[Respiration of patients with chronic lung disease at 500 and 1500 meter above sea level]

There is plentiful literature on respiration at high altitude (3000-8000 m above sea level) and its cardiopulmonary sequelae. But little is known about changes in ventilation and in pulmonary gas exchange at altitudes of 1,000-2,000 m above sea level. We studied 68 patients 500 and 1,500 m above sea level. On the arrival of the patients at 534 m above sea level we measured the arterial blood gases, pulse rate, respiratory rate and a breathing score. The same measurements were repeated on arrival at 1,500 m above sea level. A lung function test (FEV1, FVC, PEF, MEF 25-75) was also performed. The patients were divided into three groups: asthmatics, chronic bronchitics and restrictive patients. A control group was formed of patients without lung disease. Within all groups, the pO2 and the pCO2 diminishes significantly, no significant difference between the groups was found. In patients with lung disease oxygen saturation changes from 94.1% to 91.8% (COPD) and from 95.3% to 93.4% (restrictive patients). Age, smoking habits, lung function test and blood gases at 534 m are not predictors of the blood gases at altitude in COPD patients. But patients with restrictive lung disease show a positive correlation between age and change in pO2, as well as between severity of the restrictive disease and the change in oxygen saturation. The change of pO2 in COPD patients is not relevant clinically, as there is only minimal change in oxygen saturation. We conclude that patients of all degrees of COPD and patients with light to moderate restrictive lung disease can safely tolerate a difference in altitude from 534 to 1,500 m.