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MediLink -- A SmartCard-Assisted Wearable Data Acquisition
Communication System for Emergency and Mobile Medicine


1. Introduction

Telemedicine has advanced significantly in the past five years. This has been due in great part to the maturation of the Internet and the mass availability of high-bandwidth communications and data transfer, image compression techniques, as well as convergences between proprietary medical processing, large-scale database management, and commonly accepted interface and application design standards. Perhaps the most dramatic factors from the technology perspective have been the ability to provide more data, including large image files in lossless or low-loss compressed formats, at speeds that are commensurate with the needs of physicians, nurses, and other health care practitioners. However the increasing speeds and shrinking sizes of computing and telecommunications technology is in itself not a guarantee, nor even a strong convincing argument, that the elaborate and sophisticated techno-structure available today is improving health care management on a global or even regional level for the majority of the world’s population. The technology may be enabling the environment and the mechanisms for many improvements but there are questions about the adequacy for many service sectors and population groups. Due to fundamental changes and evolutions in the practice of health care and health system management, there is an increasing diversity in the number of medical personnel, locations of service, and methods of health care delivery. This spells a change that can best be summed up as increased mobility and distribution and with that a pressing need for further emphasis on developing tools and methods by which medicine can be practiced in this new cultural as well as technological milieu.

The issues and motivations for improved mobile telemedicine can be summarized in the following list:

The objectives of our consortium in the field of telemedicine since 1994 has been to identify the ways and means of improving the service and management of the medical process through sensible application of communications that will enhance response, diagnosis, treatment, and recovery. The aim has been to do so through research and development of tools that are practical for the largest population of users and that can most readily and easily be converted – at the system integration level or by the user community – from one task to another. The goals which have translated into the MediLink design are to answer the requirements of the medical community for effective mobile communications and data management:

There have been some guiding principles and examples for this strategy, originating not so much from the medical community as from computing science and contemporary hardware and software engineering. The success of object-oriented software has enabled Windows applications development to proceed rapidly and efficiently in the employment of modular, reusable code for different applications, perhaps two orders of magnitude faster than a decade ago. Moreover, at the cost perhaps of some individuality and variety in user interfaces and styles of programming, there are now some commonly accepted and expected standards for user interfaces and features within applications. This makes the learning curve faster and smoother for all users of new applications. In such intensive and time-critical environments as emergency response situations or even in home visits where the setting varies continuously, taking advantage of user familiarity and "rote behavior" is a definite help to keeping the provider’s attention on the patient, not the computer.

By effectively designing a generic set of hardware tools and software processes, one can develop not a universal general-purpose machine but a set of components that can easily be customized to specific needs. Such components, from one specific implementation to the next, can share enough in common (in terms of technologies but also from the standpoint of usage and training) to be easily understandable by different and specialized groups of users. By employing "intelligent agent" models derived from artificial intelligence and expert systems development, one can reduce the amount of specialized learning and interaction between the human user and the computer. In the case of mobile, remote, and certainly emergency medical functions, this is a critical ingredient for practicality. The point of introducing new technology is to make the job of the physician, nurse, or emergency medical technician more effective for the benefit of the patient. Many technology offerings in recent years appear to present more of a workload, more complexity, and more opportunity for error than they solve.

To mitigate the technology demand while providing better access to patient data and other health care providers during an "off-site" or "in-field" procedure has been the overriding goal in designing TransPAC and MediLink. One area of health care where there have long been perceived needs for faster and improved quality of information exchange, and where the telemedicine field has been viewed as a possible avenue for major leaps forward, is in emergency medical response, in the field and in the hospital or clinic. "Emergency" is used here in a very broad sense, referring not only to immediate life-threatening conditions that merit rapid transportation to a receiving hospital, but also conditions that may arise without expectation. These include observables that may be discovered or hinted-at during the course of a routine visit, and which bring about questions that can best be answered by either of two general situations:

  1. having additional patient medical data from the past, such as records on file in a hospital or clinic database server, or
  2. having dialogue and additional interpretation and heuristic advice from other medical practitioners that cannot easily be present at the patient site.

An architecture that can provide real-time voice functions plus real-time exchange of data in both directions, including video, with information security provisions for the benefit of both the patient and the provider, and which is moreover highly portable, minimally intrusive into the normal "script" of medical procedures, and cost-effective, is an architecture that can answer many of the current needs in medicine not being addressed by other systems.

