Journal of Applied Physiology, Vol 51, Issue 6 1507-1514, Copyright © 1981 by American Physiological Society
Intrapulmonary gas transport and perfusion during high-frequency oscillation
E. R. Schmid, T. J. Knopp and K. Rehder
The effects of high-frequency oscillation (HFO) on 1) regional pulmonary
133Xe clearance after equilibration, 2) regional distribution and
subsequent clearance of 133Xe after right atrial bolus injection, and 3)
pulmonary gas exchange were examined in anesthetized supine dogs. After
equilibration 133Xe cleared similarly from all lung regions with HFO at 16
and 30 Hz and a stroke volume of 2.6 ml/kg. Pulmonary gas exchange was
adequate. 133Xe, injected as a bolus into the right atrium, was
preferentially distributed to dependent lung regions during both HFO and
apnea, indicating vertical gradients in pulmonary perfusion. During the
subsequent pulmonary clearance of 133Xe, regional 133Xe concentrations
(CrXe) increased initially in nondependent regions. By contrast, CrXe
decreased immediately in the dependent lung region; after CrXe's became
similar in dependent and nondependent regions, all lung regions started to
clear at similar rates. The initial increases of CrXe in nondependent
regions were attributed to interregional mixing, which may contribute to
the uniformity in regional pulmonary 133Xe clearance after equilibration.
