ABSTRACT
A new compact device for measuring respiratory impedance is designed. Input respiratory impedance, an impedance of upper airways and respiratory impedance corrected for upper airways shunt can be measured in 2 minutes. The space-condition requirements are complied by integrating an oscillation generator, sensors, a mouthpiece with a screen and a reference resistor in the measuring head. The oscillation generator produces small-amplitude forced oscillations (with a tidal volume of about 1 ml) at frequencies f = 7, 10, 13, 16, and 19 Hz. Algorithms of calibration and measurement provide impedance calculation. For 55 different external impedances, complex transmission factors are measured for each of the five frequencies. The standard deviation of amount and phase of complex transmission factors are less than 5% and 0.06, respectively.