The Design Requirements and Agency Expectations for Connected Devices
The design of wireless medical devices needs to include aspects of system design which are not always obvious. The FDA document Guidance for Industry and Food and Drug Administration Staff Document issued on August 14, 2013, is an excellent starting point for identifying design aspects of a wireless system that must operate and ‘co-exist’ with other diverse devices as well as multiple instances of itself.
Information that needs to be considered in the design of a wireless system, as well as being present in the submission itself:
1. Description of the essential performance of the device, related to wireless communications
2. Detailed information of the RF wireless technology implements on the device:
•Power
•Frequency and modulation method
•Data rate
•Protocol used
•Security mechanisms (Cyber security, identification of threats, man in the middle attacks etc.)
3. Risk and Hazards associated with the medical device related to communications:
•Identification of Risks associated with wireless communications, related to co-existence
•Identification of risks associated with Cyber security, mitigations and justifications
4. Summary of the claims of the wireless system including;
•Safeguards and redundancy
•Related to risks
•Failure of device functions
5. Summary of testing and justifications:
•Summary of testing of the devices, Pass Fail Criteria
•Justification of testing, selection of interfering devices etc.
•Test results and data to support all claims
•Pass / Fail criteria
6. Labeling, which should include:
•Description of wireless technology
•Provisioning (Associating devices), Configuring and Management
•Required QOS, Quality of Service
•Security provisions and requirements (Passwords, etc.)
•An example of device labeling
7. Communication, communicating to other devices, Mobile Medical Applications:
•Identify make and model of Mobile Devices and Operating Systems
•Verification and Validation Documentation for each device
•Firmware Update, Risks and Mitigations
As an example, consider the Risks and Hazards of a medication delivery system that utilizes BTLE (Blue Tooth Low Energy) communication to the user's mobile device allowing the user to administer a bolus of medication. There is a risk of inappropriate bolus delivery. Causes of this Risk include (but are not limited to):
•Device inadvertently connects to a different mobile device in a clinical setting where there are more than one of the same devices
•Communication infrastructure uses non-guaranteed advertising packet, which may not reach their target due to collision traffic
During the early stages of system design it is important to identify risks and design mechanisms of mitigating those risks.
In conclusion, the elements listed above should be considered as early as possible in the development process to mitigate program risks.