System and method of obtaining measuring characteristic correction factors for respiratory flow measuring device using static pressure difference

A method of obtaining measuring characteristic correction factors required for respiratory flow measurement using a measuring characteristic correction factor obtaining system, the system having a syringe connected to a respiratory tube of a respiratory flow measuring device through a duct line, a detecting unit for detecting volume variation within the syringe and outputting the detected result as a voltage signal, an analog/digital (A/D) converter connected to the detecting unit and a computer for collecting information converted by the A/D converter to obtain measuring characteristic correction factors for a respiratory flow measuring device, comprising the steps of:

• converting analog signals including a volume variation signal outputted from the detecting unit and a differential pressure variation signal detected by a differential pressure sensor of the respiratory flow measuring device as a voltage signal into digital signals;
• and
• calculating characteristic coefficients R0 and R1 of a first equation by applying an instantaneous flow value F(t) obtained by differentiating the converted volume variation signal V(t) and the converted differential pressure variation signal ΔP(t) to a second equation,
• 22 Δ ⁢ ⁢ P = ⁢ R ⁡ ( F ) · F = ⁢ ( R 0 + R 1 ⁢ F ) · F = ⁢ R 0 ⁢ F + R 1 ⁢ F 2 [ first ⁢ ⁢ equation ] yk=R0+R1·xk [second equation],
• where yk=∫ΔPk(t)dt/3, xk=∫Fk2(t)dt/3, and k is a stroke number.