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End tidal CO2 (carbon dioxide) partial pressure

(Daniel Laxar) #1


we’re currently mapping our EHR to CDM and I was wondering how to map etCO2 [mmHg] to a standard concept.

There is:

  • 4353938 End tidal carbon dioxide concentration – this probably does not apply since a concentration should be a percentage (we have that as well)
  • 3035357 Carbon dioxide [Partial pressure] in Exhaled gas --at end expiration – this one seems like it would be on point, however it’s a descendant of “Laboratory”.
  • 4353940 End tidal carbon dioxide partial pressure – this sounds spot on, I just don’t get why it would be an observation rather than a measurement.

Any help is appreciated,

(Alexander Davydov) #2

Not a problem. This is how LOINC is built.

But this might be a problem since LOINC expects to have ppm or MMHg here. There is another special property [VFr/PPres] for both cases, but with only such concept in there:
Carbon dioxide [VFr/PPres] in Airway adaptor --at end expiration

This is a correct one. Wrong domain issue. It will hopefully be fixed with the next SNOMED release in OMOP.

(Daniel Laxar) #3

Hi @Alexdavv and thank you so much for taking the time!

Regarding how LOINC is build: perfect!

Regarding [Partial pressure]: thats exactly what I want. I want to store etCO2 in mmHg.

Regarding SNOMED/OMOP: have I understood correctly that this is an issue, that applies to a whole group of vital parameters (including Body Temp)? Because I’d expect e.g. Body Temp and etCO2 to be a measurement. Is that an OMOP or SNOMED issue?

I am wondering: when is the SNOMED/OMOP release due? Is there a forum post regarding that issue i can follow maybe?

Again, thank you so much,

(Alexander Davydov) #4

Not all of them are wrong, but you’re right. We identify the peaks in SNOMED for domain assignment and it’s not always straightforward. When something lives outside the typical hierarchy of measurements, we need to process it manually.
So it’s an OMOP issue, but also a SNOMED one when it comes to mixed things, e.g.:

Anesthetic observable or Vital signs and their children.

We’re planning to clean the domain within the next SNOMED release in OMOP.

SNOMED releases its International version twice a year (Janualy and July). Then we wait for UK and US Extension releases to proceed during the next few months. The current version info is available in Athena.