Influence of ventilation and transfer of gases on blood gases in pulmonary insufficiency.

Abstract

In 249 patients with primary pulmonary insufficiency, the effect of ventilation and transfer of gases on the blood gases and pH was studied. For this purpose, the presence of restrictive or obstructive disease, and/or diffusion defect was determined by spirometry and diffusion capacity study with end tidal determination of the carbon monoxide.The blood gases and pH were studied at rest and during exercise; according to the resting arterial gases tensions, three groups were made:I. One hundred seven patients had normal blood gases and pH (the mean PaO2 was 92 mm Hg, the mean PaCO2 was 39 and the mean pH was 7.43).II. Slight hypoxemia was present in one hundred twenty five patients (the meanPaO2 was 75 mm Hg, the mean PaCO2 was 43 mm Hg, and the mean pH was 7.43).HI. Seventeen patients with moderate hypoxemia and hypercarbia (mean PaO2 in mm Hg was 59, mean PaCO2 in mm Hg was 52. This was chronic because the pH was normal 7.41).The vital capacity and FEV1 and DLCOSS2 were significantly different in each of the three groups. Thus it can be concluded that restrictive and/or obstructive disease associated or not to altered transfer of gases are determining factors in the production of hypoxemia and hypercarbia, even though exceptions to this general finding were encountered.