Journal of Applied Physiology, Vol 55, Issue 4 1141-1146, Copyright © 1983 by American Physiological Society
Gas mixing in the airways of dog lungs during high-frequency ventilation
T. J. Knopp, T. Kaethner, M. Meyer, K. Rehder and P. Scheid
Washout of insoluble inert test gases of different diffusivity (He and SF6
or He and Ar) from dog lungs was studied during high-frequency ventilation
(HFV). Test gas equilibrium and subsequent washout were performed with HFV,
succeeding measurements being performed at different stroke volumes
(1.5-2.5 ml/kg body wt), oscillation frequencies (10-30 Hz), and with
different lung volumes (32-74 ml X kg-1). Test gas concentrations were
continuously measured by a mass spectrometer. The time course of washout
could be described as the sum of two exponentials. There were no consistent
differences in the time courses of washout between He and SF6 or between He
and Ar. It is concluded that gas mixing in the airways during HFV is not
significantly limited by diffusion, and this is suggested to apply during
HFV to steady-state transport of respiratory gases (e.g., O2 and CO2) as
well as to the transient state of inert gas washout.
