<status value="active" /> <date value="2026-04-29" /> <publisher value="gematik GmbH" /> <description value="Profile for capturing the refence values as a FHIR Observation resource when evaluating lung function testings. This profile defines the exchange of a single reference 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. **Constraints applied:** - `code` is constrained to a subset of the _MIV Lung Function Reference Values_ ValueSet, defined by the _HddtLungFunctionReferenceValues_ ValueSet. - `effective[x]` is restricted to `effectivePeriod` 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. - `method` is considered mandatory in order to provide information about the method used to determine the reference value. It can be either a code from the _HddtLungFunctionReferenceValueMethod_ ValueSet or a text description." /> <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="Reference measurement type for lung function" /> <binding> <strength value="required" /> <description value="Specifies for which measurement type the reference value is, using codes from the ValueSet for lung function testings. Constrained via invariant to either PEF or FEV1." /> <valueSet value="https://gematik.de/fhir/hddt/ValueSet/hddt-lung-function-reference-values" /> </binding> </element> <element id="Observation.effective[x]"> <path value="Observation.effective[x]" /> <short value="Time period for which reference value is valid" /> <definition value="The time period for which the lung function reference value is valid. If the reference value is still active, then only the start of the period is provided." /> <type> <code value="Period" /> </type> </element> <element id="Observation.value[x]"> <path value="Observation.value[x]" /> <short value="Reference lung function value" /> <definition value="The quantitative reference value, measured either in liters (L) for FEV1 or liters per minute (L/min) for PEF, represented as a UCUM Quantity." /> <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.method"> <path value="Observation.method" /> <short value="Method for determining the reference value" /> <definition value="The method used to determine the lung function reference value. Preferred is the usage of a code from the Lung Function Reference Value Method ValueSet, but as an alternative a text description of the used formula for calculating the reference value can be provided." /> <mustSupport value="true" /> </element> <element id="Observation.method.coding"> <path value="Observation.method.coding" /> <max value="1" /> <binding> <strength value="required" /> <description value="Specifies the method used to determine the lung function reference value using codes from the Lung Function Reference Value Method ValueSet." /> <valueSet value="https://gematik.de/fhir/hddt/ValueSet/hddt-lung-function-reference-value-method-codes" /> </binding> </element> <element id="Observation.method.text"> <path value="Observation.method.text" /> <definition value="In case no code is provided, specify whether the value is a personal best or predicted or calculated based on some formula." /> </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." /> <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> </differential> </StructureDefinition>