Pulseless electrical activity can be caused by a variety of pathophysiologic conditions. The sine qua non of this syndrome is the presence of an organized rhythm without the presence of a detectable pulse in an individual who is clinically in cardiac arrest. The latter is important to differentiate conditions in which the rescuer is unable to detect a pulse but there is unmistakable evidence that there is adequate blood pressure and cardiac output to maintain vital organ perfusion (e.g., a conscious patient with profound vasoconstriction due to hypothermia). There is evidence that PEA encompasses a spectrum of pathophysiologic effects ranging from good LV function with an empty ventrical or widely dilated arterial bed, to a stiff ventrical.
The underlying physiologic cause of PEA is a marked reduction in cardiac output that is due to either profound myocardial depression or mechanical factors that reduce venous return or impede the flow of blood through the cardiovascular system. Common conditions that can cause PEA are shown in TabJeZ-l. In one recent analysis, PEA was present initially during resuscitation in 22 percent of cardiac arrest cases. 19 Compared to other patients, individuals with PEA were more likely to be women whose cardiac arrest was unwitnessed, at night, and without bystander-initiated CPR. Only 2 percent of these patients survived to hospital discharge. The management of patients with PEA is directed at identifying and treating the underlying cause or causes.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.