2. The TransPAC Wearable Communications System

MediLink is an application and an expandable toolset environment for doing mobile telemedicine in virtually any type of physical environment. It is based upon a full-function PC platform designed for mobile and wireless operations, the TransPAC. This platform runs Windows95/98 and can be used as a portable unit or as a desktop system. It was originally designed in order to provide a platform for mobile engineering applications requiring real-time internet connectivity for transmission and reception of photos, video, CAD, and GIS data. TransPAC is illustrated schematically by Figure 1 below which shows the basic organization of components. The base hardware system is platform independent but in the prototype development TransPAC is built around a commercially available wearable PC unit. This unit is capable of being worn on the body through a convenient beltpack, over the shoulder, or in a backpack or chest harness. However, TransPAC is designed to accommodate other hardware platforms from other manufacturers that meet the same basic specifications for providing a fully wearable PC platform, and a future ultralight PC core unit is currently in the design stage, specifically for TransPAC, which will provide a much smaller and lighter platform than any wearable PC currently on the market.

The Mentis PC platform, illustrated in Figure 2 below, has a base system unit that contains the system board, hard drive, plus all PC card slots and interfaces including for peripherals (serial, parallel, mouse, keyboard, display) and for extended module packs that plus into the base unit. This component measures approximately 14 x 19 x 3.8 cm, weighing approximately 1.9 kg. A large 4" x 3" heat dissipation plate handles cooling of the electronics which are based upon Tape-Carrier-Package technology from Intel.

The base system unit may be operated as a desktop with AC power unit through an adapter module or it can be entirely portable using a snap-on battery pack that attaches easily and quickly to the base unit. This operation can be performed while the system is operational. A third extension pack which snaps on between the base unit and the battery pack enables the user to have one or more removable I/O units – CD-ROM, DVD, tape, or additional hard drive. These snap into the extension pack bay and communicate through connectors that link the top of the extension pack and bottom of the base unit.

The specifications for the current Mentis PC base system unit are summarized in Table 1 below.

The uniqueness of the TransPAC with respect to basic user input and output is that it accommodates any form – keyboard, mouse, pen, touch screen, and voice – with the ability to be converted easily from one medium to another depending upon the user and the situation. Moreover, multiple forms of communication and control by the user are possible in parallel, as described in Table 2, wherein different forms of input and display can be employed with one another in virtually any combination. There is no requirement for extensive manipulation of software menus or configuration panels, nor of hardware reconfiguration, in order to switch protocols.

Several wireless modem designs are currently being evaluated for providing the main data communications link for TransPAC to the outside world. Currently the Motorola Personal Messenger 100D and Series 500 modems are accomodated within TransPAC but the MediLink software is designed to handle other manufacturers’ devices such as the Alphacom and Richocet products. These are discussed further in Section 4. Once again, the governing design philosophy is to enhance user functions without overloading the user in learning, remembrance of special techniques and codes, special "four-hand" dexterity, a maze of plugs and wires, and all the other

Figure 1 : TransPAC System Architecture

Figure 2 : Basic Mentis Components



In Base Unit


CPU 166 MHz MMX Pentium X  
  200MHz MMX Pentium   X
Input/Output 2 serial ports X  
  1 parallel port (enhanced) X  
  2 infrared ports X  
  Keyboard (PS/2 style) X  
  Mouse (PS/2 style) X  
  Enhanced IDE X  
  Floppy drive X  
  Audio headset X  
  External LCD display X  
DRAM 32 MB to 128MB X  
Cache 256K to 512K X  
BIOS Phoenix (Flash, 256K) X  
Video VGA, SVGA, XGA for CRT or LCD; color 16-bit (hi-color) X  
Sound Full duplex, 16 bit 44.1KHz sampling and playback X  
MPEG Full-screen, full-motion, up to 30 fps at all resolutions X  
Network 32-bit PCI   X
PC Card 1 Type II or 1 Type III slot X  
Hard Drive 2.1 to 8GB enhanced IDE drive X  
Power Mgt. Full power mgt. Plus battery recharging circuitry X  

