Stream: implementers
Topic: Observations - composite vs individual
Rob Resendez (Feb 12 2019 at 17:08):
Looking at the us-core profile for vital signs -- http://hl7.org/fhir/us/core/us-core-vitalsigns.html#d-4-1-1formal-views-of-profile-content --
am not totally sure if the individual systolic and diastolic components within a composite blood pressure (55284-4) should have their own top-level observation entries (8480-6 and 8462-4). My interpretation is that, yes, they should
Grahame Grieve (Feb 13 2019 at 11:13):
should only be one observation containing both, with a single code
Lloyd McKenzie (Feb 13 2019 at 16:13):
More specifically, you'll have a code for "blood pressure" and then components with codes for systolic and diastolic.
John Silva (Feb 14 2019 at 10:55):
In the Rosetta / MIDL (IEEE 11073) world each of the blood pressure components has its own code; e.g. ABP (Arterial BP - MDC_PRESS_BLD_ART), ABP Systolic (MDC_PRESS_BLD_ART_SYS), Arterial Diastolic (MDC_PRESS_BLD_ART_DIA), Arterial Mean (MDC_PRESS_BLD_ART_MEAN). These are all pre-coordinated codes (and used in IHE PCD profiles if I remember right). I would expect that the ABP would be used for the FHIR Observation CodableConcept, and then each of the 3 as CodeableConcepts for each of the respective components. In the pre-coordinated world of IEEE 11073 there are separate codes for each type of BP, e.g. non-specific BP, ABP, NIBP, PAP, LAP, etc. Has the IHE done a mapping of the PCD profile to FHIR?
https://rtmms.nist.gov/rtmms/index.htm#!rosetta
Stefan Karl (Feb 14 2019 at 11:35):
I'm not aware of an IHE PCD DEC profile mapping, but there is a CompoundNumericObservation profile in the Point-of-Care Device Implementation Guide, which makes use of MDC codes for base and component codings. There is also a NIBP example with systolic/diastolic/mean values.
John Silva (Feb 14 2019 at 13:04):
@Stefan Karl - Thanks for pointing that IHE PCD DEC profile that shows both the LOINC and MDC codes for each of the NIBP values. A question though; does LOINC have a matching set of distinct codes for each of the unique MDC types of BP or do the MDC codes have to be mapped into LOINC codes and lose their specificity? (i.e. the many to one, one to many problem with codes)
Lloyd McKenzie (Feb 14 2019 at 15:45):
Note that because blood pressure has a mandatory profile, you'll need to use the required LOINC codes in addition to any IEEE or other codes
Stefan Karl (Feb 14 2019 at 16:00):
@John Silva - IHE PCD DEC prefers MDC coding, which has distinct codes for all specific blood pressures. LOINC has distinct codes as well. In the example, the specific codes are mapped to the generic LOINC codes requested by the Vital Signs profile, but keeping the original codes as "source of truth". Yes, this is a many-to-one mapping that is not reversible.
John Silva (Feb 14 2019 at 16:06):
Ok, but what happens if there isn't a one-to-one mapping between IEEE (or other) codes and LOINC codes?
Lloyd McKenzie (Feb 14 2019 at 16:13):
The profile defines codes for the systolic and diastolic components. If IHE has multiple codes for these, that's fine. You'd send the specific IHE code and the general LOINC code.
Stefan Karl (Feb 15 2019 at 09:02):
This raises another question related to the blood pressure vital signs profile: Many devices report a mean blood pressure beside the systolic and diastolic values. Vital signs profile page tells:
To supplement this vital sign observation, 8478-0 - Mean blood pressure, 8357-6 - Blood pressure method, 41904-4 - Blood pressure measurement site, 8358-4 - Blood pressure device cuff size, 41901-0 - Type of blood pressure device MAY be used as additional observations.
This suggests making a separate observation for the mean blood pressure. In my opinion, the better approach would be making it an additional component in the same Observation with systolic and diastolic values, because they are produced and interpreted together. Same for the other supplemental values, which are closely related to a single blood pressure measurement.
Grahame Grieve (Feb 15 2019 at 10:49):
I think that all of those should be component observations, not observations, and I wonder if that's just loose language (@Rob Hausam ?)
Rob Hausam (Feb 15 2019 at 13:13):
Yes, I agree with @Grahame Grieve that this is loose language here. I believe it should be worded as "... MAY be used as additional components." And possibly the prior sentence of "This is a component observation." would be better stated as "This is an observation with multiple components."? @Eric Haas?
Rob Hausam (Feb 15 2019 at 13:20):
Or maybe "This is an observation which typically contains multiple components.", since it is allowed (if needed, but not common) for it to have only a single systolic or diastolic component.
John Silva (Feb 15 2019 at 14:05):
Yes, clinically does it even make sense to have only a systolic or diastolic reported 'by themselves' (regardless if in FHIR or V2 or on paper)? I can imagine a valid clinical case where systolic and diastolic are reported together but not mean, and the mean being calculated though or also a case where the mean is reported alone, but not the systolic and diastolic. Are there any clinicians here who can tell us the use cases of how blood pressures are reported (i.e. even on paper)?
Last updated: Apr 12 2022 at 19:14 UTC
