Page 207 - Safety Risk Management for Medical Devices

186 Safety Risk Management for Medical Devices

One easy way to establish effectiveness of Risk Controls is by conformance to har-
monized standards. For example, IEC 60601-1 [8] gives allowable electrical leakage
current values, and even how to perform the tests. If you can demonstrate confor-
mance to IEC 60601-1 with respect to electrical leakage current, you can presume
that your Risk Controls are effective in reducing the risk of electrical shock. Another
good source is IEC 60601-1-8 [19]. This Standard provides guidance on alarm sys-
tems in medical electrical systems. It provides requirements for alarms of high,
medium, and low priorities, and says what color they should be, whether they should
be flashing or constantly on, and if flashing at what frequency and duty cycle. This is
very beneficial to the manufacturers, because it is very difficult to provide objective
evidence that, e.g., a particular frequency of flashing red light is effective in reducing
risk. But conforming to IEC 60601-1-8 [19] can be used as evidence of effectiveness
of the alarm.
It is important that the test samples, test environment, and testers are representative
of real life for the medical device. For example, if a medical device is intended for use
by the surgical staff in an operating theatre, then the summative test should create a
simulation of the ambiance of an operating theatre and utilize testers who are either
members of a surgical team, or a good facsimile thereof. For home-use products,
usability testing should use people who are representative of the intended users of the
product. For example, if the product is intended for home-use by elderly people in
France, then the testers should include elderly French people. This is because cultural
and language variation from market to market makes a difference on how the users of
the product perceive and understand the user interface and instructions that are
provided.
If information for safety is used as a Risk Control, in accordance with IEC 62366-1
[14], that information needs to be tested on representative users to ensure that the infor-
mation for safety is perceivable and understandable to the user, and it is actually effective
in reducing risk. This means, e.g., if the user profile is elderly people with poor eye
sights, the font and contrast of the information should be suitable for the user-profile
group.