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. 2022;51(4):309-316.
doi: 10.1159/000517469. Epub 2021 Jul 19.

Renal Resistive Index as a Predictor of Acute Kidney Injury and Mortality in COVID-19 Critically Ill Patients

Edgar Garcia Cruz  1 , Blanca Estela Broca Garcia  2 , Daniel Manzur Sandoval  1 , Rodrigo Gopar-Nieto  2 , Francisco Javier Gonzalez Ruiz  1 , Linda Diaz Gallardo  3 , Claudio Ronco  4 , Magdalena Madero  5 , Enzo Vasquez Jimenez  5
Affiliations

Renal Resistive Index as a Predictor of Acute Kidney Injury and Mortality in COVID-19 Critically Ill Patients

Edgar Garcia Cruz et al. Blood Purif. 2022.

Abstract

Background: Acute kidney injury (AKI) in patients with COVID-19 can be caused by multiple mechanisms. Renal resistive index (RRI) is a noninvasive instrument to evaluate kidney hemodynamics, and it is obtained by analysis of intrarenal arterial waves using Doppler ultrasound. This study aimed to determine the role of RRI in predicting AKI and adverse outcomes in critically ill patients with COVID-19.

Methods: This cross-sectional study included 65 patients with confirmed SARS-CoV-2 pneumonia admitted to the critical care unit from April 1, 2020, to June 20, 2020. Informed consent was obtained from all individual participants included in the study. Cardiac, pulmonary, and kidney ultrasonographic evaluations were performed in a protocolized way.

Results: In this cohort, 65 patients were included, mean age was 53.4 years, 79% were male, and 35% were diabetic. Thirty-four percent of patients developed AKI, 12% required RRT, and 35% died. Of the patients who developed AKI, 68% had RRI ≥ 0.7. Also, 75% of the patients who required RRT had RRI ≥ 0.7. In the adjusted Cox model, the RRI ≥ 0.7 was associated with higher mortality (HR 2.86, 95% CI: 1.19-6.82, p = 0.01).

Conclusions: Critical care ultrasonography is a noninvasive, reproducible, and accurate bedside method that has proven its usefulness. An elevated RRI may have a role in predicting AKI, RRT initiation, and mortality in patients with severe SARS-CoV-2 pneumonia.

Keywords: Acute kidney injury; Coronavirus disease; Renal replacement therapy; Renal resistive index.

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Conflict of interest statement

In the last 3 years, Claudio Ronco has been consulting or is a part of the advisory boards for ASAHI, Astute, Baxter, Biomerieux, B. Braun, Cytosorbents, ESTOR, FMC, GE, Jafron, Medtronic, and Toray. The other authors have no conflicts of interest to declare.

Figures

Fig. 1
Fig. 1
a Doppler sample volume position in the interlobar vessels, intrarenal artery flow. b Pulsatile venous pattern.
Fig. 2
Fig. 2
Kaplan-Meier survival estimates according to RRI. RRI, renal resistive index.
See this image and copyright information in PMC

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