The goal of this observational study is to learn about renal and hepatic blood flow abnormalities detected by bedside ultrasound in adult patients admitted to the intensive care unit (ICU) following major trauma.

The main questions it aims to answer are:

• How reliably can trained operators measure renal Doppler and venous congestion scores (RDRI and VExUS) across different hospitals?
• How common are abnormal kidney and liver blood flow patterns in major trauma patients during the first 72 hours of ICU admission?
• Are these abnormal patterns associated with acute kidney injury or the need for mechanical ventilation?

Participants admitted to ICUs or high-dependency units (HDUs) with major trauma (Injury Severity Score >15) will undergo non-invasive bedside ultrasound assessments at admission and at 24, 48, and 72 hours. No additional treatments or interventions will be given as part of this study. Kidney function will also be checked at 6 months after hospital discharge.

Inclusion Criteria:

• Age 18-65 years;
• Admission within 24h from traumatic injury;
• ISS >15

Exclusion Criteria:

1. Age <18 or >65;
2. Known heart failure (NYHA ≥II);
3. Chronic kidney disease (any stage) or chronic RRT;
4. Chronic respiratory disease needing home O₂ or ventilation;
5. Radiological evidence of vascular or parenchymal renal injury on trauma CT precluding reliable Doppler assessment

Adult patients (aged 18-65 years) admitted to intensive care units (ICUs) or high-dependency units (HDUs) at participating centres following major trauma, defined as an Injury Severity Score (ISS) greater than 15, within 24 hours of the traumatic event. Patients with pre-existing chronic kidney disease, heart failure (NYHA ≥ II), chronic respiratory disease requiring home oxygen or ventilation, or radiological evidence of renal vascular or parenchymal injury precluding reliable Doppler assessment will be excluded.