The Study of the Measurement of Heart Rate Variability Using ECG and Photoplethysmographic Signal / 中国医疗器械杂志

In comparison with the measurement of heart rate variability from ECG and from photoplethysmographic signal from 46 healthy adults in their spontaneous breathing state. The beat-to-beat intervals in ECG and pulse-to-pulse intervals in photoplethysmographic signal are extracted, and then the parameters of heart rate variability are calculated. Three kinds of algorithms are chosen to get the pulse-to-pulse intervals, which are the intervals of maximum of second derivative, the maximum of PPG signal and the tangent intersection. The results show that the correlation coefficients of the HRV parameters in the two calculation methods are highly correlated. The Bland-Altman scattered plots show the relative bias results from the algorithm of the maximum of PPG signal are smallest and singular points that deviate from the consistent limits are the least compared with the other two algorithms.

Study on the Optimum Order of Autoregressive Models for Heart Rate Variability Analysis / 生物医学工程学杂志

Heart rate variability (HRV) analysis technology based on an autoregressive (AR) model is widely used in the assessment of autonomic nervous system function. The order of AR models has important influence on the accuracy of HRV analysis. This article presents a method to determine the optimum order of AR models. After acquiring the ECG signal of 46 healthy adults in their natural breathing state and extracting the beat-to-beat intervals (RRI) in the ECG, we used two criteria, i. e. final prediction error (FPE) criterion to estimate the optimum model order for AR models, and prediction error whiteness test to decide the reliability of the model. We compared the frequency domain parameters including total power, power in high frequency (HF), power in low frequency (LF), LF power in normalized units and ratio of LF/HF of our HRV analysis to the results of Kubios-HRV. The results showed that the correlation coefficients of the five parameters between our methods and Kubios-HRV were greater than 0.95, and the Bland-Altman plot of the parameters was in the consistent band. The results indicate that the optimization algorithm of HRV analysis based on AR models proposed in this paper can obtain accurate results, and the results of this algorithm has good coherence with those of the Kubios-HRV software in HRV analysis.

Change of pulse transit time during stepwise paced breathing / 生物医学工程学杂志

To investigate the effect of stepwise paced breathing (PB) on pulse transit time (PTT), we collected physiological signals of electrocardiogram (ECG), respiration and arterial pulse wave during a procedure of stepwise PB, which consists of 6 different breathing rates changing in a protocol of 14.0-12.5-11.0-9.5-8.0-7.0 breath per minute (BPM), with each breathing rate lasting 3 minutes. Twenty two healthy adults involved in this experiment and the change of PTT was analyzed during the stepwise PB procedure. In our study, the PTT was measured by calculating the time interval from the R-spike of the ECG to the peaks of the second derivative of the arterial pulse wave. Ensemble empirical mode decomposition (EEMD) was applied to PTT to decompose the signal into different intrinsic mode function, and respiratory oscillation and trend component (baseline) in PTT were further extracted. It was found that the respiratory oscillations in the PTT increased with decreasing of the PB rate, and many of the subjects (14 out of 22) showed the phenomena of PTT baseline increasing during the stepwise PB procedure. The results indicated that the stepwise PB procedure induced a high level of cardiovascular oscillation and produced an accumulative effect of PTT baseline increase. As PTT is capable of predicting changes in BP over a short period of time, increase of PTT baseline indicates the decrease of blood pressure. The experiments showed that the stepwise PB procedure could reduce blood pressure for most subjects. For future work, it is necessary to develop certain indices differentiating the effectiveness of the stepwise PB procedure on the PTT baseline change, and to test the effectiveness of this stepwise PB procedure on blood pressure reduction for patients with essential hypertension.

Application of three kinds of method for extracting nonlinear trend in biomedical signal analysis / 中国医疗器械杂志

Biomedical signal analysis often needs to separate the trend component from the non-trend component to achieve different purposes and applications in signal analysis. This article introduces three kinds of detrending nonlinear component methods used in the process of biomedical signal analysis: wavelet analysis, empirical mode decomposition, smoothness priors approach as well as the application in the separation of the actual biomedical data. The different separation methods should be selected according to different research goals as well as the feature of the signal.

