Microcirculation: Physiological Background

Microcirculation includes all vessels with a diameter of 5–200 μm. The microcirculatory network represents the largest endothelial surface of the human body. Essential function of microcirculation is to supply oxygen to the tissues. The alterations of the microcirculation play a major role in the organ dysfunctions that are observed during shock and high-risk cardiovascular surgery. Restoration of microcirculation and tissue oxygenation are the ultimate objectives of any haemodynamic resuscitation in order to limit organ dysfunction. Unfortunately, achieving these goals remains a challenge as we lack the tools to assess the tissue microcirculation and oxygenation available at the patient’s bedside to guide therapeutic strategies. In order to be able to progress in the knowledge of microcirculation, it is essential to know the physiology of microcirculation and the causes of microvascular dysfunctions encountered in ICU. In this chapter, we propose to review the physiopathology of microcirculation.