Pathophysiology of shock-induced disturbances in tissue homeostasis

A survey is given on disturbances in tissue homeostasis induced by hypovolemic shock conditions. Fluid shifts taking place between the extra- and intravascular fluid compartments are important early compensatory responses following hypovolemia. Usually the supply-to-demand ratio of oxygen in most tissues can however, not be kept up if the hypovolemic insult is severe due to deterioration of the microcirculation. Cellular hypoxia will ensue and may with time affect the integrity of the cells. Cellular functional disturbances occur earlier and are more pronounced in peripheral non-vital tissues such as e.g. skeletal muscle than in central organs, the blood flow of which is more favoured during shock. Anaerobically produced cellular metabolites as well as intracellular components released from hypoxically injured cells in peripheral tissues may be of importance for the initiation of decompensatory reactions. Cellular components reaching the central circulation may induce direct effects on organs or systemic effects due to activation of the cascade systems. Thereby reactions leading to severe complications such as adult respiratory distress syndrome (ARDS), disseminated intravascular coagulation (DIC) and multiple organ failure may be started. The aim of shock treatment should be to reverse as rapidly and as efficiently as possible the pathophysiological disturbances induced by a shock state. If the cellular hypoxic insult can be limited then the incidence of systemic complications in the post-shock period will also be reduced.