title: [Effects of O2 inhalation on the partial arterial-alveolar pressure of CO2 in healthy patients and in patients suffering from chronic bronchitis (author's transl)].
abstract: The increase in arterial-alveolar CO2 difference (D[a-A]CO2) on 100% O2 breathing was studied in healthy subjects and in chronic bronchitic patients with or without hypoxemia. This increase in D(a-A)CO2 showing the enhancement of the dead-space effect (i.e. of the ventilation/perfusion ratio; VA/Q,), resulted from increase in PaCO2 or/and from decrease in PACO2 and was only found in hypoxic bronchitic subjects. In such subjects D(a-A)CO2 increased by about 50%. This phenomenon seems to arise from the vasomotor effect of pure O2 on pulmonary circulation and the role played by the Haldane effect in increasing PaCO2 and thus D(a-A)CO2 in some subjects is very weak. In subjects where inhalation of pure O2 produced the greatest increase in D(a-A)CO2 and in VA/Q, the calculated value of the venous admixture (QSh/QT) after measurement of D(A-a)O2 at the 30th min of hyperoxia was overestimated. Indeed D(A-a) O2 was enlarged by increasing the dead-space effect under 100% O2 breathing.
mesh_terms: D001991:Bronchitis / Q000628:therapy*; D002245:Carbon Dioxide / Q000097:blood*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D010313:Partial Pressure; D011650:Pulmonary Alveoli / Q000098:blood supply / Q000503:physiopathology*; D012119:Respiration; D014666:Vasomotor System / Q000503:physiopathology; D014692:Ventilation-Perfusion Ratio
chemical_list: D002245:Carbon Dioxide
vernacular_title: Effets de l'inhalation d'O2 pur sur la différence artério-alvéolaire de pression partielle de CO2 chez le sujet normal et le bronchiteux chronique.