Bringing medical electronics up to scratch

29 March 2010

While the transition period for the Third Edition of the medical electrical equipment standard (IEC 60601-1:2005) doesn’t end until 2012, there are many changes and ‘firsts’ of which design engineers must become familiar now. This will ensure that they design electronic products and components that will come up to scratch and can be sold on the European market. Jean-Louis Evans looks at the details.

For many, the Third Edition is a much needed update as our use of medical equipment, in both work and within the home, has changed significantly. Electronic medical equipment is more omnipresent than ever in all of our lives and a new standard was needed to reflect that change.

While the transition period is still two years off, it makes commercial sense to start using this new, complex and greatly expanded standard now. Making sure this is incorporated into the design process now will help to avoid costly re-designs and the potential of increased time to market for products further down the line.

Health aware
Previously the standard only covered products intended for use ‘under medical supervision’. However, as a nation we have never been more aware of the state of our health, and consequently there has been a boom in health-related electronic products industry. With an increase in popularity for medical products amongst consumers, the use and location of medical equipment has changed and it has therefore become necessary to ‘upscale’ the standard in terms of the types of products it covers. As a result, an increased number of health-related electronic devices, that were not covered by previous standards, could now be covered by the requirements of the new Third Edition.

This means that manufacturers of active devices, such as SAD lamps or fitness and depilation equipment etc, must now be careful of the claims they make, as the wording used when marketing a product could render it a medical device. If the product is classed as a medical device it would need to meet the complex requirements of IEC 60601-1, and this could cost extra money and a delay in getting the product to market.

As there is now an increased chance of manufacturers that sell health-related products falling foul of the law, it is essential that how a product will be used and who it is marketed to are taken into account during the design phase. This will help to ensure that products meet the more robust standards and can be legally sold post 2012.

The Third Edition of this standard also includes a further range of products that were not covered by the previous standard. Medical equipment for household use is now clearly within the scope of the Third Edition of the standard. 

Introducing subjectivity into testing?
As a harmonised standard (under the Medical Devices Directives), one of the many other ‘firsts’ is the incorporation of the concept of ‘risk management’. This includes an obligation to keep a detailed Risk Management File (RMF) and it is essential to do, as many of the tests that are required to demonstrate compliance with the standard make reference to the RMF.

This also introduces an increased level of flexibility as it means that the testing process, required to ensure compliance with the standard, may 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 as the intended use of the product requires it to withstand extreme conditions.

The test house can therefore ‘toughen’ the standards relating to use and its associated risk, such as shock, heat, etc. However, the new element of ‘risk management’ has raised some concerns that it is open to interpretation and could introduce a degree of subjectivity, moving away from objective test/fail criteria. What one test house passes could be failed by another.

What may surprise many, especially those purchasing equipment, is that for the first time the term ‘essential performance’ has also been introduced. This has expanded the scope of the standard beyond basic safety requirements to ensure that the product does the job from the end-user's perspective. There is now also a requirement covering the device’s expected service life, a reassuring addition for those purchasers making a significant investment in expensive medical equipment.

Reduced exposure
The standard also includes new concepts for Means of Patient Protection and Means of Operator Protection. In the past, a current was allowed to appear on the conductive enclosure of the medical equipment in question, exposing the user or patient to a small level of current. While there are greatly increased figures for earth leakage current in the new standard, the additional current is now confined to the earth continuity conductor of the product. This of course has significant implications for the design of many active medical devices that have been used for years - representing a massive re-design investment for manufacturers that want to keep selling their product.

Mechanical hazard protection has also been expanded significantly. This now covers ‘trapping points’, which had not been taken into consideration before. However, this makes perfect sense when you consider that equipment is used to manage patients, rather than directly treat them. If they are not thoroughly tested for hazards beyond electric shock, they may still cause harm to the patient. This means that when designing equipment such as dentist chairs and patient hoists, more detailed mechanical safety checks must now be conducted.

More hoops
While the new standard may be viewed by designers of medical equipment as yet another hoop to jump through, it is intended to keep apace with a rapidly changing technological world. Applying standards created more than thirty years ago would be pointless and not protect either the manufacturers, end-user or patient.

The good news is for those people tasked with designing such equipment is that the Third Edition of the standard includes extremely extensive explanatory material. This will of course give designers and testers an increased insight into the rationale behind clauses, and therefore a more comprehensive understanding of the requirements.

Where do you stand?
As with the older standards, the Third Edition of the medical electrical equipment standard (IEC 60601-1:2005) has two parts. This creates more complexity as Part 1 can be easily followed, but there will be many Part 2 standards which may not yet be available for specific classes of product.

Part 1 covers all medical electrical products and their electronic components. The Part 2 standards consist of 50 plus categories of specific products and their intended use e.g. operating tables, electro-surgical equipment and incubators. This will allow the general requirements under Part 1 to be varied according to the specific use of a product, e.g. Part 1 states that a product must not apply heat directly to a patient, but for some products this will be part of their intended use, so the standard cannot be strictly applied.

Part 1 of the Third Edition is complete and harmonised now, but many Part 2 standards still need to be brought into line with the Third Edition and this will take some time. If a Third Edition Part 2 standard is currently unavailable for your product, best advice would be to continue with compliance to the current standards (Second Edition Parts 1 and 2), becoming familiar with the Third Edition of Part 1. Then start designing products to the Part 2 specification of the Third Edition as soon as it is available.

While getting to grips with these significant changes when designing active medical devices may take some effort now, it will prove to be a good return on investment. For those who leave it too close to 2012 to have their products tested against the new standard, they will find that test houses will be booked solid as the deadline approaches. If your product isn’t approved in time it will have to be withdrawn from the market until tests are completed. Invest in appropriate re-designs now and have them tested against the new standard to reap rewards further down the line.

Jean-Louis Evans is Managing Director at TÜV Product Service

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