Frequency of renal dysfunction in cardiac surgery patients and its effect on outcome

The purpose of this study was to define the frequency of renal dysfunction, including acute kidney injury (AKI), in cardiac surgery patients and its effect on outcome. Materials and methods. Patients 18 years old or older underwent cardiac surgery were included in the study. AKI and chronic kidney disease (CKD) was defined and staged according KDIGO 2012 guidelines. Glomerular filtration rate (GFR) was calculated with CKD-EPI formula. Clinical, laboratory and instrumental investigations were performed to all patients. As well, continuous hemodynamic monitoring was performed in postoperative period. Statistical analysis was conducted with SPSS for Windows v. 17.0.0. Results. 239 patients (170 (72,8 %) – male, 65 (27,2 %) – female) underwent cardiac surgery in M.M. Amosov National Institute of Cardio-Vascular Surgery between 29.06.16 and 30.10.16 were included in the study. 79 patients had a renal dysfunction before surgery: 19 (7.9%) – CKD and 60 (25.1%) – AKI. Renal replacement therapy (RRT) was used in 7 patients (4 — with CKD and 3 — with AKI). AKI was developed in 38 patients (15.9%) in postoperative period and RRT was started in one case. Statistically significant risk factors associated with AKI development in postoperative period were epinephrine usage (р<0.05) and heart failure development (р<0,001). Hospital mortality was 5.9% - 14 patients (7 (50%) - male, 7 (50 %) - female). All died patients have had renal dysfunction (3 (21.4%) have had AKI on CKD and 11 (78.6%) — AKI). Among them 8 (57.1%) patients have had AKI I, 1 (7.1%) - AKI II and 5 (35.7%) - AKI III. Statistically significant risk factors associated with hospital death were multiorgan dysfunction syndrome (р<0.001), sepsis (р<0.001), epinephrine (р<0.001) and norepinehrine (р<0.001) usage. Dobutamine use was associated with significant improvement in hospital mortality (р<0.05). Conclusions: Near half of cardiac surgery patients had renal dysfunction in perioperative period. RRT was used in 3.4% patients. Because the majority of died patients have had the first stage of AKI, which rather means the risk of renal dysfunction, and statistical analysis reveals no significant association between renal function and outcome, developing of AKI in cardiac surgery patients is an indicator of severity of main disease, but not a cause of death. Renal dysfunction regardless of time of it development in relation to cardiac surgery is not risk factor of death, in contrast to multiorgan dysfunction syndrome and sepsis, which warrant the use of epinephrine.