Development of Internet Based Remote Health and Activity Monitoring Systems for the Elders

Transcription

1 Journal of Medical and Biological Engineering, 24(1): Development of Internet Based Remote Health and Activity Monitoring Systems for the Elders Chung-Hsien Kuo Fang-Ghun Huang Keng-Liang Wang Ming-Yih Lee * Huai-Wen Chen Department of Mechanical Engineering, Chang Gung University, Tao-Yuan, Taiwan, 333, ROC Received 5 January 2004; Accepted 9 March 2004 Abstract In this paper, we practice an Internet-based remote health and activity of daily living (ADL) monitoring system for the elders using the integrated medical mechatronics techniques. This system consists of the main controller, portable remote controller, host computer, intelligent monitoring application program, emergent phone call software module, voice notification module, real time video delivery, web services, and so on. The proposed system is responsible for the remote care with the elders who are living alone. In this work, the remote care components of data acquisition, voice dialing, video grabbing, status monitoring, voice notification, home security, appliance control and web services are all designed and constructed based on the Internet platform. Especially, the client-server architecture is used to integrate the hardware and software components. Therefore, this system can be used in the rapid aging society. The family and the social service related department or agencies are able to take more attentions to the elder person who is living alone via the Internet. The prototype of this system had been accomplished and initially tested in laboratory. Finally, a demonstration board that simulates the operations of security alarming, appliance control, and data acquisition are also developed to test this system. The results show that the designed purposes can be achieved. Keywords: Medical mechatronics integration, In-house healthcare system, Home automation system, Internet-based remote monitoring and control. Introduction Taiwan has been a rapidly aging society due to the reducing fertility rate and the advanced medical technologies. Currently, Taiwan s elder population is around 8.7 percent of the total Taiwan population, and it is predicted to be 25 percent by the year 2040 [14]. Hence, the aging problems are becoming the major concerns for the future healthcare policies. Therefore, the problems of increasing elder population will be more important in the future. Based on the increasing information technologies and rapidly aging society. Several researchs promoted related remote care techniques and reports. In 2000, Pellet et al. [9] proposed the client-server component architecture based healthcare network for the connection of ambulatory biochemical device. In this paper, the device vigilance system was designed based upon control process database. Bali [1] proposed the cause for the concern in the organizational and social impacts of the telehealth in In this paper, the *Corresponding author: Ming-Yih Lee Tel: ext. 5340; Fax: leemiy@mail.cgu.edu.tw social aspects of our live and shape of the telehealth industry in the future were also discussed. In addition, Person et al. [10] also proposed the Internet based consultation and referral network between Tripler Army Medical Center and hospitals in the Western Pacific. The initial experience showed that the Internet solution is possible and easy to be used as an inexpensive store and forward consultation format. Lau et al. [6] proposed the asynchronous web-based patient-centered home telemedicine system. This system focused their works on the remote investigation and monitoring of the patient who was after a shoulder replacement surgery. The asynchronous multimedia messaging of patients at home can be accessed by their surgeons using the web browser. In addition, the biosensor instruments such as glucometers and spirometers can also be connected to a personal computer so that they can be transferred to the home telemedicine web site. Guo et al. [3] proposed an Internet based telemedicine system for the telemonitorings of the medical data and the virtual instruments. The virtual instruments such as electrocardiogram (ECG), electromyogram (EMG) and electroencephalogram (EEG) were implemented using the

