Prevention and Treatment of AKI VEXUS Guided Post Cardiac Surgery

The main goal of this clinical trial is to learn if evaluation by ultrasound of venous congestion of liver and kidneys can guide treatment and prevent and treat acute kidney injury post cardiac surgery (CSA-AKI). Participants will: Be evaluated by liver and kidney veins ultrasound (treatment group) or a placebo post CSA-AKI. Fluid management for the treatment group will be based on a score that emerges from this evaluation (Venous Excess Ultrasound Score, VEXUS). Kidney function will be daily monitored and followed-up for 7 days and until discharge. Daily fluid balance and laboratory examination will be performed. Data will be recorded and collected and a statistical analysis will provide the results that will show or not a probable superiority of this evaluation comparing to the usual care.