Table 1 : Mentis Base System Unit Specifications


Application Control

& Command

Data Entry

User-to-User Communications

Internet / Intranet Access

Headset LCD Voice Voice (special user-independent command vocabulary) Cell phone

(strap-on connection to PC)

Wireless modem
6-in. flat panel


Touch screen Voice (general vocabulary) Email Standard modem
10-in. flat panel (universal-mountable) Pen (for screen) Pen Internet phone NIC and LAN
Standard CRT Mouse Mouse Paging Prior downloads
  Wrist-worn keyboard Wrist-worn keyboard Fax Prior CD write
  Standard keyboard Standard keyboard Web postings  

Table 2: TransPAC Communication and Control Protocols

demands that often turn a great technological idea into an impractical albatross in the "field" (whether that be outdoors, in an ambulance, in the patient’s home, or in a hospital ward). Therefore, when it comes to maintaining

communications that for the medical user may be real-time voice or real-time video or database access, TransPAC combines multiple channels into one pipe, so to speak, and offers the user what they are accustomed to having, but simply smaller, faster, and with less gadgetry about which to be concerned, even though the complex circuitry and logic is physically present, albeit invisible to the average user. A cell phone can be attached and used for voice communications, a wireless modem for the data, and either one or two lines can be dedicated to the tasks.

A lithium ion battery contained in the fore-mentioned battery pack that snaps into the base system unit or the extension pack will keep the system operational for upwards of 4 hours or in standby (power-saver) mode for upwards of 48 hours. If additional peripherals are attached and running, drawing upon battery power, the operational lifespan is decreased. However, in typical operations the unit can be repeatedly returned to either power-saver mode or to recharging with the adapter module after each use.

TransPAC has several modifications that set it apart from the basic Mentis or any other wearable or portable PC. These include the availability of more than one speech interface component for both speaker-independent command and control (navigation) of menus and forms-driven data entry that is derived from a speech-to-text-to-database software toolset previously developed and rigorously tested in the transportation engineering field. There is also for speaker-tailored voice recognition to be used in custom note-taking and document composition, kept separate from the former in order to limit both the scope of training as well as the possibilities for errors in speech recognition of basic keywords and command paths. There is a third form of speech processing, available for the navigation of Interactive Manuals that can be used for training or reference. These Manuals are documents composed in a web-type framework, with active links accessible through voice, mouse, or pen response, leading the user to documents consisting of multimedia content – text, graphics, animation, or full-motion video. The Interactive Manuals are created through the RTMEditor software and accessed through the RTMNavigator. Both software applications are tools developed by Interactive Solutions, producers of the Mentis hardware platform, and are in the process of being customized for use in the TransPAC.

In addition there is employed within TransPAC a unique feature bv which a microprocessor- based smart card (Active Session Card) provides simultaneously user access control and security plus the ability to pack densely compressed patient and session information including URL and database record reference links. These speech and smart card features are described in Section 4 and the overall functional diagram of the TransPAC is illustrated in Figure 3.

Communicating with both the user’s Active Session Card and the Windows95/98 registry files is the TransPAC_Config. In this module is a historical record of different device types (modems, displays, CD-ROM, second hard drives, DVD, and specialized instrumentation interfaces) that have been configured for use with the TransPAC. This is a master record that is employed by Windows to check first if a new device is present or absent and also to set up the desktop to match the layout specified by the user’s card. The user does not need to be involved in changing any setup or default configurations for modems, printers, and other devices when they are either removed or when they are replaced, only if a new type entirely (such as a new kind of wireless modem with its own drivers) is added to the system. For instance, communications to a hospital intranet or database server or to the public internet can be accomplished via wireless modem, standard (wired) modem, or LAN. At any given moment the TransPAC can be connected to one, two, or all such connections. The default method for establishing connections is (1) LAN, (2) standard modem, (3) wireless modem. TransPAC will attempt to establish communications in that order and does not require user involvement to search and try for alternate methods unless all are exhausted. In similar fashion, if the LAN connection is down, TransPAC will try using a modem to connect to a specified server. This is engiineered in order to reduce the need of the medical provider-user being forced to shift activity from the business of the medical activity over to a telecommunications activity. If the purpose of the TransPAC and the MediLink software is to make mobile medicine easier, it must not increase but rather reduce the workload.

Figure 3 TransPAC Functional Process Flow


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