MIV - Lung Function Testing

This chapter provides obligations and guidelines for manufacturers of Device Data Recorders for implementing a FHIR Resource Server for the Mandatory Interoperable Value (MIV) Lung Function Testing. For an overview of this MIV including typical use cases and key values, see the Lung Function Testing domain chapter.

This chapter builds on the HDDT Information Model, the HDDT Generic FHIR API, and the HDDT guide for retrieving device data. It constrains these guidelines with respect to the specific requirements for exposing lung function tests to DiGA, including:

• The endpoints to implement and how they differ from the Generic FHIR API model
• The relevant FHIR profiles for lung function testing and how they constrain and extend the HDDT Information Model
• Conventions for sharing FHIR resources to ensure compliance with the HDDT guide for retrieving device data
• Example requests and responses to support implementation

Implementation Duties for Manufacturers of Device Data Recorders

Manufacturers of Device Data Recorders that support the MIV Lung Function Testing

• MUST implement all requirements expressed through the RFC 2119 keywords defined in Conventions - Use of Keywords. These keywords (MUST, SHOULD, MAY, etc.) are used throughout the entire specification to indicate normative requirements.
• MUST implement and operate a FHIR Resource Server as defined in this chapter,
• MUST implement and operate an OAuth2 Authorization Server,
• MUST register the Device Data Recorder with its FHIR Resource Server and OAuth2 Authorization Server at the BfARM HIIS-VZ (BfArM Device Registry),
• MUST consider the HDDT requirements on security, privacy and operational service levels.

Further obligations MAY be defined by gematik and BfArM as part of the upcoming processes for conformance validation and registration.

FHIR Resource Server

The Device Data Recorder’s FHIR Resource Server gives DiGA access to measured data and related information about devices. A Device Data Recorder’s FHIR Resource Server that serves the MIV Lung Function Testing MUST implement the following endpoints and profiles:

• retrieval of the Resource Servers’s Capability Statement through a /metadata endpoint.
• HDDT common RESTful interactions on a Device endpoint that implements the HDDT Personal Health Device profile. These interactions are common for all MIVs. The full specification of the interactions can be found here.
• MIV-specific interactions on an Observation endpoint that implements all observation profiles relevant for the MIV Lung Function Testing. These interactions and underlying profiles are specific for implementing the MIV. The full specifications are given below.
  • HDDT Lung Function Testing
  • HDDT Lung Function Reference Value
  • HDDT Complete Lung Function Testing

The figure below shows the adaption of the HDDT Information Model for the MIV Lung Function Testing. Elements denoted as [1..1] or MS are mandatory for the MIV Lung Function Testing (see Use of HL7 FHIR).

All interactions on HDDT-specific endpoints require that the requestor presents a valid Access Token that was issued by the Device Data Recorder’s OAuth2 Authorization Server (see Pairing for details). The authorization of the request follows the principles defined for HDDT Smart Scopes. For the MIV Lung Function Testing only the following scopes MUST be set:

patient/Observation.rs?code:in=https://gematik.de/fhir/hddt/ValueSet/hddt-miv-lung-function-testing
patient/Device.rs
patient/DeviceMetric.rs

Observation Profiles

This section discusses the three Lung Function Testing profiles, which constrain the Observation resource for representing lung function testings, and all necessary supplementary information required for properly presenting and interpreting the results of lung function testings.

Observation Profile HDDT Lung Function Testing

The Observation profile HDDT Lung Function Testing represents a single measurement taken with a hand-held peak flow meter or spirometer. It records the raw measured value, either in liters (L) or liters per minute (L/min), depending whether the measured metric is the Peak Expiratory Flow (PEF) or the Forced Expiratory Volume in one second (FEV1).

For the full normative specification of this profile, see the respective StructureDefinition.

