Acute kidney injury (AKI) duration after cardiac surgery is associated with poor survival in a dose-dependent manner. However, it is not known what perioperative risk factors contribute to prolonged AKI and delayed recovery. We sought to identify perioperative risk factors that predict duration of AKI, a complication that effects short and long-term survival.
We studied 4,987 consecutive cardiac surgery patients from 2002 through 2007. Acute kidney injury was defined as a 0.3 or greater (mg/dL) or 50% or greater increase in serum creatinine from baseline. Duration of AKI was defined by the number of days AKI was present. Stepwise multivariable negative binomial regression analysis was conducted using perioperative risk factors for AKI duration. The c-index was estimated by Kendall's tau.
Acute kidney injury developed in 39% of patients with a median duration of AKI at 3 days and ranged from 1 to 108 days. Patients without AKI had a duration of 0 days. Independent predictors of AKI duration included baseline patient and disease characteristics, and operative and postoperative factors. Prediction for mean duration of AKI was developed using coefficients from the regression model and externally validated the model on 1,219 cardiac surgery patients in a separate cardiac surgery cohort (Translational Research Investigating Biomarker Endpoints-AKI). The c-index was 0.65 (p<0.001) for the derivation cohort and 0.62 (p<0.001) for the validation cohort.
We identified and externally validated perioperative predictors of AKI duration. These risk factors will be useful to evaluate a patient's risk for the tempo of recovery from AKI after cardiac surgery and subsequent short and long-term survival. The levels of awareness created by working with these risk factors have implications regarding positive changes in processes of care that have the potential to decrease the incidence and mitigate AKI.
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[Show abstract][Hide abstract] ABSTRACT: Acute kidney injury (AKI) is a serious and common complication of major surgery. This narrative review focuses on the relationship between perioperative red blood cell transfusion and AKI after cardiac surgery with cardiopulmonary bypass (CPB). Numerous observational studies have shown that these two factors are independently associated with each other. Several lines of evidence suggest that the nature of this association is one of cause and effect. The pathophysiological mechanism by which transfusions might harm the kidney has not been fully elucidated, but it is known that erythrocytes undergo irreversible morphological and biochemical changes during storage. As a result, after transfusion, they can promote a pro-inflammatory state, impair tissue oxygen delivery, and exacerbate tissue oxidative stress. This in turn can cause AKI in susceptible patients undergoing cardiac surgery with CPB, such as those with pre-existing kidney dysfunction or anaemia. Interventions aimed at avoiding perioperative blood transfusion might, therefore, reduce the risk of AKI after cardiac and other types of surgery.
Preview · Article · Dec 2012 · BJA British Journal of Anaesthesia
[Show abstract][Hide abstract] ABSTRACT: Acute kidney injury (AKI) is a common but complex clinical syndrome with multiple etiologies. These etiologies target different sites and pathways within the kidney. Novel biomarkers of 'kidney damage' (which can be tubular or glomerular) can be used to diagnose AKI, even in the absence of an increase in serum creatinine or oliguria. These biomarkers of kidney damage can be combined with biomarkers of kidney function to facilitate classification of AKI. A comprehensive review of the literature was performed using the published methodology of the Acute Dialysis Quality Initiative (ADQI) working group and used to establish consensus statements regarding the use of biomarkers in the differential diagnosis of AKI. We recommend that the pathophysiological terms 'functional change' and 'kidney damage' be used in preference to the anatomical classification using the terms pre-renal, renal and post-renal AKI. We further recommend the use of both renal and non-renal biomarkers in establishing the specific cause of AKI as soon as possible after diagnosis. The presence of underlying CKD or of sepsis poses additional challenges in differential diagnosis, since these conditions alter both baseline biomarker excretion and biomarker performance. We recommend that biomarkers be validated within the clinical context in which they are to be used. Within that context, combinations of biomarkers may, in the future, allow differentiation of the site, mechanism and phase of injury.
No preview · Article · May 2013 · Contributions to nephrology
[Show abstract][Hide abstract] ABSTRACT: Acute kidney injury is one of the most frequent and clinically important of all postoperative complications in cardiac surgery. It is estimated that almost half of subjects suffer from a deterioration of kidney function after a cardio-pulmonary by-pass. Renal insufficiency impacts upon the outcome in terms of an increase in postoperative morbidity and mortality, and a decrease in quality of life. Recently, a modified and unified classification of cardio-renal syndrome has been devised, which takes into account bilateral association between the heart and the kidneys. Because acute decompensation in heart function leads to acute kidney damage, therefore cardiac surgery-associated acute kidney injury may be recognised as a type 1 cardio-renal syndrome from a pathophysiological point of view. This paper aims to review the current data on the diagnosis of acute kidney injury and preventive strategies that can be implemented in cardiac surgery perioperative care.