2 58 J. Med. Biol. Eng., Vol. 24. No Ethernet LAN Host Computer Wireless RF Remote Controller - Transmitter Transmitter RF Healthcare Management Database Emergency Phone Call (EPC) Web Live Video Voice Notification Login Agent COM 1 RS232 COM 2 ADC Conversion Main Controller Modem Multiplexer Electronic Blood Pressure Meter Electronic Body Temperature Indicator Multiplexer Multi-Channels Power Amplifier Relay Relay Appliance Appliance Drinking Fountain Security System Toilet City Dial Network Figure 1. Integrated system development architecture LabView (National Instruments, Austin, TX, USA) modules. The proposed system was capable of extracting the valuable diagnostic information using embedded advanced biomedical signal processing algorithms. The system had been tested, and it used the Java applets and pcanywhere software to realize the medical data and signal transmissions via the 300 kpbs cable modem. Based on the importance of the Internet-based healthcare (telehealth/ remote healthcare) tendency in the future, this paper developed an integrated in-house remote healthcare and home automation system for the elder person who is living alone. The desired system can monitor the physiological parameters of the blood pressure, body temperature, heart rate, and so on. It can also collect the behavioral measurements of the activity of daily living (ADL) such as the frequencies of the drinking water and using the toilet. Meanwhile, the functions of voice notifications such as taking medicine and measuring physiological data were considered too. Meanwhile, this system integrates the home automation, live video and in-home security systems simultaneously to assist the elder and disabled person to control the appliances and to ensure the home security. In addition, the emergent phone call (EPC) module is implemented as a software application in this work. The EPC can dial the emergent phone calls from either the activation of the user s command or the decision of physiological signal monitor module in terms of the pre-registered phone numbers and prerecorded voice files via the voice modem. Especially, the proposed system can be accessed using the Internet techniques. In this manner, the family and the social service related department or agencies are more feasible to take attentions to the elder person. The proposed system is composed of the main controller, remote controller, host computer, physiological signal acquisition device, sensor sets, and video camera. The main controller is designed as a communicable single processor based controller. It is responsible for the signal collections from the sensor sets and physiological signal collection devices, home automation and security system. Additionally, the main controller can communicate with the host computer using the serial communication and the portable remote controller using the wireless RF data receiver. A healthcare management server is developed using the Microsoft Visual C++. The healthcare management server is composed of the data acquisition, EPC, database storage and accessing. A web server constructed in this paper is to integrate the information of the healthcare management server and live video service. Finally, the objectives of the proposed system are summarized as follows: 1. Provide the Internet-based services of the network reachability, network accessibility, and network convenience. 2. Reduce the healthcare efforts of the family and the social service related department or agencies. 3. Improve the quality of healthcare. 4. Increase the safety and security of the in-house healthcares. 5. Resolve the problems of the living alone elders. 6. Establish the emergency informing system to rescue the emergent patients. 7. Resolve the problems in the insufficient spaces of the hospices. 8. Increase the convenience and quality of life.

3 Internet Health and Activity Monitoring 59 Methods System Development Architecture This paper aims to develop an integrated in-house healthcare and home automation system for the elder person who is living alone. The proposed system can remotely monitor the physiological parameters such as the blood pressure, body temperature, heart rate, and so on. It can also analyze the behavioral measures such as the frequencies of the drinking water and using the toilet. In addition, this system integrates the home automation, live video and in-home security systems simultaneously to assist the elder and disabled person to control the appliances and to ensure the security. In this work, the hardware and software components are designed and constructed as shown in Fig. 1. First, the hardware components are introduced as follows. 1. Host computer: the host computer is an IBM-compatible PC. The operation system (OS) uses the Microsoft Windows The host computer is responsible for the database access and storage, intelligent monitoring, prescheduled activity (e.g., taking medicine) table registration, voice notification, emergent voice dialing, main controller connectivity and manipulating, Windows socket [2] based Internet connection, web service, etc. 2. Main controller: the main controller is desired to receive the messages and commands from a portable remote controller (RF-based data transmitter); control the devices and appliances in home; activate the home security; acquire the behavioral and physiological signals of the elder person; and communicate with the host computer to enable Internet-based remote control and monitoring. 3. Remote controller: it is designed as a portable and wireless data transmitter. The elder person is capable of controlling the appliances and dialing emergent phone calls at anywhere in the house. More specially, the design of dialing emergent phone call is quite important. When an emergent situation such as arrhythmia (irregular heart rate) occurs, the elder person can call the EPC in terms of directly pressing the corresponding function key in the remote controller to call for help. Meanwhile, the prerecorded voice message can be delivered to the family or the social service related department or agencies in terms of pre-registered phone number. Note that the design of the EPC function is not the same as the mobile phone. The proposed EPC function is more emphasized on the situation of the patient who has no time to complete an emergent phone call such as the suddenly fainting. For example, the patient cannot completely dial 3 digits such as 110 (an emergent rescue phone number in Taiwan), or the patient cannot completely describe his/ her name, location and situation. Therefore, the design of the EPC function avoids the situation of incomplete emergence phone calls. 4. Data acquisition: it is composed of the behavioral and physiological signal collections of the elder person. In this work, we practiced an electronic blood pressure and heart rate meter to collect the physiological signal. In addition, the frequencies of drinking water and using the toilet are also acquired to analyze the health behaviors. To achieve these purposes, we mount the sensors on the drinking fountain and toilet flusher to collect the corresponding data. Especially, either the physiological or the behavior signal can all be collected by the main controller. 5. Home security: in addition to collect the physiological and the behavior signals, the home security component is also developed in this system. The home security function can be used to monitor the illicit entries in terms of the magnetic switches [11], vibration switches [12], or the other home security sensors. Once the illicit entry is detected, the alarm system is automatically activated to notify the elder person through the loud sound and to inform the remote family through the city dial network. The alarm system can be canceled using a preset password. 6. Home automation: the home automation system is designed to provide a more convenient way to assist the elder person to control the devices and appliances in home such as the lamp/ light, automatic door opener, and electrical curtain opener. On the other hand, the software application programs are developed based on the PC windows-based environments. The application programs can communicate with the main controller and the voice modem to achieve the desired purposes. The software components are introduced as follows: 1. Voice dial module: the voice dial module is developed for the EPC issues. The EPC can call the emergent phone calls by either from the commands of the remote controller or the home security system. The prerecorded voice messages file can be played when the EPC dials a pre-registered phone number. 2. Live video grabbing web server: the proposed system also integrates a video server to grab the live video frames. The video frames provide more feasible and interactive visual observations to the family and the social service related department or agencies when the emergent situation occurs. 3. Status monitoring module: the status monitor module investigates the physiological and the behavior signals of the elder person, home security status, and appliance status (On/ Off). The status is recorded in the database for the further analyses. In addition, the intelligent monitoring agent is developed to recognize the irregular body temperature, blood pressure and heart rate using the control chart [4, 8] methodology. It can also used to monitor the activities of drinking water or using the toilet. 4. Voice notification: in order to notify the elders to take medicine on time, the proposed system developed the voice notification module. The trigger of the voice notification module can be activated in terms of the pre-scheduled table in host computer or the remote

