Assurance cases and infusion devices

As part of a general initiative to improve patient safety with infusion pumps, the USA Food and Drug Administration (FDA) recently issued a Guidance document to infusion pump manufacturers that recommends the use of assurance cases and the submission of assurance case reports for the approval of new devices to enter the market.

In this Guidance, the concept of an "assurance case" is recommended as a mechanism to suppliers to communicate information about their device and how risks have been identified and mitigated, e.g in Clause 6:

"In making this demonstration of substantial equivalence for your infusion pump, FDA recommends that you submit your information through a framework known as an assurance case or assurance case report."

The Guidance explicitly recommends a Claims-Arguments-Evidence assurance case approach. It is stated that claims are decomposed into other claims, ultimately supported by evidence. Arguments are seen as how the evidence is linked to the claims. A standard set of well-known classes of risk (operating hazards, Electrical, Software, Use etc) is provided to help applicants cover areas that they are required to be shown to be mitigated. However suppliers are still expected to do their own hazard identification.

Adelard's involvement

Since the publication of this Guidance, Adelard has been supporting both the FDA and manufacturers of infusion pumps, while we are involved in ongoing research that aims to promote and facilitate the application of assurance cases widely in healthcare.

In particular, Adelard:

• supports the FDA by offering expert consultation based on experience from other safety critical industries where the concept of the safety and assurance case is widely adopted.
• offers consulting services to infusion pump manufacturers to support the development of assurance arguments.
• offers its ASCE tool to infusion pump manufacturers.
• is involved in an ongoing research project for the Health Foundation in the UK that aims to bring in experience from the application of the safety case in other industries to healthcare.

Adelard resources

Adelard has over twenty years of consulting and applied research experience in the specification, design, assessment and safety assurance of safety-critical systems. A selection of reports and publications can be found in our resources page.

The Adelard Assurance and Safety Case Environment (ASCE) is a software tool used widely across safety critical domains for more than 10 years for the creation and management of safety cases. More information about ASCE can be found here.

Other resources

Below are other links to current work in the field of assurance of infusion pumps.

• Connecting for Health of the NHS has produced a guidance document on the production of the "supplier safety case". The report can be found here.
• The USA Software Engineering Institute of Carnegie Mellon University have published a report on Assurance cases for medical devices. The report provides a general overview of the safety/assurance case concept, and provides some background about infusion pumps. The report can be found here. A presentation that provides background on assurance cases and some detail about the infusion pump project they are working on can be found here.
• The University of Pennsylvania, in collaboration with the FDA, and the Fraunhofer Center for Experimental Software Engineering (CESE) are developing models of a Generic Infusion Pump. This includes a description of the device, a set of safety requirements, a hazard analysis, and state machine descriptions of its behaviour.
• The EWICS medical devices working group has considered the assurance case approach for a medical bed. A paper describing the work is available here.