Further evidence favoring a cardiac mechanism in irreversible hemorrhagic shock

Abstract

Cardiac output curves of normal dogs and dogs in various stages of hemorrhagic shock were determined with devices for continuous recording of cardiac output and atrial pressures to feed an X-Y recorder. Normal cardiac output curves were recorded during the early stages of shock but, after the animal had developed irreversible shock, a cardiac output curve indicative of cardiac failure was always recorded. As the irreversible shock progressed, successive cardiac output curves indicated progressive failure of the heart. A special feature of these experiments was that by increasing or decreasing the blood volume the cardiac output could be held constant. When the cardiac output was held constant, both the right and left atrial pressures slowly rose to extremely high values as shock progressed, and after a time the heart was unable to maintain normal output at even extremely high atrial pressures. The evidence is entirely consistent with the idea that the irreversible stage in hemorrhagic shock is caused by rapid progressive cardiac failure.