Venous Congestion

Acute kidney injury affects more than 30% of patients after cardiac surgery, and is associated with an excess in mortality. There is a clinical continuum between acute kidney injury (transient if \<48h, persistent if \>48h), the development of acute kidney and chronic renal failure. Each of these entities characterising renal recovery is associated with an increase in long-term morbidity and mortality. Fluid management in patients with acute kidney injury is challenging, as both hypovolaemia and hypervolaemia are detrimental. Venous congestion (reflecting intravascular hypervolaemia), is a well-established haemodynamic factor contributing to acute kidney injury after cardiac surgery. An ultrasound score, based on the venous doppler pattern explored in intra-abdominal organs, has recently been developed and is a better predictor of acute kidney injury than central venous pressure. Whether using the VeXUS score to guide fluid removal in haemodynamically stabilised patients could promote renal recovery after acute kidney injury remains to be investigated. Before designing a large randomised trial to test such a strategy, its feasibility in a pilot randomised trial is assessed.

In critically ill patients, appropriate fluid administration is one of the cornerstones of hemodynamic management, as both hypovolemia and fluid overload can negatively impact clinical outcomes. For years, fluid responsiveness-defined as an increase in cardiac output following volume administration-has guided decision-making in the postoperative ICU. However, fluid responsiveness alone does not guarantee fluid tolerance, which refers to the venous system's ability to accommodate volume without developing venous congestion or adverse effects such as pulmonary edema, renal or hepatic dysfunction. The tidal volume challenge (TVC)-which consists of a transient increase in tidal volume from 6 to 8 mL/kg-has been shown to predict fluid responsiveness by enhancing the hemodynamic interaction between the heart and lungs during the cardiac cycle, as measured through dynamic arterial indices such as pulse pressure variation (PPV) or stroke volume variation (SVV). However, these indices do not provide information about fluid tolerance or the state of venous congestion. Doppler ultrasound of the portal vein, specifically the portal pulsatility index (which under normal conditions presents as a continuous waveform due to the damping effects of the hepatic parenchyma and venous compliance), has been proposed as a non-invasive marker of systemic venous congestion. Studies have shown that an increase in the portal pulsatility index following volume loading may indicate the development of venous congestion and, therefore, poor fluid tolerance. Since the tidal volume challenge transiently increases intrathoracic pressure and allows dynamic evaluation of cardiovascular responses, we propose that this interaction be assessed not only through arterial dynamic indices (which assess responsiveness) but also through changes in venous flow patterns-specifically, variations in portal pulsatility-so that both fluid responsiveness and tolerance can be predicted with the same test.

Preload responsiveness and venous congestion have largely been investigated independently in recent literature. However, recent data report a similar incidence of venous congestion regardless of fluid responsiveness status, challenging the concept of a linear continuum between preload independence and fluid intolerance. These findings support the need for a more individualized hemodynamic management strategy that takes venous congestion risk into account. The right ventricle plays a central role in this framework. Its function is to maintain an adequate venous return pressure gradient to ensure cardiac output while limiting upstream venous congestion, under strong dependence on its afterload. In physiological conditions, the right ventricle adapts to changes in afterload by increasing contractility to preserve right ventriculo-arterial coupling and optimize its performance. In chronic cardiopulmonary diseases, right ventriculo-arterial uncoupling is a well-established prognostic factor, including the presence of occult uncoupling revealed by fluid loading. In critically ill patients, right ventricular systolic dysfunction associated with venous congestion-defining right heart failure-is strongly associated with increased mortality, as is right ventriculo-arterial uncoupling itself. To support the concept of fluid tolerance, the investigators hypothesize that impairment of right ventriculo-arterial coupling may exist or occur during fluid loading in critically ill patients, independently of preload responsiveness, and may be associated with worsening upstream venous congestion.

This study evaluates whether natriuresis-guided diuretic therapy improves outcomes in patients with acute heart failure (AHF) and severe congestion. All patients hospitalized with AHF will be screened using Venous Excess Ultrasound (VExUS) and randomized 1:1 to either natriuresis-guided escalation of loop diuretics or standard care. The primary endpoint, evaluated in patients with VExUS grade 3 (severe congestion), is a hierarchical composite (win ratio) of 90-day mortality, 90-day rehospitalization, and hospital length of stay. Key secondary endpoints (hierarchical) include (1) difference in win ratio between patients with VExUS 3 versus VExUS 0-2 at hospital admission (assessed by interaction testing and statistically tested only if the primary endpoint is significant) and (2) win ratio (primary endpoint) tested among patients with VExUS 0-2 at hospital admission (statistically tested only if the first key seconday endpoint is significant). Exploratory endpoints include in-hospital clinical, hemodynamic, and biochemical outcomes (mortality, eGFR, NT-proBNP, NYHA class, VExUS score, natriuresis/diuresis, and patient-reported dyspnea), associations between congestion markers (VExUS, FibroScan, lung ultrasound, clinical score, and NT-proBNP), as well as quality of life at 90 days, GDMT optimization score at discharge, and long-term time to readmission and mortality assessed through registry linkage.

The aim of the VeMic study is to explore if venous congestion is linked with microcirculatory impairment in elective cardiac surgery patients in the postoperative ICU stay.