4 60 J. Med. Biol. Eng., Vol. 24. No Remote Family/ Hospital In-House Software Components HTTP Web Browser Intelligent Status Monitoring Software Coding/ Web Host Control Software Elders Wireless RF Voice Dial Video RS 232 In-House Hardware Components RS 232 Portable Remote Controller ADL Acquisition TCP/ IP Host Computer and Voice Notification Appliance Control Control/ Signal Security Components Main Controller Physiological Signal Collection Figure 2 Components of remote elder health and ADL monitoring system Elder Health and ADL Monitoring System Development Architecture Hardware Components Software/Network Components Remote Controller (89C51 Processor) Portable FR Remote Controller Main Controller (89C51 Processor) Physiological Signal Collection Behavioral Data (ADL) collection Security Components Host Computer Appliance Control Voice Modem Emergent Phone Call Sound Speaker Voice Notification Video CCD Camera and AXIS Video Host Control and Monitoring (Microsoft Visual C++) Main Controller Manipulation EPC Dial Module Intelligent Control Chart Monitoring and Abnormal Event Detection Voice Notification Module Physiological Status Acquisition ADL Behavioral Status Acquisition Video Web Link Web (ASP.NET) Physiological Database Link Behavioral Database Link Appliance Status Database Link Security Status Database Link Event Report Database Link Family/ Hospital Web Browser Based Remote Monitor Figure 3 System hardware and software development architecture family/ hospital notification via the Internet. In addition to notify the taking medicine, this module can also be used to notify the elders for not drinking water or using the toilet for a certain long time in terms of the intelligent monitoring agent in the host computer. 5. Integrated web service: in this work, an integrated web service is constructed to integrate the previously described live video grabbing, status monitoring, and appliance control. The remote users such as the family and the social service related department or agencies are able to monitor the status of the elder person who is living alone through the Internet. In summary, the proposed hardware and software components of the remote elder health and activity of daily living (ADL) monitoring system can be configured and integrated as shown in Fig. 2. The detail implementations are shown in the following subsections.