Comprehensive testing system for cardiorespiratory interaction research / 生物医学工程学杂志

To investigate the modulation effects of breathing movement on cardiovascular system and to study the physiological coupling relationship between respiration and cardiovascular system, we designed a comprehensive testing system for cardiorespiratory interaction research. This system, comprising three parts, i. e. physiological signal conditioning unit, data acquisition and USB medical isolation unit, and a PC based program, can acquire multiple physiological data such as respiratory flow, rib cage and abdomen movement, electrocardiograph, artery pulse wave, cardiac sounds, skin temperature, and electromyography simultaneously under certain experimental protocols. Furthermore this system can be used in research on short-term cardiovascular variability by paced breathing. Preliminary experiments showed that this system could accurately record rib cage and abdomen movement under very low breathing rate, using respiratory inductive plethysmography to acquire respiration signal in direct-current coupling mode. After calibration, this system can be used to estimate ventilation non-intrusively and correctly. The PC based program can generate audio and visual biofeedback signal, and guide the volunteers to perform a slow and regular breathing. An experiment on healthy volunteers showed that this system was able to guide the volunteers to do slow breathing effectively and simultaneously record multiple physiological data during the experiments. Signal processing techniques were used for off-line data analysis, such as non-invasive ventilation calibration, QRS complex wave detection, and respiratory sinus arrhythmia and pulse wave transit time calculation. The experiment result showed that the modulation effect on RR interval, respiratory sinus arrhythmia (RSA), pulse wave transit time (PWTT) by respiration would get stronger with the going of the slow and regular breathing.

Design of hand-held heart rate variability acquisition and analysis system / 中国医疗器械杂志

A design of handheld heart rate variability acquisition and analysis system is proposed. The system collects and stores the patient's ECG every five minutes through both hands touching on the electrodes, and then -uploads data to a PC through USB port. The system uses software written in LabVIEW to analyze heart rate variability parameters, The parameters calculated function is programmed and generated to components in Matlab.

The development of heart rate variability analysis system / 中国医疗器械杂志

A heart rate variability (HRV)analysis system is presented. The change of the activity of Sympathetic and vagus nerve is evaluated by detecting the parameters of heart rate variability of the tested in different states using the system. The system provides a tool for the study of heart rate variability.

Research on the respiratory sinus arrhythmia in the process of guided breathing / 生物医学工程学杂志

To investigate the effects of gradually guided breathing on respiratory sinus arrhythmia (RSA), 15 healthy men's simultaneous ECG and respiratory signals during the guided breathing process (14 beats/min-12.5 beats/ min--1 beats/min--9.5 beats/min--8 beats/minute--7 beats/min) were acquired. Based on the frequency domain and time domain methods, the effects of respiratory rate on RSA were studied. A general tendency increase features the three parameters of RSA as respiratory rate decreased. RSA represents the reflection control of respiratory system to cardiovascular system. The results suggested that the function of the reflection control of respiratory system to cardiovascular system increaseed with guided breathing decreasing. The conclusion indicates that the cardiovascular system could be improved by regulating the mode of respiration.

Study of analysis of the singularity of R-wave by using wavelet transform / 生物医学工程学杂志

Singularity is a basic feature of biological signals. Based on the variations of wavelet transform modulus maxima in multi-scales, we studied the basic theorem for analyzing the singularity and proposed an algorithm for calculating lipschitz exponent. Then we applied the algorithm to calculate the singularity of R-wave in ECG. Our study found that the level of singularity of R-waves in ECG between the 10 arrhythm patients randomly chosen and the healthy persons was significantly different, with the level of singularity of R-wave of normal persons remarkably higher than that of arrhythmia patients.

Research progress of quantitative analysis for respiratory sinus arrhythmia / 生物医学工程学杂志

Respiratory sinus arrhythmia (RSA) is known as fluctuations of heart rate associated with breathing. It has been increasingly used as a noninvasive index of cardiac vagal tone in psychophysiological research recently. Its analysis is often influenced or distorted by respiratory parameters, posture and action, etc. This paper reviews five methods of quantification, including the root mean square of successive differences (RMSSD), peak valley RSA (pvRSA), cosinor fitting, spectral analysis, and joint timing-frequency analysis (JTFA). Paced breathing, analysis of covariance, residua method and msRSA per liter tidal volume are adjustment strategies of measurement and analysis of RSA in this article as well. At last, some prospects of solutions of the problems of RSA research are given.

An acquisition and analysis system of ECG based on LabVIEW / 医疗卫生装备

A realtime system used for acquisition and analysis of ECG based on LabVIEW is presented in this paper.This realtime system can accomplish the functions such as the acquisition and display of ECG and the calculation of Instantaneous Heart Rate(IHR)and the Average Heart Rate(AHR).The system can be implemented easily.In addition,the user can modify and add functions of the system according to his needs conveniently.