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

Abstract

Background 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. Objective The 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. Methods In 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. Results RRI 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). Conclusions Critically 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.

Right Ventricular Dysfunction and Its Association With Mortality in Coronavirus Disease 2019 Acute Respiratory Distress Syndrome*

“…Patients with RV dilation with systolic impairment may have exhausted this compensatory response and are unable to preserve RV forward flow, contributing to an increased need for RRT and mortality. This mechanism of organ dysfunction with RV determined alterations in systemic blood flow is supported by ultrasound studies, demonstrating disrupted renal blood flow in accordance with AKI severity in COVID-19 ( 30 ). The increased prevalence of RV pressure overload and trend toward increased prevalence of RV volume overload (as estimated by the LVEI) in this RV phenotype may also contribute to its strong association with mortality.…”

The Impact of COVID-19 on Renal Resistive Index in Kidney Transplant Recipients

“…It is thought that immune system dysregulation also contributes to this process [12] . In critically infected COVID-19 patients, the development of acute kidney injury (AKI) has been correlated with increased mortality rates [13] . Therefore, for the early diagnosis of AKI in COVID-19 patients, especially in intensive care units, measurement and evaluation of the RRI appears to be an effective and easy option [13] .…”

“…In critically infected COVID-19 patients, the development of acute kidney injury (AKI) has been correlated with increased mortality rates [13] . Therefore, for the early diagnosis of AKI in COVID-19 patients, especially in intensive care units, measurement and evaluation of the RRI appears to be an effective and easy option [13] . Watchorn et al reported that COVID-19 patients with AKI had greater microvascular and macrovascular renal perfusion impairment and an increase in the RRI compared to AKI patients without COVID-19 and to septic shock-related AKI patients with other aetiologies [10] .…”

Decreased renal perfusion during acute kidney injury in critical COVID-19 assessed by magnetic resonance imaging: a prospective case control study

“…Our observations of reduced renal perfusion during AKI in COVID-19 are in line with prior observations in AKI due to bacterial septic shock [ 7 , 9 ], and thoracic surgery [ 10 ]. Results of renal ultrasound in critical COVID-19 have also implied reduced perfusion either using contrast enhancement or as an indirect observation of larger values of resistance index [ 18 , 19 ]. We also show increased resistive index correlated with lower total renal blood flow.…”

“…1d, e). Cortical R 2 * was 17 (1/s) [16][17][18][19] in the AKI group and 17 (1/s) [16][17][18] in the NO AKI group. In the renal medulla, R 2 * was 29 (1/s) [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] in patients with AKI compared with 27 (1/s) [23][24][25][26][27][28][29] in patients with NO AKI.…”