Microcirculatory alterations in critically ill patients and the effect of venous congestion on kidney function

Hemodynamic management of critically ill patients aims to provide optimal hemodynamic support to maintain oxygenation. In routine clinical practice, macrohaemodynamic parameters such as systemic blood pressure, heart rate, and cardiac output are used as indices for assessing hemodynamic status. However, in states of cardiovascular compromise, improvement in systemic hemodynamic parameters following resuscitation does not necessarily correspond to a similar improvement in the microcirculation. This discrepancy between macro- and microcirculation is referred to as "loss of hemodynamic coherence," which underscores the necessity for microcirculatory monitoring of critically ill patients.

The kidneys are among the primary organs that are particularly susceptible to the effects of hemodynamic changes and hypoxia, which can ultimately result in the development of acute kidney injury. The kidneys and heart exhibit a close bidirectional interaction, whereby injury of one organ can affect the other. This concept is known as cardiorenal syndrome and has a significant impact on the morbidity and mortality of critically ill patients.

In the current thesis, we investigate the nature of microcirculatory alterations in critically ill patients using bedside microcirculatory hand-held vital microscopy techniques to visualize their anatomy, hemodynamics, and (patho)physiology. We have also characterized acute kidney injury in hemodynamically compromised patients, particularly in the setting of venous congestion.