Transfer Function Estimates in Derived Respiration Analysis: Retrograde Study of the Respiratory Drive Mechanism

We extracted several respiratory components from electrocardiography and photoplethysmography to investigate respiratory drive mechanism. Transfer function analysis was used to compare the derived respiration to the reference respiration measured from nasal airflow to validate suitability of derived respiratory components. Magnitude squared coherence estimate (MSCE) and phase spectrum were calculated to investigate the significance and phase difference, respectively. From the experiment, it was validated that every derived respiration has high significance (MSCE > 0.5) from the transfer analysis estimates. Moreover, phase difference, a time relationship between respirations, showed that respiratory components have the sequential relationship.