Main operating function: What the IEC 62366 doesn’t define
I have updated the article on the main operating functions (eg taking the definition of the next edition of IEC 62366 into account) and consolidated various other articles on the same theme.
The IEC 62366 formulates requirements for the main operating functions of medical devices. Unfortunately, they do not define the term function and causes confusion. This article provides a definition and examples of medical products main operating functions.
Definition of IEC 62366: 2007
The IEC 62366 defines the term main functions as follows:
"One either frequently used or with the safety of the medical device related function, which is connected to a user-interaction"
The term "function" does not define the norm. You will learn in this article:
Definition of IEC 62366: 2015
The next edition of IEC 62366 changes the definition of the main operating function:
function that involves USER interaction that is related to the SAFETY of the MEDICAL DEVICE
Requirements of IEC 62366 to main operations
The IEC 62366 requires to identify and document the main operations. For them, safety-critical features must be determined to be included in the verification and validation of serviceability.
Too bad that the norm forgets to define the term function. Maybe that is why some confusion in the informative annex occurs, with some examples.
Which confusions they are, and which mistakes of your main operating functions of your medical device product you should avoid with the identification (and hence testing), you can view in a short (<5min) video.
IEC IEC 62366 calls in Appendix G.4.2 for examples of main operations like
But that is not correct: 1. is a function 2. is an object, and 3. are two subtasks. My "Usability Guru" Thomas Geis helped me with a definition:
Function (from a user perspective): "Control elements and Information on the user interface that are needed in carrying out a task with help of the system."
Examples of controls would be: "set flow", "zoom", "emergency stop" or for example, in surgical tools, "cut", "lifting", "hold". Examples of information would be: "Current blood pressure", alarm "heart rate too low", feedback "lamp replacement required in 5 days"
Functions are implemented with "user interface elements" (such as a slider, push buttons, displays). For controls that are typically the "tools" of the user interface, information in the "usage objects" of the user interface.
When a function is "frequently" used or is classified as safety-critical, it was named one of IEC 62366 main operating functions.
Whether an operating function is critical to safety, results from the risk analysis. If the patient, a user, or a third party may suffer a defect, it is critical to safety: In general for each function or each UI element as part of risk management, you can, and must, review what happens when the user
In the recognition one distinguishes between the false reading (perception) and the wrong understanding (cognition).
Users can only enter, select and perform cognitive performances such as recognising, understanding and distinguishing. Precisely these requirements, to input, choose or recognise something on a system, which are the usage requirements .
Frequently used functions
You can deduce whether an operating function should be classified as frequently, if it is used as part of a core task. If so, the assumption that it is frequently used, should be true.
This requires, however, that you not only identify the usage requirements, but also the core task.
In the seminar " Usability, Requirements & IEC 62366", you will learn both. This seminar will provide you with all the knowledge and skills to
As stated above, it is important to check the following:
The test of 1. is equivalent to a usability verification, the 2nd and 3rd to the usability validation. Read more for the validation of medical devices (also the usability validation).
The IEC 62366 uses the term "function" diligently, for example in the context of the main operating function, without having the concept of the term function defined at all. On the contrary, the way it is written above it confuses functions, tasks and objectives.
Thomas Geis helped me gather additional definitions:
The previous sentence is not an official definition of "function", one can deduce this definition from the Usability Guide of the DAkkS. It does not lack real definitions of the term function. Thomas Geis has found no less than 10 (!) definitions of the term function that I have summarised for you in the glossary.