Journal of Applied Physiology, Vol 52, Issue 1 173-183, Copyright © 1982 by American Physiological Society
Lobe weight gain and vascular, alveolar, and peribronchial interstitial fluid pressures
W. Hida, H. Inoue and J. Hildebrandt
Interstitial fluid movements in acute pulmonary edema were studied by
recording interstitial fluid pressure [Px (f)] relative to pleural pressure
(atmospheric), together with lobe weight gain or loss (delta W). Px (f) was
measured by wicks inserted between lobar bronchus and artery while alveolar
pressure (PA) was fixed at either 5 or 20 cmH2O. When vascular pressure
(Pvas) was raised abruptly from -5 to +25 cmH2O by air inflation for 60
min, Px (f) became abruptly less negative, then remained stable. However,
during vascular inflation with plasma, delta W began a steady increase, but
plotted against delta W, Px(f) became less negative in several phases.
After an immediate rise due to interdependence effects following vascular
distension, Px (f) remained almost unchanged for 4-7 min as delta W
increased 15-80% of initial lobe weight (Wi), representing a transport lag
between leakage and measuring sites and suggesting that interstitial edema
was not homogeneous. Next, Px (f) increased progressively as weight
increased a further 70-200% of Wi and finally slowed its rise near zero
pressure. When Pvas was lowered, Px (f) became abruptly more negative,
again by interdependence; however, as delta W then decreased 20-50% of Wi
over 30 min, Px (f) did not change consistently. It was possible to relate
the rate of weight gain occurring between 2 and 5 min after Pvas was raised
to two pressure gradients, Pvas - Px (f) and Pvas - PA, and to relate the
time lag to filtration rate and Pvas - Px (f).
