Journal of Applied Physiology, Vol 58, Issue 2 645-652, Copyright © 1985 by American Physiological Society
Radiographic visualization of airway wall movement during oscillatory flow in dogs
N. Gavriely, J. Solway, J. M. Drazen, A. S. Slutsky, R. Brown, S. H. Loring and R. H. Ingram Jr
It has been suggested that radial movement of the central airway walls
during oscillatory flow might contribute to the increased frequency
dependence of compliance seen in chronic obstructive pulmonary disease
(COPD) (J. Appl. Physiol. 26: 670-677, 1969). Radial airway wall motion has
also been invoked to explain the frequency-dependent decreases in the
efficiency of gas exchange during low-volume high-frequency ventilation
(HFV) in histamine-bronchoconstricted dogs and in patients with respiratory
insufficiency. To test the possibility that airway wall motion increases
with bronchoconstriction, we measured central airway diameters using
cinebronchoradiography in anesthetized tracheostomized dogs during
oscillatory HFV [50 and 100 ml tidal volume (VT) at frequencies (f) of 2,
6, and 12 Hz], under control conditions, during electrical stimulation of
the vagi, and after exposure to histamine aerosol. Cineradiobronchograms
from two dogs were evaluated quantitatively for tracheal diameter and for
lengths and diameters of a number of major airways. Under control
conditions, the diameter of the airways fluctuated 7-9% of the mean with VT
of 50 ml and 9-18% with VT of 100 ml in the range of frequencies studied.
Bronchoconstriction produced by aerosolized histamine increased radial
airway wall movement to 10-47% with VT of 50 ml, and during vagal
stimulation diameters changed 7-20% at VT of 50 ml. After histamine, the
central airways displayed large diameter changes during HFV, whereas more
peripheral airways were markedly constricted and did not change in
diameter.(ABSTRACT TRUNCATED AT 250 WORDS)
