Daming Wei

3G mobile phone applications in telemedicine - a survey

In this paper, we review current 3G mobile phone applications in telemedicine. Mobile phones are the backbone of mobile communications and have experienced explosive growth. 3G mobiles provide a next generation mobile phone service that aims to offer high-speed 2Mb/s communication using high transmission efficiency in the high frequency 2GHz band. This offers a groundbreaking way to use mobile phones. Mobile phone service became ubiquitously available throughout Japan as 3G mobile phone offers major advantages for interactive video traffic. With the emergence of mobile phone networks, a number of systems which use mobile phones to transfer vital signs such as electrocardiogram (ECG) and heart rate have increased instead of early mobile medical system using satellites to establish communications between remote sites and base hospitals. Applications of mobile phone have become diversified and derive many services. It is predicted that the proportion of 3G mobile phones would overtake that of 2G mobile phones by 2006.

State of the Art in Gait Analysis Using Wearable Sensors for Healthcare Applications

The ability to measure human movement accurately forms an essential part of a clinical assessment, thus allowing the efficacy of therapeutic interventions to be determined. The most commonly used clinical method for assessing human movement is goniometry, motion capture system, Electromagnetic tracking systems and so on. There are some essential limitations in each method. Inertial sensors such as accelerometers, magnetometers and gyroscopes have the potential to be used for assessing human movement in various environments. Numerous studies have reported using systems based on accelerometers or gyroscopes. These two types of sensors may also be combined to study human motions with good accuracy. The present study employed an inertial system which utilized such fusion technology which is reported to provide motion data with better accuracy. This paper reviews walking analysis using wireless inertial sensors currently, analyzes the features of this methods comparing with other methods, and indicates the key problem and the future direction and application domains.

Separation of electrocardiographic and encephalographic components based on signal averaging and wavelet shrinkage techniques

During ambulatory monitoring, it is often required to record the electroencephalogram (EEG) and the electrocardiogram (ECG) simultaneously. It would be ideal if both EEG and ECG can be obtained with one measurement. We introduce an algorithm combining the wavelet shrinkage and signal averaging techniques to extract the EEG and ECG components from an EEG lead signal to a noncephalic reference (NCR). The evaluation using simulation data and measured data showed that the normalized power spectrum unvaried in all frequency bands for the EEG components, and the sensitivity and specificity of R-wave detection for the ECG component were nearly 100%.

A study on Japanese mobile phone market and its applications

The prevalence of Internet-capable mobile phones in Japan, since first services were introduced in 1999, is so significant that a new culture or lifestyle is being created. Under these circumstances, various companies and universities have launched many projects utilizing mobile phones. This article discusses current technological trends, the mobile phone market in Japan, and mobile applications in general. Our health monitoring and management system using mobile phones, supported by the Ministry of Education, Culture, Sports, Science and Technology in Japan, is described as an example of such newly enabled applications.

Development of a scalable healthcare monitoring platform

Design and implementation of a universal platform based upon mobile telephony and Internet infrastructure for healthcare monitoring and other related applications are described. The platform hierarchy comprises three layers for sensing, communication, and management. The core of the sensing layer is a wearable sensor unit suitable for vital signs monitoring without discomfort and constraint during daily activities. The communication layer conducts bi-directional data/command signals via either wired or wireless means to bridge between the sensor and management layers. The management layer performs data mining and functional assessment. This article describes the architecture design considerations and systemic implementation to meet various practical needs and provide scalable solutions not only for home healthcare but also other applications driven by vital signs. Three applications platformed on this architecture are described.

An approach for extractions of pulse and respiration information from pulsatile pressure signals

We present an approach to extract respiration signal and pulse signal that have been included in measured pulsatile signals of a pillow cuff installed on the occiput of user. In this article, we investigate a separation approach based on ICA (independent component analysis). Since there are only two observations which are two linear mixtures of three sources, pulse, respiration and noise, a usual ICA only cannot separate them perfectly. To solve this problem, we proposed a two-step algorithm; the first step includes a standard ICA and the second step includes two pieces of filter processing. In the ICA step, we can remove the noise from the mixtures of pulse and respiration signal. The filter processing can further separate the pulse and respiration. We shall present our simulation and experimental results. The obtained results are compared with reference pulse and respiration that are measured simultaneously with pillow cuff measuring, which shows effectiveness of our approach.

