Renal Doppler to Predict Acute Kidney Injury (AKI) in ARDS Patients. (RED-AKI Study)

This is a multicenter international observational prospective cohort study. The main questions it aims to answer are: * PRIMARY AIM: To describe the capability of IRVF demodulation at diagnosis of ARDS to predict development of AKI within 7 days from the ARDS onset * SECONDARY AIMS: A)Describe the capability of IRVF demodulation or pattern of IRVF (continuous, pulsatility, biphasic, monophasic) to predict development of AKI within 14 days from the ARDS onset. B) To describe the RD parameters and VexUS in the AKI and no AKI patients over time. C) Describe the impact of invasive mechanical ventilation (IMV) on the intrarenal venous congestion and VexUS., D) Evaluation of effect of CRRT on IRVF pattern, VexUS and parameters. E) Describe the feasibility of renal doppler to assess IRVF in critically ill respiratory patients. F) Evaluate the incidence of AKD and CKD Participants will Adult patients with diagnosis of ARDS admitted to intensive care unit and undergoing invasive mechanical ventilation