Most discussions regarding mechanical ventilation focus on oxygenation and carbon dioxide clearance. However, positive pressure ventilation exerts profound effects on cardiovascular physiology, particularly on the right ventricle.
The right ventricle is uniquely vulnerable in critical illness. Unlike the left ventricle, which is designed to pump against high systemic pressures, the right ventricle functions within a low-pressure pulmonary circulation.
Small increases in afterload can produce dramatic reductions in RV performance. Mechanical ventilation can worsen RV function through several mechanisms.
The first is increased intrathoracic pressure. Positive pressure ventilation reduces venous return and decreases RV preload. More importantly, positive pressure ventilation influences pulmonary vascular resistance.