5 Internet Health and Activity Monitoring 61 Keyboard LCD Monitor RF Receiver RF Wireless Module (Receive) Scan Keyboard Input LCD Information RS 232 Host Computer 89C51 Single Processor Sensor Sets Appliance Controls Power Supply Door Security Drinking Water Toilet Flusher Blood Pressure Meter Lamp DC Power Figure 4 Control architecture of main controller pump Pressure Sensor Human Body Data to Main Controller 89C51 Single Processor Differential Amplifier High Pass Filter (0.8Hz) Low Pass Filter (38Hz) ADC Conversion Signal Amplifier (150~ 200X) Figure 5 Signal block diagram of the in-lab designed electronic blood pressure measure device Hardware Implementations Based on the components indicated in Fig. 2, the proposed system needs not to develop these hardware and software components but also to integrate them properly. Fig. 3 shows the development architecture of this system. The system development tools includes the 89C51 single processor, Microsoft Visual C++, Microsoft Active Page (ASP).Net, Microsoft Internet Information Services (IIS), and Microsoft Access database [16]. Main Controller Implementation The main controller is the kernel of the hardware system. Its control architecture is shown in Fig. 4. The main controller is composed of an 8 bit single processor (89C51 type) and several periphery circuits. The periphery circuits include the input data pins, output data pins and the ultra (serial) communication. The input data pins are specified to receive the RF data, scan the keyboard, collect the status of the ON/ OFF sensors, and receive the parallel data of the analog-to-digital converter (ADC), and they are described as follows. 1. The RF data receiver module receives the commands from the remote controller. 2. The keyboard scanning is used to scan the keyboard input, and the scanned password can be used to cancel the activation of alarm. 3. The ON/ OFF sensors are categorized into the limit switch, magnetic switch and vibration switch. The limit switches are mounted on the drinking fountain and toilet flusher to count the times of drinking water and using toilet. The magnetic switch and vibration switch are used for the home security issues. They are mounted on the door and windows to detect the illicit entries. 4. The ADC conversion is used to measure the analog signals from the sensors such the body temperature and the blood pressures. In this work, an electronic blood pressure measure device was developed. The signal block diagram of the in-lab designed electronic blood pressure measure device is shown in Fig. 5. Based on the signal flow diagram, the control circuit was layouted using the Protel software [17] and practically implemented. On the other hand, the output data pins are used to control the appliances. The control signals are further amplified to control the relays of the corresponding appliances. Note that the predefined appliance control procedures are executed in terms of different digit codes (commands from remote controller). Finally, the ultra communication enables the dual-direction communications between the host computer

6 62 J. Med. Biol. Eng., Vol. 24. No RF Wireless Module (Send) Keyboard RF Transmitter 89C51 Single Processor Power Supply (Battery) Scan Keyboard Input Figure 6 Control architecture of remote controller and the main controller. The following messages are delivered using the serial communications. 1. Physiological signal collection: the host computer can active the operation of the physiological signal measure devices, and then acquire the results. 2. Appliance control and status collection: the host computer can control the appliance. The host computer can also collect the status of the appliance. 3. Behavior signals collection: the newly updated behavior data can be transmitted to the host computer. 4. Home security status collection: the host computer can monitor the home security status from the installed sensors. 5. Dialing EPC: when the main controller receives the dialing EPC command from the remote controller, it transmits the dialing request to the host computer immediately. Remote Controller Implementation The control architecture of proposed remote controller is shown in Fig. 6. It provides a more feasible and convenient way to control the main controller. It also consists of an 8 bit single processor (89C51 type) and several periphery circuits. The periphery circuits include the input data pins and output data pins. The input data pins are specified to scan the keyboard; the output data pins are desired to send request commands to the RF transmitter module. The keyboard input commands are classified into two categories, and they are: 1. Activating the function of dialing EPC. Each digit number correlates to a specified phone number and a prerecorded voice message file. Note that the corresponding phone numbers and prerecorded voice message files must be stored in the files of the host computer. 2. Controlling the devices and appliances such as the lamp/ light, automatic door opener, and electrical curtain opener. Software Implementation The software components include the status monitoring, appliance control, live video capture, voice dialing, and web service. They are described as follows: Status Monitoring, Appliance Control and Voice Dialing The status monitoring and control application program is developed using the Microsoft Visual C++ [5, 16]. The status of the physiological signal, behavior signal, appliance status, and security status is recorded in the database. The application program invokes the open database connectivity (ODBC) [7] to connect the Microsoft Access database for the data storage. In addition, the application program also enables the serial communication port to communicate with the main controller using the serial port. In addition, the EPC dial service is also implemented. In this work, we use the VTapi ActiveX Control [13] to control the voice modem. By using the VTapi ActiveX Control, the prerecorded file with the corresponding phone number can be delivered. In order to monitor the physiological and behavioral signals of the elders, the intelligent monitoring system is constructed based on the rule based inference and the control charts. The control chart is one of the important tools of statistics process control (SPC) used in the process control. It can be used to identify the assignable causes. In this work, we use the concept of the control chart to monitor the physiological and behavioral signals automatically. In summary, seven validation rules are used to identify the abnormal signals in advance. 1. When one data is out of 3 times sigma, the patient is suggested to go to hospital for diagnosis. 2. When arbitrary two data is out of 2 times sigma in three continuous data, the patient must check health status. 3. When arbitrary four data is out of one sigma in five continuous data, the patient must take care. 4. If there is 8 continuous data locate in the same side of the control chart, the patient must take care. 5. The patient must take care when five continuous data are increasing (or decreasing) monotonically. 6. The patient must check health status when six continuous data are increasing (or decreasing) monotonically. 7. The patient must go to hospital immediately when seven continuous data is increasing (or decreasing) monotonically. When any abnormal signal is identified, the events are recorded in the database. The family and hospital can check the events through the Internet. Especially, for serious case, the events can automatically call the EPC to inform the corresponding person. Live video Capture In this work, we use the AXIS 2400 Video [15] to grab the live videos. The AXIS 2400 Video provides four channel inputs for the analog CCD cameras. The video frames can be captured and transformed to the digital images. Especially, the built-in Web, FTP (File Transfer Protocol) and TCP/ IP (Transmission Control Protocol/ Internet Protocol) communication channel [2] functions increase the network integrability. In this work, we use the built-in Web to control the zoom and direction of the CCD. Fig. 7 shows the architecture and photo of the AXIS 2400 Video [15].

