The most appropriate adjunctive treatment is nifedipine. This patient is exhibiting signs of high-altitude pulmonary edema (HAPE). The mechanism of HAPE is believed to be a noncardiogenic exaggerated hypoxic vasoconstriction of the pulmonary vasculature. HAPE usually occurs at altitudes in excess of 2500 meters (8200 feet). Typical symptoms consist of cough, dyspnea, and exertional intolerance; symptoms are usually insidious in onset but may occasionally occur abruptly and awaken a patient from sleep. Other features, such as headache, fatigue, nausea, vomiting, and disturbed sleep, may or may not be present. Dyspnea at rest is a key feature of HAPE. On physical examination, tachypnea and tachycardia are typical, and crackles or wheezing can be auscultated. Pink frothy sputum or frank hemoptysis may occur, followed by worsening gas exchange and possibly respiratory failure. Treatment is with supplemental oxygen and rest, both of which will acutely reduce pulmonary artery pressures. Descent from altitude should be considered, particularly if oxygen is not available. Adjunctive therapies include vasodilators such as nifedipine or phosphodiesterase-5 inhibitors (sildenafil or tadalafil). Nifedipine may act by relaxing vascular smooth muscle and can be used as a treatment as well as a preventive agent in patients who have previously experienced HAPE.
Acetazolamide is the preferred drug for preventing acute mountain sickness and high-altitude cerebral edema, but it is not useful in preventing HAPE.
Dexamethasone is the preferred drug (in addition to supplemental oxygen) for the treatment of severe acute mountain sickness and high-altitude cerebral edema. It is not effective in the treatment of HAPE.
Ibuprofen is a reasonable first choice for symptoms of mild acute mountain sickness such as headache and nausea; however, it is not useful in treating HAPE.