The transition period for the Third Edition of the Medical Electrical Equipment Standard (EN 60601-1:2006) came to an end on 1 June 2012 and it now incorporates the concept and application of risk management in the design and production of medical devices. Paul Laidler, who heads up
TÜV SÜD Product Service’s UK machinery division discusses dealing
with risk in medical equipment design
While technology evolved at a fast rate, traditionally test standards developed much more slowly. This new approach in the Third Edition aims to reduce this disconnect so that safety legislation keeps pace with both the rapid changes in technology and acceptance of it into our daily lives.
Whereas the Second Edition was an entirely test-based standard, the new version requires that a detailed risk management File (RMF) be produced and many of the tests that are required to demonstrate compliance with the Standard make reference to it. It also requires that the RMF be updated, so it is a ‘live’ document and must be revised to match any changes in manufacturing processes or in the materials used.
The RMF allows for the required testing process to be modified depending on how the device must comply with some aspects of the standard. A good example of this is that some medical equipment may need to be robust enough to be used in the battlefield, or withstand extreme weather conditions.
While in the past there was a simple ‘pass’ or ‘fail’ against test criteria, now if a device does not meet some of the criteria, a manufacturer can mitigate that risk within the RMF by including a researched rationale of the associated risk and why the product is still safe to use.
However, while you may be able to provide an excellent risk rationale, or prove ‘equivalent safety’, parts of the standard remain compulsory as some elements would be almost impossible to justify, for example electrical leakage currents.
The risk management process includes a whole raft of considerations including built-in safety, usability, installation, service, the environment it will be used in, what the equipment will be connected to and any unforeseen misuses. This actually strengthens the process as it is very difficult to consider all possible elements pertaining to a specific piece of equipment in a traditional standard-based approach.
But, how do you asses risk? Risk is a combination of the probability of occurrence of harm and the severity of that harm. Manufacturers usually work out a number for each and multiply them to reveal the risk level. However, this approach is not always reliable and it is therefore important not to just accept the final risk level, but review how likely this is to occur as part of the risk management process and mitigate for it if necessary.
The manufacturer’s risk management process must be used throughout the design process and it is essential that for any new product, that risk is first assessed, followed by tests to show compliance with the standard. This means thinking about the RMF first and at each subsequent stage of product development. It pays to assess if a new risk has been introduced at every phase, instead of looking at risks retrospectively, as any failure that is identified late in a development programme could result in a costly redesign.
For existing products, historical user data, such as failures, accident rates, customer complaints and warranty returns, can be used as part of the risk management process. Also, if it is a new product, it can be benchmarked against similar ones already on the market by using their data.
For the first time, the Third Edition has introduced the term ‘essential performance’, expanding the scope of the standard beyond basic safety to ensure that the product does the job from the end-user’s perspective. This also introduces the possibility of misuse within the RMF and requires that recommendations relating to this are included within the user manual.
While there is no definite answer on how far you should go with identifying possible misuse, best advice would be to ‘go as far as society’s values and common sense suggest’. The RMF is the proof that you have considered misuse as far as practicable and mitigated risk to the best of your ability.
When first considering the changes brought in by the Third Edition, manufacturers may only see additional red tape, rather than product improvement opportunities. However, the RMF should actually be viewed as a useful tool that helps reduce risk at all stages of product development and can provide a genuine contribution to the development process by making a medical device more saleable.
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