The format for this is clearly explained in Bluetooth LE GATT specification:
https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.characteristic.blood_pressure_measurement.xml
Unfortunately, I have not been able to find Zigbee specifications that would clearly explain how to retrieve and decode data from a Zigbee blood pressure monitor. Could you please provide the specification?
What about formats for other measurements, like blood glucose?