Snapshot View of the Profile

Profile: Observation – Lung Function Testing

This structure is derived from Observation

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Observation	C	0..*	Observation	Measurements and simple assertions Constraints: obs-6, obs-7
implicitRules	?!Σ	0..1	uri	A set of rules under which this content was created
modifierExtension	?!	0..*	Extension	Extensions that cannot be ignored
status	?!Σ	1..1	code	Measurement status Binding: ObservationStatus (required): Codes providing the status of an observation. Fixed Value: final
code	Σ	1..1	CodeableConcept	Raw measurement type for lung function Binding: Lung Function Testing Values from LOINC (required): Specifies the type of measurement using codes from the ValueSet for lung function testings. Constrained via invariant to either PEF or FEV1.
effective[x]	Σ	1..1	dateTime	Time of measurement
value[x]	SΣC	0..1	Quantity	Measured lung function value
value	Σ	1..1	decimal	Numerical value (with implicit precision)
comparator	?!Σ	0..1	code	< | <= | >= | > - how to understand the value Binding: QuantityComparator (required): How the Quantity should be understood and represented.
system	ΣC	1..1	uri	System that defines coded unit form Fixed Value: http://unitsofmeasure.org
code	Σ	1..1	code	Coded form of the unit Binding: UCUMCodes (required): 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.
device		1..1	Reference(Device – Personal Health Device | DeviceMetric – Sensor Type and Calibration Status)	Reference to personal health device
Documentation for this format

For information on general constraints and terminology bindings see the full StructureDefinition for this profile.

Observation Profile HDDT Lung Function Reference Value

The Observation profile HDDT Lung Function Reference Value represents a value, used as a baseline when interpreting individual lung function tests of a patient (see section Reference Value).

For the full normative specification of this profile, see the respective StructureDefinition for this profile.

Snapshot View of the Profile

Profile: Observation – Lung Function Reference Value

This structure is derived from Observation

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Observation	C	0..*	Observation	Measurements and simple assertions Constraints: obs-6, obs-7
implicitRules	?!Σ	0..1	uri	A set of rules under which this content was created
modifierExtension	?!	0..*	Extension	Extensions that cannot be ignored
status	?!Σ	1..1	code	Measurement status Binding: ObservationStatus (required): Codes providing the status of an observation. Fixed Value: final
code	Σ	1..1	CodeableConcept	Reference measurement type for lung function Binding: Lung Function Reference Values from LOINC (required): 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.
effective[x]	Σ	0..1	Period	Time period for which reference value is valid
value[x]	SΣC	0..1	Quantity	Reference lung function value
value	Σ	1..1	decimal	Numerical value (with implicit precision)
comparator	?!Σ	0..1	code	< | <= | >= | > - how to understand the value Binding: QuantityComparator (required): How the Quantity should be understood and represented.
system	ΣC	1..1	uri	System that defines coded unit form Fixed Value: http://unitsofmeasure.org
code	Σ	1..1	code	Coded form of the unit Binding: UCUMCodes (required): 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.
method	S	0..1	CodeableConcept	Method for determining the reference value Binding: ObservationMethods (example): Methods for simple observations.
coding	Σ	0..1	Coding	Code defined by a terminology system Binding: Lung Function Reference Value Method (required): Specifies the method used to determine the lung function reference value using codes from the Lung Function Reference Value Method ValueSet.
text	Σ	0..1	string	Plain text representation of the concept
device		0..1	Reference(Device – Personal Health Device | DeviceMetric – Sensor Type and Calibration Status)	Reference to personal health device
Documentation for this format

For information on general constraints and terminology bindings see the full StructureDefinition for this profile.

Observation Profile HDDT Complete Lung Function Testing

The Observation profile HDDT Complete Lung Function Testing represents a percentage-based value, calculated by dividing the individual lung function testing by the reference value.

For the full normative specification of this profile, see the respective StructureDefinition for this profile.

