Evaluation of the microcirculation in critically ill patients

Abstract

The first goal of therapies in critically ill patients is to improve tissue perfusion and oxygenation. Hemodynamic monitoring has long been limited to measurements of cardiac output and global oxygen delivery. The clinical introduction of hand-held vital microscopes in the late 1990s enabled the real-time, non-invasive, bedside observation of blood flow in the microcirculation (vessels with diameter<100 µm), i.e. the real site of oxygen and nutrient exchange between blood and cells. Microcirculatory alterations have been described during sepsis and shock states and were associated with mortality. These can occur independently of systemic hemodynamic alterations. Sublingual videomicroscopy allowed evaluating the microvascular response to resuscitation procedures, including oxygen therapy, fluids, blood transfusions, vasopressors. Future research directions should be aimed to integrate microcirculatory monitoring with standard hemodynamic measurements and verify the utility of microcirculation as a therapeutic target. Continuous technological developments are imperative to facilitate the introduction of sublingual videomicroscopy in the clinical practice.