The effect of trachea and tongue displacement on upper airway
airflow dynamics.
Rowley, James A., Solbert Permutt, Shannon Willey, Philip L. Smith,
Alan R. Schwartz.
Division of Pulmonary and Critical Care Medicine, Department of
Medicine, The Johns Hopkins Medical Institutions, Baltimore, MD
21224
APStracts 3:0074A, 1996.
We have previously shown that caudal trachea displacement alters the
airflow dynamics of the upper airway. In the present study, we
specifically examined the effects of tongue and trachea displacement
on upper airway airflow dynamics. To determine how tongue and trachea
displacement modulate maximal inspiratory airflow (Imax), we analyzed
pressure-flow relationships obtained in the isolated upper airway of
paralyzed cats. Imax and its determinants, the pharyngeal critical
pressure (Pcrit) and the nasal resistance (Rn) upstream to the flow
-limiting site (FLS), were measured as tongue displacement and trachea
displacement were systematically varied. Three results were obtained:
1) there was no independent effect of tongue displacement on Imax,
Pcrit or Rn (p=NS for all three); 2) there was an increase in Imax
with 2 cm of trachea displacement from 55+/-21 ml/s to 264+/-66 ml/s
(p<0.001), which was associated with a decrease in Pcrit (
-1.3+/-0.6 cmH2O to -11.0+/-2.5 cmH2O, p<0.001) and an increase
in Rn (15.4+/-5.8 cmH2O/l/s to 50.5+/-15.6 cmH2O/l/s, p<0.001);
3) there was an interactive effect of tongue and trachea displacement
on Imax (p=0.024) and Pcrit (p=0.025) but not Rn. We conclude that
tongue and trachea displacement exert differing influences on airflow
dynamics and present a mechanical model of the upper airway that
explains these results.
Received 14 June 1995; accepted in final form 16 January 1996.
APS Manuscript Number A629-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96