Journal of Applied Physiology, Vol 39, Issue 6 1004-1007, Copyright © 1975 by American Physiological Society
Chest wall distortion and regional lung volume distribution in erect humans
A. E. Grassino and N. R. Anthonisen
Using 133Xe measured the regional distribution of FRC and of boluses
administered at FRC in seated subjects during relaxation, lateral
compression of the lower rib cage, and contraction of the inspiratory
muscles so that mouth pressure was 50 cmH2O subatmospheric. Lateral
compression increased apex-to-base differences of volume and bolus
distribution, suggesting an increase of the apex-to-base gradient of
pleural surface pressure. Changes in rib cage shape were measured with
magnetometers and were qualitatively similar to those associated with
increases in apex-to-base difference of pleural surface pressure in
animals. Inspiratory effort decreased apex-to-base difference in volume and
induced a similar trend in bolus distribution. Though changes in the rib
cage shape were directionally similar, they were much smaller than those
associated with decreased pleural surface pressure gradients in animals,
and the changes in regional volume we observed were more likely due to
forces generated by diaphragmatic contraction. These results were
compatible with the apex-to-base gradient of pleural pressure being
strongly influenced by shape adaptation between lung and chest wall.
