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Open Access Highly Accessed Research

Doppler resistive index to reflect regulation of renal vascular tone during sepsis and acute kidney injury

Antoine Dewitte12*, Julien Coquin13, Bertrand Meyssignac1, Olivier Joannès-Boyau1, Catherine Fleureau1, Hadrien Roze13, Jean Ripoche2, Gérard Janvier13, Christian Combe24 and Alexandre Ouattara13

Author Affiliations

1 CHU de Bordeaux, Service d'Anesthésie-Réanimation II, avenue de Magellan, F-33604 Pessac, France

2 University of Bordeaux, Bioingénierie tissulaire, U1026, 146 rue Léo-Saignat, F-33000 Bordeaux, France

3 University of Bordeaux, Adaptation cardiovasculaire à l'ischémie, U1034, 125 avenue du Haut-Lévèque, F-33600 Pessac, France

4 CHU de Bordeaux, Service de Néphrologie Transplantation Dialyse, place Amélie Raba-Léon, F-33000 Bordeaux, France

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Critical Care 2012, 16:R165  doi:10.1186/cc11517


See related commentary by Lerolle, http://ccforum.com/content/16/6/174

Published: 12 September 2012

Abstract

Introduction

Renal resistive index (RI), determined by Doppler ultrasonography, directly reveals and quantifies modifications in renal vascular resistance. The aim of this study was to evaluate if mean arterial pressure (MAP) is determinant of renal RI in septic, critically ill patients suffering or not from acute kidney injury (AKI).

Methods

This prospective observational study included 96 patients. AKI was defined according to RIFLE criteria and transient or persistent AKI according to renal recovery within 3 days.

Results

Median renal RIs were 0.72 (0.68-0.75) in patients without AKI and 0.76 (0.72-0.80) in patients with AKI (P=0.001). RIs were 0.75 (0.72-0.79) in transient AKI and 0.77 (0.70-0.80) in persistent AKI (P=0.84). RI did not differ in patients given norepinephrine infusion and was not correlated with norepinephrine dose. RI was correlated with MAP (ρ= -0.47; P=0.002), PaO2/FiO2 ratio (ρ= -0.33; P=0.04) and age (ρ=0.35; P=0.015) only in patients without AKI.

Conclusions

A poor correlation between renal RI and MAP, age, or PaO2/FiO2 ratio was found in septic and critically ill patients without AKI compared to patients with AKI. These findings suggest that determinants of RI are multiple. Renal circulatory response to sepsis estimated by Doppler ultrasonography cannot reliably be predicted simply from changes in systemic hemodynamics. As many factors influence its value, the interest in a single RI measurement at ICU admission to determine optimal MAP remains uncertain.