Research Of Noninvasive Monitoring Of Cardiacfunction By Electrical Bioimpendance

In the 1990s, the trend of the impedance cardiography's applications is from short-time diagnose to long-time monitoring. This paper is to research the feasibility of the noninvasive cardiac function monitor baseing on electrical bioimpedance. The study includes two parts: (1) Developing a experimental cardiac function monitor.(2) Making some clinical experiments to prove the feasibility of this method. The experimental instrument is composed of hardware and software .The hardware bases on PC, that is a extended board according with ISA bus .There are analog circuits and digital circuits on the board , the analog circuits not only magnify the bioimpedance signals and ECG signals but also detect the QRS ;the digital part performs the communication with PC and AiD conversion The software bases on Windows 95, including reliable signal processing module and practical operational interface .In the course of signal processing , we adopted the average algorithm and dynamic-templet-matching algorithm , at same time we analysed the impedance signal with wavelet for the first time , all these make the results of the calculation more reliable. We also made special VxD which improved the experimental instrument's stability .In a word , the experimental instrument had had very good practicability. In the study's anaphase , we made some clinical experiments and adopted a new method differing from calculating the correlation coefficient. From the result of the experiments, we can see the good future of the bioimpedance based cardiac function monitor .But because samples of these experiments are not enough, we can draw a more certain conclusion only after making more clinical experiments in the future.