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.
Algorithms ; Nonlinear Dynamics ; Signal Processing, Computer-Assisted ; Wavelet Analysis

Objective To study the characteristic of histological structure of the pineal gland of the adult yak. Methods HE and Achucarro-Hortega staining,light microscopy and transmission electron microscopy were used. Results The pineal gland was composed of pinealocytes,occasional glial cells,capillaries and neural elements.The pinealocyte appppered clear electronic density and its cytoplast included numerous mitochondria,rough and smooth endoplasmic reticulum,microtubules,microfilament and ribosome.Golgi complex was rare.The typical heterogenous organelle of pinealocyte of yak was spherical synaptic ribbon,which located near the plasma membrane.The glial cells contained abundant of mitochondria,and their processes which appeared bulbous invested the pineal periphery and incompletely separated the pinealocytes.Synapse and junctional complex existed between the pinealocytes and glial cells.Capillaries in pineal gland of the yak were belong to continuous capillaries,and pigment cells were observed around the vascellum in the gastr-distally of the pineal gland. Conclusion Neuroepithelial and epithelioglandular cell conjuction can be observed in the pineal gland of adult yak.Capillaries are belong to continuous capillaries.There are aboundant of organelle except Golgi complex in the pinealocyte.

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.
Adult ; Blood Pressure ; Blood Pressure Determination ; Electrocardiography ; Essential Hypertension ; Humans ; Hypertension ; Pulse Wave Analysis ; Respiration ; Respiratory Rate

This paper introduces a free and publicly open ICU database: multi-parameter intelligent monitoring in intensive care II: MIMIC-II, which has been built up and maintained by the laboratory of computational physiology at the Massachusetts Institute Technology, Beth Israel Deaconess Medical Center and Philips Healthcare over the past decade. This paper briefly introduces its infrastructure, implementation and applications in clinical studies. Clinical study pertaining to circadian variation in heart rate and blood pressure during sepsis is shown as a typical example of research performed with MIMIC-II. In this study, it was found there was significant difference in circadian variation in both heart rate and blood pressure between survival and non-survival groups in septic patients. This study tackled several important techniques necessary for the investigation of the circadian rhythm.
Blood Pressure ; Circadian Rhythm ; Critical Care ; Data Mining ; Databases, Factual ; Heart Rate ; Humans ; Medical Informatics

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.
Adult ; Algorithms ; Electrocardiography ; Heart Rate ; Humans ; Photoplethysmography ; Reproducibility of Results

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.
Adult ; Autonomic Nervous System ; Electrocardiography ; Heart Rate ; Humans ; Models, Cardiovascular ; Reproducibility of Results ; Software

Objective To design a high performance and low power consumption ECG signal acquisition system which can meet the demand for long time monitoring of the physiological status of patients.Methods The prototype system utilized low power ECG analog front end ADAS1000 and MSP430F5529 microcontroller to achieve configuration of AFE and back-reading of ECG data by SPI bus. Results This system implemented 24-hour dynamic ECG monitoring of patients in active state, and the data acquired were accurate and reliable.Conclusion The system realizes PCB integration, low power consumption, and can be used for battery powered portable application such as wearable devices.

The forced oscillation technique (FOT) is a noninvasive method for respiratory mechanics measurement. For the FOT, external signals (e.g. forced oscillations around 4-40 Hz) are used to drive the respiratory system, and the mechanical characteristic of the respiratory system can be determined with the linear system identification theory. Thus, respiratory mechanical properties and components at different frequency and location of the airway can be explored by specifically developed forcing waveforms. In this paper, the theory, methodology and clinical application of the FOT is reviewed, including measure ment theory, driving signals, models of respiratory system, algorithm for impedance identification, and requirement on apparatus. Finally, the future development of this technique is also discussed.
Algorithms ; Electric Impedance ; Oscillometry ; Physical Therapy Modalities ; Respiratory Mechanics

Objective To study the curative effect of continuous alternant drainage surgery on improved central venous catheter cerebellomedullary cistern and continuous alternative drainage of ventricle in treating cerebroventricular hemorrhage.Methods 118 cases of patients with cerebroventricular hemorrhage were randomly divided into two groups:the improve group(n=59)was applied with continuous alternative drainage of ventricle and improved central venous catheter cerebellomedullary cistern,and the control group(n=59)was applied with traditional drainage of ventricle combined with lumbar centesis.Results In the improved group 3 cases(5.1%)died,and 7 cases(11.9%)developped with obstructive waterhead.In control group 8 cases(13.6%)died,and 15 cases(25.4%)developped with obstructive waterhead.The cleanup speed of cerebroventricular hemorrhage for patients in the improved group was much faster than that in the control group(P＜0.01).The curative effect of the improved group was distinctly better than that of the control group(P＜0.05).Conclusion Cerebroventricular hemorrhage treated by continuous alternative drainage of ventricle and the improved central venous catheter cerebellomedullary cistern and and continuous alternative drainage of ventricle can distinctly reduce mortality,deformity,complication and sequelae.

Objective To design a wearable rehabilitation device suitable for home and society COPD treatment aiming at the deficiency in the COPD pulmonary rehabilitation in China. Methods Physical activity therapy and pulmonary physical therapy methods which play very important role in the COPD pulmonary rehabilitation were studied. Physiological parameters of the COPD patient were acquired non-intrusively with wearable technique. Biofeedback technology was used in the respiratory rehabilitation therapy. Target heart rate and SPO2 were used as parameters for the activity intensity assessment. Results Wearable COPD pulmonary rehabilitation device based on breathing biofeedback was fabricated. Conclusion This device is a favorable rehabilitation tool for COPD patients to do self-training at home or community.