Hmmm...

I was just trying out bloggers email-to-blog feature in my last post with the images put in the right place... but it looks like its really messy if you have pictures within the document...
wont advise you to try it ... except you are a tester...

I have now put in the pics here...
I just hope they make sense...

The Anatomy of the Blood Pressure Archetype 2

Whew!

I need to close up this discussion of the blood pressure archetype to proceed onto how to pass this into OpenMRS.

This is the second part of a discussion of this exemplary archetype.

To reiterate, the sections of this archetype include the following nodes:

archetype_id, adl_version, concept, original_language, definition, translations

description and ontolology.

Please observe that the root node is ‘archetype’ and it has three important attributes.

This archetype was made in the pre-ADL-version2 days and doesn’t have the

ADL2-mandatory node, revision_history.

I would like to say that all I am stating here follow the ADL2 specification, and there is no originality, so to speak... all kudos go to the OpenEHR spec guys!

Lets say something about the 8 main sections:

1. the adl_version section

This is the version of the archetype definition language (adl) used in authoring the archetype.

It has a value of v1 in the blood pressure archetype (as can be seen in the screenshot above), v1 representing version one.

adl is the formal language used in authoring 'raw' archetypes (remember?)

2. concept

is the central concept this archetype represents...

at0000 is its value in the blood pressure archetype.

Thus, at0000 represents the archetype's central concept.

"at", the prefix for the value, short for "archetype term".

All archetype terms can be found in the ontology section.

A peep into the ontology section of the archetype tells me that at0000 corresponds to blood pressure.

Well, I didn’t even have to spy there, because at0000 always represents the whole archetype, which in this case is blood pressure. Each archetype is defined by a concept.

Come to think of it, what’s it with the blood pressure? I think since Laennec invented the steths, clinical practice has really changed. And its a crucial vital sign... something the management guys would call a KPI (Key performance indicator)...

Oops... I'm here to talk about archetypes...

3. ontology

This would probably be better understood if it were called 'terminology' because it doesn’t necessarily store the rich semantic stuff you find in popular ontologies.

If you are from OWL or Protégé or RDF, etc, you'll probably not find your description logics here.

To see the relationship between archetypes and OWL, see here.

The ontology mainly holds the terminology listing within, in different languages. It also contains descriptions (and translations) of terms in child nodes named items.

Have a look at a screenshot below (sorry for the blur):

It also contains mappings (if available) to external terminologies. These are contained in the child node, term_bindings.

My thinking is that a collection of all the archetypes would comprise a whole large terminology that can be used to drive a system. Running a vocabulary is, however, not a goal of the OpenEHR foundation.

4. original_language

This is as-it-reads; the original language in which the archetype was designed... It includes children that specify the ISO code for the language as well as the ISO code_string. These were ISO_639-1 and en, the last time I checked...

5. translations

Of course, this relates to translations from the original language.

The OpenEHR is built for the global Babel of languages - the motivation for metadata to handle language translations. Child elements here have values that include the ISO code_string (de for German), the ISO code and the translator's name and affiliations, including any accreditation.

Archetypes need to be translated completely – and mostly this involves the ontology and description sections, because these sections carry metadata that might need to be displayed in form templates.

The screenshot above shows the translation section of the blood pressure archetype.

6. archetype_id

This is a unique identifier for an archetype and corresponds to openEHR-EHR-OBSERVATION.blood_pressure.v1 (as you can see below)

This identifier gives clues as to which type the archetype is (e.g. an observation archetype). It also mentions its central concept (blood pressure) and its version (v1).

7. description

This contains metadata about the author such as name, email, organization and the archetype was created. It also contains information on the current state of the archetype (draft, in this case).

It also discusses the main purpose of the archetype, as well as its use, misuse and keywords that are important. The details subsection contains succinct domain information. And this contributes to the richness of archetypes and one of its central motivations - which is modeling domain knowledge.

This knowledge also can exist in multiple translations (as you can see in German here)

The blood pressure archetype was originally constructed in English but has a German translation. The purpose is "to record the systemic blood pressure of a person. The measurement records the systolic and the diastolic pressure by some means suitable for the result to be seen as a surrogate for the general and systemic blood pressure"

8. definition

To quote the ADL2 document, the definition section contains the main formal definition of the archetype" It is based on a special form of ADL called constraint ADL.

It is used to define constraints on data. Keywords that can help understand the definition section include: matches, ~matches, is_in, ~is_in, occurrences, existence, cardinality, ordered, unordered, unique, infinity, use_node, allow_archetype, include, exclude. These allow constraints that are related to the underlying information model… or lets say database.

Here the archetype “links” to the EHR (electronic health record) space and can specify or “call” on another archetype or specify a lookup column, etc. More details of this can be found in the ADL document here or here. And you might need some reading on the OCL.

In summary, this is a terribly ‘rough’ but ‘practical’ summary of better and more formal documents in the OpenEHR space. Please have a look at www.openehr.org.