Lung protective ventilation strategy in acute respiratory distress syndrome (ARDS) has been widely accepted, however, the mortality of ARDS has not been significantly decreased, which supposed to be related to circulatory failure in ARDS patients. Mechanical ventilation in ARDS patients will elevate intra-thoracic pressure, which will decrease venous return and increase pulmonary vascular resistance. Meanwhile, the pathophysiology of ARDS itself will induce pulmonary arterial hypertension. Inappropriate settings of mechanical ventilation may also cause over-stretch of alveoli and increased afterload of right heart, leading to right heart dysfunction or acute cor pulmonale. When practicing lung protective ventilation strategy in ARDS patients, we need to monitor right heart function to modify mechanical ventilation, so as to prevent acute cor pulmonale.