The goal of this prospective observational study is to examine the potential association between intra-abdominal pressure and venous congestion as assessed by abdominal ultrasound, in critically ill patients in the Intensive Care Unit (ICU).

The main question it aims to answer is whether there is association between intra-abdominal pressure and Venous Excess Ultrasound (VExUS) score.

Participants will be sonographically assessed and their intra-abdominal pressure measured once within the first 3 days of ICU admission.

Inclusion Criteria:

• Intubated ICU patients on controlled mechanical ventilation, receiving sedation. Patients must have urethral catheter in place.

Exclusion Criteria:

• age < 18 year old
• pregnancy / lactation
• primary liver disease (hepatic cirrhosis, hepatic space-occupying lesions, Budd-Chiari syndrome, portal vein thrombosis) or hepatic surgery
• end stage renal failure or on chronic dialysis
• non-intubated patients or intubated patients on non-controlled mechanical ventilation mode
• absence of urethral catheter, presence of suprapubic catheter, continuous bladder irrigation
• poor abdominal echogenicity

Consecutive adult patients admitted in a 31-bed University-affiliated general ICU in a tertiary hospital (Evangelismos General Hospital, Athens, Greece). The ICU admitts both medical and surgical patients.