Journal of Applied Physiology, Vol 38, Issue 1 33-38, Copyright © 1975 by American Physiological Society
Effect of positive-pressure breathing on aADN2 in hyaline membrane disease
A. J. Corbet, J. A. Ross, P. H. Beaudry and L. Stern
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.
