Developing Medical Device Software to be Compliant With IEC 62304 Consolidated Version Edition 1.1

A software functional safety standard such as that prescribed by IEC 62304 with its many sections, clauses and sub-clauses may at first seem intimidating. However, once broken down into digestible pieces, its guiding principles offer sound guidance in the establishment of a high quality software development process, not only leading up to initial product release but into maintenance and beyond. Such a process is paramount for the assurance of true reliability and quality ? and above all the safety and effectiveness of medical devices. One of the more significant changes imposed by amendment 1 of the standard concerns a new risk-based approach to the safety classification of medical device software. The previous concept was based exclusively on the severity of the resulting harm. Downgrading of the safety classification of medical device software from C to B or B to A used to be possible by adopting hardware-based risk mitigation measures external to the software. The new amendment now replaces this concept with safety classification as shown in a decision tree. The classification assigned to any medical device software has a tremendous impact on the code development process from planning, developing, testing, and verification through to release and beyond. It is therefore in the interests of medical device manufacturers to invest the effort to get it right the first time, minimizing unnecessary overhead by resisting over classification, but also avoiding expensive and time-consuming rework resulting from under classification. This paper will explain how the classification of each software item has a significant impact in the overhead involved with its development. It will present an introduction to the use of automated static analysis, dynamic coverage analysis, data and control coupling analysis, and unit/integration testing, and discuss how the required use of such tools varies depending on the classification.