Map HL7 v2 message fields to FHIR R4 resources for interoperability translation

Steps

1. Reference the HL7 v2 to FHIR mapping tables published in the HL7 FHIR specification (https://hl7.org/fhir/v2maps.html) and the HL7 v2 to FHIR Implementation Guide for validated field-level mappings.
2. Map the PID segment to a FHIR Patient resource: PID-3 → Patient.identifier[], PID-5 → Patient.name[], PID-7 → Patient.birthDate (reformatted), PID-8 → Patient.gender (with value translation: M→male, F→female, U→unknown).
3. Map the PV1 segment to a FHIR Encounter resource: PV1-2 patient class → Encounter.class (using HL7 v3 ActCode system), PV1-44 → Encounter.period.start, PV1-45 → Encounter.period.end.
4. Map OBX segments (observation results) to FHIR Observation resources: OBX-3 (observation identifier, usually LOINC) → Observation.code, OBX-5 (value) → Observation.value[x] (type based on OBX-2), OBX-11 (result status) → Observation.status.
5. Handle data type translation explicitly: CWE/CE (coded with exceptions) components map to FHIR CodeableConcept with coding[]; NM (numeric) maps to valueQuantity; TX/FT (text) maps to valueString.
6. Validate the mapped FHIR resources against the relevant profiles (US Core where applicable) and check for required fields that have no corresponding v2 source field.