Early Impact of Cardiopulmonary Bypass on Renal Function after Valve Replacement Surgery

Renal dysfunction following cardiopulmonary bypass is well recognized. The pathophysiology of renal injury is multifactorial and culmination of the interplay of several pathophysiological mechanism. Cardiac surgery requiring cardiopulmonary bypass (CPB) is being carried out on an extended patient population of different age groups and undergoing complex surgical procedure, and thus it places them at an increased risk of renal impairment. Valve replacement surgery is a major and complex surgical procedure requiring CPB. This study was therefore designed to observe the impact of CPB and short term outcome on patients with reduced estimated Glomerular Filtration Rate (eGFR) (60-89ml/min/1.73m²) after valve replacement surgery. This cross-sectional study was conducted in the Department of Cardiac Surgery, National Institute of Cardio Vascular Diseases (NICVD) during the period of January 2015 to August 2016. After fulfillment of enrollment criteria 100 patients were studied for the purpose of the study and they were grouped in two, patients with normal eGFR (≥90ml/min/1.73m²) in Group A and patients with reduced eGFR (60-89ml/min/1.73m²) in Group B. A total of 100 patients, 50 in each group were studied for renal function alteration after valve replacement surgery under cardiopulmonary bypass. The incidence of Acute Kidney Injury (AKI) was higher in Group B. Chi-square test was done and p value was 0.011 which is statistically significant. Postoperative blood loss (ml/hr) (p=0.038), duration of Intensive Care Unit (ICU) stay (in hours) (p=0.009), postoperative hospital stay (days) (p=0.014) was significantly higher and postoperative Urine Output (ml/hr) (p=0.001) was significantly lower in patients with reduced eGFR (60-89ml/min/1.73m²) in Group B. Deterioration of renal function is more in patient with eGFR (60-89ml/min/1.73m²) after valve replacement surgery under cardiopulmonary bypass in comparison with patients with eGFR (≥90ml/min/1.73m²).