In MML Version 3.0, the MML Version 2.3 specification is revised so that MML can use the HL7 CDA. MML Version 3.0 instances can be called HL7 CDA-based MML documents. Since the HL7 CDA documents can be applied to the information exchange method suggested by HL7, to exchange data between medical information applications via messages, it is possible to exchange an HL7 CDA-based MML document according to the message exchange rules of HL7. Also, it is possible to seamlessly integrate two different cases, when the HL7 CDA-based MML document exists independently as a persistent information object and when the document is exchanged according to the HL7 message exchange rules. This specification mentions only items of the HL7 CDA necessary to satisfy these. Items not mentioned in the specification comply with the specification of the HL7 CDA.
From the viewpoint of HL7 Version 2.x , an HL7 CDA-basedMML document is a multimedia object and is exchanged as a package in MIME (Multipurpose Internet Mail Exchange: RFC2046) format and encoded as an encapsulated data type (encapsulated data type : ED). The HL7 CDA-based MML document is integrated into an OBX (Observation Segment) in the message which is endeavoring to exchange the document. The package in MIME format is encoded in the OBX as an encapsulated data type of HL7 Version 2.x. Set the value of OBX 2 (Field 00570 Value Type) to ED. Set the data type components in OBX 5 as follows:
The following is an example of an HL7 CDA-based MML document in the MDM (Medical document management, event T02) message. 1
It is expected that an MML document which is based on the HL7 CDA (the HL7 Version 3 Standard: Clinical Document Architecture Framework Release 1.0) shall be exchanged via the HL7 Version 3 message that is endeavoring to exchange the document. Currently, there is no officially accredited standard (such as a standard accredited by ANSI) related to HL7 Version 3 other than the HL7 CDA and drafts are repeatedly revised. Therefore, the explanation in this chapter are based upon the reference information model RIM Version0.982 , current at the time of the creation of the HL7 CDA. It is possible that the manner in which messages are written will change due to content changes such as the HL7 Version 3 RIM and Data Types.
According to the reference information model RIM Version 0.98 on which the HL7 CDA is based, the Service.txt RIM attribute includes the MIME package which is encoded as the encoded data type. Set the data type components as follows:
Sending an HL7 CDA-based MML document via an HL7 Version 3 message. 3