CEA, Leti, MINATEC Campus, Université Grenoble Alpes, F-38000 Grenoble, France.
CNRS, Grenoble INP, GIPSA-Lab, Université Grenoble Alpes, F-38000 Grenoble, France.
Sensors (Basel). 2023 Jul 2;23(13):6096. doi: 10.3390/s23136096.
The development of a capnometry wristband is of great interest for monitoring patients at home. We consider a new architecture in which a non-dispersive infrared (NDIR) optical measurement is located close to the skin surface and is combined with an open chamber principle with a continuous circulation of air flow in the collection cell. We propose a model for the temporal dynamics of the carbon dioxide exchange between the blood and the gas channel inside the device. The transport of carbon dioxide is modeled by convection-diffusion equations. We consider four compartments: blood, skin, the measurement cell and the collection cell. We introduce the state-space equations and the associated transition matrix associated with a Markovian model. We define an augmented system by combining a first-order autoregressive model describing the supply of carbon dioxide concentration in the blood compartment and its inertial resistance to change. We propose to use a Kalman filter to estimate the carbon dioxide concentration in the blood vessels recursively over time and thus monitor arterial carbon dioxide blood pressure in real time. Four performance factors with respect to the dynamic quantification of the blood concentration are considered, and a simulation is carried out based on data from a previous clinical study. These demonstrate the feasibility of such a technological concept.
腕部二氧化碳测量带的开发对于在家中监测患者具有重要意义。我们考虑了一种新的架构，其中非分散式红外线（NDIR）光学测量靠近皮肤表面，并与开放式腔室原理相结合，在收集室中实现空气的连续循环。我们提出了一种用于设备内血液和气体通道之间二氧化碳交换的时间动态模型。二氧化碳的传输通过对流扩散方程进行建模。我们考虑了四个隔室：血液、皮肤、测量室和收集室。我们引入了状态空间方程和与马尔可夫模型相关联的转移矩阵。我们通过结合描述血液隔室中二氧化碳浓度供应及其对变化的惯性阻力的一阶自回归模型，定义了一个增广系统。我们建议使用卡尔曼滤波器来递归地估计血液中二氧化碳浓度，并实时监测动脉二氧化碳血压。考虑了四个关于血液浓度动态量化的性能因素，并基于先前临床研究的数据进行了模拟。这些证明了这种技术概念的可行性。
