The future of medical device design

As implementation of the Third Edition of the medical electrical equipment standard draws ever closer, Jean-Louis Evans has a few pointers for developers

The transition period for the Third Edition of the medical electrical equipment standard (IEC 60601-1:2005) comes to an end in May 2012. It therefore makes sense for manufacturers to start designing against this new greatly expanded standard now to avoid costly re-designs further down the line and ensure that their products can continue to be sold on the European market. It would also be wise for end-users and purchasers in the medical laboratory environment to be aware of the requirements that suppliers of their products must now meet.

One such requirement is the incorporation of the concept of ‘risk management’ and the requirement to keep a detailed Risk Management File (RMF). This is essential to do, as many of the tests that are required to demonstrate compliance with the standard make reference to the RMF.

The standard also 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 as the intended use of the product requires it to withstand extreme conditions.

This increased level of flexibility that has been introduced means that the test house can therefore ‘toughen’ the testing relating to use and its associated risk, such as shock and heat. 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 an objective test/fail criteria. What one test house passes could be failed by another.

Batteries and charging units are also included within the Third Edition for the first time. It would therefore be prudent for manufacturers to use batteries that already comply with the Third Edition. If this is not the case, they will require additional testing, which can be a time consuming and expensive process. This is because the batteries must be proven safe under all possible environmental conditions and safety tests must cover issues such as misuse, temperature and ingress of fluids.

What may surprise many is that for the first time, the term ‘essential performance’ has been introduced. This means that the scope of the standard is now expanded beyond basic safety requirements to ensure that the product does the job from the end-user's perspective.

There is now also a new requirement covering the device’s expected service life. This means that for the first time the lifetime of the equipment must be planned for and documented. By implication this means that manufacturers must openly estimate the mean time between failures, availability of the spare parts required to rectify that, and for how long they will support the equipment. This can only be good news for those who make significant investments in expensive medical equipment as they can now get a clearer idea of the return on their investment when comparing equipment from different manufacturers.

[caption id="attachment_24341" align="alignright" width="200" caption="The medical device community faces more red tape as more standards come into force"][/caption]There is a also a record keeping implication as the Medical Devices Directive requires manufacturers to keep records for the lifetime of non-implantable products for five years after the manufacture of the last product. For implantable products this is 15 years.

The standard includes new elements of Means of Patient Protection (MOPP) and Means of Operator Protection (MOOP). Also, 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. There are greatly increased figures for earth leakage current in the new standard, but 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 potential massive re-design investment for manufacturers selling in Europe.

Another significant expansion is mechanical hazard protection. For example, for the first time this covers ‘trapping points’, which allow for the inclusion of equipment that is used to manage patients, rather than that which directly treats them. If such equipment is not thoroughly tested beyond electric shock hazards, there may still be potential harm caused to the patient. This means that when designing equipment such as patient hoists, more detailed mechanical safety checks must now be conducted.

For those people responsible for the design of medical equipment, the good news is that the Third Edition includes much more extensive explanatory material. This will of course give them an increased insight into the rationale behind clauses, and therefore a more comprehensive understanding of the requirements.

For many, the Third Edition is a much needed update as our use of such equipment, in both work and within the home, is more omnipresent than ever in our lives and an updated standard was needed to reflect these changes.

Technological advances have led to the development of an increasing number of electronic or electrical products, and to a boom in the home health market. The new standard has therefore moved with the times to allow for these changes. Previously the standard only covered products intended for use ‘under medical supervision’ but now health-related electronic devices for the home may now be covered by the requirements defined in the Third Edition.

It is therefore essential that how a product will be used and who it is marketed to is taken into account during the design phase, to ensure that it meets the more robust standards and can be legally sold post 2012. Consequently, manufacturers that produce such active medical devices, including devices such as SAD lamps or fitness and depilation equipment, must now be careful of the claims they make. If a medical claim is made, the product will be considered as a medical device.

As with the previous versions, the Third Edition of the medical electrical equipment standard (IEC 60601-1:2005) has two parts. 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 this might be the intended use of a particular product and the Part 1 standard is therefore varied accordingly.

There is also another level in IEC 60601-1:2005’s hierarchy – collateral standards. These are more selective than the general requirements of Part 1, either in terms of the topic that they cover or the type of equipment, but they are not as specific as the Part 2 standards. These collateral standards are generally not pass or fail standards, but concepts that must be shown to have been taken into account during the design of the equipment. In all cases these may be overridden by the requirements of a Part 2 standard within specific equipment categories.

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. Best advice to manufacturers of medical products would therefore be to continue with compliance to the current standards (Second Edition Parts 1 and 2), while becoming familiar with the Third Edition of Part 1, if a Third Edition Part 2 standard is currently unavailable for your product. 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. Those manufacturers that leave it too close to 2012 to have their products tested against the new standard will find that test houses will be booked solid as the deadline approaches.

The fact remains that if a product is not approved in time it will have to be withdrawn from the market. Once those tests are completed and approved, the product can of course be sold in Europe once more. However, substantial ground against the competition will have been lost.

For those responsible for purchasing such equipment it is also worth bearing this in mind, to ensure that your suppliers are complying with the new legal requirements of the Third Edition. Awareness and action now will reap rewards for both parties in the future.

While the new standard may be viewed by many in the medical equipment world as more red tape, the updates have been made to ensure that safety legislation keeps apace with both the rapid changes in technology development and our acceptance of it into our daily lives. Simply carrying on with standards that were first introduced more than 30 years ago would not protect the manufacturer, end-user or patient.

Author: Jean-Louis Evans, Managing Director at TÜV Product Service