FMEA timing and new vs. previously implemented control measures

FMEA timing and new vs. previously implemented control measures – 1/2007

When is the best time to do a FMEA? To answer this question, consider the phases of product development:

Phase 1 – Researching new opportunities (funding, design starts) Phase 2 – Proving feasibility (breadboards) Phase 3 – Scheduled development (prototypes) Phase 4 – Validation (clinical trials) Phase 5 – Commercialization (launch)

The number of phases or their names differ in companies but conceptually, these phases describe the product development process (with a similar set of phases for processes).  For medical diagnostic manufacturers, FMEA is often conducted as part of a FDA submission and this can occur in Phases 2, 3, or 4, with Phase 3 being common.

However, the best time to start a FMEA is in Phase 1. The FMEA should be revisited in each phase. Here are some reasons for starting the FMEA this early.

Purpose of FMEA – The purpose of FMEA is to affect the design and the most practical time to do this is when competing designs are being considered, not after choices have been made, contracts signed, and prototypes being built and tested. Of course, there are other reasons for performing a FMEA. FDA requires risk assessment (hazard analysis) but a FMEA conducted late in the product development process is largely a documentation exercise – rarely does this FMEA affect the design.

Design Reviews and FMEA – Most projects have design reviews including in Phase 1 and one might think that these can be considered as FMEA activities. They can’t. In a typical design review, the design is presented and questions are allowed.  Whereas these questions could affect the design, they are less likely to do so than a FMEA, which is a challenge of the design in the form of a brainstorming session with much more time devoted to proposing potential errors, their causes, effects, and control measures (mitigations) that could affect the design.

Formal vs. Informal FMEA – If one reviews the documentation version of a FMEA, (e.g., a FMEA that has been carried out late in the product development cycle), it is clear that the design has been affected by considering error prevention and detection. A FMEA is a documentation exercise when the control measures have been previously chosen. Putting in control measures to prevent errors outside of FMEA can be considered an informal FMEA. The danger in this approach is that the control measures are often supplied by the designer. There is neither a team nor a challenge session.

Actually, it would be naïve to think that without a FMEA, all products will have a spate of serious flaws. Designers (or people who implement the design) who incorporate effective control measures as part of the design make the need for a FMEA less apparent. However, the team brainstorming design challenge session in a FMEA reduces the risk that the designer has missed something.

Moreover, when FMEA is informal, one might be adding control measures to a design that should not have been chosen in the first place.  A designer does not often question his or her own design! and the designer and the person who implements the design (the engineer) may be different people.

An Example – A small instrument is being developed. Rather than choosing an OEM keypad, a designer specifies a unique keypad which must be developed from scratch including all of the interfaces. The risks of such a design choice are much higher than selecting a keypad with known characteristics. The unique keypad increases risk of events that could lead to patient harm, worse reliability, and delay to the product launch. (It is up to the designer to supply the benefits off the unique keypad). The time to challenge this choice is before work on the unique keypad starts, not after prototypes have been built and are under test.

To make this example more challenging, assume that the designer is charismatic, cozy with upper management, and claims that the unique keypad and other similar design features will win design awards and dramatically increase sales. How does someone who is less charismatic and less well known by management successfully challenge the design? One needs to speak in the language of management – money. One should request a marketing study such as a conjoint analysis to prove the assumption of increased sales. (In a conjoint analysis, one asks customers to rank potential product features such as elegant vs. ordinary design, size of sample, cost, and so on). One should also demonstrate the downside risk to the design by showing the effect on profitability of a delay in the product launch (caused by the design choice). If one is using decision analysis financial models, one could show the decrease in expected net present value caused by the increased risk of a patient harm event and lower reliability (as well as the delay in launch).

A suggested new  FMEA item – distinguishing between new vs. previously implemented control measures

Consider another example:

Error – incorrect result reported Cause – clot in system Effect – potential wrong medical decision Control measure – clot detection system prevents result from being reported

This is a pretty standard (partial) entry in a FMEA table. However, it is most likely that the clot detection system has not been implemented as a part of the FMEA and may have been part of the original design requirements1. Hence this is a case of FMEA as documentation since any design for this product will have a clot detection system. Yet, regardless of when the FMEA is conducted, it is possible that some control measures have resulted from the FMEA exercise. If this is the case, one would like to know this and distinguish these control measures from previously implemented control measures and this distinction (which control measure is new vs. previously implemented) is missing in most FMEAs.

Whereas there is no guarantee that new control measures are required to lower risk, one can evaluate past projects by examining risk outcomes and the historical FMEAs – it should be possible to distinguish after the fact, between previously implemented and new control measures. This presents one with a one way test. If past risk outcomes have been poor and there have been no (or few) new control measures in FMEAs, then it would be prudent to measure new control measures in future FMEAs.

1It is possible to perform a FMEA on the design requirements, e.g., before any design work starts. However, it is also likely that clot detection is simply a feature required by marketing to be competitive.


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