Snapshot View of the Profile

Profile: Observation – Complete Lung Function Testing

This structure is derived from Observation

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Observation	C	0..*	Observation	Measurements and simple assertions Constraints: obs-6, obs-7
implicitRules	?!Σ	0..1	uri	A set of rules under which this content was created
modifierExtension	?!	0..*	Extension	Extensions that cannot be ignored
status	?!Σ	1..1	code	Measurement status Binding: ObservationStatus (required): Codes providing the status of an observation. Fixed Value: final
code	Σ	1..1	CodeableConcept	Percentage measurement type for lung function Binding: Lung Function Relative Values from LOINC (required): 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.
effective[x]	Σ	1..1	dateTime	Time of measurement
value[x]	SΣC	0..1	Quantity	Calculated lung function value as percentage of reference value
value	Σ	1..1	decimal	Numerical value (with implicit precision)
comparator	?!Σ	0..1	code	< | <= | >= | > - how to understand the value Binding: QuantityComparator (required): How the Quantity should be understood and represented.
system	ΣC	1..1	uri	System that defines coded unit form Fixed Value: http://unitsofmeasure.org
code	Σ	1..1	code	Coded form of the unit Binding: UCUMCodes (required): 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.
device		1..1	Reference(Device – Personal Health Device | DeviceMetric – Sensor Type and Calibration Status)	Reference to personal health device
Slices for derivedFrom	Σ	2..2	Reference(DocumentReference | ImagingStudy | Media | QuestionnaireResponse | Observation | MolecularSequence)	Related measurements the observation is made from Slice: Unordered, Closed by profile:resolve()
derivedFrom:measurement	Σ	1..1	Reference(Observation – Lung Function Testing)	Reference to raw lung function testing
derivedFrom:referenceValue	Σ	1..1	Reference(Observation – Lung Function Reference Value)	Reference to lung function reference value
Documentation for this format

For information on general constraints and terminology bindings see the full StructureDefinition for this profile.

Conventions and Best Practice

Reference Value

The HDDT specification models the reference value as an Observation, because the PEF reference value is a “personal best”, and is thus a measurement that can change periodically. In certain contexts, a FEV1 reference value, measured as a “personal best” may also be applicable.

Typically, the FEV1 reference value is calculated based on the patient’s demographical data, but the estimation approach varies. For example, the Global Lung Function Initiative (GLI) guidelines from 2012 state, that a patient’s race should be taken into account for the reference value calculation, while the more recent guidelines (GLI 2022) provide a race-neutral formula for the calculation.

For the correct interpretation of the patient’s lung function measurement values, it is crucial for physicians to know how exactly the reference value was calculated. In the HDDT Lung Function Reference Value Observation profile, the manufacturer of the Device Data Recorder MUST specify a method, of how the reference value was created. The manufacturer SHOULD use a code from the HDDT Lung Function Reference Value Method Codes CodeSystem. Alternatively, the manufacturer MAY provide a plain text description of the method for calculating the reference value.

Derived From Element

The FHIR specification for the MIV Lung Function Testing consists of three separate FHIR profiles. The profile HDDT Complete Lung Function Testing depends on the other two (HDDT Lung Function Testing, and HDDT Lung Function Reference Value), as it is a calculation, displayed as a percentage, of an individual measurement, divided by the reference value.

In order to properly model this information in the HDDT Complete Lung Function Testing FHIR profile, and provide it to the DiGA, the manufacturer of the Device Data Recorder MUST use the derivedFrom element to reference one of each HDDT Lung Function Testing and HDDT Lung Function Reference Value resource instances.

Since the reference value is either a normal value for a population group and is calculated only once, or if it is a “personal best” it changes once every few weeks, multiple complete lung function tests SHOULD reference the same instance of the HDDT Lung Function Reference Value resource.

Examples

Full example

The following object diagram shows the relationships between the FHIR resources involved in representing lung function testing according to the HDDT Information Model. Presented here is an instance of each HDDT Observation profile, representing an individual lung function measurement. For readability reasons, the relationship between profiles and resource instances, some connections to the Personal Health Device, and elements that are not mandatory or MS for the MIV Lung Function Testing (see Use of HL7 FHIR) have been omitted.

The following code example shows the concrete JSON representation of the HDDT Lung Function Testing resource (FEV1) shown in the object diagram.

{
  "resourceType" : "Observation",
  "id" : "example-fev1-single-measurement",
  "meta" : {
    "profile" : [
      🔗 "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-function-testing"
    ]
  },
  "status" : "final",
  "code" : {
    "coding" : [
      {
        "system" : "http://loinc.org",
        "code" : "20150-9",
        "display" : "FEV1"
      }
    ]
  },
  "effectiveDateTime" : "2025-12-28T08:00:00Z",
  "valueQuantity" : {
    "value" : 3.4,
    "unit" : "L",
    "system" : "http://unitsofmeasure.org",
    "code" : "L"
  },
  "device" : {
    🔗 "reference" : "Device/example-device-peak-flow-meter"
  }
}

The following code example shows the concrete JSON representation of the HDDT Lung Function Reference Value resource shown in the object diagram.

