Relation of mouth flow to body surface flow during forced oscillation at the chest.
We have investigated the body surface flow/mouth flow transfer function (magnitude ratio and phase difference) in seven healthy male subjects driven at the chest from 4 to 30 Hz. The measurements were performed with a specially designed plethysmograph and analyzer. The subjects were driven with a mechanical oscillator placed on the sternum. After differences in gas temperature and humidity were taken into account, the data were in agreement up to 15 Hz with a simple second-order model including an airway compartment, with a resistance and an inertance, and a shunt compliance representing alveolar gas. At larger frequencies, closer inspection revealed that a third-order model was optimal. We interpret these results as indicating a compartmentalization of gas compliance within the thorax, communicating via a resistive element. Airway inertance did not seem to be distributed.
D006801:Humans; D006813:Humidity; D008168:Lung / Q000502:physiology; D008297:Male; D008954:Models, Biological; D009055:Mouth / Q000502:physiology*; D009991:Oscillometry; D010991:Plethysmography / Q000295:instrumentation / Q000379:methods; D012119:Respiration; D013696:Temperature; D013909:Thorax / Q000502:physiology*