Introducción: The implementation of renal POCUS in critical care is a valuable tool that complements the physical examination of critically ill patients. It is non-invasive, accessible, harmless, and inexpensive, allowing renal perfusion to be evaluated at the bedside of patients through ultrasound measurements such as the renal resistance index (RRI) and intrarenal venous Doppler (IVD), which are considered early predictors of acute kidney injury (AKI). Objetivos: To determine the relationship between the renal resistance index (RRI) and the degree of AKI according to KDIGO in neurocritical patients, and to correlate intrarenal venous Doppler (IVD) flow abnormalities with the degree of AKI according to KDIGO. Métodos: An observational, analytical, prospective, and longitudinal study was conducted in a neurocritical patient ICU with 43 participants. RRI and IVD measurements were performed at admission, 72 hours, and 7 days. The study evaluated which parameter better predicts AKI according to KDIGO. Resultados: In the study of 43 critically ill patients, the correlation results between RRI value and AKI according to KDIGO were not significant. On the other hand, the correlation between intrarenal venous Doppler (IVD) at admission, 72 hours, and 7 days with AKI according to KDIGO was significant with a value of r: 43=0.95 (P=0.54); 0.49 (P=0.001); 0.58(P=0.000). Analyzing by classification tree, it was determined that the variables that best predict the risk of developing AKI before it occurs are intrarenal venous Doppler (IVD) measurement at 7 days and the cumulative fluid balance value. Conclusiones: There is a positive and significant correlation between intrarenal venous Doppler (IVD) and AKI. Intrarenal venous Doppler (IVD) and cumulative fluid balance predict the risk of developing AKI in critically ill patients. On the other hand, renal resistance index was not related to AKI in the studied population.