Heart rate estimation from dual pressure sensors of a dialysis machine

Dialysis patients often suffer from cardiovascular diseases, motivating the use of continuous monitoring of cardiac activity in clinical routine. Cardiac pressure pulses propagate through the vascular system and enter the extracorporeal blood circuit of a dialysis machine, where the pulses are captured by pressure sensors. The cardiac pulses are obscured by the much stronger pressure pulses originating from the peristaltic blood pump. We have previously shown that a cardiac signal can be extracted from the venous pressure signal. However, that method has been found to perform less well at very low cardiac pressure pulse amplitudes. In the present study, we propose a novel method which addresses this issue by using the signals from both the arterial and the venous pressure sensors. The method is compared to the previous method on clinical data using a photoplethysmogram as reference. The results suggests that heart rate can be estimated more accurately from pressure signals with lower cardiac signal amplitude when both arterial and venous pressure are used, compared to when only the venous signal is used.