Effect of Hydration on Doppler Velocity of Renal Arteries

Abstract

Abstract Context Doppler sonography is a noninvasive method to evaluate the hemodynamic status of the kidney, and its parameters are used as direct and indirect predictors of certain parenchyma and renovascular diseases. However, the effect of hydration on kidney hemodynamics has not been explored via Doppler sonography. Objective To examine differences in arterial Doppler velocities of normal adult kidney before and after hydration. Methods A total of 60 native kidneys in 30 normal adult participants (mean age, 26 years) were assessed using Doppler sonography. Quantitative ultrasound Doppler parameters of peak systolic velocity (PSV), end diastolic velocity (EDV), and resistive index (RI) of the main renal artery and the intrarenal (interlobar) arteries were measured immediately before and 1 hour after ingestion of 500 mL of water. We tested differences in Doppler parameters before and after hydration using a paired t test, analyzed the correlation of the increase in PSV to the increase in EDV after hydration using Pearson correlation coefficient (PCC), and examined intraobserver reliability using intraclass correlation coefficient (ICC). Results Statistical analyses revealed that the differences in PSV and EDV values before and after hydration at the main renal artery and interlobar arteries of the kidney were significant (P<.001), whereas the RI at the main renal artery and interlobar arteries were not (P>.05). PCC for the correlation of the increase in PSV to the increase in EDV was greater than 0.80. ICC for intraobserver repeatability in performing kidney Doppler sonography was 0.92. Conclusion Our results suggest that Doppler sonography is able to demonstrate changes in kidney hemodynamics within 1 hour after hydration. The normal kidney reflects proportional increases in PSV and EDV at the main renal artery and interlobar arteries, while maintaining vascular resistance. Doppler flow velocities of renal arteries can be considered as noninvasive quantitative markers for evaluating the response of kidney hemodynamics to hydration.