Pharmacologic management of circulatory shock: cardiovascular drugs and corticosteroids

Effective use of cardiovascular drugs in the management of circulatory shock requires knowledge of the pathophysiologic changes occurring in the different types and stages of shock and an understanding of the specific hemodynamic actions of drugs used to correct shock. Objectives of therapy are to: (1) restore circulating blood volume, (2) ensure of increase perfusion of critical organs by selectively reducing arteriolar resistance, (3) augment cardiac output, and (4) increase perfusion pressure. If blood volume is not restored, drugs may be ineffective and can even induce deleterious effects. If reflex sympathetic discharge has induced generalized vasoconstriction, it is irrational to expect beneficial results from administration of exogenous vasconstrictor agents. Instead, selective vasodilatation of vascular beds in critical tissues (eg, myocardium, intestines, and kidneys) accompanied by increased perfusion pressure and cardiac output can prove useful. Large doses of adrenocorticosteroids are used commonly in the therapy of different shock conditions, based primary on empiric tests of efficacy. Although such steroids may not influence the course of shock by direct cardiovascular effects, beneficial actions may result from mechanisms such as protection of cell membrane integrity and stabilization of lysosomes.