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HL7 Messaging: How Systems Speak the Same Language

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What is HL7?

HL7 stands for Health Level Seven, a set of international standards used to transfer clinical and administrative data between healthcare systems. It's the common language that allows systems like EPMA, EPR, pharmacy, and labs to communicate smoothly, reducing risk and improving coordination of care.

Lab analysis on computer

Why HL7 Matters in EPMA

HL7 messaging supports:

  • The transfer of medication orders from EPMA to pharmacy or stock systems

  • Automatic syncing of patient data across systems

  • Reception of alerts, observations, and lab results

  • Ensuring consistent, accurate data exchange between EPMA and the wider EPR

 

Reliable messaging is essential for safety, accuracy, and seamless workflows.

Coding Station

Common HL7 Message Types

  • ADT (Admit, Discharge, Transfer)

Shares patient movement and encounter info

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  • ORM (Order Entry)

Sends medication or diagnostic orders

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  • ORU (Observation Result)

Returns lab/imaging results

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  • RDE (Pharmacy/Treatment Orders)

Transmits medication orders to pharmacy systems

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  • ACK (Acknowledgment)

Confirms message receipt

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Common Challenges

  • Delays or failures in message delivery

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  • Duplicate or missing data due to incorrect message formatting

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  • Mapping issues between different vendor systems

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  • Managing versioning (e.g. HL7 v2 vs v3 vs FHIR)

Coding

HL7 v2 vs FHIR:
What's the Difference?

HL7 v2

  • Format: Delimited text

  • Ease of Use: Complex

  • Flexibility: Rigid

  • Adoption: Widely used

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FHIR

  • Format: JSON/XML

  • Ease of Use: Developer-friendly

  • Flexibility: Modular and web-based

  • Adoption: Growing rapidly

Doctor in Scrubs Reading Notes

Real-World Examples in EPMA

  • A prescriber updates a medication

→ RDE message sent to pharmacy

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  • A patient is admitted

→ ADT message automatically creates a profile in EPMA

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  • A critical potassium level is recorded

→ ORU message alerts the EPMA system

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  • A nurse edits the drug chart

→ system sends ORM/ACK messages to sync changes

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Summary

HL7 messaging is the invisible glue that binds EPMA to the rest of the hospital’s digital ecosystem. Whether it's sending an order, receiving a result, or syncing patient data, HL7 ensures everyone is working with the same, up-to-date information.

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Knowing how these messages work empowers digital pharmacy teams to design better workflows and troubleshoot smarter.

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