FURTHER STUDIES OF HIGH ALTITUDE PULMONARY OEDEMA

Abstract

Six patients with acute high-altitude pulmonary edema are described: they were 5 children and one adult, residents of the Peruvian Andes. All were acclimatized to a 12,250 ft. elevation but developed pulmonary edema upon return from a stay at sea level varying from 2 days to 3 months. Clinical symptoms appeared from 9 to 36 hours after arrival and consisted of dyspnea, cough, nausea, vomiting, chest discomfort, and hemoptysis. Physical findings included cyanosis, tachycardia, hypotension, pulmonary rales, but no evidence of heart failure or pneumonia. Roentgenograms revealed pulmonary vascular congestion and patchy pulmonary densities. Cardiac enlargement or a consistent decrease in heart size with recovery was not seen. Electrocardiograms which were suggestive of acute right heart strain at the time of entry became normal upon recovery. Bed rest and oxygen administration resulted in prompt, complete recovery with clearing of the roentgenological signs in 24-72 hours. Two fatal instances of probable acute high altitude pulmonary edema occurring at elevations of 9,400 and 14,000 ft. are described with a report of the autopsy findings. One patient demonstrated, in addition to severe confluent pulmonary edema, a diffuse pneumonitis and thrombi in small pulmonary arteries and capillaries. The histological findings suggested the possibility of a viral pneumonitis facilitating the occurrence of the pulmonary edema. The mechanism of acute high altitude pulmonary edema is unknown. In the majority of cases there is no evidence of an underlying pneumonia. Mountaineers, previously acclimatized residents of high-altitude areas, especially children, returning to the altitude after a short stay at sea level, and subjects who have experienced previous attacks should be aware of the possibility of acute high-altitude pulmonary edema whenever a rapid ascent is made to an altitude in excess of 9,000 ft. Gradual acclimatization should prevent most attacks. Treatment should consist of prompt removal to a lower elevation, absolute bed rest, and oxygen administration.