Journal of Applied Physiology, Vol 40, Issue 6 883-888, Copyright © 1976 by American Physiological Society
Phasic reflux of pulmonary blood flow in atelectasis: influence of systemic PO2
J. C. Newell, M. G. Levitzky, J. A. Krasney and R. E. Dutton
In 16 dogs ventilated with 100% O2, control blood flow to the left lung was
35 +/- 2% of aortic flow. When left lung atelectasis was induced, left
pulmonary artery flow fell to 19 +/- 2% of aortic flow. A large retrograde
component of flow developed in this pulmonary artery, suggesting that blood
flows into the pulmonary arteries of both lungs during systole, but flows
back out of the collapsed lung and into the uncollapsed lung during
diastole. Systemic PaO2 remained above 78 mmHg. Subsequently, when the
ventilation of the right lung was changed from oxygen to room air, systemic
PaO2 fell to 64 +/- 3 mmHg and atelectatic left lung flow rose from 19 +/-
2% to 28 +/- 2% f aortic flow. This was associated with a reduction in
reflux from the atelectatic lung. These results suggest that the
attenuation of flow to an atelectatic lung is more pronounced if systemic
normoxemia is maintained by adequate oxygenation of the normal lung.
