Right ventricular performance in adult respiratory distress syndrome

In adult respiratory distress syndrome (ARDS), the pulmonary artery hypertension is followed by increases in right ventricular diastolic and systolic volumes and a decreased ejection fraction. The stroke volume is preserved by the Frank-Starling mechanism as preload increases, even in the presence of severe pulmonary artery hypertension. In contrast, if there coexists a depression of the right ventricle contractility, as during right ventricular contusion, septic shock or a viral myocarditis, the compensatory Frank-Starling mechanism, that maintains right ventricular pump function, seems limited. Thus, it appears that the contractile state of the right ventricle can influence the clinical course of ARDS. In addition, patients with ARDS require mechanical ventilation with positive end-expiratory pressure (PEEP), which has a detrimental effect on right ventricular loading conditions. Most investigators agree that the most important effect is a decreased right ventricular preload, secondary to the increased pleural pressure due to PEEP. However, in patients with severe pulmonary artery hypertension, the PEEP-induced increase in right ventricular afterload may become more preponderant, and inotropic support to maintain right ventricular stroke volume may be necessary.