Respiratory Rate Simultaneous Estimation from Two ECG-derived Respiratory Waveforms Using an Adaptive Frequency Tracking Algorithm

Monitoring the respiratory rate (RR) in a fast, inexpensive and continuous manner is of great interest as its direct measurement requires bulky, expensive and inconvenient equipment. In this study, the RR is estimated in an instantaneous manner from the electrocardiogram (ECG) using two ECG-derived respiratory waveforms: the respiratory sinus arrhythmia (RSA) and the modulation of R-peak amplitudes (RPA). An adaptive weighted oscillator-based (W-OSC) frequency tracking algorithm is used to estimate their common frequency. The algorithm is evaluated on a public data set and it is shown that combining RSA and RPA is beneficial to using either alone.