Is it possible to predict the risk of ischaemic bowel after cardiac surgery?

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A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'Is it possible to predict the risk of ischaemic bowel after cardiac surgery?' Altogether 80 papers were found as a result of the reported search, of which 7 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. This best evidence topic presents 68 214 cardiac surgical patients from seven major cardiothoracic centres dated from 1980 to 2011. The incidence and mortality rates of bowel ischaemia after cardiac surgery range from 0.07-0.5 and 59-64%, respectively. Advanced age and peripheral vascular disease are the common preoperative risk factors, which were reported by 3 papers each. The most common intraoperative risk factors were prolonged cross-clamp and cardiopulmonary bypass time, which were reported by 3 papers each. Five of 7 papers reported that the use of intra-aortic balloon pump was a significant risk factor. The use of inotropes, postoperative blood loss and postoperative renal failure were reported by 3 of 7 papers, each to be a significant risk factor for postoperative bowel ischaemia in cardiac surgery patients. We, therefore, conclude that these are probably the most significant and useful predictive risk factors for bowel ischaemia after cardiac surgery. Thus, careful intraoperative management to minimize cardiopulmonary bypass and cross-clamp time and optimal care of patients' postoperative haemodynamic status, particularly in elderly patients with severe atherosclerotic disease, are useful in preventing this rare but lethal postoperative complication. Besides that, a heightened clinical suspicion in patients with these risk factors may lead to prompt diagnosis of bowel ischaemia, allowing intervention to prevent mortality. The variability of the study design and risk factors studied in each paper impose limitation to summarize the predicting risk factors.