Diagnostic accuracy of arterial and venous renal Doppler assessment for acute kidney injury in critically ill patients: A prospective study

Renal Resistive Index (RRI) and Venous Impedance Index (VII) might be of additional value for diagnosing Acute Kidney Injury (AKI). The purpose of this study was to assess the diagnostic accuracy of RRI and VII for AKI. In the prospective Simple Intensive Care Studies-II (NCT03577405), we measured RRI and VII in acutely admitted adult intensive care patients within 24 h of admission. AKI was defined by the Kidney Disease Improving Global Outcome (KDIGO) criteria. The primary outcome was persistent AKI, defined as non-resolved AKI on day three. We tested specificity, sensitivity and diagnostic accuracy of both RRI and VII for persistent AKI. In total, 371 patients were included of whom 123 patients (33%) had persistent AKI. RRI and VII did not differ between patients with and those without persistent AKI (p = .08 and p = .59). RRI had a moderate specificity (72%, 95%CI 66–78%) and low sensitivity (32%, 95%CI 24–41%) and VII had high sensitivity (93%, 95%CI 85–98%) and low specificity (11%, 95%CI 6–16%) for persistent AKI. Overall diagnostic accuracy of RRI and VII was moderate. In acutely admitted critically ill patients, measures of renal perfusion by renal ultrasound were not different between patients with and without AKI, and show limited diagnostic accuracy for AKI. Registered:NCT03577405 •First study to assess venous Doppler measurements in critically ill patients.•No association between arterial or venous renal Doppler and persistent AKI.•Moderate diagnostic accuracy of both measurements for AKI.•Sufficient sample size and methods following STARD guidelines.