Verification of the Respiratory Parameters Derived from Impedance Pneumography during Normal and Deep Breathing in Three Body Postures

We designed a small, battery-powered impedance pneumograph intended for holter monitoring of respiratory activity. Volume-related signal from impedance pneumo-graphy (IP) and airflow signal from reference method, pneumotachometry (PNT), were registered. First derivate of IP with PNT and IP with integral of PNT signals were compared in order to calculate slope values of linear regression. The effect of respiratory rate, depths of breathing, body posture, sex and body mass index (BMI) on slope values and coefficients of determination (R-2) was determined. The measurements were conducted on a group of young volunteers without any respiratory diseases. An electrode configuration known for its good linearity between impedance and volume signals was chosen. Average R-2 between IP signal and integral of PNT signal was 98.05%, and between first derivative of IP signal and PNT signal - 95.75%. It was demonstrated that the slope values were individually different and affected mostly by body posture.