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Standardizing Computer Interfacing to Medical Devices
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By Nicholas Cain
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The first medical devices with the means to pass data to acomputer appeared in the 1970's. Of course in those days thereweren't many computers to actually connect to the devices, butthis rapidly changed with the advent of the PC. However despitethe increased availability of computers there was still limiteduse in connecting a computer to a medical device as thereweren't many applications to send the data too. It had stillbecome essential for medical devices to provide a means toconnect a computer though. If a medical device didn't have acomputer interface it would appear less sophisticated, and theinterface became a required component even though only aminority of researchers wished to use it. Most hospitals todayare still using paper charting and record storage rather thanusing computers.
However, today the computer revolution in hospitals is well andtruly under way, and in the last few years a desire to includemedical device data in patient records, computer charting, andcomputer aided diagnosis has arisen. So, after all these yearsof medical devices having computer interfaces, there is now areal demand (plus the clinical system vendors working quickly tosupply the infrastructure to cater for that demand) surely it'sjust a matter of plugging them in and using the data.
However, even though the interfaces have existed for manydecades it has not meant that they exist in a mature, usableform. In fact the lack of desire to use them has meant theopposite case. Every medical device computer interface isdifferent - they require different connectors, different cables,and each requires software to be developed to acquire the data.Occasionally the manufacturers supply software (or can provideit on demand), but the software is usually a demonstration onhow to develop your own software, and more typically themanufacturer only supplies a document (a protocol) describingthe interface. Consequently there exists a vast chasm betweenwhat is wanted from medical devices, and what a user cancurrently achieve.
Almost fifteen years ago there was already awareness of thisproblem, and work began on a standard to make all devicescommunicate in a common manner. Initially called the MedicalInterface Bus (MIB), it became IEEE 1073 (and now also ISO11073), and is still an ongoing project. IEEE 1073 is massivelycomprehensive, but can be broken down into three areas; ˇ¤Physical connections Cabling and the plug and socket aredefined. Having the same cable for every medical device wouldsimplify the installation and management of devices immensely.IEEE 1073 goes much further than this though, and considers thepracticality and safety of connecting to devices. For exampleutilizing connectors that attach effectively and securely (theserial port connector on your PC has fiddly screws to attachfirmly, and without tightening them it doesn't take much toknock the cable out), and then defining optical isolation forprotecting the patient from electrical risk. ˇ¤ Lower LevelProtocol The commands for the computer to talk to the device aredescribed in the standard. Clearly an application developerdoesn't want to write new software for every device theirapplication might wish to connect to. Again, the IEEE 1073 goesfurther than just defining a few commands. The lower levelprotocol (LLP) defines the ability to detect what device isconnected automatically, giving a plug 'n play capability. TheLLP then also allows the computer and device to negotiate thefastest speed to communicate. ˇ¤ Upper Level Protocol Once thecomputers are talking, IEEE 1073 describes how the medicalparameters should be described (the nomenclature). This isessential to a truly comprehensive standard, but is also themost challenging area. However, the IEEE are not the only grouptrying form a nomenclature standard, and so considerations needto be made towards standards such as LOINC and SNOMED.
So, has a decade been enough time to create a standard?Technically the standard seems complete enough to implement, andprobably has been for a long while now. However looking at thedevice market today it would appear it's not ready, as therearen't any compliant devices. I've encountered some devices thattouch on some of the concepts, such as negotiating communicationspeeds, and have used some of the medical parameter identifiersfrom the upper level protocol, but each device still requiredsoftware writing for each specific device. So what's going on?
What are the barriers to medical device manufacturers adoptingthis standard?
To start with it's not clear what version of the standardindustry should be using. There's no obvious grand approved 1.0version, only a proliferation of drafts, approval of workgroupsand ballots and general confusion. There seems to be a distinctlack of tools or examples to guide through not just the learningprocess, but also an implementation (if you were to attemptone). This leads easily to the reasons most commonly given bydevice manufacturers as to why they've not adopted the standard- too complicated and too expensive. It would seem that IEEE1073 is trying to be too comprehensive, and is creating barriersto early adopters because of it.
So the future looks bleak for IEEE 1073. Other standards suchas HL7 and DICOM have flourished due to market forces creatingsophisticated products that need to interoperate. IEEE 1073differs from these by encompassing more than just digitalcommunication, and including hardware recommendations. Maybe ifthey concentrated on releasing a complete standard just for theupper and lower level protocols (i.e., only the softwarerecommendations), and then encouraged someone to create thetools to help design and develop the medical device firmware,then smaller companies would use the standard. The groundswellsupport would lead to more innovative products that requiredevice connectivity. The industry would benefit even if thestandard wasn't taken up in it's entire form. There has been ahuge amount of effort and thought put into the standard by manyexperienced people, and all device manufacturers should read theimplementation details of the standard to avoid their interfacesfalling foul of the common pitfalls.
As an endnote, if you've checked out who I am and what mycompany does, you might be wondering why I would be keen to seea standardized medical device interface? At this very moment weare in the beginnings of an explosion in healthcare informatics.Clinical systems are now at affordable prices for large scaletake-up, standards like HL7, DICOM etc are easily mature enoughfor companies to rely on them and create highly sophisticatedproducts. I'm prepared to be part of this wave of innovation,and I'm looking forward to using our device connectivityexpertise and create new and exciting products in the future.I'm just happy that my current products are going to give us aheadstart while everyone else is still waiting for a standardlike IEEE 1073 to be truly taken up.
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