Application of Photoplethysmographic Pulse Signal for Human Physiological Information Acquisition

Photoplethysmographic (PPG) technology is a morden photoelectronic method to monitor pulse wave. Nowadays, PPG pulse detection has been widely used with the merit of accurate and convenience, in comparison with traditional palpation and other measurement instruments. It has been widely accepted that many human physiological information including heart rate, respiration rate, blood pressure, blood oxygen and so on, can be obtained from PPG pulse. These parameters are necessary in clinical medicine because they can reflect patient's health status and in close relation with cardiovascular diseases. In this paper, after briefly outlining the PPG technology, the theories of PPG pulse analysis to obtain heart rate, respiration rate, blood oxygen saturation, as well as the method for calculating the time-domain indexes of pulse wave signal (the time delay between the systolic and diastolic peaks ΔT, crest time, pulse interval, pulse characteristic parameter K and inflection point area ratio) are described in detail. Furthermore, the algorithm flow to acquire physiological information from PPG pulse wave is proposed and executed by using MATLAB. The extracted physiological parameters from PPG signals are verified with the experimental data. Meanwhile, the internal relationship between the PPG signals and cardiovascular diseases is analyzed, to discuss the possibility of providing an auxiliary judgment for cardiovascular diagnosis.