Laboratorio de Biofotónica, ESIME ZAC, Instituto Politécnico Nacional, Ciudad de México, 07738, Mexico; Laboratorio de Espectroscopía, UPIIH, Instituto Politécnico Nacional, Ciudad del Conocimiento y la Cultura, San Agustín Tlaxiaca, Hidalgo, 42162, Mexico.
Laboratorio de Espectroscopía, UPIIH, Instituto Politécnico Nacional, Ciudad del Conocimiento y la Cultura, San Agustín Tlaxiaca, Hidalgo, 42162, Mexico.
Comput Methods Programs Biomed. 2020 Apr;187:105237. doi: 10.1016/j.cmpb.2019.105237. Epub 2019 Nov 21.
Local tissue oxygenation determines the relationship between the supply and the demand for oxygen by the tissue and it is an important indicator of the physiological or pathological condition of the tissue. Moreover, some therapeutic methods strongly depend on the oxygen content of the tissue. In photodynamic therapy, when molecular oxygen is present, the irradiation of the photosensitizer with light triggers the generation of reactive oxygen species that kill the target diseased cells within the treated tissue. To ensure the best possible therapy response, the tissue must be well oxygenated; hence, oxygen concentration measurement becomes a decisive factor. In this work, the design, construction and calibration of a module to locally measure the blood oxygen saturation in tissue is presented.
The system is built using a red (660-nm) and an infrared (940-nm) light emitting diodes as light sources, a photodiode as a detector, and a homemade handheld fiber optic-based reflectance pulse oximetry sensor. In addition, the developed sensor was modeled by means of multilayered Monte Carlo simulations, to study its behavior when used in different thickness and melanin content skin.
From the simulation reflectance values, the oxygen saturation calibration curves considering different melanin concentrations and skin thicknesses were obtained for two different skin models, one comprising three skin layers and the second, assuming seven different layers for the skin. A comparison of the performances of the developed pulse oximeter sensor with a commercial one is also presented.
A new pulseoximeter for the measurement of local oxygenation in tissue was developed. Its calibration strongly depends on the site of measurement due to the influence of tissue thickness, vascularization, and melanin content. A three-layer skin model is proved to be suitable for the calibration of the pulseoximeter in thin and medium thickness skin.
局部组织氧合决定了组织中氧的供需关系，是组织生理或病理状态的重要指标。此外，一些治疗方法强烈依赖于组织中的氧含量。在光动力疗法中，当存在分子氧时，光敏剂的光照射会引发活性氧的产生，从而杀死治疗组织内的靶病变细胞。为了确保获得最佳的治疗反应，组织必须得到良好的氧合；因此，氧浓度测量成为一个决定性因素。在这项工作中，介绍了一种用于局部测量组织血氧饱和度的模块的设计、构建和校准。
该系统使用红色（660nm）和红外（940nm）发光二极管作为光源，光电二极管作为探测器，以及自制的基于手持光纤的反射式脉搏血氧仪传感器。此外，通过多层蒙特卡罗模拟对开发的传感器进行建模，以研究其在不同厚度和黑色素含量的皮肤中使用时的行为。
从模拟反射值中，获得了考虑不同黑色素浓度和皮肤厚度的两种不同皮肤模型的氧饱和度校准曲线，一种模型包括三层皮肤，另一种模型假设皮肤有七层不同的层。还比较了开发的脉搏血氧仪传感器与商业传感器的性能。
开发了一种用于测量组织局部氧合的新型脉搏血氧仪。由于组织厚度、血管化和黑色素含量的影响，其校准强烈依赖于测量部位。三层皮肤模型被证明适用于薄中和中厚皮肤的脉搏血氧仪校准。
