HL7 FHIR vs. Legacy HL7v2 for Pulmonary Function Data Exchange: What Respiratory Labs Need to Know Before Their Next EMR Upgrade

Choosing between HL7 FHIR and legacy HL7v2 for pulmonary function data exchange is not simply a technical decision. It is a clinical one. Respiratory labs handle uniquely complex data: flow-volume loops, spirometry results, diffusion capacity values, and sleep study outputs that do not map neatly into generic messaging formats. Before your next EMR upgrade, understanding how each standard handles this complexity will determine whether your integration supports or hinders patient care.

TL;DR

  • HL7v2 is the long-established standard powering most hospital integrations today, but it is in maintenance mode and was not designed for modern, API-driven workflows.

  • FHIR is the modern standard built for interoperability, cloud systems, and patient-facing applications, and it is increasingly mandated by regulators.

  • Respiratory labs face unique data complexity that makes the choice of integration standard more consequential than in general pathology.

  • Migration from legacy systems to FHIR-ready platforms is more straightforward than most labs expect, especially with the right vendor.

  • Rezibase supports both HL7v2 and FHIR-based integrations, giving respiratory labs flexibility regardless of where their hospital is on the upgrade journey.

About the Author: This article is written by the Rezibase team, specialists in respiratory and sleep lab technology with over 37 years of combined experience building and supporting clinical physiology systems across Australia, New Zealand, the UK, and Ireland.

What Is HL7v2 and Why Has It Dominated Healthcare for Decades?

HL7v2 (Health Level Seven Version 2) is a pipe-delimited messaging standard first introduced in 1987 and designed to enable communication between hospital systems such as laboratory information systems, order entry platforms, and patient administration systems.

Its longevity is a testament to its practicality. HL7v2 messages are compact, well-understood by most integration engines, and deeply embedded in hospital infrastructure. According to the National Institute of Biomedical Imaging and Bioengineering, HL7v2 has been used for communicating laboratory data for decades and remains the backbone of many clinical workflows globally.

However, as noted by the NIBIB, the v2 base standards are now in "maintenance" mode according to HL7 itself. This means no new features are being developed. The standard is being kept alive, not evolved.

Key characteristics of HL7v2:

  • Pipe-and-hat delimited text format

  • Requires custom segment mapping for non-standard data

  • Strong legacy support across most EMRs and hospital systems

  • Limited support for modern REST APIs or web-based applications

  • Highly variable implementation between vendors

What Is HL7 FHIR and Why Is It Gaining Ground?

FHIR (Fast Healthcare Interoperability Resources) is a modern standard developed by HL7 International that uses RESTful APIs, JSON, and XML to enable flexible, real-time health data exchange.

According to ICANotes, "FHIR is designed for modern, connected care using APIs and cloud-based workflows, while HL7 remains common in legacy healthcare settings." FHIR breaks health data into modular "resources" (e.g., Patient, Observation, DiagnosticReport) that can be queried, updated, and shared independently, making it far more adaptable for respiratory data than a fixed message format.

Any hl7 fhir implementation guide will highlight that FHIR's RESTful architecture makes it significantly easier to build integrations with mobile applications, cloud platforms, and patient portals compared to HL7v2.

Key characteristics of FHIR:

  • RESTful API-based architecture

  • Supports JSON, XML, and Turtle formats

  • Modular resource model suited to complex clinical data

  • Actively developed and increasingly mandated by regulators

  • Better suited to cloud-native and SaaS platforms

How Do HL7v2 and FHIR Compare for Respiratory Lab Data?

Respiratory function data is more structured and numerically dense than a typical pathology result. A single spirometry report may include dozens of discrete values, a flow-volume loop image, predicted normal values, and an interpretive comment. Here is how the two standards compare in this context:

Feature

HL7v2

FHIR

Data format

Text-based, pipe-delimited

JSON/XML, resource-based

Flow-volume loop support

Workaround required

Native via Observation/Media resources

Normal values transmission

Non-standard, varies by vendor

Structured Observation resources

API support

Minimal

Native REST API

Cloud compatibility

Limited

Designed for cloud

Regulatory trajectory

Maintenance mode

Actively mandated

Implementation complexity

Lower for legacy systems

Higher upfront, lower long-term

According to Romexsoft, "FHIR excels in patient-facing apps, mobile solutions, and real-time data exchange," while earlier HL7 standards remain practical for legacy system communication and internal hospital workflows.

