Interactions between macrocirculation and microcirculation in shock

Abstract

Microcirculatory alterations, frequently observed in shock states, are associated with the development of multiple organ failure and death. These microcirculatory alterations occur even when systemic hemodynamic variables are within resuscitation goals. In this review, we discuss the link between the microcirculation and systemic hemodynamics. Several studies suggested that microvascular perfusion may be dependent from systemic hemodynamics in severely hypotensive patients. However, the threshold of blood pressure at which this occurs is not well defined and it is difficult to define which mean arterial pressure target should be reached. The microcirculation is usually independent of systemic hemodynamics in the usual range of systemic hemodynamic values encountered when resuscitation targets are met. Fluids and vasoactive agents affect the microcirculation independently of their systemic effects.