Directives and standards needed when designing for medical applications

4 min read

The interest in medical technology is growing at an astonishing pace, probably even faster than the technology itself is being developed. Many medical devices, assisted living products and monitoring devices are making more and more use of radio technology to assist in their operation, particularly in the transport of data.

This has resulted in many of the companies driving these products looking to develop protocols and standards to improve their interoperability and to their ensure designs are of the highest quality. As well as the wide variety of technologies – covering both functionality and communication – which are available for the designer to support their medical device platform, the market is also seeing a number of innovative products which contain multiple communication transports. This convergence of technologies opens up endless possibilities for enhancing the support and care for patients. It is already common for the consumer to have their own devices at home for monitoring health aspects, such as blood pressure or blood sugar monitors, and these are readily available in many high street stores. These are the simple traditional home products which tend to have a singular application without any means of recording and forwarding the data. However, the growth of wireless technology has seen these products increasingly incorporate such technology in their function. So how does the inclusion of wireless technology assist the patient and the health professional? In a simple example, a patient could perform their own assessment at home; for instance, taking a blood pressure measurement, performing a glucose test or simply weighing themselves. The data would be obtained locally; in the example of blood pressure, the patient would use a blood pressure meter which incorporates a communication transport such as ZigBee or Bluetooth wireless technology. At the conclusion of the measurement, the data would be sent to a base 'hub' situated in the user's home which, in turn, forwards this to a health professional via the telephone network or via a broadband connection. It is not difficult to see that the designers of these products are playing an important part in easing the burden on the patient and the health services supporting this care. However, the design of such a product is only one part of an intricate process of getting the product to market. In addition to the design, there are certification and regulatory requirements which usually have to be satisfied before the product can be placed on the market. The regulatory requirement is a legal requirement of the domain in which the product is to be placed, whereas certification is usually a (non legal) requirement of the organisation which owns or manages the intellectual property of the technology being employed in the product. The level of compliance which needs to be applied is dependent on the functionality of the product and the technology it employs. Take, for example, the development for the European market of the blood pressure monitor mentioned above. In order to be placed on the European market, this would have to satisfy the requirements of the Medical Device Directive. This Directive covers a multitude of medical products and a common route for medical electronic equipment is to test to the IEC/EN 60601-X-X suite of standards. These standards address a number of requirements such as safety, EMC and usability and the specific standard to be applied depends on the function of the device. A clinical evaluation of the product may or may not apply; this again is product and placement dependent and there are professional bodies in existence which can offer advice on which procedures apply. This process is usually the first tier of the compliance process. The blood pressure monitor also contains an rf device, which introduces another tier of compliance. Therefore, it must also satisfy the requirements of the Radio and Telecommunications Terminal Equipment (RTTE) Directive, which has requirements for radio, EMC and safety. One compliance route available is by testing to harmonised standards, the applicability of which is dependent on the radio technology being used. Although the basic function, safety and EMC performance of such a device may be covered under IEC/EN 60601-1-2 and IEC/EN 60601-1-1 respectively, the RTTE Directive also requires that the safety and EMC performance of the radio element is also satisfied; possibly by applying the harmonised standards mentioned above. This may seem like a duplication of work, but some parts of the compliance testing process may be performed simultaneously, minimising cost. A good compliance professional would be able to provide expert advice on a suitable route. These are the two main Directives which apply to the rf enabled blood pressure monitor in its simplest form. However, compliance is by no means limited to these two. Depending on functionality of the product and the intended operating environment, there are other Directives which may be relevant for medical electronic devices. For example, if the device was to be operated in a potentially explosive atmosphere, compliance with the Atmosphere Explosive (ATEX) Directive would also have to be considered. This introduces a further tier! This basic example demonstrates the importance of a designer or other person intending to put a product on the market fully exploring all possibilities of where the product is to be used as early as possible in the development phase. Doing so will help to minimise cost, as retrospective compliance assessment can be very expensive. Furthermore, if a particular radio technology or protocol is used, there may be certification issues or membership requirements to be dealt with in order to use the intellectual property. This may have marketing benefits in that a certification program for a given technology may be a process of interoperability testing to demonstrate that the product works with other similar products, but from different manufacturers. Such programs tend to have a logo based approach; once certification has been completed and demonstrated to be compliant, a logo may be attached to the product so the consumer can be confident that it will interoperate as intended in an rf environment without any obstruction. In summary, it can be seen that there could be many levels to complete compliance for a product before it is placed on the market. It can be complicated, but it doesn't need to be so long as adequate forethought is given to the process at the early stage of development. Joe Lomako is business development manager with TRaC.