{
  "resourceType": "Questionnaire",
  "status": "active",
  "item": [
    {
      "linkId": "cardiac",
      "text": "Cardiac Measurements",
      "type": "group",
      "item": [
        {
          "linkId": "cardiac-sbp",
          "code": [
            {
              "system": "http://loinc.org",
              "code": "8480-6"
            }
          ],
          "text": "Systolic blood pressure (mmHg)",
          "type": "decimal",
          "extension": [
            {
              "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-unit",
              "valueCoding": {
                "system": "http://unitsofmeasure.org",
                "code": "mm[Hg]",
                "display": "mmHg"
              }
            }
          ]
        },
        {
          "linkId": "cardiac-dbp",
          "code": [
            {
              "system": "http://loinc.org",
              "code": "8462-4"
            }
          ],
          "text": "Diastolic blood pressure (mmHg)",
          "type": "decimal",
          "extension": [
            {
              "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-unit",
              "valueCoding": {
                "system": "http://unitsofmeasure.org",
                "code": "mm[Hg]",
                "display": "mmHg"
              }
            }
          ]
        },
        {
          "linkId": "cardiac-qt",
          "code": [
            {
              "system": "http://loinc.org",
              "code": "8634-8"
            }
          ],
          "text": "QT interval (ms)",
          "type": "decimal",
          "extension": [
            {
              "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-unit",
              "valueCoding": {
                "system": "http://unitsofmeasure.org",
                "code": "ms",
                "display": "ms"
              }
            }
          ]
        },
        {
          "linkId": "cardiac-hr",
          "code": [
            {
              "system": "http://loinc.org",
              "code": "8867-4"
            }
          ],
          "text": "Heart rate (beats per minute)",
          "type": "decimal",
          "extension": [
            {
              "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-unit",
              "valueCoding": {
                "system": "http://unitsofmeasure.org",
                "code": "/min",
                "display": "/min"
              }
            }
          ]
        },
        {
          "linkId": "cardiac-map",
          "code": [
            {
              "system": "http://loinc.org",
              "code": "8478-0"
            }
          ],
          "text": "Mean arterial pressure (mmHg)",
          "type": "decimal",
          "readOnly": true,
          "extension": [
            {
              "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-calculatedExpression",
              "valueExpression": {
                "language": "text/fhirpath",
                "expression": "(((%resource.item.where(linkId='cardiac').item.where(linkId='cardiac-sbp').answer.valueDecimal) + (2 * (%resource.item.where(linkId='cardiac').item.where(linkId='cardiac-dbp').answer.valueDecimal))) / 3).round(1)"
              }
            }
          ]
        },
        {
          "linkId": "cardiac-qtc-bazett",
          "text": "QTc, Bazett (ms)",
          "type": "decimal",
          "readOnly": true,
          "extension": [
            {
              "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-calculatedExpression",
              "valueExpression": {
                "language": "text/fhirpath",
                "expression": "((%resource.item.where(linkId='cardiac').item.where(linkId='cardiac-qt').answer.valueDecimal) / (60 / (%resource.item.where(linkId='cardiac').item.where(linkId='cardiac-hr').answer.valueDecimal)).sqrt()).round(0)"
              }
            }
          ]
        },
        {
          "linkId": "cardiac-qtc-fridericia",
          "text": "QTc, Fridericia (ms)",
          "type": "decimal",
          "readOnly": true,
          "extension": [
            {
              "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-calculatedExpression",
              "valueExpression": {
                "language": "text/fhirpath",
                "expression": "((%resource.item.where(linkId='cardiac').item.where(linkId='cardiac-qt').answer.valueDecimal) / (60 / (%resource.item.where(linkId='cardiac').item.where(linkId='cardiac-hr').answer.valueDecimal)).power(1 / 3)).round(0)"
              }
            }
          ]
        }
      ]
    }
  ]
}