Ventilation-perfusion inequality.
D000368:Aged; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood*; D011656:Pulmonary Emphysema / Q000503:physiopathology; D011660:Pulmonary Heart Disease / Q000503:physiopathology; D012131:Respiratory Insufficiency / Q000209:etiology*
D002245:Carbon Dioxide; D010100:Oxygen