The filter processing in forced oscillation respiratory impedance measurements / 中国医学物理学杂志

In the measurement of the forced oscillation respiratory impedance, we designed a narrow-band second-order band-pass comb filter which is centered at the forced oscillation frequencies for eliminating the interference of spontaneous breathing. The result shows that an increase of signal-to-noise ratio (SNR) reaches 6.0 dB, and keeps it almost constant over the whole frequency band when compared with a conventional high-pass filtering. So we can assess correctly the impedance of respiratory system.