What Are the Real Risks of Staying on HL7v2 for Respiratory Labs?

Staying on HL7v2 is not inherently wrong, but it carries compounding risks that respiratory labs should understand before committing to another upgrade cycle on the same architecture.

Risks of remaining on HL7v2:

  • Increasing difficulty finding integration engineers who specialise in v2 mapping

  • Regulatory pressure toward FHIR compliance in Australia, the UK, and globally

  • Limited ability to support patient-facing portals or mobile result delivery

  • Custom segment workarounds for respiratory data can introduce transcription errors

  • Any hl7 integration engine comparison will increasingly favour FHIR-native platforms for new deployments

According to Healthcare Integrations, "HL7 v2 remains critical for existing hospital workflows, while FHIR is essential for innovation and compliance with new regulations." The practical implication is that respiratory labs cannot afford to ignore FHIR in their planning horizon, even if they are not ready to migrate today.

How Hard Is It to Switch from a Legacy Respiratory System to a FHIR-Ready Platform?

The honest answer is: less difficult than most labs assume, particularly when the receiving platform is designed to handle the transition.

Modern platforms like Rezibase are built to work with both HL7v2 and FHIR, which means the migration does not require a hospital-wide integration overhaul on day one. Rezibase connects with Patient Administration Systems, EMRs, Electronic Orders Systems, and DICOM Modality Worklists, supporting whatever integration layer your hospital currently runs.

A typical migration path looks like this:

  1. Audit your current data sources and device types

  2. Confirm your EMR's current HL7 version and FHIR roadmap

  3. Select a respiratory platform that supports both standards during transition

  4. Use vendor-assisted tools to bring across historical patient records

  5. Validate discrete data integrity, including normal values and test results

  6. Go live with the new system running in parallel before full cutover

Rezibase's Magic Import feature simplifies step four considerably, automatically extracting discrete data including flow-volume loops directly from device reports, regardless of the machine manufacturer.

Frequently Asked Questions

Is HL7v2 still supported by major EMRs in 2026?
Yes. Most major EMRs continue to support HL7v2, but many are actively building FHIR APIs alongside it. Expect dual-standard support for the foreseeable future.

Can FHIR transmit flow-volume loop data from spirometry?
Yes. FHIR's Observation and Media resources can carry both discrete numerical values and associated image or waveform data, making it well-suited to spirometry outputs.

What does "HL7v2 maintenance mode" mean for respiratory labs?
It means no new capabilities will be added to the v2 standard. Labs relying solely on v2 will not benefit from future interoperability improvements.

Do I need to replace my entire EMR to adopt FHIR?
Not necessarily. Many hospitals are adding FHIR APIs to existing EMRs. A FHIR-ready respiratory platform can connect to these APIs without requiring a full EMR replacement.

Is Rezibase compatible with both HL7v2 and FHIR?
Yes. Rezibase integrates with hospital systems using both standards, giving labs flexibility during and after their EMR upgrade.

How long does a respiratory system migration typically take?
Timelines vary, but with a well-prepared vendor and clear data mapping, most respiratory labs complete their core migration within a few months.

Is FHIR mandated in Australia or the UK?
Both countries are moving in this direction. Australia's National Digital Health Strategy and NHS digital transformation programs both point toward FHIR as the long-term standard.

About Rezibase

Rezibase is Australia's most advanced cloud-based respiratory and sleep reporting platform, trusted by over 35 sites including NHS institutions in the UK and NSW Health in Australia. Built by respiratory scientists Peter Rochford and the late Jeff Pretto, and now part of the Cardiobase family, Rezibase is the only platform of its kind that combines 37 years of respiratory science expertise with a modern, vendor-neutral, cloud-native architecture. From spirometry reporting and sleep studies to full accreditation management and EMR integration, Rezibase is designed to reduce clinical risk, eliminate double data entry, and make life easier for the scientists and clinicians who rely on it every day.

Ready to see how Rezibase handles HL7 integration for your respiratory or sleep lab? Visit rezibase.com to book a demo or start your 30-day free trial.

References

EMR Integration Maturity Model for Respiratory and Sleep Departments: Assessing Where Your Lab Falls on the Interoperability Spectrum ›

EMR Integration Maturity Model for Respiratory and Sleep Departments: Assessing Where Your Lab Falls on the Interoperability Spectrum ›