Failure Mode and Effects Analysis (FMEA) is a design review tool used to identify and correct all possible failures in a product, service, design or manufacturing process. This step-by-step approach was first initiated in the 1940s by the United States Army and further developed by NASA in the early 1960s.
As one of the most used methodologies for quality and reliability, FMEAs provide a way to systematically assess points of failure in a specific design, process, or system and list the consequences of these failures. When the failures have been identified, the risks associated with them can be evaluated, and a plan developed to discover, avert, and reduce the severity of the most critical ones.
The following section outlines the basic steps needed to carry out FMEA. Other questions that are connected to the two key types of FMEAs and their relationship to medical device manufacturing will also be addressed:
The steps in performing FMEA remain basically the same, regardless of whether a design, process, or system is analyzed. The order of these steps are:
Because of their flexibility, FMEAs are considered "living documents" that reflect the iterative process of improving the quality and reliability of a product, system, design or service.
DFMEAs are used to evaluate and address potential failure modes either early on in the product design process or in its end stages. PFMEAs, on the other hand, analyze a specific process and ways the process can prevent a defective product from going to market. Both are performed using the same basic steps as listed for the FMEA previously.
The two types of FMEAs offer different outcomes. The outcome from performing DFMEA is that the product transfer from design to production results in a better product. An added benefit is that when failures are identified early on in the design process, costs stay low.
A Process Control Plan (PCP) is the outcome that offers the most benefits to the user. While the PFMEA Worksheet and the Process Flow Diagram (PFD) are both important tools for understanding the process steps, the PCP stands as proof that the chance of the highest-risk failures has been dramatically decreased, making the process more robust. The PCP also provides appropriate ways to detect a defective product before it ships.
Medical device manufacturers perform DFMEAs to identify and evaluate failure modes for medical device specifications as well as for other aspects of device design. PFMEAs are performed to improve manufacturing processes.
However, manufacturers have extended the traditional use of FMEAs: they have been using them as risk management tools to evaluate failure modes for medical device safety. The problem with performing FMEA to evaluate device safety is that this methodology does not align with ISO 14971, the standard for the application of risk management to medical devices. This approach could create difficulties for manufacturers because their risk management system is out of date and no longer complies with ISO 14971.
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Although FMEAs and ISO 14971 share the term "risk," this term has different meanings for each methodology. It is easy to understand why manufacturers confuse the two meanings and, by extension, assume that FMEA is adequate for analyzing failure modes for medical device safety. However, the difference in meaning is significant.
Risk in the context of ISO 14971 relates to the safety of a medical device and considers correct and incorrect use of that device. The foundation of a risk management system rests on the identification and evaluations of hazards--potential sources of harm--and hazardous situations as they apply to the device.
This is a stricter interpretation of the term "risk" in comparison to its usage in FMEA, which is consistently linked only to identifying and assessing design or process failure modes. Also, FMEA is a step-by-step approach that has sufficient flexibility for a user to define risk criteria. By comparison, a risk management system is a formal framework in which concepts such as risk, hazards, and harm are rigorously defined.
It's important to note that a medical device may never exhibit the kind of failure that is documented in FMEA. But it will still have risks of causing harm, which is the focus of a risk management system and is the core idea behind ISO 14971. Because this standard has been widely accepted in the medical device regulatory community, users of FMEAs who have relied upon these approaches to evaluate safety risks for medical devices should seriously consider implementing a compliant risk management system instead.