The current definition of renal failure is based on the KDIGO criteria, which combine clinical markers (diuresis) with biological markers (creatininemia) to define AKI. Limitations in the assessment of renal function using creatinine levels (muscle mass dependency, large volume of distribution, delayed elevation relative to alteration in glomerular filtration rate) have prompted the search for alternative assessment methods that could enable earlier and more accurate detection of renal dysfunction. Analysis of renal perfusion through measurement of the renal resistance index could be an avenue of research for diagnostic and prognostic assessment of renal damage.