Spectral analysis and LDB based classification of heart sounds with mechanical prosthetic heart valves / 生物医学工程学杂志

Auscultation, the act of listening for heart sounds to aid in the diagnosis of various heart diseases, is a widely used efficient technique by cardiologists. Since the mechanical prosthetic heart valves are widely used today, it is important to develop a simple and efficient method to detect abnormal mechanical valves. The study on five different mechanical valves showed that only the case of perivalvular leakage could be detected by spectral estimation. Though it is possible to classify different mechanical valves by using time-frequency components of the signal directly, the recognition rate is merely 84%. However, with the improved local discriminant bases (LDB) algorithm to extract features from heart sounds, the recognition rate is 97.3%. Experimental results demonstrated that the improved LDB algorithm could improve classification rate and reduce computational complexity in comparison with original LDB algorithm.

Detector efficiency for non-helical trajectory of cone beam reconstruction / 生物医学工程学杂志

Using the present cone beam reconstruction formula for general trajectory, we have investigated the issue of detector efficiency for non-helical trajectory. The results reveal that the two factors dominating the detector efficiency are detector geometry and filtering directions. The methods for to higher detector efficiency are proposed, and the reliability and feasibility are tested by simulation results.

Biocompatibility of artificial lung membrane materials / 中国组织工程研究

Artificial lung, also called oxygenator, has the properties of oxygenation, heterotherm, blood store, filtration, and blood retrieval, oxygenates venous blood with low oxygen to arterial blood with high oxygen, similar to human physiological condition, and functions as an ideal artificial organ. Membrane artificial lung has been widely used in extracorporeal circulation of cardiovascular surgery, as well as rescue of respiratory failure, i.e. extracorporeal life support or extracorporeal membrane oxygenation. And the intravascular oxygenator has been primarily used in clinic. In particular, membrane oxygenator is essential for patients with severe disease, poor heart function, and long-duration operation. Currently, based on membrane material modification and optimization, as well as experimental and clinical evaluations of various properties, studies of artificial lung focus on improvement of gas exchange and biocompatibility, so as to provide reliable means of rescuing patients.

Cough sound detection bases on EMD analysis and HMM recognition / 生物医学工程学杂志

Cough is one of the most common symptoms of many respiratory diseases; the characteristics of intensity and frequency of cough sound offer important clinical messages. When using these messages, we have need to differentiate the cough sound from the other sounds such as speech voice, throat clearing sound and nose clearing sound. In this paper, based on Empirical Mode Decomposition (EMD) and Hidden Markov Model (HMM), we proposed a novel method to analyze and detect cough sound. Employing the property of adaptive dyadic filter banks of EMD, we gained the mean energy distribution in the frequency domain of the signals in order to analyze the statistical characteristics of cough sound and of other sounds not accompanied by cough, and then we found the optimal characteristics for the recognition using HMM. The experiments on clinical date showed that this optimal characteristic method effectively improved the detective rate of cough sound.

A cough sound recognition algorithm based on time-frequency energy distribution / 生物医学工程学杂志

The cough sound is a very important symptom of well over 100 kinds of diseases. Cough sound analysis can provide much information which is useful for diagnosing. Detecting the frequencies and intensity of cough can evaluate the efficiency of therapy quantitatively. In this paper, we put forward an algorithm for cough sound recognition. We first decompose signals with wavelet transform and calculate the normalized energy at each time-frequency point. Then we obtain the normalized energy distribution statistically. After that, we pick out the time-frequency points maximizing a certain discriminant measure of normalized energy distribution between cough sound and non-cough sound, and then we use the normalized energy belonging to these time-frequency points as the inputs of Linear discriminant analysis/Generalized singular value decomposition (LDA/GSVD) classifier. The experimental results show that the classification accuracies achieved by using the algorithm is about 85%, and the computation complexity is low.

The Efficacy of Invasive and Non-invasive Mechanical Ventilation in Treating Severe Respiratory Failure with Chronic Obstructive Pulmonary Diseases / 医学研究杂志

Objective To discuss the efficacy and relative factors that affect the sequential therapy of invasive and non-invasive mechanical ventilation in treating severe respiratory failure.Methods We analyzed the clinical data of the patient who was hospitalized in Respiratory Department of the Sixth Hospital of Luohe on 3th February 2008.Results The patient received invasive mechanical ventilation for 4 days,then changed to mask non-invasive positive pressure ventilation for 10 days,while receiving comprehensive treatment of anti-infection and bronchial expansion,etc.Then the patient was recovered.Conclusion The sequential therapy of invasive and non-invasive mechanical ventilation in treating severe respiratory failure is effective.The efficacy depends on the optimum converting time between invasive and non-invasive mechanical ventilation,the choice of ventilator and the patient′s compliance.

Effect Observation of Combination of Inhaled Ipratropium Bromide and Saibutamol in Treatment of Chronic Obstructive Pulmonary Disease / 医学研究杂志

Objective To observe the different efficacy of combination of inhaled ipratropium bromide and salbutamol and inhaling the two drugs separately. Methods Sixty -five patients with COPD were divided into 3 groups,and treated with different drugs. We observed the lung function FEV1 , the improvement of symptoms and side - effects. Results The FEV_1 and improvement of symptoms in combination group were significantly better than those in seperatin group (P

The preprocessing of subtraction and the enhancement for biomedical image of retinal blood vessels / 生物医学工程学杂志

Image segmentation is still a difficult problem since its effect would vary with the subjects processed. An approach of subtracting background from the entire image of retinal blood vessels presented in this paper. The background subtraction is based on the real image itself taken photographically and is not dependent on the prior knowledge of system for recording image, the approach achieves the grayscale enhancement of retinal blood vessels in preprocessing and provides a quality image for the next process of binarization. This experiment in the preprocessing of subtraction shows good enhancement effect.