Abstract 16438: Increased Plasma Heme Oxygenase-1 is Associated with Acute Kidney Injury after Cardiac Surgery
Introduction: Intraoperative hemolysis and inflammation are associated with acute kidney injury (AKI) following cardiac surgery. Plasma free hemoglobin induces heme oxygenase-1 (HO-1) expression, and HO-1 degrades heme but is increased in experimental models of AKI. The effect of cardiac surgery on plasma HO-1 concentrations is unknown. This study tested the hypothesis that plasma HO-1 concentrations are increased in cardiac surgery patients who develop AKI.
Methods: We measured plasma free hemoglobin, HO-1, and inflammatory markers at baseline, post-cardiopulmonary bypass (CPB), and on postoperative day 1 (POD1) in 74 adult patients undergoing cardiac surgery. AKI was defined as an increase in serum creatinine concentration of 50% or 0.3 mg/dL within 72 hours of surgery. Longitudinal measures of free hemoglobin, HO-1, and interleukins were analyzed using mixed effects models with time and AKI group as fixed effect and a random subject effect.
Results: Twenty-eight percent of patients developed AKI. CPB was associated with increased free hemoglobin (10.2±2.5 mg/dl at baseline to a peak of 242.5±27.2 post-CPB; P<0.001) and plasma HO-1 (4.2±0.2 ng/ml at baseline to 6.6±0.5 on POD1; P<0.001). Post-CPB free hemoglobin correlated with POD1 expression of HO-1 (r=0.41, P=0.001), and free hemoglobin, HO-1, and interleukin (IL)-6 were significantly increased in patients that subsequently developed AKI (Figure). IL-8 (P=0.10) and IL-10 (P=0.07) were not associated with AKI.
Conclusions: Plasma HO-1 is associated with intraoperative hemolysis and is increased in cardiac surgery patients that develop AKI. Future studies are needed to determine whether HO-1 may serve as an early biomarker of AKI in cardiac surgery patients.
- © 2012 by American Heart Association, Inc.