Introduction

Analyses such as DFMEA or PFMEA are well known and while not everyone would be able to do faultless analysis for construction or process, the general idea of them is already familiar even to students with only quality management lectures. However, it is worth knowing that in addition to these two basic analyses, there are several more that are worth knowing if only because they are obligatory in some situations. One of them is the UFMEA (use FMEA) analysis. Its task in the process of ensuring the quality of the product, so that it meets the customer’s expectations, is shown in Figure 1.

 

UFMEA analysisi of risk associated with the use of product

Figure 1 basic areas of UFMEA risk assessment Source: own development

The “U” in UFMEA comes from the word “use”. This analysis refers to what the user of the analysed product will do with product and what mistakes they may make. Therefore you should look for any problems arising from the fact that the user of the product will act in an unusual way, but, given the design of the product, possible way – such an example: the user will by mistake press two buttons on the control panel at the same time.

It is worth checking the official definition of use error given by the Food and Drug Administration (FDA) [2], which indicates that it is both a user action and a lack of user action, which that are different actions from what the manufacturer expected. It is therefore necessary here to creatively go beyond what is described, for example, in the instructions for use (the so-called IFU), because the lack of action is usually not described there. It is therefore extremely important in UFMEA to work in groups to look at the analysed product and its use from different points of view.

It can be said that, in a sense, the UFMEA analysis imperfections in the design, which makes it possible to misapply the product. Of course, not every product needs to be immune to all unusual actions of the user, but certainly where it will affect its safety or the provision of the basic function of the product, the designer should think about it. From everyday examples, one can show, for example, the “problem” of refueling a car. Many times one hears stories about diesel drivers who have filled up with gasoline by mistake. In the other direction, such a mistake is not possible, because they have secured the filler of a gasoline car from inserting the dipstick of the distributor pouring diesel (it is worth mentioning that some brands have also already secured diesels from refueling gasoline).

UFMEA is one of the methods that can be used within the framework of human factors engineering (HFE ) and usability engineering (UE – Usability Engineering), i.e. within the fields that deal with analysing the impact of the so-called human factor. Why is UFMEA mandatory? Because for medical device manufacturers, documentation of the UFMEA is required by the FDA, and without approval from that organization, no medical device can be marketed in the USA market.

 

Workflow with UFMEA

There is no unitary standard describing UFMEA. However, various documents describing related topics, such as the guide Applying Human Factors and Usability Engineering to Medical Devices [2], can be helpful in working with this analysis. Thus, in the lack of a standard, the detailed procedure for working with UFMEA should be developed internally by the company – and this should include such issues as, for example: risk assessment scales, the form, rules for determining risk levels (indicators), unacceptable risk levels, etc.

Of course, when preparing a standard for working with UFMEA, it is worth relying on generally known and widely used standards for DFMEA and PFMEA, such as the new automotive standard issued in 2019 by the AIAG and VDA organizations or the international standard IEC 60812 issued in 2018. In these standards, you can find not only proposals for forms, but also adaptable risk assessment scales and indicators, such as RPN, ARPN or AP.

The general principle of working with UFMEA is the same as for its related analyses and includes the following steps:

  • describing the expected “behavior” of the product (e.g. the device is to be turned on),
  • describing the possible error to be made,
  • describing the consequences of this error (failure effect) and assessing on a set scale their severity (in typical UFMEA analyses, one looks at the patient perspective and the hospital perspective – if the device is to be used there),
  • describing the possible failure causes – in UFMEA the causes are supposed to be due to user errors,
  • determination of the probability of occurrence of a given cause during the use of the product,
  • determination and analysis of the level of risk,
  • planning improvement activities – if required.

 

In simple terms it can be said that the analysis is supposed to indicate the most risky, from the point of view of the user’s actions, phases of the product’s use and help plan the necessary changes to the product (e.g. designing the device’s control buttons further apart, so that someone accidentally wanting to turn off the sound, for example, does not turn off the whole device).

Help in determining where improvement actions need to be implemented, in addition to the typical indicators already mentioned above (RPN, ARPN, AP), can be risk matrix – such as the one shown in Figure 2. In it, you can clearly see the UFMEA results arranged in two assessment planes: on the horizontal axis S (severity of the error – 1 means an imperceptible effect, 10 means an impact on the health of the patient), on the vertical axis O (probability of the occurrence a failure cause  – 1 means a cause that is practically unlikely, 10 means a cause that will occur practically every time). On the matrix, red indicates a situation (failure and cause) that requires action, green indicates a “safe” situation, and yellow indicates an intermediate situation (improvement actions are worth considering, but they are not necessary).

Risk Matrix

Figure 2: Example result of UFMEA analysis – common cause of significant error
. Source: own development (PQ-FMEA program)

In the absence of a uniform standard for UFMEA, each company must establish its own way of working, which includes not only the form, but also, for example: rules for defining functions, failure causes and effects. An exemplary solution in this regard, the so-called “function and defect tree”.

Summary

One should not forget the basic purpose of UFMEA – it is not to be a method used to prove that we have a well-designed device (e.g. medical), but to help prepare it for work in such a way that it is as resistant as possible to unintentional user errors. It should be a method consciously built into the whole process of designing a product and showing the next steps of its improvement. The aforementioned FDA organization recommends, for example, in this regard that at least four revisions of the UFMEA – from the initial status (where the original risks can be seen) to the final status (where the risks associated with the final version of the product are shown – appropriately minimized, of course, compared to the original ones) – should be presented when submitting documentation related to product approval.

In conclusion, it can be said that the UFMEA analysis deals with a very interesting aspect of device reliability assurance that is not paid attention to in typical DFMEA and PFMEA analyses. Thus, it is worthwhile for it to gain much more popularity than it has now and start being used outside the medical device industry as well.

Author: Tomasz Greber

Related sources

  1. Greber T., Analiza FMEA. Kompendium wiedzy praktycznej, Wrocław, 2023 r.
  2. FDA (Food and Drug Administration), Applying Human Factors and Usability Engineering to Medical Devices, 2016 r.