الفهرس 
Pathophysiology and Types of ShockOnly 14 pages are availabe for public view
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Abstract
Shock is a state of inadequate perfusion where oxygen delivery to the tissues fails to meet oxygen demands. A shock state might emerge from a reduction in oxygen tissue delivery (VO2), or from an increase in oxygen demands (DO2). The four types of shock included are (A) hypovolemic, (B) cardiogenic, (C) obstructive, (D) distributive. Cardiogenic shock is a physiologic state in which inadequate tissue perfusion result from cardiac dysfunction, occuring most commonly following acute myocardial infarction. So initiation of inotropic and/or vasopressor drug therapy may be necessary. Manifestations of shock include signs of peripheral hypoperfusion such as oliguria, systemic hypotension and decreased CO with elevated PAOP although physical examination reveals findings of volume overload, including pulmonary and peripheral edema, and hepatomegaly.
Management of the shocked patient includes oxygen therapy, mechanical ventilation, fluid therapy and inotropic support. Conventional inotropic agents seem to be useful in restoring hemodynamic parameters and improving peripheral organ perfusion but can increase short and long-term morbidity and mortality in these patients. The basis of the acute inotropic response to an increased adrenergic drive is the rapid increase in the tissue levels of the second messenger, cyclic AMP. Inotropic agents inculde dopamine, dobutamine, epinephrine, norepinephrine, isoprenline, ephedrine, phenylephrine, vasopressin, milrinone, levosimendan.
Epinephrine is a mainstay of resuscitation therapy during cardiopulmonary arrest. Also, it is the drug of choice for anaphylaxis as it decreases mediator release from mast cells. Acute cardiovascular dysfunction is anticipated in 20% or more patients in the perioperative period of cardiac surgery. The proposed pharmacological treatment included low-to-moderate doses of dobutamine and epinephrine, milrinone, or levosimendan. Catecholamines are associated with a great incidence of tachyarrhythmia. Vasopressor administration is required in cases of septic shock for persistent hypotension once adequate intravascular volume expansion has been achieved. Steroid therapy should be considered where the blood pressure is poorly responsive to intravenous fluids and vasopressor therapy. After nearly 50 years of clinical development, durable mechanical circulatory support devices are widely available for patients with advanced heart failure. The field of circulatory support has matured dramatically in recent years. It was designed as a temporary support to allow ventricular recovery or as a bridge for patients to cardiac transplantation, these devices are now being used as a permanent form of “destination” therapy.