<status value="active" /> <date value="2026-04-29" /> <publisher value="gematik GmbH" /> <description value="Profile for capturing the relative lung function testings (i.e. an individual measurement divided by the corresponding reference value) as FHIR Observation resources. This profile defines the exchange of a single relative value for the Mandatory Interoperable Value (MIV) \"Lung Function Testing\" which is technically defined by the ValueSet _hddt-miv-lung-function-testing_. This MIV is e.g. implemented by peak flow meter that can connect to a Personal Health Gateway (e.g. a mobile app for tracking lung function values) through wireless or wired communication. **Obligations and Conventions:** Each Lung Function Testing MAY either hold a reference to a _Sensor Type And Calibration Status_ [DeviceMetric](https://hl7.org/fhir/R4/devicemetric.html) resource or to a _Personal Health Device_ [Device](https://hl7.org/fhir/R4/device.html) resource (eXclusive OR). Typically the reference will be to a [Device](https://hl7.org/fhir/R4/device.html) resource, but the option to reference a [DeviceMetric](https://hl7.org/fhir/R4/devicemetric.html) resource is provided for compatibility with the overarching HDDT specification. Each instance of this Observation MUST reference the Observations holding the corresponding raw measurement and reference value via the `derivedFrom` element. **Constraints applied:** - `code` is constrained to a subset of the _MIV Lung Function Relative Values_ ValueSet, defined by the _HddtLungFunctionRelativeValues_ ValueSet. - `effective[x]` is restricted to `effectiveDateTime` and constrained as mandatory. - `value[x]` is restricted to `valueQuantity`. The elements `valueQuantity.value`, `valueQuantity.system`, and `valueQuantity.code` are constrained in a way that a value MUST be provided and that UCUM MUST be used for encoding the unit of measurement. `Observation.valueQuantity` MAY only be omitted in case of an error that accured with the measurement. In this case, `Observation.dataAbsentReason` MUST be provided. - `derivedFrom` is constrained to require exactly two references: one to the raw lung function testing Observation and one to the lung function reference value Observation." /> <copyright value="Copyright (c) 2026 gematik GmbH" /> <fhirVersion value="4.0.1" /> <kind value="resource" /> <abstract value="false" /> <type value="Observation" /> <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Observation" /> <derivation value="constraint" /> <differential> <element id="Observation.code"> <path value="Observation.code" /> <short value="Percentage measurement type for lung function" /> <binding> <strength value="required" /> <description value="Specifies the type of measurement using codes from the ValueSet for lung function testing as percentage of the reference value. Constrained via invariant to either PEF or FEV1." /> <valueSet value="https://gematik.de/fhir/hddt/ValueSet/hddt-lung-function-relative-values" /> </binding> </element> <element id="Observation.effective[x]"> <path value="Observation.effective[x]" /> <short value="Time of measurement" /> <definition value="The time when the lung function testing was taken." /> <min value="1" /> <type> <code value="dateTime" /> </type> </element> <element id="Observation.value[x]"> <path value="Observation.value[x]" /> <short value="Calculated lung function value as percentage of reference value" /> <definition value="The lung function value represented as percentage of the reference value" /> <type> <code value="Quantity" /> </type> <mustSupport value="true" /> </element> <element id="Observation.value[x].value"> <path value="Observation.value[x].value" /> <min value="1" /> </element> <element id="Observation.value[x].system"> <path value="Observation.value[x].system" /> <min value="1" /> <fixedUri value="http://unitsofmeasure.org" /> </element> <element id="Observation.value[x].code"> <path value="Observation.value[x].code" /> <definition value="The UCUM code representing the unit of the lung function testing. The UCUM code MUST be compliant with the example unit that is linked with the LOINC code given as `Observation.code`." /> <min value="1" /> <binding> <strength value="required" /> <description value="Defines the unit of measurement using codes from the UCUM units ValueSet. The UCUM code MUST be compliant with the unit that is linked with the LOINC code given as `Observation.code`." /> <valueSet value="http://hl7.org/fhir/ValueSet/ucum-units" /> </binding> </element> <element id="Observation.device"> <path value="Observation.device" /> <short value="Reference to personal health device" /> <definition value="References a Device resource that describes the personal health device." /> <min value="1" /> <type> <code value="Reference" /> <targetProfile value="https://gematik.de/fhir/hddt/StructureDefinition/hddt-personal-health-device" /> <targetProfile value="https://gematik.de/fhir/hddt/StructureDefinition/hddt-sensor-type-and-calibration-status" /> </type> </element> <element id="Observation.derivedFrom"> <path value="Observation.derivedFrom" /> <slicing> <discriminator> <type value="profile" /> <path value="resolve()" /> </discriminator> <description value="Slice to require one reference to a measurement and one to a reference value" /> <rules value="closed" /> </slicing> <min value="2" /> <max value="2" /> </element> <element id="Observation.derivedFrom:measurement"> <path value="Observation.derivedFrom" /> <sliceName value="measurement" /> <short value="Reference to raw lung function testing" /> <definition value="Reference to the lung function testing Observation that holds the actual measured value." /> <min value="1" /> <max value="1" /> <type> <code value="Reference" /> <targetProfile value="https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-function-testing" /> </type> </element> <element id="Observation.derivedFrom:referenceValue"> <path value="Observation.derivedFrom" /> <sliceName value="referenceValue" /> <short value="Reference to lung function reference value" /> <definition value="Reference to the Observation holding the reference range and information about the reference range determination method." /> <min value="1" /> <max value="1" /> <type> <code value="Reference" /> <targetProfile value="https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-reference-value" /> </type> </element> </differential> </StructureDefinition>