FMEA & FTA Integration in MBSE Approach for Healthcare Systems & Solutions

During the development of today's healthcare systems & solutions, with ever growing complexity, Failure Mode and Effects Analysis (FMEA) and Fault Tree Analysis (FTA) are used for the assessment of technical risk as well as estimation of the impact of potential failure modes on reliability & availability of healthcare and patient safety. The complexity in fully new system & solution developments as well as in evolutionary or incremental product development cycles make these assessments ever more challenging. The challenges may include but are not limited to managing internal & external interfaces and complexity, assuring completeness of the risk assessment, estimation and forecasting the impact of change on reliability & availability, implementing reliability & maintainability design improvements, and generating the required regulatory artifacts. With the integration of the use of FMEA's and FTA's in the enterprise deployed Model Based Systems Engineering (MBSE) approach and toolset, challenges related to assessment of risk and the impact of design changes on reliability & availability of the system & solution are addressed at the early stages of development activities. In the deployed MBSE approach methodology and MBSE environment the system functional requirements of the system & solution are linked to their functional decomposition and assessed for potential failure modes and risks using a standardized design FMEA approach implemented in the MBSE way of working. The identified potential failure modes can be used to create a standardized regulatory required artifact. Next to that these are used as basic events to construct FTA's using AND/OR logic on functional level. The design implementation/realization level analysis is based on the physical decomposition of the product, therefore the FTA's are used to quantitatively calculate and forecast defined reliability & availability parameters based on estimations or field/test data obtained. Impact of design improvements related to reliability & maintainability on the system & solution level as well as on the lower levels can directly be assessed using the constructed FTA. Multi-level analysis is possible by connecting the individual level FTA's using intermediate events. The approach today can deal with systems & solutions that have been designed in a series or parallel/redundant way. The formula's used to calculate the reliability & availability parameters are embedded in the constraint blocks and standard MBSE diagrams associated to the AND/OR gates, building on the OMG Risk Analysis and Assessment Modeling Language (RAAML) standard [1]. Parameters calculated may include but are not limited to: reliability (R(t)), availability (A(t)), Mean Time Between Failure (MTBF) and maintenance cost on the appropriate levels of the system & solution. The approach allows for creating a hierarchical reliability & availability model [2] which includes Hardware as well as Software elements and feeding it with (near real-time) field data.