Relationships among upper and lower respiratory system resistance, opening of the glottis, respiratory flow at the mouth (Vm) and lung volume (Vl) were evaluated in normal nonsmokers. Total respiratory resistance (Rt) was continuously measured with the forced oscillation technique at 10 Hz and partitioned into upper respiratory resistance (Ru) and lower respiratory resistance (Rl) by measuring lateral pressures with catheter tip manometers at the mouth and within the trachea (transnasal approach). Simultaneously with the measurement of respiratory technics, the cross sectional area of the glottis was determined by transnasal cinebronchofiberscopy using a 1mm Teflon disc deposited on the vocal cords. Accurate timing of the mechanical events with the glottal area was ensured by filming a digital clock through a fiberoptic bundle attached to the bronchofiberscope. Corrections were made for shunt impedance of the mouth. Topical anesthesia and instrumentation of the upper airways did not change Rt. A relationship was established among glottis opening, Ru and Vm which could be described by Rohrer's equation for laminar and tubulent flow. Correlations were also found between Rl and Vl, but no reproducible relationships could be established between glottis opening and Vm or Vl. Since Ru is a function of two independent variables (cross sectional area of the glottis and Vm), both must be measured to assess the contribution of Ru to Rt.
|State||Published - Dec 1 1976|
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