[Observation] !!! Using valueQuantity without UCUM value?

[annabel-uzl]

Following up on #13
In the business rules it says

"Les unités sont définies par le standard unitsofmeasure.org (voir en annexe, Unités de mesure)"

However, we encounter some issues since not all our 'units' can be translated to ucum values. We have some Observations that have the following 'units':

• Vingers (Fingers)
• %/ TIB ODI > 3% en %/ TIB ODI > 4% (TIB stands for "Time in Bed", ODI is the "Oxygen Desaturation Index". This gives the percentage of time that there was a decrease in oxygen, related to sleepapneu
• ...

In the FHIR documentation it says 'If the unit can be coded in UCUM and a code is provided, it SHOULD be a UCUM code. If a UCUM unit is provided in the code, then a canonical value can be generated for purposes of comparison between quantities. Note that the unit element will often contain text that is a valid UCUM unit, but it cannot be assumed that the unit actually contains a valid UCUM unit.'

So just to be sure: can we use the valueQuantity without filling in the code, only the unit and thus not using an ucum system? (System is empty?)

[annabel-uzl]

Following this question:
APGAR scores have in the examples a unit of 'score', see https://hl7.org/fhir/R4/observation-example-1minute-apgar-score.json.html This corresponds to the {score} UCUM value. However, we doubt the necessity of this unit as the fact that a score is measured is already clarified by the code and the unit seems redundant.

What do you think?