title: Pulmonary gas exchange in asymptomatic smokers and nonsmokers.
abstract: Pulmonary gas exchange has been studied in 14 healthy smokers and 16 healthy nonsmokers (mean age: 36 years) breathing hypoxic, normoxic and hyperoxic gas mixtures, in a sitting position, at rest and on exercise. Alveolar-arterial oxygen tension difference is increased in smokers in hypoxia, at rest and on exercise, and the pulmonary diffusing capacity for oxygen is decreased. In normoxia the alveolar-arterial oxygen tension difference is increased on exercise. There is no difference between the two groups in hyperoxia. For the whole group there exists a negative relationship between (A-a)DO2 in normoxia and the diffusion indices measured on exercise. Arterio-alveolar carbon dioxide tension difference and the ratio physiological dead space/tidal volume are almost identical in both groups in any condition. A diffusion defect seems to be the more constant alteration of gas exchange in asymptomatic smokers.
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D005082:Physical Exertion; D011653:Pulmonary Diffusing Capacity; D012119:Respiration; D012126:Respiratory Dead Space; D012146:Rest; D012907:Smoking / Q000503:physiopathology*; D013990:Tidal Volume
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen