Murphy D, Burton P, Coombs R, Tarassenko L, Rolfe P
Clin Phys Physiol Meas. 1987;8 Suppl A:131-40. doi: 10.1088/0143-0815/8/4a/017.
We have been investigating the use of electrical impedance methods for the study of cerebral haemodynamics in the newborn for many years. Of particular interest has been the early detection of intraventricular haemorrhage, which is a major cause of death or handicap in low birthweight infants. Several problems exist in obtaining representative impedance measurements from the newborn, most notably movement artefact, respiratory-based modulation and a blood-flow related pulsatile component. Movement artefact is by far the most significant problem; in order to perform long-term monitoring we have developed an effective algorithm for rejection of corrupted data. To remove the respiratory component, which can be 1-2% of the impedance measurement, we link to the output of a respiratory monitor (standard in intensive care units) as a means of synchronising measurements to a fixed point in the respiratory cycle. Similarly, to remove the blood-flow pulsatile component, measurements are gated from the R-wave of the recorded ECG. Our total system consists of a front-end measurement system that passes image data over a serial link to a host computer. Data storage, image reconstruction and display is performed on the host, which can be any of a wide range of personal computers. The front-end contains the impedance measurement circuit, electrode switching electronics and a microprocessor for control, and is of a sufficiently small size to fit into the incubator next to the baby. Incorporating a microprocessor into the front-end produces a very flexible system that has many benefits, including: asynchronous operation from host, 'intelligent' pre-processing of measurements, command driven operation from host, etc. Software development for the front-end is performed on the host with program down-load for interactive debugging. Details of the front-end electronics and software, system performance, preliminary clinical results and other application areas of the impedance imaging technique to the care of the newborn are presented.
多年来，我们一直在研究使用电阻抗方法来研究新生儿的脑血流动力学。特别令人感兴趣的是脑室内出血的早期检测，这是低体重儿死亡或致残的主要原因。从新生儿获取具有代表性的阻抗测量值存在几个问题，最显著的是运动伪影、基于呼吸的调制以及与血流相关的脉动成分。运动伪影是迄今为止最严重的问题；为了进行长期监测，我们开发了一种有效的算法来剔除损坏的数据。为了去除占阻抗测量值1 - 2%的呼吸成分，我们连接到呼吸监测器（重症监护病房的标准设备）的输出，以此将测量与呼吸周期中的固定点同步。同样，为了去除血流脉动成分，测量值从记录的心电图的R波进行门控。我们的整个系统由一个前端测量系统组成，该系统通过串行链路将图像数据传输到主机计算机。数据存储、图像重建和显示在主机上进行，主机可以是多种个人计算机中的任何一种。前端包含阻抗测量电路、电极切换电子设备和用于控制的微处理器，其尺寸足够小，可以安装在婴儿旁边的保育箱中。将微处理器集成到前端产生了一个非常灵活的系统，具有许多优点，包括：与主机异步运行、测量的“智能”预处理、由主机进行命令驱动操作等。前端的软件开发在主机上进行，并通过程序下载进行交互式调试。本文介绍了前端电子设备和软件的详细信息、系统性能、初步临床结果以及阻抗成像技术在新生儿护理中的其他应用领域。
