Verification of interactive software for medical devices: PCA infusion pumps and FDA regulation as an example

Abstract

Medical device regulators such as the US Food and Drug Administration (FDA) aim to make sure that medical devices are reasonably safe before entering the market. To expedite the approval process and make it more uniform and rigorous, regulators are considering the development of reference models that encapsulate safety requirements against which software incorporated in to medical devices must be verified. Safety, insofar as it relates to interactive systems and its regulation, is generally a neglected topic, particularly in the context of medical systems. An example is presented here that illustrates how the interactive behaviour of a commercial Patient Controlled Analgesia (PCA) infusion pump can be verified against a reference model. Infusion pumps are medical devices used in healthcare to deliver drugs to patients, and PCA pumps are particular infusion pump devices that are often used to provide pain relief to patients on demand. The reference model encapsulates the Generic PCA safety requirements provided by the FDA, and the verification is performed using a refinement approach. The contribution of this work is that it demonstrates a concise and semantically unambiguous approach to representing what a regulator's requirements for a particular interactive device might be, in this case focusing on user-interface requirements. It provides an inspectable and repeatable process for demonstrating that the requirements are satisfied. It has the potential to replace the considerable documentation produced at the moment by a succinct document that can be subjected to careful and systematic analysis.