Blood transfusions are associated with urinary biomarkers of kidney injury in cardiac surgery

Abstract

Objective Cardiac surgery is a major cause of acute kidney injury. In this setting receipt of blood transfusions appears to associate with a higher risk of AKI, as measured using serum creatinine values. We examined this association further, using urinary biomarkers of kidney injury. Methods 1210 adults underwent cardiac surgery and were divided into three groups based on the receipt of intraoperative packed red blood cell units (PRBC): no blood (n=894), ≤ 2 PRBC (n=206) and > 2 PRBC (n=110). AKI was defined as: i) Doubling of serum creatinine from the pre-operative value; ii) first post-operative urinary interleukin-18 in the 5th quintile; iii) first postoperative urinary neutrophil gelatinase-associated lipocalin in the 5th quintile. We determined the relative risk for AKI outcome according to PRBC group after adjusting for 12 pre-operative and surgical variables. Using the Sobel test for mediation analysis, we also evaluated the role of biomarkers in causing AKI through alternative pathways. Results AKI was more common in those who received >2 PRBC. In patients receiving > 2 PRBC, the adjusted RRs were 2.3 (95% CI 1.2-4.4, p 0.01), 1.36 (95% CI 1.0-1.9, p 0.05), and 1.34 (95% CI 1.0-1.8, p 0.06) for doubling of serum creatinine, urinary IL-18 in the 5th quintile (>60 pg/ml), and urinary NGAL in the 5th quintile (>102 ng/ml), respectively. Furthermore, the effect of PRBC transfusion on AKI was partially mediated by IL-18. Conclusions Receipt of two or more PRBC during cardiac surgery is associated with a greater risk of AKI defined by serum creatinine and kidney injury biomarkers.

Reassessment of Acute Kidney Injury after Cardiac Surgery: A Retrospective Study

“…We observed a higher frequency of coronary heart disease, hypertension, and diabetes mellitus among men, suggesting that these factors may contribute to some extent to men being more likely than women to experience AKI. Our data revealed that RBC transfusion during surgery was an independent risk factor for AKI, which was in agreement with the findings of previous studies (24). However, although RBC transfusion was found to be associated with a high risk of AKI, the “ideal” transfusion thresholds in cardiac patients remain largely unknown (25).…”

Nadir Oxygen Delivery on Bypass and Hypotension Increase Acute Kidney Injury Risk After Cardiac Operations

“…This stands in contrast to recent data in cardiac surgery suggesting that blood products can be associated with AKI [32,33] and that urinary AKI biomarkers are also associated with AKI [34]. Our investigation, however, examined significantly more detailed perioperative and postoperative interventions than these studies, and the possibility remains that unmeasured confounders related to patient care may cloud the blood product-AKI relationship.…”

AKI Associated with Cardiac Surgery

“…Karkouti (144) identified 20 observational studies showing an association between transfusion of packed red blood cells and AKI (and 1 study that found no difference). Since that time, additional studies have added to the growing body of literature suggesting that anemia and the use of packed red blood cells are independent risk factors for AKI after cardiac surgery (145)(146)(147). Catalytic iron (i.e., circulating iron not bound to any proteins) can produce hydroxyl radicals, cause oxidative tissue damage, and has been proposed as a nephrotoxin (148).…”