated with anti-emetic medications, such as delirium,22 as well as complications of PONV may result in extended lengths of stay, which in turn directly affect costs to the health care system.

Over the past several decades, PONV has been the focus of numerous studies and systematic reviews. Consequently, various peri-operative predictors of nausea and vomiting have been identified, including: female sex, history of motion sickness and/or PONV, non-smoker, increased age, obesity, type of anesthetic agents, and type and duration of surgery. While several complex prognostic scoring systems and models have also been developed, validation studies suggest that the original, more simplified risk tools developed by Apfel et al20 and Koivuranta et al1 provide better discrimination and calibration for predicting PONV in patients who have undergone various surgical procedures.17, 23, 24

However, consistent evidence remains somewhat elusive, particularly in the cardiac surgery population. For example, in a prospective study of patients undergoing ‘fast-track’ or early extubation cardiac surgery (N = 1221), risk factors for PONV included: age less than 60 years, female sex, and previous history of PONV.13 Koizumi et al12 reported a 70% incidence of PONV in female patients post-cardiac surgery; age and body mass index (BMI), dose of fentanyl, and duration of surgery were, however, not statistically significant. On another hand, Grap et al10 found that antiarrhythmic, diuretic, and antihypertensive medications, as well as severity of depression were significantly associated with nausea during hospitalization post-cardiac surgery. The inconsistent evidence stems from a number of factors, including the lack of a satisfactory definition of severe nausea, and incomplete data capture. Moreover, the existing risk scores were developed as generic tools and therefore may not be valid in cardiac surgery patients. Risk stratification may facilitate the development of protocols for the prophylaxis and treatment of PONV in this population.

The prevention of PONV has been challenging for care providers, as the factors thought to increase the risk of these symptoms are difficult, if not impossible to manipulate. Although various researchers have explored both pharmacological and alternative treatments for the prevention of PONV following cardiac surgery, the incidence remains high.15, 19, 25, 26, 27, 28 Therefore, this research was designed to explore the predictors of severe PONV in the cardiac surgery population. Specifically, the study objectives were to: (1) identify the features associated with PONV in patients undergoing a cardiac surgery procedure, (2) determine if the modified Apfel et al20 PONV risk assessment tool accurately predicts PONV in our cardiac surgery population, and (3) develop a predictive model to identify cardiac surgery patients at higher risk of developing PONV.

Section snippets

Research design

A retrospective cohort analysis of consecutive patients undergoing cardiac surgery over 2-year time period.

Sample and setting

All cardiac surgery procedures were performed in a single, tertiary centre in western Canada, with an annual case volume of approximately 1100 patients. Data from all patients undergoing isolated coronary artery bypass graft (CABG), isolated valve, or combined CABG and valve surgery procedures between 2009 and 2011 were retrospectively analyzed (N = 2994). A power analysis determined that

Results

Comparisons between the high versus low risk group revealed no significant differences in age, intraoperative steroid use, or intubation status on admission to the CSICU. Not surprisingly, based on the study inclusion criteria, significant differences in gender, smoking status, and history of PONV were observed (see Table 1). While the peak incidence of moderate/severe nausea for the low risk group was highest in the first 2 h post-CSICU admission, for the high risk group, the peak incidence

Discussion

In this study, we explored the predictors of severe PONV in the cardiac surgery population. Based on a modified PONV assessment tool, approximately 50% of the high-risk group experienced two or more nausea events in the early post-operative period. This suggests that the odds of PONV are approximately 8 times greater in the high risk group compared to those identified as being low risk by the PONV calculator tool. Female sex and history of PONV emerged as the key predictors of any early PONV.

Conclusion

Despite advances in technology and pharmacotherapy, the incidence of PONV has remained relatively unchanged for the past four decades. Numerous researchers have explored predictors, preventive strategies, and interventions, to no avail. Due to the high rate of occurrence, this issue is particularly critical in the area of cardiac surgery. The identification of key PONV predictors of those at highest risk in the CSICU and critical time points for PONV risk establishes the foundation for further

Acknowledgments

We acknowledge Cardiovascular and Health Research in Manitoba (CHaRM) for supporting the design, implementation, and analysis of this research.

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