Smart combination of ECG and PPG signals: an innovative approach towards an electronic device for vital signs monitoring

Continuous vital signs monitoring is an important aid for preventing, diagnosing and timely treating different pathologies, especially in the field of cardiovascular and respiratory diseases. The aim of this work is to present a multiparameter tool for vital signs monitoring, starting from photoplethysmographic (PPG) and electrocardiographic (ECG) signal extraction and processing. In particular, a multi-wavelength photoplethysmographic sensor is used for the prediction of heart rate and the degree of blood hemoglobin oxygenation; with a simultaneous mining of the PPG signal with the ECG signal, it is also possible to determine the value of systolic pressure, by calculating the Pulse Transit Time (PTT), that is, the time interval between the R wave of the ECG signal and the subsequent systolic peak of the PPG signal. Such algorithms have been validated using reference instruments (sphygmomanometer and pulse oximeter): the performance is promising, with an average relative error of less than 5%. Results suggest that this innovative approach to vital signs monitoring can lead to the development of an electronic device that is simple to use, low cost and non-invasive.