三波长无创血氧饱和度测量算法及应用

A Calculation Method for Three-Wavelength Blood Oxygen Saturation Measurement and Its Application

传统的二波长血氧仪需要在医院非常安静的环境下才能正常测量血氧饱和度。然而,患者肢体运动干扰限制了血氧仪的使用范围,尤其是在可穿戴的、走动环境下的使用。本研究提出在探头内除660nm和940nm测量光源外增加810nm光源作为参考信号,根据Beer-Lambert定理建立新的测量算法,在硬件方面采用非线性均衡电路,在软件方面构造自适应滤波器,以便从光电容积脉搏波信号中移除运动干扰信号。实验证明,该方法明显降低了运动干扰,使得测量准确、可靠,在使用可穿戴式设备的移动监护和小儿科监护方面具有广泛的应用前景。

The conventional two-wavelength oximeters acquire blood oxygen saturation in very quiet environments such as hospital wards. Hence the motion of the extremities for patients limit oximeters in wearable and ambulatory environments. It was proposed in this paper to equip the probe with an 810nm source in addition to the present 660nm and 940nm measurement sources as an internal reference signal. A new algorithm based on the Beer-Lambert law was established and the nonlinear equalization circuitry was adopted in hardware and an adaptive filter was adopted in software in order to remove motion artifacts from photoplethysmographic signals. The experimental results showed that the proposed approach achieved a significant reduction in the sensitivity to motion artifacts, thus ensuring the accuracy and reliability of the measurement. The proposed method may have implications to the wearable devices and the pediatric monitoring.