{
  "resourceType" : "Observation",
  "id" : "example-fev1-reference-value",
  "meta" : {
    "profile" : [
      🔗 "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-reference-value"
    ]
  },
  "status" : "final",
  "code" : {
    "coding" : [
      {
        "system" : "http://loinc.org",
        "code" : "20149-1",
        "display" : "FEV1 predicted"
      }
    ]
  },
  "effectivePeriod" : {
    "start" : "2025-05-01"
  },
  "valueQuantity" : {
    "value" : 4.5,
    "unit" : "L",
    "system" : "http://unitsofmeasure.org",
    "code" : "L"
  },
  "method" : {
    "coding" : [
      {
        "system" : "https://gematik.de/fhir/hddt/CodeSystem/hddt-lung-function-reference-value-method-codes",
        "code" : "GLI-2022"
      }
    ]
  },
  "device" : {
    🔗 "reference" : "Device/example-device-peak-flow-meter"
  }
}

The following code example shows the concrete JSON representation of the HDDT Complete Lung Function Testing resource shown in the object diagram.

{
  "resourceType" : "Observation",
  "id" : "example-fev1-relative-value",
  "meta" : {
    "profile" : [
      🔗 "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-function-testing-complete"
    ]
  },
  "status" : "final",
  "code" : {
    "coding" : [
      {
        "system" : "http://loinc.org",
        "code" : "20152-5",
        "display" : "FEV1 measured/predicted"
      }
    ]
  },
  "effectiveDateTime" : "2025-12-28T08:00:00Z",
  "valueQuantity" : {
    "value" : 75.5,
    "unit" : "%",
    "system" : "http://unitsofmeasure.org",
    "code" : "%"
  },
  "device" : {
    🔗 "reference" : "Device/example-device-peak-flow-meter"
  },
  "derivedFrom" : [
    {
      🔗 "reference" : "Observation/example-fev1-single-measurement"
    },
    {
      🔗 "reference" : "Observation/example-fev1-reference-value"
    }
  ]
}

Minimal Example

The following object diagram shows a minimal representation of a lung function measurement, according to the HDDT Information Model taken with a peak flow meter. For readability reasons, the relationship between profiles and resource instances, some connections to the Personal Health Device, and elements that are not mandatory or MS for the MIV Lung Function Testing (see Use of HL7 FHIR) have been omitted.

The following code example shows the concrete JSON representation of the HDDT Lung Function Testing resource (PEF) shown in the diagram.

{
  "resourceType" : "Observation",
  "id" : "example-peak-flow-simple",
  "meta" : {
    "profile" : [
      🔗 "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-function-testing"
    ]
  },
  "status" : "final",
  "code" : {
    "coding" : [
      {
        "system" : "http://loinc.org",
        "code" : "19935-6",
        "display" : "Maximum expiratory gas flow Respiratory system airway by Peak flow meter"
      }
    ]
  },
  "effectiveDateTime" : "2025-12-28T08:00:00Z",
  "valueQuantity" : {
    "value" : 612,
    "unit" : "L/min",
    "system" : "http://unitsofmeasure.org",
    "code" : "L/min"
  },
  "device" : {
    🔗 "reference" : "Device/example-device-peak-flow-meter"
  }
}

MIV-specific Endpoints and Interactions

Observation - READ

Manufacturers of Device Data Recorders that support the MIV Lung Function Testing MUST implement a read interaction on the /Observation endpoint of the FHIR Resource Server. The implementation MUST conform to the HDDT Generic FHIR API. Observation resources shared through the read interaction MUST comply with the FHIR profiles listed in section FHIR Resource Server of this chapter.

Observation - SEARCH

Manufacturers of Device Data Recorders that support the MIV Lung Function Testing MUST implement a search interaction on the /Observation endpoint of the FHIR Resource Server. The implementation MUST conform to the HDDT Generic FHIR API, and implement the search parameters listed on page FHIR Resource Server - Search Parameters. Observation resources shared through the search interaction MUST comply with the FHIR profiles listed in section FHIR Resource Server of this chapter.

