Oxygen inhalation can decrease the pulmonary artery pressure. Evidence shows that inhalation of 100% oxygen can significantly decrease the increased pulmonary artery pressure and is accompanied by improvements in symptoms [13] . In addition, oxygen inhalation can increase arterial oxygen saturation and improve tissue oxygen supply, thus alleviating hypoxia. For patients with severe HAPE, hyperbaric oxygen is preferred. Some researchers [14, 15] have proposed mechanical ventilation for patients with respiratory distress. Hyperbaric oxygen treatment not only increases the oxygen concentration and subsequently the alveolar and arterial partial pressure of oxygen, but also increases pulmonary ventilation and alveolar pressure, which inhibit fluid exudation. Oxygen inhalation can also rectify respiratory alkalosis, which prevents the transportation of peripheral blood to the lung.