Renal insufficiency after cardiac surgery: a challenging clinical problem

Abstract

Acute renal insufficiency (ARI) after cardiac surgery is a complex and frequent clinical problem. It increases short- and long-term mortality, the incidence of post-operative complications such as respiratory infections, sepsis, and gastrointestinal bleeding, and intensive care unit (ICU) and hospital lengths of stay.1,2 Identified risk factors for post-operative ARI in cardiac surgical patients include pre-operative renal insufficiency, advanced age, history of congestive heart failure, diabetes mellitus, recent exposure to nephrotoxic agents such as contrast dye, intra-aortic balloon pump, emergency operation, prolonged cardiopulmonary bypass (CPB) time, low urinary output during CPB, and need for deep hypothermic circulatory arrest ( Figure 1 ).2,3 Figure 1 Risk factors for acute renal insufficiency after cardiac surgery. Analysing the pre-operative risk factor trends in cardiac surgery during the 1990–1999 decade in the large, voluntary, nationwide STS database, Ferguson et al. 4 showed that the incidence of pre-operative renal insufficiency increased from 3.0 to 4.6%. Recently, Swaminathan et al. 5 showed that, among coronary artery bypass grafting (CABG) patients, the incidence of acute renal failure increased significantly from 1.1 to 4.1%. While the proportion of a diagnosis of acute renal failure cases requiring haemodialysis decreased from 15.8 to 8.7%, the percentage of survivors with post-operative special care requirements increased from 35.5 to 64.5%.5 Over the last few years, the prognostic importance of mildly elevated pre-operative serum creatinine levels or small increases in post-operative creatinine values became apparent, leading to a shift in our understanding of the importance of even small degrees of acute kidney injury. Antunes et al. 6 reported, among 2122 patients with pre-operative creatinine serum levels <2.0 mg/dL having CABG and an … *Corresponding author. Tel: +32 4 366 7163, Fax: +32 4 221 31 58, Email: philippe.kolh{at}chu.ulg.ac.be