Philips Chair of Medical Information Technology, Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany.
Physiol Meas. 2011 Oct;32(10):1575-90. doi: 10.1088/0967-3334/32/10/006. Epub 2011 Aug 26.
Although respiratory rate is an important vital sign for early detection of deterioration, on general wards it is not routinely monitored. Since patients may not tolerate cables attached to their chest, we developed an unobtrusive and contactless measurement method which can be placed under a mattress. The sensor array uses the Maxwell-Wagner relaxation effect by capacitive injection of a high-frequency voltage into the torso and subsequent measurement of respiratory-induced phase shift. Simulations of the entire measurement scenario indicate an improved signal-to-noise ratio if a differential method is applied with specific positioning of the electrodes. A prototype was designed and the simulations were confirmed with measurements on a phantom and in a human self-experiment by the authors using self-constructed hardware. Movement artifacts were detected using an artifact detection algorithm which allows reliable estimation of the respiratory rate.
虽然呼吸频率是早期发现恶化的重要生命体征，但在普通病房中并未常规监测。由于患者可能无法忍受连接到胸部的电缆，因此我们开发了一种不显眼且非接触式的测量方法，可以放置在床垫下。传感器阵列通过将高频电压电容注入到躯干中并随后测量呼吸引起的相位偏移来利用 Maxwell-Wagner 弛豫效应。如果应用具有特定电极定位的差分方法，则整个测量场景的模拟表明可以提高信噪比。设计了一个原型，并使用作者使用自制硬件在人体自实验和体模上的测量对模拟结果进行了验证。使用一种可以可靠估计呼吸率的伪影检测算法检测运动伪影。
