Mesenteric ischaemia following cardiac surgery: the influence of intraoperative perfusion parameters

OBJECTIVES Mesenteric ischaemia (MesI) remains a rare but lethal complication following cardiac surgery. Previously identified risk factors for MesI mortality (age, poor left ventricular (LV) function, cardiopulmonary bypass time and blood loss) are non-specific and cannot necessarily be modified. This study aims to identify potentially modifiable risk factors for MesI mortality through analysis of peri- and intraoperative perfusion data. METHODS Patients who underwent cardiac surgery between 2006 and 2011 at Papworth Hospital were retrospectively divided into 3 outcome categories: death caused by MesI; death due to other causes and survival to discharge. A published MesI risk calculator was used to estimate risk of MesI for each patient and then to create 3 cohorts of matched patients from each outcome group. Pre-, intra- and postoperative variables were collected and conditional logistic regression methods were used to identify parameters associated specifically with MesI deaths after cardiac surgery. RESULTS A total of 10 409 patients underwent cardiac surgery between 2006 and 2011. The incidence of MesI was 0.3% (30 patients). Two hundred and sixty-one patients died of non-MesI causes and 10 118 survived. It was possible to identify 25 patients in each group at equivalent risk of MesI. The following parameters were found to be associated with MesI mortality: recent myocardial infarction [odds ratio (OR) 4.98, 95% confidence interval (CI) 1.58–15.71, P = 0.01], standard EuroSCORE (OR 1.12, 95% CI 1.03–1.21, P = 0.01), vasopressor dose on bypass (OR 1.28, 95% CI 1.04–1.57, P = 0.02), metaraminol dose on bypass (OR 1.52, 95% CI 1.12–2.06, P = 0.01) and lowest documented mean arterial pressure (OR 0.90, 95% CI 0.83–0.97, P = 0.01). No other intraoperative perfusion-related parameters (e.g. flow, average activated clotting time or pressure) were associated with MesI mortality. CONCLUSIONS Our study not only confirms previously known predictive factors, but also demonstrates a new association between intraoperative vasopressor use and MesI mortality.