Pulse transit time measurement method with artifact tolerance for home healthcare

To measure the arterial stiffness at home is important in order to prevent and treat arteriosclerosis. Pulse wave velocity (PWV) is one of the indexes of arterial stiffness. We have proposed a device that measures PWV at home. The device measures pulse transit time (PTT) and calculates PWV using the PTT. The PTT measurement is used electrocardiogram (ECG) and photoplethysmogram (PPTG). The operator of the device is user oneself. At home, it is difficult to judge whether the measurement condition is appropriate because medical staff is not at home. Motion artifacts are problem that occur as well. The method with artifact tolerance is useful for both increasing the measuring precision and decreasing re-measurement to suppress the motion artifact automatically. Therefore, the purpose of this research is to propose a pulse transit time measurement method with artifact tolerance, and to evaluate its measurement precision. We proposed the method that outlier of PTT is excluded using an average and a standard deviation (SD). The average and the SD are calculated using R-wave and peaks of PPTG in 30 seconds. An experiment that ECG or PPTG has deliberate motion artifacts was performed with developed measurement system. To evaluate, we used the developed measurement system that has the pulse transit time measurement method with artifact tolerance. Precision of the measurement system was 7.97% when ECG or PPTG with the artifact. It was smaller than 8.4% that is precision of the existing medical equipment. Therefore the proposal method that has sufficient artifact tolerance was confirmed.