7 Internet Health and Activity Monitoring 63 (a) Figure 10 Photo of in-lab designed main controller (b) Figure 7 Control architecture and photo of AXIS 2400 Video [15] Web Browser Client Site (Family/ Hospital) HTTP Request HTTP Response Database Tier Service Tier Host Control Program Main Controller Access Database ASP.NET Web Intelligent Monitoring Program Real Time Control Chart Web Event Report Program Detected Event Logs Figure 8. Web service architecture In-House Healthcare Web Client Browser Tier Internet Client Browsers from Remote Family Database Application Service index.aspx <HTML> <BODY> Time Now <% T=Now() Response.Write(T) %> </BODY> </HTML>. Live Video Web AXIS Video Serial Main Controller Client Browsers from Social Service Related Department or Agencies Figure 9 Modified three-tier architecture Web Service In addition to the local monitoring and control of the in-house healthcare system, this system also provides the Internet accessibility. In this portion, we established a web server using the Microsoft IIS (Internet Information Services) server. The web pages promote the functions of application program except the voice dialing. The web pages are developed in terms of the html protocol. In addition, the ASP (Active Page).Net [16] is also used to connect the status database for the remote accessing of the Internet users. Finally, the AXIS 2400 Video is also embedded in the web server to provide remote video accesses. The web service architecture is shown in Fig. 8. System Integration In this section, the proposed hardware and software components are integrated. We used a modified three-tier architecture to integrate this system, as shown in Fig. 9. The three tiers are the database server, service server, and client browser tiers. The service server tier is further categorized into the web server and application service server. The application server is designed as the status monitoring and appliance control server. The application program updates the status database for the web server accessing. In this manner, the web server can get the newest data and status of the main controller via the application server. Results In this section, the results are introduced. All hardware and software components and modules are designed and developed in laboratory. These components had been initially tested and validated based on the individually hardware test, software simulation, database connectivity, network connection, and web services, and the integrated validations. Fig. 10 shows the in-lab designed main controller. Fig. 11 shows the in-lab designed portable remote controller. In order to collect the body temperature, heartbeat and blood pressure, the digitalized physiological measure instruments were also developed. Fig. 12 shows the in-lab designed electronic blood pressure meter. Note that these digitalized instruments can be controlled by the main controller.

