EHR Integration Patterns for Bedside Devices

The four integration layers

Almost every EHR integration a hospital ships in 2026 uses one of four patterns:

1. HL7 v2 messages over MLLP — vitals, ADT, orders, results. High volume, low ceremony.
2. FHIR REST APIs — modern read/write for third-party applications, patient-facing apps, and analytics.
3. SMART on FHIR — an OAuth 2.0 profile that lets a third-party app launch inside the EHR with a scoped session.
4. CDS Hooks — a webhook fired by the EHR at defined workflow points (order entry, medication review) that returns cards a clinician can act on.

Typical bedside data flows

When to use which

• If the data is event-driven and high-volume (vitals, ADT, orders): HL7 v2.
• If a third-party UI needs to read or write patient data on demand: FHIR REST.
• If the third-party UI must launch inside the chart: SMART on FHIR.
• If a clinical decision should surface at a specific workflow moment: CDS Hooks.

Standards reference

• HL7 v2.5.1 / v2.8 — event-driven messaging.
• HL7 FHIR R4 — resource-based APIs; USCDI-aligned in the US.
• SMART App Launch 2.0 — OAuth 2.0 + OpenID Connect profile.
• CDS Hooks 2.0 — webhook specification.
• 21st Century Cures Act / ONC Certification — the US regulatory driver.