Bluetooth Low Energy & GATT
How your pulse oximeter actually talks to a phone: BLE radio plus the GATT data model of services and characteristics.
In one line
BLE is the short-range, low-power radio in nearly every consumer health device; GATT (Generic Attribute Profile) is the data model that says what the device exposes and how to read it.
How it works
A device advertises; a phone or gateway connects. Data is organised as services
(e.g., Heart Rate service 0x180D) containing characteristics (Heart Rate
Measurement 0x2A37) you can read, write, or — most usefully — subscribe to via
notifications so each new reading is pushed. The Bluetooth SIG standardises health
profiles (heart rate, blood pressure, glucose, pulse oximeter, weight scale), which is
why a standards-following device works with any compliant app.
Where it shows up in digital health
Almost every RPM kit's first hop is BLE: cuff → phone/gateway app → cloud. Integration work means mapping GATT characteristics into your data model — and onward into FHIR Observations with proper units (UCUM) and device identity. Vendor devices that ignore the standard profiles and use proprietary GATT services are the recurring pain you will meet in real integrations.