*2.4.2 Color Doppler in renal ultrasonography*

Renal blood flow is evaluated by color Doppler to measure renal artery resistive index. It is a measure of tissue resistance to perfusion caused by vasoconstriction. This has been studied as a predictor of occult hemorrhagic shock in polytrauma patients with normal hemodynamic status in presentation. A value greater than 0.7 was studied to be predictive [18].