Example: FHIR-Search for relative values LOINC code

Example: FHIR-READ

Request: GET /Observation/example-fev1-reference-value

Description: With FHIR-read interactions, a client can access a single resource instance by querying its internal ID. In this case it is suitable for obtaining the reference value of a FEV1 measurement, by querying the ID, in the derivedFrom of a complete Lung Function Testing. Restrictions by the OAuth scopes apply—if the client is not allowed to read this resource, a 404 error will be returned.

Response: Returned object is a single Observation resource.

{
  "resourceType" : "Observation",
  "id" : "example-fev1-reference-value",
  "meta" : {
    "profile" : [
      🔗 "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-reference-value"
    ]
  },
  "status" : "final",
  "code" : {
    "coding" : [
      {
        "system" : "http://loinc.org",
        "code" : "20149-1",
        "display" : "FEV1 predicted"
      }
    ]
  },
  "effectivePeriod" : {
    "start" : "2025-05-01"
  },
  "valueQuantity" : {
    "value" : 4.5,
    "unit" : "L",
    "system" : "http://unitsofmeasure.org",
    "code" : "L"
  },
  "method" : {
    "coding" : [
      {
        "system" : "https://gematik.de/fhir/hddt/CodeSystem/hddt-lung-function-reference-value-method-codes",
        "code" : "GLI-2022"
      }
    ]
  },
  "device" : {
    🔗 "reference" : "Device/example-device-peak-flow-meter"
  }
}

Example: FHIR-Search minimal

Request: GET /Observation?code=19935-6&date=2025-12-15

Description: Obtain all of the Observations where code is the LOINC code for peak expiratory flow measurements (PEF) on a specific date. OAuth scopes apply, and only Observations are returned that the client is allowed to access.

Response: Returned object is a Bundle containing all Observation resource instances matching the search criteria.

{
    "resourceType": "Bundle",
    "id": "8f3a5c2d-9b1e-4a7f-8c3d-2e6f9a1b4c5d",
    "type": "searchset",
    "entry": [
        {
            "fullUrl": "https://himi.example.com/fhir/Observation/example-peak-flow-measurement-1",
            "resource": {
                "resourceType": "Observation",
                "id": "example-peak-flow-measurement-1",
                "meta": {
                    "profile": [
                        "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-function-testing"
                    ]
                },
                "status": "final",
                "code": {
                    "coding": [
                        {
                            "code": "19935-6",
                            "system": "http://loinc.org",
                            "display": "Maximum expiratory gas flow Respiratory system airway by Peak flow meter"
                        }
                    ]
                },
                "effectiveDateTime": "2025-12-15T08:00:00+01:00",
                "valueQuantity": {
                    "system": "http://unitsofmeasure.org",
                    "value": 580,
                    "code": "L/min",
                    "unit": "L/min"
                },
                "device": {
                    "reference": "Device/example-device-peak-flow-meter"
                }
            },
            "search": {
                "mode": "match"
            }
        },
        {
            "fullUrl": "https://himi.example.com/fhir/Observation/example-peak-flow-measurement-2",
            "resource": {
                "resourceType": "Observation",
                "id": "example-peak-flow-measurement-2",
                "meta": {
                    "profile": [
                        "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-function-testing"
                    ]
                },
                "status": "final",
                "code": {
                    "coding": [
                        {
                            "code": "19935-6",
                            "system": "http://loinc.org",
                            "display": "Maximum expiratory gas flow Respiratory system airway by Peak flow meter"
                        }
                    ]
                },
                "effectiveDateTime": "2025-12-15T20:30:00+01:00",
                "valueQuantity": {
                    "system": "http://unitsofmeasure.org",
                    "value": 595,
                    "code": "L/min",
                    "unit": "L/min"
                },
                "device": {
                    "reference": "Device/example-device-peak-flow-meter"
                }
            },
            "search": {
                "mode": "match"
            }
        }
    ]
}

Example: FHIR-Search maximal

Request: GET /Observation?date=2025-12-15&_include=Observation:device

Description: Obtain all of the Observations made on a certain date (the code from the MIV Lung Function Testing is implicitly included). OAuth scopes apply, and only Observations are returned that the client is allowed to access.

Response: Returned object is a Bundle containing all Observation resource instances matching the search criteria.

