| Summary: | 碩士 === 中原大學 === 生物醫學工程研究所 === 102 === The goal of this work is to develop a real-time analysis system for studying heart rate variability (HRV) in response to respiratory regulation. This system is comprised of three components: an acquisition module of electrocardiogram (ECG), a calculating module for real-time analysis and a liquid-crystal display (LCD) module. The acquisition module is used for acquiring analog ECG signals. The calculation module converts the analog ECG to digital form, detects R-waves of ECG, calculates R-R intervals (RRI), re-samples RRI and then transforms the re-sampled RRI to frequency domain via fast Fourier transform software. Standard deviation of normal to normal intervals was calculated in time-domain by the calculation module at the same time. All the information including the acquired ECG, calculated statistics and plots were displayed on the LCD and stored in a computer through universal asynchronous receiver/transmitter. To verify the developed system, a commercial ECG generator, FLUKE MPS450, was used to produce normal ECG. The results show that the standard error and the standard deviation of RRI measured by the real-time analysis system were 3.77 % and 0.33 %, respectively. The ECG from MPS450 and human subjects were analyzed by the developed system and a commercial system (CheckMyHeart, DailyCare Biomedical). The HRV of the acquired ECG were calculated and then converted to frequency domain. The HRV frequency spectra for both systems were very similar. For the studies of autonomic nervous system (ANS) activity upon respiratory regulation, three factors were taken into account: respiratory rate (6 and 20 breathing/minute) and elapse time (2 and 5 minutes) of respiration regulation and lying/sitting position of subjects. Each study involved ten subjects. The results show that the ANS activity was inhibited by the fast respiratory rate (i.e. 20 breathing/minute) and was activated by the long elapse time (i.e. 5 minutes) with the 6 breathing/minute respiratory rate. It is obvious that the parasympathetic system of the subjects in lying position was activated by the respiratory regulation compared to those sitting on a chair. In conclusion, a prototype real-time analysis system for HRV measurement is accomplished; and it is capable of automatically providing information for analyzing ANS activity in response to respiratory regulation. The system has potential to provide a non-invasive mean to analyze ANS activity in our daily life.
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