[Microcirculation of intensive care patients. From the physiology to the bedside]

The microcirculation is unique in its anatomy and physiology and is a self-contained organ system within the human body. It is the site where gas exchange and nutrient supply takes place, but it is also the site which experiences pathological alterations during various shock states and therefore compromises the oxygen supply to tissues and organs. Systemic inflammation for example leads amongst others to increased heterogeneous blood flow, formation of interstitial edema, altered viscosity, leukocyte activation, disturbances in the coagulation system, and to a breakdown of the endothelial barrier function. These alterations inevitably lead to limitations of the oxygen supply to tissues. Without interruption of these pathomechanisms, the dysfunction of the microcirculation will consequently result in organ dysfunction. In this review article a short description of the microcirculatory physiology, the interaction between the macrocirculation and the microcirculation, as well as microcirculatory alterations generated by a systemic inflammatory response will be given. Finally, various therapy options will be described, which, experimentally, can lead to an improvement in microcirculatory dysfunction.