Shock.

Shock is a syndrome in which an acute deficiency of vital tissue perfusion due to hemodynamic dysfunction leads to progressive metabolic and functional deterioration that, if not reversed, will lead to death. The common feature of shock is that cardiac output is inadequate to perfuse all the organs with sufficient blood to maintain tissue integrity. This inadequacy of perfusion is usually but not always accompanied by hypotension and intense regional vasoconstriction. The perfusion deficit may result in a cascade of further complications, such as the release of vasodilator factors that increase capillary permeability and may further lower blood pressure, leading ultimately to cardiac dysrhythmias and death. Shock can result from both cardiovascular and noncardiovascular illnesses (Table 87.1). Cardiac causes are the focus of concern for the cardiologist, and it is critical to exclude noncardiac causes before launching into aggressive cardiovascular therapy. [ABSTRACT FROM AUTHOR]