Nishidate Izumi, Yasui Riku, Nagao Nodoka, Suzuki Haruta, Takara Yohei, Ohashi Kaoru, Ando Fuminori, Noro Naoki, Kokubo Yasuaki
Tokyo University of Agriculture and Technology, Graduate School of Bio-Applications and Systems Engineering, Tokyo, Japan.
EBA Japan Co., Ltd., Tokyo, Japan.
Front Physiol. 2022 Sep 19;13:933397. doi: 10.3389/fphys.2022.933397. eCollection 2022.
We propose a method to perform simultaneous measurements of percutaneous arterial oxygen saturation ( ), tissue oxygen saturation ( ), pulse rate (), and respiratory rate () in real-time, using a digital red-green-blue (RGB) camera. Concentrations of oxygenated hemoglobin ( ), deoxygenated hemoglobin ( ), total hemoglobin ( ), and were estimated from videos of the human face using a method based on a tissue-like light transport model of the skin. The photoplethysmogram (PPG) signals are extracted from the temporal fluctuations in , , and using a finite impulse response (FIR) filter (low and high cut-off frequencies of 0.7 and 3 Hz, respectively). The is calculated from the PPG signal for . The ratio of pulse wave amplitude for and that for are associated with the reference value of measured by a commercially available pulse oximeter, which provides an empirical formula to estimate from videos. The respiration-dependent oscillation in was extracted from another FIR filter (low and high cut-off frequencies of 0.05 and 0.5 Hz, respectively) and used to calculate the . experiments with human volunteers while varying the fraction of inspired oxygen were performed to evaluate the comparability of the proposed method with commercially available devices. The Bland-Altman analysis showed that the mean bias for , , , and were -1.4 (bpm), -1.2(rpm), 0.5 (%), and -3.0 (%), respectively. The precisions for , , , and were ±3.1 (bpm), ±3.5 (rpm), ±4.3 (%), and ±4.8 (%), respectively. The resulting precision and RMSE for were pretty close to the clinical accuracy requirement. The accuracy of the is considered a little less accurate than clinical requirements. This is the first demonstration of a low-cost RGB camera-based method for contactless simultaneous measurements of the heart rate, percutaneous arterial oxygen saturation, and tissue oxygen saturation in real-time.
我们提出了一种使用数字红-绿-蓝（RGB）相机实时同步测量经皮动脉血氧饱和度（ ）、组织血氧饱和度（ ）、脉搏率（ ）和呼吸率（ ）的方法。利用基于皮肤组织样光传输模型的方法，从人脸视频中估计氧合血红蛋白（ ）、脱氧血红蛋白（ ）、总血红蛋白（ ）和 的浓度。使用有限脉冲响应（FIR）滤波器（低截止频率和高截止频率分别为0.7和3Hz）从 、 和 的时间波动中提取光电容积脉搏波（PPG）信号。 由用于 的PPG信号计算得出。 与 的脉搏波幅度之比与商用脉搏血氧仪测量的 的参考值相关，该商用脉搏血氧仪提供了一个从视频中估计 的经验公式。 中与呼吸相关的振荡从另一个FIR滤波器（低截止频率和高截止频率分别为0.05和0.5Hz）中提取，并用于计算 。在改变吸入氧分数的情况下，对人类志愿者进行了实验，以评估所提出的方法与商用设备的可比性。布兰德-奥特曼分析表明， 、 、 和 的平均偏差分别为-1.4（bpm）、-1.2（rpm）、0.5（%）和-3.0（%）。 、 、 和 的精度分别为±3.1（bpm）、±3.5（rpm）、±4.3（%）和±4.8（%）。 得到的精度和均方根误差与临床准确性要求相当接近。 的准确性被认为比临床要求略低。这是首次展示基于低成本RGB相机的方法用于实时非接触式同步测量心率、经皮动脉血氧饱和度和组织血氧饱和度。
