Respiratory Rate Extracted And Realized Based On Photoplethysmography

Respiratory rate is one of physiological parameters of some illnesses,especially acute ones,the monitoring of respiratory rate is more important.One of the early features and symptoms of childhood pneumonia is abnormal changes in respiratory rate,but the traditional measurement of respiratory rate is complicated,uncomfortable and unsuitable for continuous monitoring.The photoplethysmography(PPG)signal is easy to measure and comfort,which makes it widely used.It can not only measure the physiological parameters such as pulse rate,heart rate and the likes,but also obtain the respiratory information.The main difficulty of single-channel PPG signal for respiratory frequency monitoring is the interference of artifacts.Its frequency band is similar to the respiratory frequency range,so the result of respiratory rate detection is inaccurate.In response to the above problems,this paper proposes two methods.Based on single PPG signal respiratory rate estimation,the first method changes the previous single domain estimation into time domain and frequency domain simultaneously estimation.The results of the two methods are fused to obtain the final result.Compared with the previous work,the proposed method shows strong anti-interference and high respiratory frequency estimation accuracy.Another method changes the single PPG signal into a multi-wavelength PPG signal.Therefore,this paper designed a multi-wavelength PPG signal acquisition equipment,the STM32 is core of the whole system,it could control operation time sequence of AFE4400 which it drives four-channel Pulse sensor and gathers PPG signal.The algorithm section base on time-domain estimation of single-channel PPG signal method,then it evaluates the quality of RIV signal using signal-quality-index algorithm and removes some low index signal,that all is the whole estimation project of respiratory rate.Comparing the case of four-channel,two-channel and single-channel PPG data,the results show that the estimated results of four-way PPG signal respiration rate is obviously better than single-channel PPG signal.