Ventricular fibrillation mechanisms and cardiac restitutions

BACKGROUNDnThe action potential duration (APD) and the conduction velocity (CV) restitution have been reported to be important in the maintenance and conversion of ventricular fibrillation (VF), whose mechanisms remain poorly understood. Multiple-wavelet and/or mother-rotor have been regarded as the main VF mechanisms, and APD restitution (APDR) and CV restitution (CVR) properties are involved in the mutual conversion or transition between VF and ventricular tachycardia (VT).nnnMETHODS AND RESULTSnThe effects of APDR (both its slope and heterogeneity) and CVR on VF organization and conversion were examined using a rule-based whole-heart model. The results showed that different organizations of simulated VF were manifestations of different restitution configurations. Multiple-wavelet and mother-rotor VF mechanisms could recur in models with steep and heterogeneous APDR, respectively. Suppressing the excitability either decreased or increased the VF complexity under the steep or shallow APDR, respectively. The multiple-wavelet VF changed into a VT in response to a flattening of the APDR, and the VT degenerated into a mother-rotor VF due to the APDR heterogeneity.nnnCONCLUSIONSnOur results suggest that the mechanisms of VF are tightly related to cardiac restitution properties. From a viewpoint of the rule-based whole-heart model, our work supports the hypothesis that the synergy between APDR and CVR contributes to transitions between multiple-wavelet and mother-rotor mechanisms in the VF.

Simulation of Intracardial Potentials with Anisotropic Computer Heart Models

To date, most interests in simulation studies with whole heart models are in body surface or epicardial potentials in order to compare the results with measurements in experimental and clinical practices. The focus of this study is paid on intracardial potentials as they are comparable with measurements during the invasive Electrophysiological Study (EPS) and the catheter ablation, which are becoming a dominant means in the therapy of arrhythmias. In this paper, simulations are implemented based on anisotropic computer heart models and a simulation system previously developed. The heart model consists of about 50,000 discrete cell elements with 1.5 mm spatial resolution. An algorithm in computing intracardial potentials inside the four cavities of the heart is developed. The HRA (high right atrium), HIS (His bundle), RVA (right ventricle apex), and CS (coronary sinus) potentials are shown and compared between a normal heart model and a heart model with the Wolff-Parkinson-White (WPW) syndrome. By employing the intracardial potential parameters and morphology, the position of the accessory pathway between the atria and ventricula in the WPW computer heart model can be qualitatively located. It is concluded that the simulated intracardial potentials based on an anisotropic whole heart model can well approximate the realistic intracardial potentials

Development of Lead System for ECG-Derived Respiration Aimed at Detection of Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome is the most common type of sleep apnea, characterized by repetitive pauses in breathing during sleep. Recent studies have investigated screening methods based only on an electrocardiogram (ECG). Generally, in ECG-based screening, the ECG-derived respiration (EDR) is often used, which is caused by the variance in the cardiac electrical axis due to the chest movement associated with the respiration itself. This method might be effective for diagnosing the sleep apnea severity, called the apnea-hypopnea index, which is defined by the duration and occurrence rate of apnea episodes. However, conventional ECG lead systems are not necessarily optimized for this purpose. In this study, nine bipolar electrodes located across the entire ventral thoracic region were devised, based on the conventional lead system, to effectively measure thoracic breathing. To evaluate the most effective electrode placements, two eupneic and three apneic tasks with nine electrodes were conducted, and EDRs were calculated. Then, the respiratory rates were estimated from the EDRs, and the eupnea and apnea groups were classified using features of the EDRs. Consequently, it was found that three electrodes located at the lower thoracic region yielded accurate estimations of the respiratory rate and discrimination rate.

Load-Prediction Scheduling for Computer Simulation of Electrocardiogram on a CPU-GPU PC

Multi-core CPU and GPU technologies upgrades a PC to a personal supercomputer. Many algorithms have been proposed to achieve dynamic scheduling in CPU-GPU hybrid environments. Among them, only pure self-scheduling (PSS) can achieve perfect load balancing in this extremely heterogeneous environment. But PSS can not take full advantage of GPU performance, reduce the overhead of the tail problem, and reduce the dynamic scheduling overhead. In this paper, load-prediction scheduling (LPS) was introduced to solve the above problems. To demonstrate the efficiency of LPS in practical applications, it was implemented to parallelize computer simulation of electrocardiogram. Experimental results of LPS on the computer simulation of electrocardiogram (ECG) show that the LPS algorithm is more efficient than PSS.