Adverse cardiovascular effects of PEEP can include progressive reductions in cardiac output as mean airway pressure and, secondarily, mean intrathoracic pressure rise. The principal mechanism appears to be a progressive decrease in venous return to the heart. Other mechanisms may include leftward displacement of the interventricular septum (interfering with left ventricular filling) because of the increase in pulmonary vascular resistance (increased right ventricular afterload) from overdistention of alveoli, leading to an increase in right ventricular volume. Left ventricular compliance may therefore be reduced; when this occurs, the same preload requires a higher filling pressure. Intravenous fluid administration usually at least partially offsets the effects of CPAP and PEEP on cardiac output. Circulatory depression is most often associated with end-expiratory pressures greater than 15 cm H2O.
PEEP: Cardiovascular Effects
- RV Preload: reduced (decreased venous return)
- RV Afterload: increased (due to overinflation of alveoli)
- LV Compliance: reduced by shifting IVS (secondary to increased RV afterload)
- Thomas Luecke, Paolo Pelosi Clinical review: Positive end-expiratory pressure and cardiac output. Crit Care: 2005, 9(6);607-21