Respiratory diseases in relation to changes in atmospheric pressure.

In this paper are reviewed the present status of respiratory diseases in relation to high and low altitude environments. H igh A ltitu d e Sickness I n t k o d u c t i o n Mountain sickness occurs in both an acute form and a chronic form. Only re­ cently has this been studied to any degree; however, the first description was by a Peruvian in 1897.8 In 1937, Hurtado de­ scribed a case of pulmonary edema in an Indian who became acutely ill after return­ ing home from sea level to the high alti­ tude.7 In 1945, a 39 year old man was examined who had developed pulmonary edema after going to a height of 11,550 feet. In 1949, a 29 year old man was described who died from an acute pulmonary illness in La Oroya, Peru, at an elevation of 12,250 feet. Lundberg, in 1952, described several cases of acute pulmonary edema. Mountain sickness or high altitude pulmonary edema occurs in individuals who quickly go from sea level to altitudes of 9,000 to 15,000 feet. Natives who have lived at high altitudes for a considerable time and then visit at sea level are most susceptible when they return to their mountain homes. Young children are also particularly susceptible under these circumstances. Most episodes in mountaineers occurred on their initial exposure to high altitude without proper acclimatization time. Men living at high altitudes have a higher total blood volume and a greater proportion of pulmonary blood volume than that present in sea level inhabitants. Persons going to high altitudes tend to develop greater blood volume in the pulmonary bed. Houston had reported mountaineers who have described cases of rapid death attributed to pneumonia. This occurred in healthy persons who were en­ gaged in strenuous exercise over 14,000 feet. Death in 12 to 24 hours resulted if the symptoms were severe and remained untreated. The period of acclimatization should be gradual in going to different altitudes and should last from 3 to 7 days. Persons who develop high altitude pulmonary edema have stayed at sea level any where from two days to two months. There seems to be an individual predisposition to high alti­ tude pulmonary edema.15 During acclima­ tization, undue physical exertion should be avoided for the first 48 hours. Mountain sickness can be divided into two types, the