Treatment of right ventricular dysfunction in acute respiratory failure.

The pathophysiology and managements of right ventricular (RV) dysfunction in acute respiratory failure (ARF) is complicated. Results presented in this paper indicate that volume expansion may not be appropriate therapy to maintain or increase cardiac output (CO) when flow is reduced because of increased RV afterload. Volume will increase RV wall stress and O2 requirements so that despite increased preload, CO may fall. If RV afterload is significantly increased, such changes can occur despite a relatively normal RV end-diastolic pressure (RVEDP). Further, increased RV afterload and/or volume expansion can result in increased RV volumes and secondary alteration in left ventricular (LV) diastolic mechanics. Such changes, especially if wedge pressure increases, would tend to increase pulmonary edema. Also, because of potential changes in viscosity and pulmonary vascular resistance (PVR), packed red blood cells may not be indicated to increase CO, arterial O2 content and tissue O2 delivery in the setting of ARF. Therapy designed to reduce PVR may be appropriate to increase flow in the setting of increased RV afterload. However, such therapy may also reduce systemic vascular resistance, blood pressure (BP) and RV perfusion pressure. Such changes could lead to RV ischemia and reduced CO. Alternatively, agents which increased RV perfusion and/or contractility will increase CO by reducing RV end-diastolic and end-systolic volumes and may be the treatment of choice to increase flow when RV afterload is elevated.