Microcirculation Alterations in Patients With Severe Sepsis

The microcirculation is the place where oxygen exchanges take place at the organ level. The microcirculation has been neglected for a long time by clinicians due to technical difficulties to access it at bedside, but recent technological advances have allowed the identification of microcirculatory alterations in patients with sepsis. Microcirculatory alterations are frequently observed in sepsis even when systemic hemodynamics are within targets. These alterations are characterized by the heterogeneity of perfusion with nonperfused vessels in close vicinity of well perfused ones. These findings contribute to the alterations in oxygen extraction in sepsis and explain why signs of tissue hypoperfusion can be observed even in presence of normal or high venous oxygen saturation (ie, microcirculatory shunt). These alterations are associated with organ dysfunction and mortality. Different mechanisms can be involved in their development and this has major implications for the potential therapies that can be applied. This review focuses on the implications and mechanisms associated with these microcirculatory alterations and on potential therapeutic strategies.