Comparison of Heart Rate Derived from ECG and Pulse Wave Signals during Controlled Breathing Test for Biofeedback Systems

This study investigated the possibility of using the pulse wave signal to determine the heart rate for implementing in systems using biofeedback principles. The replacement of electrocardiogram with pulse wave provides the methodological simplicity and eliminates the need for medical consumables, like disposable electrodes and patient cables. For the study, electrocardiogram, pulse wave, and the respiratory signals of healthy patients were recorded during a series of breathing exercises. After that, based on the ECG and PPG signals, the time intervals between heartbeats were independently calculated and the difference in the obtained values was considered. The initial results show slight deviation in the estimated time between heartbeats from two approaches: heart rate values calculated from the pulse wave signal recorded with the photoplethysmography sensor sufficiently coincide with the values obtained by the standard method, using the electrocardiogram signal and R-R interval measurement. The value of the deviation has an inverse relationship with the respiration rate of the subjects. Therefore, the PPG registration channel may become a good substitute for standard electrocardiogram registration, especially when used at home.