An example to demonstrate using the bodyPosition and delta extensions

{
  "resourceType": "Observation",
  "id": "map-sitting",
  "text": {
    "status": "generated",
    "div": "<div xmlns=\"http://www.w3.org/1999/xhtml\"><p><b>Generated Narrative with Details</b></p><p><b>id</b>: map-sitting</p><p><b>status</b>: final</p><p><b>category</b>: Laboratory <span>(Details : {http://terminology.hl7.org/CodeSystem/observation-category code 'laboratory' = 'Laboratory', given as 'Laboratory'})</span></p><p><b>code</b>: Mean blood pressure <span>(Details : {LOINC code '8478-0' = 'Mean blood pressure', given as 'Mean blood pressure'})</span></p><p><b>subject</b>: <a>Patient/example</a></p><p><b>encounter</b>: <a>Encounter/example</a></p><p><b>effective</b>: 02/04/2018 10:30:10 AM --&gt; 05/04/2018 10:30:10 AM</p><p><b>issued</b>: 03/04/2018 3:30:10 PM</p><p><b>value</b>: 60 mm Hg<span> (Details: UCUM code mm[Hg] = 'mmHg')</span></p><p><b>interpretation</b>: Below low normal <span>(Details : {http://terminology.hl7.org/CodeSystem/v2-0078 code 'L' = 'Low', given as 'Low'})</span></p></div>"
  },
  "extension": [
    {
      "url": "http://hl7.org/fhir/StructureDefinition/observation-bodyPosition",
      "valueCodeableConcept": {
        "coding": [
          {
            "system": "http://snomed.info/sct",
            "code": "33586001",
            "display": "Sitting position (finding)"
          }
        ]
      }
    },
    {
      "url": "http://hl7.org/fhir/StructureDefinition/observation-delta",
      "valueCodeableConcept": {
        "coding": [
          {
            "system": "http://snomed.info/sct",
            "code": "1250004",
            "display": "Decreased (qualifier value)"
          }
        ]
      }
    }
  ],
  "status": "final",
  "category": [
    {
      "coding": [
        {
          "system": "http://terminology.hl7.org/CodeSystem/observation-category",
          "code": "laboratory",
          "display": "Laboratory"
        }
      ]
    }
  ],
  "code": {
    "coding": [
      {
        "system": "http://loinc.org",
        "code": "8478-0",
        "display": "Mean blood pressure"
      }
    ]

  "resourceType" : "Observation",
  "id" : "map-sitting",
  "status" : "final",
  "category" : [{
    "coding" : [{
      "system" : "http://terminology.hl7.org/CodeSystem/observation-category",
      "code" : "laboratory",
      "display" : "Laboratory"
    }]
  }],
  "code" : {
    "coding" : [{
      "system" : "http://loinc.org",
      "code" : "8478-0",
      "display" : "Mean blood pressure"
    }]

  },
  "subject": {
    "reference": "Patient/example"

  "subject" : {
    "reference" : "Patient/example"

  },
  "encounter": {
    "reference": "Encounter/example"

  "encounter" : {
    "reference" : "Encounter/example"

  },
  "effectivePeriod": {
    "start": "2018-04-02T10:30:10+01:00",
    "end": "2018-04-05T10:30:10+01:00"

  "effectivePeriod" : {
    "start" : "2018-04-02T10:30:10+01:00",
    "end" : "2018-04-05T10:30:10+01:00"

  },
  "issued": "2018-04-03T15:30:10+01:00",
  "valueQuantity": {
    "value": 60,
    "unit": "mm Hg",
    "system": "http://unitsofmeasure.org",
    "code": "mm[Hg]"

  "issued" : "2018-04-03T15:30:10+01:00",
  "valueQuantity" : {
    "value" : 60,
    "unit" : "mm Hg",
    "system" : "http://unitsofmeasure.org",
    "code" : "mm[Hg]"

  },
  "interpretation": [
    {
      "coding": [
        {
          "system": "http://terminology.hl7.org/CodeSystem/v2-0078",
          "code": "L",
          "display": "Low"
        }
      ],
      "text": "Below low normal"
    }
  ]

  "interpretation" : [{
    "coding" : [{
      "system" : "http://terminology.hl7.org/CodeSystem/v2-0078",
      "code" : "L",
      "display" : "Low"
    }],
    "text" : "Below low normal"
  }]

}