[Effect of smoking on PaO2 at rest and during moderate exercise]

The most data on smoker's arterial oxygen tension (PaO2) were carried out at rest and from non arterial blood sample. The aim of this retrospective study was to compare smokers and nonsmoker's arterial oxygen tension (PaO2) at rest and during a moderate exercise. 98 male smokers between 23 and 69 years old and 98 male nonsmokers with the same age bracket were recruited among subjects submitted to arterial blood gas analysis according to the following protocol: 2 arterial blood samples were taken at rest, with an interval of 5 minutes, followed by a third one taken at the end of a moderate effort (50 watts during 5 minutes) on a bicycle in the supine position. Wilcoxon's test was used to compare the measured biological parameters between smokers and nonsmokers. Unlike nonsmokers, smoker's PaO2 increased meaning fully during moderate exercise. However, like at rest, it remained lower than nonsmoker's PaO2.: 87.6 +/- 15.8 mmHg Versus 94.1 +/- 10.4 mmHg (p < 0.0001). These beneficial effects of exercise on smoker's PaO2, although limited among heavy smokers group, suggested that hypoxia observed at rest must be due to troubles in ventilation/perfusion ratio in the lungs. In comparison to nonsmokers, the most significantly hypoxia was founded in smokers between 40 and 59 years old. The variation of PaO2 in nonsmokers was normal in comparison with age, but strongly disturbed in smokers at rest as well as during a moderate exercise, despite the lack of correlation between PaO2 and the intensity of tobacco consumption (expressed as number of pack-years). Thus, the smokers' PaO2 deterioration concerned together its value and its variation in comparison with age.