See the patterns page for implementation and usage patterns.

FHIR defines the Device Resource as a type of a manufactured item that is used in the provision of healthcare without being substantially changed through that activity. The device may be a medical or non-medical device. FHIR and US Core further differentiate devices into two “classes”:

• Devices that interact with the human body but do not stay in it are referred to as non-implantable medical devices.
• Implantable devices are those which stay in the human body with a medical objective for an extended period of time, or even a lifetime.
  [Definition reference: Imam W. How to use ISO 13485:2016 to manage implantable devices, ISO 13485 Blog. July 4, 2016. Available at: https://advisera.com/13485academy/blog/2017/07/04/how-to-use-iso-134852016-to-manage-implantable-medical-devices/. Accessed 28 January 2020.]

The FHIR Device Resource addresses both implantable and non-implantable devices. US Core only references Implantable Device. QI-Core inherits Implantable Device from US Core and builds directly from FHIR for the QI-Core Device Resource.

Therefore, when creating an expression for an eCQM or a CDS artifact, assure you are using the appropriate Device or Implantable Device resource.