Color Doppler-Based Renal Pulsatility and Resistive Index as a Predictor Tool of Acute Kidney Injury in COVID-19 Patients; A Case-Control Study

Introduction: Preliminary studies have shown that up to 30% of covid-19 patients hospitalized have acute kidney injury. Studies have shown an association between pulmonary and subsequent renal dysfunction.Methods: This cohort study was conducted from September 2021 to April 2022. 140 Covid-19 patients were evaluated for renal ultrasonographic indices, including renal resistive index (RI) and pulsatility index (PI) in both kidneys. Patients were divided into two groups. Patients with an intrarenal arterial resistive index (RI) > 0.7 were chosen as the case group, and patients with RI <0.7 were selected as the control group. The patients followed during hospitalization for incidence of acute kidney injury (AKI) by recording hourly urine output and daily serum creatinine level.Results: The mean age of covid-19 patients was 54.71 ± 13.91 (64 women and 76 men). The mean left kidney pulsatility index in patients with RI >0.7 was 0.17±1.008 and in patients with RI0.7 was 0.19 ± 1.026, and in patients with RI<0.7 was 0.38 ± 1.33, which were significantly different (p = 0.001).Conclusions: Study findings indicated that pulsatility and resistive indices have a significant relationship with the incidence of kidney failure, and Covid-19 patients with higher pulsatility and resistive index were more susceptible to acute kidney failure.Advances in knowledge statementPulsatility index is a forgotten index in predicting acute kidney injury.