Journal of Applied Physiology, Vol 45, Issue 3 437-441, Copyright © 1978 by American Physiological Society
Pressure outside the extrapulmonary airway in dogs
S. G. Spiro, B. H. Culver and J. Butler
We have measured the static and dynamic transmural pressures of
extrapulmonary airways during positive pressure lung inflation in
anesthetized dogs suspended in the standing position. Thin, fluid-filled
catheters measured pressures within and on the anterior surface of the
airways in the mediastinum and neck. The change from mediastinal to
cervical static extra-airway pressures (Pea) was not abrupt but occurred
through the thoracic outlet and the root of the neck. The static Pea in the
mediastinum was more positive than pleural pressure when lung volume was
increased with positive pressures. During forced deflation equal pressure
points (EPP) were in labor bronchi from which airway narrowing extended
towards the mouth. Under these conditions, the dynamic mediastinal Pea
mouthward of the EPP remained close to pleural pressures even at high
volumes. This suggested that forces of restitution generated in the
surrounding tissues by the narrowing of the airways did have a small effect
in reducing the pressure affecting their anterior surface.
