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Martin Hurrell wrote: When we were on the telecon the other day I suggested that ET tubes provide an example of missing concepts in SNOMED CT. This probably arises because tubes can have a number of attributes, armoured/reinforces, cuffed, blockers etc. some of which can exist in the same physical device. So to capture all possibilities would mean a proliferation of terms which I suspect is avoided by authors. An example would be an ‘armoured, cuffed ET tube’.
Rather than trying to find every example of this issue it seems more helpful to look at why it arises. I think it’s because SNOMED CT’s ontology is designed to support the classification of concepts more from the POV of terminologists than of users (understandable of course!). In many cases it would helpful to use simpler concept descriptions and more attributes (qualifiers) rather than using pre-coordinated terms. Since SNOMED CT isn’t going to be re-written in the near future a practical (SNOMED compatible) alternative could be to use the Compositional Grammar (CG) to do the job.
Taking the airway example just given, I can’t find a SNOMED term for ‘Cuffed ET tube’, nor come to that, ‘Uncuffed ET tube’ (although there is a term for ‘Uncuffed tube’, tube type undefined). There are, however, useful terms under the concept ‘Device cuff’ (SCTID 272188009) all of which are in IOTA. So, using terms in IOTA, a description of a cuffed, armoured, endotracheal tube could be rendered in the CG as:
309801005 | Armored endotracheal tube | + 2248009 | endotracheal tube cuff |
(a real example is the ‘PRO-Breathe® ArmourFlex® Cuffed ET Tube’ (FDG880) www.proactmedical.co.uk/proshop_support_docs/ETtubes/ET_brochure.pdf).
So, I think that it might be helpful to review the SNOMED CT qualifiers and to identify ones that are needed and sort out some inconsistencies. I don’t think there would be that many but there are some. For example, why have ‘uncuffed tube’ but not ‘cuffed tube’? Is it necessary to distinguish between the physical device components ‘endotracheal tube cuff’ and ‘endobronchial tube cuff’ when they always exist as part of an ET or bronchial tube, respectively - why not just use the generic term ‘tube cuff’ (SCTID 257373001) in association with a description of the parent object?. To go further, why not make ‘armored’, ‘X-ray opaque’, ‘Pre-formed’, ‘steerable tip’ etc. qualifiers that can be attributes of airway devices? This could be done by adding relatively few terms to the SNOMED qualifiers and then using the CG to define any required complex object description.
An obvious advantage of pre-coordinated terms is that, hopefully, they're all valid. Using the CG to associate attributes with concepts it would be possible to define things that couldn't exist e.g. a tube that was simultaneously 'cuffed' and 'uncuffed'. I suppose the ideal would be to bite the bullet, define all valid pre-coordinated terms, but at the same time define associated qualifiers / attributes so that terms could be derived automatically from simple user input.