A New Approach for Integration of
Telemedicine Applications into Existing
Information Systems in Healthcare
Alexander HORSCH, Catharina NÄTSCHER,Helmut SUSSMANN,
Dept. of Medical Statistics and Epidemiology
Technical University of Munich, Ismaninger Str. 22, 81675 Munich, Germany
Abstract. In order to take the full advantage of telemedicine applications, they must seamlessly be integrated into healthcare services and their information systems (e. g. HIS, POS, RIS). In our approach an HL7/XML-based integration module is used 1) to exchange documents with information systems; 2) to generate and administer documents internally; 3) to present documents. The module fills in pre-defined CDA-conforming XML templates with data from HL7 V2 messages. The approach is first applied to the teleconsultation service EST in the project ENDOTEL.
Keywords: Telemedicine, teleconsultation, integration, HL7, XML, CDA.
Healthcare services have nowadays become complex enterprises. A complicated structure and a large data flow require complex management and information systems on the basis of efficient data networks . On the other hand, budgets for healthcare are strictly limited.
The expected benefit from a broad use of telematics in healthcare, especially to reduce or at least preserve costs while keeping or even increasing the level of quality, can only be achieved if telemedicine applications are seamlessly integrated .
Up to now, most teleconsultation applications are isolated solutions with no connection to existing information systems (e.g. HIS, POS, RIS). This hampers their broad usage in routine.
2. Technical Background
Due to the fact that healthcare services are implemented on heterogenous platforms, telemedicine applications must be able to use Electronic Data Interchange (EDI) in order to communicate. EDI can be considered as an intervention-free exchange of structured data between applications of participating communication partners . It can best be realized on the so-called Application Layer, i.e. layer seven, of the Open Systems Interchange (OSI) reference model . This level serves as interface to the user.
The most common protocol for the exchange of medical data, HL7 (Health Level 7), is based on this OSI layer .
In hospitals, commercial communication servers like DATA gate (STC software Technologies corporation, the USA) or Cloverleaf (HCI Health-care Communications Inc., Dallas, the USA) are utilized as integration component for information systems .
These servers offer open interfaces for data exchange. On an inquiry, the server will return data from an information system as a message in a certain format (e.g. HL7, XML). In contrary to a document, such a message will be kept only for short time after receipt. Its content usually is imported into the receiver’s application and then deleted, immediately. The data received from the message are stored in a data base and can be put into another message.
3. Environment, MM
The concept has been developed in the context of the telemedicine project ENDOTEL for the Endoscopy Store-and-forward Teleconsultation Service (EST) . A global UML analysis of the data flow of a teleconsultation is the basis for the concept.
At present a prototype of the HL7/XML module is developed. As HL7 message source during development the Cloverleaf Communications Server has been chosen due to its availability in our university hospital. Record-oriented HL7 V2 messages are supplied as text files . Then these messages are locally stored, uploaded and mapped.
For the development of the CDA templates the CDA level 1 Release 1 standard accredited by ANSI is used . The header structure of the templates is adapted to the needs of a teleconsultation service .
Documents are stored in the native XML data base Tamino (Software AG, Darmstadt, Germany). It offers the possibility to store and administer XML documents as units. That has a substantial advantage: CDA documents can be stored and archived in their native form.
ENDOTEL has a client/server architecture. All data are created and saved locally on the client (Fig.1, black arrows). The server has only cache functionality. The inquiring physician creates a new consultation case by manually typing in all necessary header data. Afterwards, he generates additional multimedia data by means of integrated editors and adds them to the actual document. Then the document is sent and stored on the server. The answering physician retrieves the document from the server. Thus the document is stored on the hard-disk of his client.
Theoretically, there are two points for the integration of the service into existing information systems, as shown by the striped elements in Fig. 1. Striped bars represent the interfaces, striped arrows describe the data flows: First, on the side of the inquiring physician, the takeover of data from an existing information system (arrows 1-3); second, on the side of the answering physician, the import of received data into his information system (arrows 4-5). The first issue saves time and increases quality of data. The second issue is important for documentation and billing.
In the second version of the EST the first issue is addressed.
Fig. 1: Analysis of data flow and points of integration
The core of our concept consists of a HL7/XML module and CDA-conforming XML templates . The templates have a CDA similar structure, but they include special tags, which are defined within the namespace “EST” (www.endotel.de). A CDA document must have a world-wide unique ID. In the EST this ID is created when a document is being sent. All internal XML documents only have internal ID's assigned by the EST. Therefore, they can be processed and deleted. This is particularly important: when the user creates an EST document, he can add or delete media and even change the header data (e.g. writing error).
It can take a lot of time and several steps to create a document, and the management of CDA-conforming documents could become complicated and confusing. One would have to store and administer unnecessary intermediate documents with unique ID's. For this reason have we decided to build a document repository, in which alterable XML documents up to dispatching are stored. Before dispatching a complete, not alterable CDA document is produced automatically and the XML draft is deleted completely. Thus, two document lines are generated: 1) alterable XML documents; 2) not alterable, archivable CDA documents. The first are used as drafts and exist on the EST client only up to the point of sending. The CDA documents are used for the exchange between the physicians.
If required, the CDA documents can be forwarded natively or embedded in a HL7 message (this is not supported in the current EST version).
The suggested concept has the following two disadvantages:
First of all, because exchange of information is done by messages, the same data exist at the same time in different places (in the EST and in the information system). As a consequence, it can happen that the EST contains non-actual data. This problem can be solved by regular updates.
The second disadvantage refers to the choice of the data base. Native XML data bases have a disadvantage: for scientific evaluation an additional module (parser) must be implemented.
A further issue could be the message format: We have not chosen the most recent HL7 V3 version, but HL7 V2 because it is well-established.
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1 Medizinische Hochschule Hannover, 2 BMG Bonn.
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