Journal of Applied Physiology, Vol 56, Issue 4 948-953, Copyright © 1984 by American Physiological Society
Pressure-volume curve of lung and lobes in kittens
J. P. Mortola, A. Rossi and L. Zocchi
In the neonatal period, the incomplete aeration of the lung parenchyma and
the presence of some pulmonary fluid could determine inequalities in the
mechanical behavior of lung regions, favoring unevenness of ventilation
distribution. We studied the pressure-volume (PV) curve of excised lungs of
kittens in the 1st wk of life 1) by changing the volume a known amount and
measuring the corresponding changes in transpulmonary pressure (PL) and 2)
by ventilating them at a fixed PL at a rate of 20 cycles/min. An expiratory
load equal to the value of PL at the resting volume of the respiratory
system was added to avoid the collapse of the lung. A lobar bronchus was
then tied, and the measurements were repeated. The difference in PV curves
before and after ligature therefore represented the PV curve of the lobe.
This was done for all the lobes (upper and middle right, lower right, lower
left, upper left) in a random order. A total of 20 lungs and 61 lobes have
been studied. Individual lobes were not different in terms of dry-to-wet
weight ratio, compliance per unit weight, or per maximal volume and shape
of the PV curve, indicating a similar mechanical behavior. Dynamic lung
compliance averaged 76% +/- 15 SD of the static value, suggesting some
degree of asynchronous behavior of lung regions or viscoelastic properties
of the tissue.
