Journal of Applied Physiology, Vol 47, Issue 6 1143-1147, Copyright © 1979 by American Physiological Society
Volume shifts with partial submersion of isolated lung lobes
G. T. Ford, D. Gillett and N. R. Anthonisen
When an isolated lung lobe is partially submerged, volume moves from the
submerged part to the unsubmerged part. We partially submerged isolated dog
lobes of known weight and volume, and measured airway pressure and, by
water displacement, the volume of the submerged part. The lobe was then
air-dried and sectioned at the waterline and each part weighed. Multiplying
lobar volume by the fractional weight of the submerged part yielded the
volume of the submerged part before immersion, and therefore the volume
shift to the unsubmerged part due to immersion. Dividing this volume shift
by the immersion-induced change in airway pressure gave the compliance
(Cr') of the unsubmerged part. Cr' was compared to Cr, the compliance of
the unsubmerged part when it was inflated with air. Cr/Cr' was linearly
related to the degree of immersion: as immersion increased Cr/Cr' fell; so
when lobes were 80% immersed Cr/Cr' was 0.3--0.5, indicating that
compressing the lower part of the lung made the upper easier to expand.
This behavior could be explained if with immersion lung units moved from
the submerged part to the unsubmerged part and this shift increased with
the degree of immersion. We demonstrated that when one part of a lobe was
compressed lung units moved away from the compressive force and that this
movement could occur without similar movement of the pleural surace. Tissue
movement probably accounted at least in part for our results.
