Post-surgical acute kidney injury

Acute kidney injury (AKI) has been proven to increase patient mortality in all clinical settings: general out-ofhospital population, in-hospital admissions, adult and pediatric intensive care units (ICU), adult and pediatric cardiac surgery, and (last but not least) the relatively high portion formed by post-operative general surgery patients. In a study population of 1,166 patients without previous renal insuffi ciency, Abelha and colleagues [1] elegantly showed that 7.5% met AKI criteria. Interestingly, AKI was diagnosed when criteria of class I (or greater) of the Acute Kidney Injury Network (AKIN) classifi cation were present. On multivariate analysis, American Society of Anesthesiologists (ASA) physical status, Revised Cardiac Risk Index (RCRI) score, high-risk surgery, and congestive heart failure were identifi ed as the independent preoperative risk factors for AKI during the post-operative period. Th e RCRI score includes the following variables: high-risk surgery, ischemic heart disease, congestive heart failure, cerebrovascular disease, and insulinrequiring diabetes mellitus. According to these data, AKI patients were the most severely ill after ICU admission (higher Simplifi ed Acute Physiology Score II and Acute Physiology and Chronic Health Evalu a tion II), had the longest ICU length of stay, and were independently at risk for hospital mortality. In our opinion, even if the accompanying editorial points out that one of the most important limitations of this report was the exclusion of patients with pre-operative renal dysfunction [2] (which has been identifi ed as a major risk factor for perioperative AKI in most studies), patients with preoperative renal dysfunction are already those who receive the greater attention for prevention or treatment (or both) of further renal insult. So it must be remarked that an important message of this study is that post-operative AKI must be suspected in all patients with the clinical characteristics analyzed by Abelha and colleagues [1]. Th e next step will be to analyze such a cohort for the eff ect of intra-operative and post-operative therapeutic staregies on AKI risk: the prevention from use of nephrotoxins (nephrotoxic antibiotics, non steroidal antiinfl ammatory drugs, and some forms of hydroxyethyl starch), the eff ort to avoid extreme intra-operative hypotension or anemia, and fi nally the contri bution of specifi cally targeted therapies (for example, bicarbonate infusion, N-acetilcysteine, fenoldo pam, poly mixin hemoperfusion, and prophylactic dialysis).