Effect of positive-pressure breathing on aADN2 in hyaline membrane disease.
In seven subjects with hyaline membrane disease and breathing 40-70% oxygen in nitrogen, the effect of continuous positive-pressure breathing (CPPB) was examined by application of a continuous negative pressure (10 cm water) about the thorax and assessment of the alveolar-arterial tension differences for nitrogen (aADn2) and oxygen (AaDo2). On CPPB, there was a decrease in the aADn2 by a mean 9 mmHg and a decrease in the AaDo2 by a mean 44 mmHg. This corresponded to a decrease in the total venous admixture (Qva/Qt) of 0.20 and to a decrease in the venous admixture due to a true right-to-left shunt (Qs/Qt) of 0.19. These data were interpreted to mean a significant improvement in Va/Qc imbalance within open ventilated parts of the lung, which could be responsible, particularly by relief of local alveolar hypoxia, for reduction of the pulmonary vascular resistance and the true right-to-left shunt.
D002245:Carbon Dioxide; D006801:Humans; D006819:Hyaline Membrane Disease / Q000503:physiopathology / Q000628:therapy*; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D009584:Nitrogen; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011048:Polarography; D011175:Positive-Pressure Respiration; D011650:Pulmonary Alveoli; D011652:Pulmonary Circulation; D014692:Ventilation-Perfusion Ratio
D002245:Carbon Dioxide; D009584:Nitrogen; D010100:Oxygen