Inhaled Nitric Oxide for High Amplitude Pulmonary Edema (HAPE)

Inclusion Criteria: 1. Individuals aged between 18 and 65 years. 2. A score on the Lake Louise Acute Mountain Sickness Scale ranging from 3 to 9 points, as outlined in Annex 2, recorded in 2018. 3. Chest X-ray findings that demonstrate either thickening of the lung texture bilaterally or the presence of nodular opacities in the lower regions of both lungs. 4. Capacity to provide informed consent in accordance with local regulatory requirements. Exclusion Criteria: 1. Confirmed contraindications for the use of nitric oxide include the following (refer to "5.3.4 NO Contraindications"): * Severe hypoplasia of the left heart or duct-dependent congenital heart disease; * Life-threatening congenital anomalies and congestive heart failure; * Congenital methemoglobinemia; * Severe hemorrhagic conditions, including intracranial hemorrhage, intraventricular hemorrhage, and pulmonary hemorrhage. 2. Severe left ventricular dysfunction, characterized by a left ventricular ejection fraction (LVEF) of less than 40%. 3. Pulmonary edema resulting from other cardiac, pulmonary, thoracic, or systemic disorders. 4. Coexistence with high altitude cerebral edema. 5. A history of lung malignancy, lung resection, or lung transplantation. 6. Barotrauma, which may include pneumothorax, subcutaneous and mediastinal emphysema, or the presence of a closed drainage tube in the thoracic cavity. 7. Clinically significant or persistent thrombocytopenia, defined as a platelet count of less than 50×10\^9/L. 8. Administration of pulmonary hypertension medications, such as sildenafil, bosentan, or prostacyclins, within the preceding 30 days. 9. Noncompliance with study protocols and unwillingness to provide informed consent. 10. Any other conditions that the clinician deems render the subject unsuitable for participation in the study.