MECHANICAL CHARACTERISTICS OF THE HUMAN AIRWAY IN RELATION TO THE USE OF THE INTERRUPTER VALVE
Porton technical paper
CHEMICAL DEFENCE EXPERIMENTAL ESTABLISHMENT PORTON DOWN (UNITED KINGDOM)
Pagination or Media Count:
Electrical and mechanical analogues have been used to formulate hypotheses concerning the mechanical characteristics of the respiratory tract, and these hypotheses have been confirmed by examination of unscanned pressure records obtained from the Clements Valve during the repetitive interruption of airflow in man. At normal respiratory frequencies, impedance is due mainly to the sum of resistance components. Impedance reaches a minimum at a frequency of about 30 cps, and small resonant peaks are seen at 6.6, 18.7, 28, and 56 cps. Gas inertance and mouth wall compliance are important determinants of the rate of pressure equilibration between the lungs and the mouth. Damping is normally less than critical. The secondary rise of pressure seen after flow interruption is due to continuing movement of the diaphragm compressing the lung gas volume against a tense chest nall. If airway resistance is increased, damping may exceed the critical value, and 90 pressure equilibration may occupy 100 m.sec. These findings are considered in relation to the use of the Clements interrupter valve.
- Anatomy and Physiology