Smoking and blood oxygen tension in healthy middle-aged males

The blood oxygen tension (PaO2) was measured using a Clark-type microelectrode on 'arterialised' capillary blood samples obtained from 74 sitting subjects; these were asymptomatic and spirographically normal men aged 42-63 (average 53.7) years. The mean PaO2 of smokers (83.8+/-6.0 mm Hg) was slightly, non-significantly lower as compared to non-smokers (85.5+/-4.9 mm Hg). The trend towards lower mean values with increase in current cigarette consumption or amount smoked in life did not result in significant differences between smoker sub-groups. The lower normal limit for the whole group was 73.3 and the average PaO2 85.3 mm Hg. Though no significant influence of tobacco use could be demonstrated, the histogram of specific subjects shows a bi-modal distribution in smokers, suggesting the existence of a sub-group (about one third of the smokers) who tend to have lower PaO2s, possibly as a consequence of sub-clinical 'small airway disease'.