Zhao Yanyu, Applegate Mattew B, Istfan Raeef, Pande Ashvin, Roblyer Darren
Boston University, Department of Biomedical Engineering, 44 Cummington Mall, Boston, MA 02215, USA.
Boston University School of Medicine, Section of Cardiovascular Medicine, Boston, MA 02118, USA.
Biomed Opt Express. 2018 Nov 5;9(12):5997-6008. doi: 10.1364/BOE.9.005997. eCollection 2018 Dec 1.
Pulse oximetry is a ubiquitous optical technology, widely used for diagnosis and treatment guidance. Current pulse oximeters provide indications of arterial oxygen saturation. We present here a new quantitative methodology that extends the capability of pulse oximetry and provides real-time molar concentrations of oxy- and deoxy-hemoglobin at rates of up to 27 Hz by using advanced digital hardware, real-time firmware processing, and ultra-fast optical property calculations with a deep neural network (DNN). The technique utilizes a high-speed frequency domain spectroscopy system with five frequency-multiplexed wavelengths. High-speed demultiplexing and data reduction were performed in firmware. The DNN inversion algorithm was benchmarked as five orders of magnitude faster than conventional iterative methods for optical property extractions. The DNN provided unbiased optical property extractions, with an average error of 0 ± 5.6% in absorption and 0 ± 1.4% in reduced scattering. Together, these improvements enabled the measurement, calculation, and real-time continuous display of hemoglobin concentrations. A proof-of-concept cuff occlusion measurement was performed to demonstrate the ability of the device to track oxy- and deoxy-hemoglobin, and measure quantitative photoplethysmographic changes during the cardiac cycle. This technique substantially extends the capability of pulse oximetry and provides unprecedented real-time non-invasive functional information with broad applicability for cardiopulmonary applications.
脉搏血氧饱和度测定法是一种普遍存在的光学技术，广泛用于诊断和治疗指导。当前的脉搏血氧仪可提供动脉血氧饱和度的指标。我们在此介绍一种新的定量方法，该方法扩展了脉搏血氧饱和度测定法的功能，并通过使用先进的数字硬件、实时固件处理以及利用深度神经网络（DNN）进行超快速光学特性计算，以高达27Hz的速率提供氧合血红蛋白和脱氧血红蛋白的实时摩尔浓度。该技术利用了一个具有五个频率复用波长的高速频域光谱系统。高速解复用和数据缩减在固件中进行。DNN反演算法的基准测试结果表明，其比传统的光学特性提取迭代方法快五个数量级。DNN提供了无偏差的光学特性提取，吸收平均误差为0±5.6%，约化散射平均误差为0±1.4%。这些改进共同实现了血红蛋白浓度的测量、计算和实时连续显示。进行了概念验证袖带阻塞测量，以证明该设备跟踪氧合血红蛋白和脱氧血红蛋白以及测量心动周期中定量光电容积脉搏波变化的能力。该技术极大地扩展了脉搏血氧饱和度测定法的功能，并提供了前所未有的实时无创功能信息，在心肺应用中具有广泛的适用性。
