Obesity and oxidative stress predict AKI after cardiac surgery.

Billings FT, Pretorius M, Schildcrout JS, Mercaldo ND, Byrne JG, Ikizler TA, Brown NJ
J Am Soc Nephrol. 2012 23 (7): 1221-8

PMID: 22626819 · PMCID: PMC3380645 · DOI:10.1681/ASN.2011090940

Obesity increases oxidative stress, endothelial dysfunction, and inflammation, but the effect of obesity on postoperative AKI is not known. We examined the relationship between body mass index (BMI) and AKI in 445 patients undergoing cardiac surgery and whether oxidative stress (F(2)-isoprostanes), inflammation (IL-6), or antifibrinolysis (plasminogen activator inhibitor-1 [PAI-1]) contribute to any identified relationship. Overall, 112 (25%) of the 445 patients developed AKI. Higher BMI was independently associated with increased odds of AKI (26.5% increase per 5 kg/m(2) [95% confidence interval, 4.3%-53.4%]; P=0.02). Baseline F(2)-isoprostane (P=0.04), intraoperative F(2)-isoprostane (P=0.003), and intraoperative PAI-1 (P=0.04) concentrations also independently predicted AKI. BMI no longer predicted AKI after adjustment for the effect of F(2)-isoprostanes, suggesting that obesity may affect AKI via effects on oxidative stress. In contrast, adjustment for IL-6 or PAI-1 did not substantially alter the association between BMI and AKI. Further, deconstruction of the obesity-AKI relationship into direct (i.e., independent of candidate pathways) and indirect (i.e., effect of BMI on AKI via each candidate pathway) effects indicated that F(2)-isoprostanes, but not IL-6 or PAI-1, partially mediate the relationship between obesity and AKI (P=0.001). In conclusion, obesity independently predicts AKI after cardiac surgery, and oxidative stress may partially mediate this association.

MeSH Terms (22)

Acute Kidney Injury Aged Angiotensin-Converting Enzyme Inhibitors Biomarkers Body Mass Index Cardiac Surgical Procedures Diuretics F2-Isoprostanes Female Humans Interleukin-6 Male Middle Aged Obesity Oxidative Stress Plasminogen Activator Inhibitor 1 Postoperative Complications Ramipril Randomized Controlled Trials as Topic Risk Factors Signal Transduction Spironolactone

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