8 64 J. Med. Biol. Eng., Vol. 24. No Figure 11 Photo of in-lab designed portable remote controller Figure 15 Detected abnormal event logs and the detail of event Figure 12 Photo of electronic blood pressure meter Figure 13 GUI of the application program On the other hand, the software modules are also introduced. Fig. 13 shows the graphical user interface (GUI) of the application program. In this figure, the status of the serial port, collected signal, and voice dialing can be shown in the GUI. In addition, the registered phone number and the corresponding voice message file (wave type file) can also be managed using the GUI. In addition, the control chart of abnormal signals can be recognized using the constructed automatically control chart analysis, as shown in Fig. 14. In this figure, the mean and control limits are all addressed. Fig. 15 shows the detected abnormal event logs and the event details. Meanwhile, the voice notification schedule management dialog is also developed, as shown in Fig. 16. The web services are also constructed. Only the authorized users can access this system. Fig. 17 shows the snapshot of the client browser. In this figure, the monitoring of the physiological signals, behavior signals, and appliance status are all indicated. Simultaneously, the live video frames can also be controlled in ranged zooms and direction. Finally, in order to demonstrate the proposed system, a demonstration circuit board of simulating the operations of the security alarming, appliance control, and data acquisition is developed in this paper, as shown in Fig. 18. The simulated sensors and devices are indicated in this figure. Finally, the proposed system had been successfully tested in our laboratory. The results show that the proposed system achieves the designed purposes. Discussion Figure 14 Control chart monitor of the body temperature This paper uses the hardware, software and communication development technologies to accomplish an integrated medical mechatronics system. The remote patient and hospital can use the browser to take more attention to the living alone elders in terms of the proposed main controller, video server and physiological signals and behaviors data. The system had been successfully integrated and tested in our laboratory. The proposed control chart based abnormal signal detection and recognition is used to development intelligent monitoring module. In addition to remotely monitor the health

9 Internet Health and Activity Monitoring 65 Figure 16 Voice notification schedule management dialog Figure 17 Snapshot from client browser 5. The voice notification module can notify the elder to take medicine on time, and to inform the elder for not drinking water and using toilet. 6. The EPC function provides an emergent cal for help mechanism by using portable remote controller, and the pre-recorded voice files can be played in the phone automatically. 7. The proposed system is developed based on the Internet and city dial network, it can integrate with telemedicine system in the future. Conclusions This paper proposes an Internet-based solution for the increasing aging problems. The proposed system integrates the techniques of the specific electric control circuit design, sensor data acquisition, wireless control, emergent phone call service, software programming, web server development, home automation and security, remote monitoring and control, and live video grabbing. Especially, all the hardware and software components are all implemented and integrated properly. This system decreases the loading of healthcare and increases the security and safety of the elder person. Finally, this system had been successfully tested and validated based on a demonstration electric board. The results show that the proposed solution can achieve the desired purposes. In the future, the intelligent diagnosis system can be developed based on the monitoring system to increase the system performance. Acknowledgements This work was supported by the Medical Mechatronics Education Resource Center, Ministry of Education, Taiwan, R.O.C., under the 2001 Student Hand-On Competition Project. References Figure 18 Photo of demonstration circuit board of the elder, this system can be also used in the home security and home automation. Such a solution plays important role in the rapid aging society. Hence, the proposed system can be characterized as following: 1. Promote a solution to resolve the increasing aging problems. 2. The family and patient may take more attention to the living alone elders through the Internet. 3. The heath status can be measured and recorded using the proposed in-lab designed controller and instruments. 4. The sick signs can be recognized using the proposed control chart engine in advance. [1] R.K. Bali, Organizational and Social Impacts of Telehealth: a Cause for Concern, Proc. of IEEE EMBS International Conference on Information Technology Applications in Biomedicine, 54-59, [2] G. Coulouris, J. Dollimore and T. Kindberg, Distributed Systems - Concepts and Design, England: Addison-Wesley, [3] Z. Guo and J.C. Moulder, An Internet Based Telemedicine System, IEEE EMBS International Conference on Information Technology Applications in Biomedicine, , [4] C.H. Kuo and H.P. Huang, Failure Modeling and Process Monitoring for Flexible Manufacturing Systems By Using Colored Timed Petri Net, IEEE Transaction on Robotics and Automation, 16: , [5] D.J. Kruglinski, Inside Visual C++ - The Standard Reference for Programming with Microsoft Visual C++, Version 4, Washington:Microsoft, [6] C. Lau, R.S. Churchill, J. Kim, F.A. Matsen and Y. Kim, Asynchronous Web-Based Patient-Centered Home Telemedicine System, IEEE Transactions on Biomedical Engineering, 49: , 2002.

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