Evaluation of Nephroprotective Efficacy of Hypoxic Preconditioning in Patients Undergoing Coronary Artery Bypass Surgery

Abstract

Background: Nonpulsatile blood flow plays an important role in the pathogenesis of renal dysfunction in patients with extracorporeal circulation. In our opinion, hypoxic preconditioning (HP) can be used to protect kidneys from postsurgical dysfunction. The aim of this study was to evaluate nephroprotective efficacy of HP in myocardial revascularization with extracorporeal circulation. Methods: The randomized, controlled trial was performed in 63 patients undergoing coronary artery bypass grafting (CABG). Thirty-three patients were subjected to HP during CABG; 30 patients were included in the comparison group. All patients underwent dynamic renal scintigraphy with 99mТc-diethylenetriaminepentaacetic acid and were subjected to measuring the concentration of lipocalin in blood serum before and after CABG. Results: After CABG, the mean values of the total glomerular filtration rate (GFR) and GFR for each kidney significantly decreased only in patients of the comparison group. Significant increases in the concentration of serum neutrophil gelatinase-associated lipocalin occurred 5 h after surgery both in the group with HP (70.65 ± 46.71 to 127.58 ± 98.46 ng/ml) and in the comparison group (65.01 ± 38.64 to 171.65 ± 89.91 ng/ml). At the same time, the mean difference values between pre- and postoperative lipocalin levels were 56.94 ± 51.75 ng/ml in the study group and 106.64 ± 51.27 ng/ml in the comparison group; these differences were highly statistically significant (р = 0.004). Conclusion: The results of our study showed that (i) HP exerts nephroprotection in patients undergoing on-pump CABG, and (ii) determination of the lipocalin-2 level can be used for early diagnosis of acute kidney injury in cardiac surgery patients.