{
    "resourceType": "Bundle",
    "id": "a7e4b9c2-3f1d-4e8a-9b2c-5d6f8a1e3c4b",
    "type": "searchset",
    "entry": [
        {
            "fullUrl": "https://himi.example.com/fhir/Observation/example-fev1-single-measurement",
            "resource": {
                "resourceType": "Observation",
                "id": "example-fev1-single-measurement",
                "meta": {
                    "profile": [
                        "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-function-testing"
                    ]
                },
                "status": "final",
                "code": {
                    "coding": [
                        {
                            "code": "20150-9",
                            "system": "http://loinc.org",
                            "display": "FEV1"
                        }
                    ]
                },
                "effectiveDateTime": "2025-12-28T08:00:00Z",
                "valueQuantity": {
                    "system": "http://unitsofmeasure.org",
                    "value": 3.4,
                    "code": "L",
                    "unit": "L"
                },
                "device": {
                    "reference": "Device/example-device-peak-flow-meter"
                }
            },
            "search": {
                "mode": "match"
            }
        },
        {
            "fullUrl": "https://himi.example.com/fhir/Observation/example-fev1-reference-value",
            "resource": {
                "resourceType": "Observation",
                "id": "example-fev1-reference-value",
                "meta": {
                    "profile": [
                        "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-reference-value"
                    ]
                },
                "status": "final",
                "code": {
                    "coding": [
                        {
                            "code": "20149-1",
                            "system": "http://loinc.org",
                            "display": "FEV1 predicted"
                        }
                    ]
                },
                "effectivePeriod": {
                    "start": "2025-05-01"
                },
                "valueQuantity": {
                    "system": "http://unitsofmeasure.org",
                    "value": 4.5,
                    "code": "L",
                    "unit": "L"
                },
                "method": {
                    "coding": [
                        {
                            "code": "GLI-2022",
                            "system": "https://gematik.de/fhir/hddt/CodeSystem/hddt-lung-function-reference-value-method-codes"
                        }
                    ]
                },
                "device": {
                    "reference": "Device/example-device-peak-flow-meter"
                }
            },
            "search": {
                "mode": "match"
            }
        },
        {
            "fullUrl": "https://himi.example.com/fhir/Observation/example-fev1-relative-value",
            "resource": {
                "resourceType": "Observation",
                "id": "example-fev1-relative-value",
                "meta": {
                    "profile": [
                        "https://gematik.de/fhir/hddt/StructureDefinition/hddt-lung-function-testing-complete"
                    ]
                },
                "status": "final",
                "code": {
                    "coding": [
                        {
                            "code": "20152-5",
                            "system": "http://loinc.org",
                            "display": "FEV1 measured/predicted"
                        }
                    ]
                },
                "effectiveDateTime": "2025-12-28T08:00:00Z",
                "valueQuantity": {
                    "system": "http://unitsofmeasure.org",
                    "value": 75.5,
                    "code": "%",
                    "unit": "%"
                },
                "derivedFrom": [
                    {
                        "reference": "Observation/example-fev1-single-measurement"
                    },
                    {
                        "reference": "Observation/example-fev1-reference-value"
                    }
                ],
                "device": {
                    "reference": "Device/example-device-peak-flow-meter"
                }
            },
            "search": {
                "mode": "match"
            }
        },
        {
            "fullUrl": "https://himi.example.com/fhir/Device/example-device-peak-flow-meter",
            "resource": {
                "resourceType": "Device",
                "id": "example-device-peak-flow-meter",
                "meta": {
                    "profile": [
                        "https://gematik.de/fhir/hddt/StructureDefinition/hddt-personal-health-device"
                    ]
                },
                "status": "active",
                "type": {
                    "coding": [
                        {
                            "code": "334990001",
                            "system": "http://snomed.info/sct",
                            "version": "http://snomed.info/sct/11000274103/version/20251115",
                            "display": "Peak flow meter (physical object)"
                        }
                    ]
                },
                "definition": {
                    "reference": "DeviceDefinition/device-definition-peak-flow-001"
                },
                "deviceName": [
                    {
                        "name": "Peak Flow Pro",
                        "type": "user-friendly-name"
                    }
                ],
                "modelNumber": "Smart 2",
                "manufacturer": "HealthTech GmbH",
                "serialNumber": "PFM0011223344",
                "expirationDate": "2027-12-15"
            },
            "search": {
                "mode": "include"
            }
        }
    ]
}