The hypothesis is that fluid-responsive patients who show signs of venous congestion experience a worsening of microcirculatory status after fluid administration compared to patients without signs of venous congestion

Shock is a common and serious cause of admission to intensive care. Vascular filling is one of the cornerstones of shock treatment, aimed at increasing cardiac output and restoring adequate organ perfusion through rapid intravenous administration of a solution. However, this vascular filling can be accompanied by venous congestion, which can be harmful. Fluid administration must therefore be sparing and carefully considered. However, it is difficult to assess the correct amount of intravenous fluid to inject. Multi-site venous ultrasound (inferior vena cava, suprahepatic vein, portal vein, renal vein), recently published under a score called VExUS, could be a useful bedside tool for documenting venous congestion and avoiding excessive vascular filling. Nevertheless, this tool has been little evaluated in the general intensive care population, particularly in patients with acute respiratory distress syndrome (ARDS). Its link with other venous sites (femoral, popliteal) has also been little studied to date. The main objective of our study is to describe the distribution of the VEXUS score among patients in a general intensive care unit. The secondary objectives are: * To study the feasibility of measuring the VEXUS score in patients with ARDS, including during prone positioning, a recommended and frequently used treatment for this condition, which could make it difficult to acquire venous ultrasound data. * In this case, other more accessible venous flows could be analysed, namely the femoral venous flow and the popliteal venous flow. We will therefore also study their feasibility during prone positioning sessions. * Subsequently, we will study the correspondence between the VEXUS score and these other types of venous flow (femoral, popliteal). * Finally, we will evaluate the association between the VEXUS score in our general intensive care population and the long-term prognosis of patients, in this case death on day 28 and the occurrence of acute renal failure requiring renal replacement therapy during the intensive care stay.

Postoperative delirium (POD) is an acute brain dysfunction characterized by inattention, impaired consciousness, and cognitive and orientation disturbances, and is a common complication after cardiac surgery. The high incidence of up to 52% of POD in cardiac surgery patients lead to a range of adverse clinical outcomes.The brain tissue is enclosed in a rigid anatomical structure; when there is an obstruction to venous return from the brain, intracranial pressure can increase, and blood supply to the brain tissue can decrease, leading to central nervous system dysfunction. Systemic venous congestion can occur when there is right heart dysfunction or excessive volume load. When right heart failure and/or volume overload occurs, changes in right atrial pressure are transmitted to the venous system of organs throughout the body, with dilatation of the inferior vena cava (IVC), obstruction of blood return from the hepatic, portal, and renal veins, and abnormal venous flow signals and altered ultrasound Doppler flow patterns. The primary objective of this prospective cohort study is to explore if intraoperative systemic venous congestion is associated with POD after cardiac surgery. This study will also investigate the relationship between intraoperative systemic venous congestion and postoperative complications, and the relationship between each separate venous congestion and POD after cardiac surgery.

Venous pressure is often overlooked as an important hemodynamic parameter. Elevated venous pressure and blood stasis in organ tissues can lead to interstitial edema. Intraoperative venous blood stasis can rapidly increase interstitial pressures within organ tissues, especially in organs encapsulated by tissue envelopes, such as the kidney, thereby rapidly reducing effective circulating blood flow to the organ. Systemic venous blood stasis, which tends to occur in patients with right heart failure or pulmonary hypertension, as well as in patients with fluid overload, can lead to intraoperative stasis in multiple organs and tissues, mediating the development of multisystem complications, including acute kidney injury. Therefore, timely, effective, and accurate intraoperative assessment of systemic venous blood stasis is particularly important. When right heart failure and/or volume overload occurs in the body, changes in right atrial pressure are transmitted to the venous system of organs throughout the body, with dilatation of the inferior vena cava (IVC), obstruction of blood return from the hepatic, portal, and renal veins, and abnormal venous flow signals and altered ultrasound Doppler flow patterns. The primary objective of this prospective cohort study is to explore if intraoperative systemic venous congestion during cardiac surgery is associated with postoperative CSA-AKI. In doing so, we seek to identify a promising physiological marker that can provide cues for the prediction of CSA-AKI. This study will also investigate the relationship between intraoperative systemic venous congestion and postoperative complications, and explore the relationship between each separate venous congestion and AKI after cardiac surgery.

The objective of this study is to assess how fluid resuscitation, in the context of fluid responsiveness, affects the incidence and progression of systemic venous congestion in critically ill cardiac patients. Additionally, the study aims to evaluate the impact on clinical outcomes, with a particular focus on acute kidney dysfunction. This assessment will utilize the VExUS score in conjunction with comprehensive bedside echocardiographic evaluations.

Fluid responsiveness is a critical determinant guiding fluid therapy in critically ill patients. However, excessive fluid administration can result in fluid overload, leading to venous congestion and worse clinical outcomes. Venous congestion, a marker of impaired fluid clearance, is increasingly recognized as a significant contributor to poor prognosis. Previous studies have demonstrated the coexistence of fluid responsiveness and venous congestion in critically ill patients. Notably, these studies were limited by the absence of fluid challenge-the gold standard for assessing fluid responsiveness-leaving the dynamic relationship between fluid responsiveness and venous congestion incompletely understood. This study aims to investigate the interplay and temporal evolution of fluid responsiveness and venous congestion following a standardized fluid challenge in critically ill patients.