The Cardiovascular Effects of Positive End-Expiratory Pressure

Positive end-expiratory pressure (PEEP) is effective treatment for severe, refractory hypoxia, but cardiac output may be reduced which can result in a decrease in oxygen delivery. Evidence favors an impedance to systemic venous return as the major factor in decreasing cardiac output Right ventricular function appears to remain normal. Additional direct reduction of left ventricular function at high levels of PEEP is secondary to geometric changes that cause a decrease in compliance. Neural or humoral mechanisms may be operative, but to date have been incompletely characterized. Endocardial ischemia at high levels of PEEP may also be a cause of cardiac output depression.