Abstract
IntroductionIn the setting of early acute kidney injury (AKI), no test has been shown to definitively predict the progression to more severe stages.MethodsWe investigated the ability of a furosemide stress test (FST) (one-time dose of 1.0 or 1.5 mg/kg depending on prior furosemide-exposure) to predict the development of AKIN Stage-III in 2 cohorts of critically ill subjects with early AKI. Cohort 1 was a retrospective cohort who received a FST in the setting of AKI in critically ill patients as part of Southern AKI Network. Cohort 2 was a prospective multicenter group of critically ill patients who received their FST in the setting of early AKI.ResultsWe studied 77 subjects; 23 from cohort 1 and 54 from cohort 2; 25 (32.4%) met the primary endpoint of progression to AKIN-III. Subjects with progressive AKI had significantly lower urine output following FST in each of the first 6 hours (p<0.001). The area under the receiver operator characteristic curves for the total urine output over the first 2 hours following FST to predict progression to AKIN-III was 0.87 (p = 0.001). The ideal-cutoff for predicting AKI progression during the first 2 hours following FST was a urine volume of less than 200mls(100ml/hr) with a sensitivity of 87.1% and specificity 84.1%.ConclusionsThe FST in subjects with early AKI serves as a novel assessment of tubular function with robust predictive capacity to identify those patients with severe and progressive AKI. Future studies to validate these findings are warranted.
Highlights
In the setting of early acute kidney injury (AKI), no test has been shown to definitively predict the progression to more severe stages
We identified a subset of patients from the Southern Acute Kidney Injury Network (SAKInet) cohort at the George Washington University who fulfilled the study criteria
We cannot overemphasize the point that patients need to be euvolemic before undertaking any type of furosemide challenge, and that volume replacement is mandatory in patients who are not obviously volume overloaded, as the mean urine output (UO) in response to the challenge was over 1.3 L in 6 hours
Summary
In the setting of early acute kidney injury (AKI), no test has been shown to definitively predict the progression to more severe stages. Because serum creatinine and oliguria are often late signs of significant AKI, more sensitive diagnostic tests are required [6,7,8,9]. This clinical need has led to the development of multiple candidate AKI biomarkers [6,8,9,10]. Since most common form(s) of intrinsic AKI involve acute tubular injury, we sought to develop a functional assessment of renal tubular function. We surmised that furosemide-induced increases in urine output might be a method to assess the integrity of renal tubular function in the setting of early AKI. We sought to develop and standardize a furosemide stress test (FST) for patients with AKI and describe its performance characteristics
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