Extracorporeal membrane oxygenation (ECMO) has been widely used in patients with severe acute respiratory distress syndrome (ARDS). But how to choose mechanical ventilation strategy is still not clear for severe ARDS patients supported by ECMO. Our previous work found that, compared to the traditional "lung rest" strategy, transpulmonary pressure guide new lung ventilation strategy can better maintain lung volume reduction lung collapse, atelectasis occurs. The severe ARDS patients receiving ECMO therapy were randomized divided into a new ventilation strategy group and the conventional ventilation strategy group. The new ventilation strategy is transpulmonary pressure guide ventilator setting method, and the conventional ventilation strategy is Extracorporeal Life Support Organization (ELSO) guide ventilation method. Compare the difference between the two groups of patients in lung injury, and explore the lung protection mechanism of new lung ventilation strategies guided by transpulmonary pressure. Our research group considered that transpulmonary pressure guide new lung ventilation strategy can provide more effective lung protection. And it will be further used in clinical work.

Inclusion Criteria:

• ARDS cause reversible;
• Pure oxygen is given, but PaO2/FiO2<80;
• P(A-a)O2>600mmHg;
• Murray score≥3.0;
• pH<7.2;

Exclusion Criteria:

• peak inspiratory pressure>30cmH2O;
• high FiO2>0.8;
• ventilation>7 days;
• contraindication to heparinization;
• non-reversible central nervous system injury
• chronic disease with a short life expectancy