Effects of Hemodilution and Transfusion on Acute Renal Injury and Neutrophil Gelatinase-Associated Lipocalin.

Abstract

Dear Editor, We read the article titled “The Value of Urinary Neutrophil Gelatinase-Associated Lipocalin for Early Detection of Acute Renal Injury in Patients Undergoing Cardiopulmonary Bypass “ with a great interest (1). The fact that early diagnosis and treatment of acute renal injury can prevent delay-induced increase in morbidity and mortality is known and also specified by the authors. As stated by the authors, impaired renal perfusion and development of renal injury are resulted from many reasons. It has been reported in some studies that decreased haematocrit value associated with hemodilution developing during cardiopulmonary bypass leads to renal injury (2–4). The authors mentioned that extended time of cardiopulmonary bypass, cross-clamp, and intubation increased the risk of the possibility for the development of acute renal injury. However, they did not tell about preoperative haemoglobin, haematocrit, cardiac output values, and hemodynamic factors, which are known to be the most important parameters affecting renal perfusion of patients, and also about their changes in periopeative period and their effect on the development of acute renal injury. Moreover, studies have demonstrated that blood transfusions performed to patients in perioperative period also cause acute renal injury and an increase in the values of neutrophil gelatinase-associated lipocalin (NGAL) in early period (3, 5). In this study, whether patients received transfusion or not and if received, its effect on the development of acute renal injury were not explained in this study. We think that if the study aims to detect the risk factors in patients with renal injury development and altered NGAL, the evaluation of the relationship between the development of renal injury and the changes in haemoglobin, haematocrit, cardiac output, and haemodynamic parameters during perioperative period influencing renal perfusion will contribute to the determination of risk factors. We congratulate the authors on this current study that draws attention on an important issue. We suggest that further studies should be performed on acute renal injury and its early markers. In the light of data obtained in these studies, the frequency of acute renal injury can be reduced by detecting the factors leading to acute renal injury and early diagnostic markers.