The pulsatile pattern of the portal vein is considered a marker of right ventricular dysfunction, but volemia may also contribute to this phenomenon. The separate influence of each factor remains debated, as the interplay between right ventricular dysfunction and volume status is complex. Additionally, right ventricular dysfunction can originate from either diastolic or systolic dysfunction, further complicating the understanding of their distinct impacts on portal vein pulsatility.

The pulsatile pattern of the portal vein has been recognized as a potential marker of right ventricular dysfunction, reflecting altered hemodynamics in the venous system. However, the role of volemia, or the volume status of a patient, might also significantly influence this pulsatility, complicating the interpretation of portal vein flow patterns. The distinct and combined effects of right ventricular dysfunction and volemia on portal vein pulsatility are still subjects of ongoing debate. Right ventricular dysfunction itself can arise from multiple mechanisms, including primary diastolic dysfunction, where the ventricle has impaired filling and relaxation, or systolic dysfunction, characterized by reduced contractility and ejection capacity. Understanding whether diastolic or systolic dysfunction plays a predominant role in altering portal vein pulsatility is crucial, as these nuances have important implications for accurately identifying the determinants of portal vein pulsatility index and tailoring appropriate clinical interventions.

Inclusion Criteria:

• Informed consent.
• Mechanically ventilated patients within 6 hours after ICU admission following surgery who are considered for fluid administration to optimize haemodynamics.
• Sinus rhythm.

Exclusion Criteria:

• A condition known to interfere with portal vein flow assessment or interpretation (liver cirrhosis or chronic hepatic disease, suprahepatic or portal vein thrombosis).
• Any mechanical circulatory support.
• Cardiac transplant.
• Poor transthoracic echocardiographic window.

Mechanically ventilated postoperative adult patients after cardiac surgery within 6 hours after intensive care unit admission.