WANG Huimin1， YANG Lu2， LIANG Xingyu1
（1. School of Information and Communication Engineering， North University of China， Taiyuan 030051， China；2. Science and Technology on Electronic Test & Measurement Laboratory， North University of China， Taiyuan 030051， China）
Abstract： Photoplethysmogram (PPG) is a noninvasive method for detecting human cardiovascular pulse wave using optical technology. The PPG containing a lot of physiological information is from the MIMIC database. This paper proposes a combinatorial method of ensemble empirical mode decomposition (EEMD), cepstrum, fast Fourier transform (FFT) and zero-crossing detection to improve the robustness of the estimation of pulse rate (PR), heart rate (HR) and respiratory rate (RR) from the PPG. First, the PPG signal was decomposed into finite intrinsic mode functions (IMF) by EEMD. Because of its adaptive filtering property, the different signals were reconstructed using different IMFs when estimating different physiological parameters. Second, the PR was obtained by zero-crossing detection after rejecting low frequency IMFs containing artifacts. Third, IMFs with frequency between 1.00 Hz to 1.67 Hz (60 beats/min to 100 beats/min) were selected for estimating HR. Then, the frequency band that reflects the heart activity was analyzed by the cepstrum method. Finally, the respiratory signal can be extracted from PPG signal by IMFs with frequency between 0.05 Hz to 0.75 Hz (3 breahts/min to 45 breaths/min). Then the spectrum of signal was obtained by FFT analysis and the RR was estimated by detecting the maximum frequency peak. The algorithm has been tested on MIMIC database obtained from 53 adults. The experiment results show that the physiological parameters extracted by this integrated signal processing method are consistent with the real physiological parameters.And the computation load of this method is small and the precision is high (not larger than 1.17% in error).
Key words： photoplethysmogram (PPG); pulse rate (PR); respiratory rate (RR); heart rate (HR); cepstrum
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从光电容积图中提取脉搏率、呼吸率和心率的新方法
王慧敏1， 杨 录2， 梁星雨1
（1. 中北大学 信息与通信工程学院， 山西 太原 030051；2. 中北大学 电子测试技术重点实验室， 山西 太原 030051）
摘 要: 光电容积描记图(PPG)是一种利用光学技术无创检测人体心血管脉搏波的方法。 PPG信号来源于MIMIC数据库， 它含有许多生理信息。 本文提出了将集合经验模态分解(EEMD)、 倒谱、 快速傅里叶变化和过零点检测相结合的方法， 从PPG中可靠地估算脉搏率(PR)、 心率(HR)和呼吸频率(RR)。 首先， 将PPG信号通过EEMD分解为有限个固有模态函数(IMF)。 因为EEMD有自适应滤波特性， 所以估算不同的生理参数时， 可以用不同的IMF分量来重构信号。 其次， 估算脉搏率时， 舍去低频含有伪迹的IMF， 再通过过零点检测可以得到瞬时脉搏率。 然后， 估算心率时， 用1 Hz~1.67 Hz (60次/分钟~100次/分钟)的IMF来重构信号， 再求倒谱， 选取反映心脏活动的频带来得到心率。 最后， 估算呼吸率时， 用0.05 Hz~0.75 Hz (3次/分钟~45次/分钟)的IMF来重构信号， 然后对呼吸信号求快速傅里叶变化得到频谱图， 寻找频谱图中的峰值得到呼吸率。 对来自MIMIC数据库的53个成人PPG信号进行了仿真。 仿真结果表明： 使用该综合信号处理方法提取的生理参数与实际生理参数一致， 且该方法有运算量小， 精确度高的优点(误差不超过1.17%)。
关键词: 光电容积描记技术； 脉搏率； 心率； 呼吸率； 倒谱
引用格式： WANG Huimin， YANG Lu， LIANG Xingyu. Physiological parameter estimation from the photoplethysmogram. Journal of Measurement Science and Instrumentation, 2020, 12（2）： 188-194. DOI： 10.3969／j.issn.1674-8042.2021.02.008
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