Dosing 'asNeeded' and 'asNeededCodeableConcept' instructions
Dosage.asNeeded[x]
The asNeeded structure can be used to define a simple “as required” (or “pro re nata” expressed as “PRN” for those who still prefer to use Latin abbreviations) instructions. In this case use the asNeededBoolean option. The absence of asNeededBoolean is equivalent to where asNeededBoolean has a value of “false”.
The asNeededCodeableConcept option is used to bound the dosage instruction to a coded term. Any number of coded terms can be used from the SNOMED-CT hierarchy as a descendant of 404684003 Clinical Finding (finding). An extensive medication-as-needed-reason value-set is defined within FHIR which is a subset of the SNOMED-CT clinical findings hierarchy.
Examples
Dosage.asNeeded
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<!-- "file": "example-dosage-inter2.xml" --> | |
<!-- Zopiclone 3.75mg tablets, 1 tablet, at BEDTIME, PRN, oral --> | |
<MedicationRequest> | |
<id value="a8ca980c-72aa-11e7-8cf7-a6006ad3dba0"/> | |
<meta> | |
<profile value="https://fhir.hl7.org.uk/STU3/StructureDefinition/CareConnect-MedicationRequest-1"/> | |
</meta> | |
<contained> | |
<Medication> | |
<id value="med1"/> | |
<code> | |
<coding> | |
<system value="http://snomed.info/sct"/> | |
<code value="321177003"/> | |
<display value="Zopiclone 3.75mg tablets"/> | |
</coding> | |
</code> | |
</Medication> | |
</contained> | |
<intent value="order"/> | |
<medicationReference> | |
<reference value="#med1"/> | |
</medicationReference> | |
<subject> | |
<identifier> | |
<system value="https://fhir.nhs.uk/Id/nhs-number"/> | |
<value value="9999999999"/> | |
</identifier> | |
</subject> | |
<dosageInstruction> | |
<timing> | |
<repeat> | |
<frequency value="1"/> | |
<period value="1"/> | |
<periodUnit value="d"/> | |
<when value="HS"/> | |
</repeat> | |
</timing> | |
<asNeededBoolean value="true"/> | |
<route> | |
<coding> | |
<system value="http://snomed.info/sct"/> | |
<code value="26643006"/> | |
<display value="oral"/> | |
</coding> | |
</route> | |
<doseQuantity> | |
<value value="1"/> | |
<unit value="tablet"/> | |
<system value="http://snomed.info/sct"/> | |
<code value="428673006"/> | |
</doseQuantity> | |
</dosageInstruction> | |
</MedicationRequest> |
Dosage.asNeededCodeableConcept
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<!-- "file": "example-dosage-complex14.xml" --> | |
<!-- Metoclopramide, orally 10mg to be taken when required for nausea up to three times daily --> | |
<MedicationRequest> | |
<id value="a8ca980c-72aa-11e7-8cf7-a6006ad3dba0"/> | |
<meta> | |
<profile value="https://fhir.hl7.org.uk/STU3/StructureDefinition/CareConnect-MedicationRequest-1"/> | |
</meta> | |
<contained> | |
<Medication> | |
<id value="med1"/> | |
<code> | |
<coding> | |
<system value="http://snomed.info/sct"/> | |
<code value="56549003"/> | |
<display value="Metoclopramide"/> | |
</coding> | |
</code> | |
</Medication> | |
</contained> | |
<intent value="order"/> | |
<medicationReference> | |
<reference value="#med1"/> | |
</medicationReference> | |
<subject> | |
<identifier> | |
<system value="https://fhir.nhs.uk/Id/nhs-number"/> | |
<value value="9999999999"/> | |
</identifier> | |
</subject> | |
<dosageInstruction> | |
<timing> | |
<repeat> | |
<frequencyMax value="3"/> | |
<period value="1"/> | |
<periodUnit value="d"/> | |
</repeat> | |
</timing> | |
<asNeededCodeableConcept> | |
<coding> | |
<system value="http://snomed.info/sct"/> | |
<code value="422587007"/> | |
<display value="nausea"/> | |
</coding> | |
</asNeededCodeableConcept> | |
<route> | |
<coding> | |
<system value="http://snomed.info/sct"/> | |
<code value="26643006"/> | |
<display value="oral"/> | |
</coding> | |
</route> | |
<doseQuantity> | |
<value value="10"/> | |
<unit value="milligram"/> | |
<system value="http://unitsofmeasure.org"/> | |
<code value="mg"/> | |
</doseQuantity> | |
</dosageInstruction> | |
</MedicationRequest> |