Changes of Renal Resistive Index in Critically Ill Patients Undergoing Continuous Renal Replacement Therapy.

"The kidneys are preliminarily visualized in a 2D projection, followed by identifying interlobar or arcuate vessels using color Doppler. Flow measurements in these vessels are performed using pulsed-wave Doppler. Renal Resistive Index is determined over three cardiac cycles (five in the case of atrial fibrillation) in two different arteries, each in a different kidney section. Subsequently, measurements from each artery are averaged. If possible, the examination should be conducted bilaterally.~The investigators do not have access to previous measurements (each study is recorded on a separate card)."