一种脉搏呼吸频率提取系统的设计与实现

Design and implementation of photoplethysmography detection system for determining respiratory rate

目的设计一种以绿光发光二极管（LED）为光源、反射式测量方式测量的脉搏信号采集系统,以此光电脉搏信号提取不同呼吸状态下人体呼吸频率信息。方法选择16例健康受试者,年龄22-33岁,身高155-178 cm,体质量49-85 kg。进行对照试验来验证系统性能,分别采集受试者呼吸过慢、自然呼吸、呼吸过速3种状态下脉搏信号并提取呼吸频率信息,利用热敏电阻同步采集人体鼻腔呼吸信号作为参考呼吸信号。结果脉搏呼吸频率提取系统测量范围为7-34次/分,最大测量误差为2次/分,平均测量误差为0.14次/分。两种方法获得的呼吸频率3种呼吸状态下平均误差为0.12次/分、0.18次/分、0.48次/分,3种呼吸状态下的平均误差率分别为0.78%、1.87%、1.48%。结论脉搏呼吸频率提取系统可以完成3种状态下呼吸频率提取,且与参考呼吸频率具有良好的一致性,可以成为现有呼吸频率监测方法的一种补充。

Objective To develop a reflection-mode photoplethysmography（PPG） detection system with green light-emitting diode（LED） for extracting respiratory rate from PPG signals under different breathing conditions. Method A total of 16 healthy volunteers were enrolled in the controlled trial, with age of 22-33 years old, height of 155-178 cm and body weight of 49-85 kg.PPG signals were recorded at bradypnea/ normal/ tachypnea breathing rhythm to estimate respiratory rate, the respiratory wave was detected simultaneously with thermistor as reference signal. Results The extraction range of respiratory rate measurement system was 7-34 breaths per minute（bpm）, the maximum measurement error was 2 bpm with mean error of 0.14 bpm. The mean error of respiratory rate under 3 breathing conditions from 2 methods were 0.12 bpm, 0.18 bpm and 0.48 bpm, respectively, the mean error rate were 0.78 %, 1.87 % and 1.48 %, respectively. Conclusion It is demonstrated that the proposed system could extract respiratory rate under 3 breathing conditions, and the calculated values are in good consistency with the reference values, which could be a supplement to the existing respiratory rate monitoring measurement.