ARDS is an exudative change in the lungs, there can be no coughing, coughing and other common respiratory disease manifestations, common symptoms are as follows: 1, dyspnea, respiratory distress: is the main manifestation; 2, difficult to correct hypoxemia: refers to according to conventional oxygen therapy, such as nasal catheter, mask oxygen, hypoxemia is difficult to correct; 3, low oxygen saturation: normal human oxygen saturation is 95%-98%, depending on age Different, the value may be slightly different, ARDS patients oxygen saturation is below 90%, even below 85%; 4, low partial pressure of oxygen: blood gas examination suggests that partial pressure of oxygen is below 60mmHg for respiratory failure, ARDS patients partial pressure of oxygen can be as low as 20mmHg.