Journal of Applied Physiology, Vol 63, Issue 5 1788-1795, Copyright © 1987 by American Physiological Society
Resistance and reactance of the excised human larynx, trachea, and main bronchi
T. X. Jiang, M. Cauberghs and K. P. Van de Woestijne
Laboratorium voor Longfunktieonderzoek, Campus Gasthuisberg, Leuven, Belgium.
We investigated the impedance of excised preparations of the human larynx
before and after resection of the vocal cords and of the trachea whether or
not in connection with the main bronchi for steady (75-700 ml.s-1) and
oscillatory flows (4-64 Hz). To simulate the influence of respiratory flow
on oscillatory resistance (Rosc), oscillatory and steady flow were
superimposed. This resulted in a marked increase of Rosc, dependent on the
value of steady flow, a change of the frequency dependence of Rosc, and a
decrease of the reactance. The latter effects were particularly pronounced
in the preparations of the larynx, especially with a narrow glottis
opening. The influence of steady flow on oscillatory resistances is
probably the expression of interactions of steady and oscillatory flow
regimes in the larynx. Similar but less pronounced interactions are also
met in the trachea. These effects lead to a systematic overestimation of
upper airway resistance when measured during spontaneous breathing by means
of a forced oscillation technique.
