Renal resistive index is associated with acute kidney injury in COVID-19 patients treated in the intensive care unit

Mårten Renberg,Daniel Hertzberg,Max Bell,Naima Kilhamn,Olof Jonmarker,Claire Rimes-Stigare

doi:10.1186/s13089-021-00203-z

Mårten Renberg, Daniel Hertzberg + Show 4 more

Open Access

https://doi.org/10.1186/s13089-021-00203-z

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Abstract

BackgroundRenal resistive index (RRI) is a promising tool for the assessment of acute kidney injury (AKI) in critically ill patients in general, but its role and association to AKI among patients with Coronavirus disease 2019 (COVID-19) is not known.ObjectiveThe aim of this study was to describe the pattern of RRI in relation to AKI in patients with COVID-19 treated in the intensive care unit.MethodsIn this observational cohort study, RRI was measured in COVID-19 patients in six intensive care units at two sites of a Swedish University Hospital. AKI was defined by the creatinine criteria in the Kidney Disease Improving Global Outcomes classification. We investigated the association between RRI and AKI diagnosis, different AKI stages and urine output.ResultsRRI was measured in 51 patients, of which 23 patients (45%) had AKI at the time of measurement. Median RRI in patients with AKI was 0.80 (IQR 0.71–0.85) compared to 0.72 (IQR 0.67–0.78) in patients without AKI (p = 0.004). Compared to patients without AKI, RRI was higher in patients with AKI stage 3 (median 0.83, IQR 0.71–0.85, p = 0.006) but not in patients with AKI stage 1 (median 0.76, IQR 0.71–0.83, p = 0.347) or AKI stage 2 (median 0.79, min/max 0.79/0.80, n = 2, p = 0.134). RRI was higher in patients with an ongoing AKI episode compared to patients who never developed AKI (median 0.72, IQR 0.69–0.78, p = 0.015) or patients who developed AKI but had recovered at the time of measurement (median 0.68, IQR 0.67–0.81, p = 0.021). Oliguric patients had higher RRI (median 0.84, IQR 0.83–0.85) compared to non-oliguric patients (median 0.74, IQR 0.69–0.81) (p = 0.009). After multivariable adjustment, RRI was independently associated with AKI (OR for 0.01 increments of RRI 1.22, 95% CI 1.07–1.41).ConclusionsCritically ill COVID-19 patients with AKI have higher RRI compared to those without AKI, and elevated RRI may have a role in identifying severe and oliguric AKI at the bedside in these patients.

Highlights

Renal resistive index (RRI) is a promising tool for the assessment of acute kidney injury (AKI) in critically ill patients in general, but its role and association to AKI among patients with Coronavirus disease 2019 (COVID-19) is not known
Between April 15 and May 15 in 2020, the six COVIDICUs were screened on specific dates for each intensive care unit (ICU) when at least one of the operators was available and able to perform measurements
At the time of RRI measurement, AKI patients had a higher Sequential Organ Failure Assessment (SOFA) score, a higher incidence of mechanical ventilation and vasopressor use, lower estimated glomerular filtration rate (eGFR) and were more often oliguric compared to patients without AKI

Summary

Introduction

Renal resistive index (RRI) is a promising tool for the assessment of acute kidney injury (AKI) in critically ill patients in general, but its role and association to AKI among patients with Coronavirus disease 2019 (COVID-19) is not known. Acute kidney injury (AKI) is a common complication in critically ill patients with COVID-19. Elevated RRI has shown promise in early detection and prognostication of AKI in mixed ICU populations [12,13,14,15,16], and the method seems feasible within the scope of point-of-care ultrasonography (POCUS) [17]

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