Correction of dilutional anemia induces renal dysfunction in diabetic patients undergoing coronary artery bypass grafting: a consequence of microcirculatory alterations?

Abstract

In this study we aimed to evaluate the effects of dilutional anemia resulting from cardiopulmonary bypass (CPB) and its correction with red blood cell (RBC) transfusion on tissue oxygenation and renal function in diabetic patients undergoing coronary artery bypass grafting (CABG). 70 diabetic patients who underwent elective CABG and whose hematocrit values had been between 24-28% at any time during CBP were prospectively randomized and equally allocated to two groups: patients who received RBC during CPB (group I, n = 35) vs. did not receive RBC during CPB (group II, n = 35). Besides routine hemodynamic and biochemical parameters, biomarkers of ischemia and renal injury such as ischemia modified albumin (IMA), protein oxidation parameters [advanced oxidative protein products (AOPP), total thiol (T-SH)], neutrophil gelatinase-associated lipocalin (NGAL) and estimated glomerular filtration rate (eGFR) were measured in both groups. In group I, T-SH, NGAL and urea levels were found to be significantly increased postoperatively compared to preoperative measurements (p < 0.05). Also, postoperatively, NGAL, creatinine, aspartate aminotransferase and AOPP levels were higher in group I than group II (p < 0.05). The correction of anemia with RBC transfusion in diabetic patients undergoing CABG could increase the risk of renal injury. Further studies verifying the effects of blood transfusions at the microcirculatory level are needed to optimize the efficacy of transfusions.