Define a Usability Specification

Pattern Attributes

Intervention Process
Domain Medical
Work Programme SPRTMDRC
Research Area Any
Evidence Type Standard
Evidence Source Standard
Evidence Strength Hypothetical
Trigger product_domain == medical, doing_usability_engineering == true

Problem

A new medical device is to be developed and it needs to be compliant with IEC 62366. In order to achieve compliance you need to develop a usability specification to help guide the development of a usable medical device.

Analysis

An integral part of a usability engineering process is the production of a usability specification. The usability specification is used to help guide the development of the user interface to the medical device by identifying key interactions and interaction scenarios in which the device is to be used. To ensure regulatory approval the usability specification must be clearly documented.

Solution

  1. Identify the primary operating functions of the medical device by reviewing the application specification and identifying the functions of the device that will be most important when considering user interaction.
  2. Define use scenarios (including context of use) relating to the primary operating functions. They include the end result of the task they are trying to achieve, the reason for performing the tasks, the functional state of the medical device when a task is initiated and readouts of displays and printouts that the user sees while performing the task. Use scenarios should include both common routine tasks and rarely used tasks that can be performed in an emergency situation.
  3. Define requirements for determining whether the primary operating functions are easily recognisable to users. This should define any additional requirements that should be achieved to ensure users can determine how to accomplish their task.
  4. Define user interface requirements for the primary operating functions, including those to mitigate risks. This should examine each of the primary operating functions and define the requirements necessary to achieve these through the user interface. For example “the symbol for battery low should be clearly visible on display”
  5. Define testable requirements for usability verification to ensure that the user interface meets the requirements of the usability specification.
  6. Define testable requirements for usability of the primary operating functions. For each of the primary operating functions more specific testable requirements should be defined. These will help guide the testing of the medical device’s usability.

Application of the medical device.

References

  1. IEC 62366:2007 “Medical Devices - Application of usability engineering to medical devices”

  2. Flood, D., Mc Caffery, F., Casey, V., Regan, G.,(2013) “A Methodology for Software Process Improvement Roadmaps for Regulated Domains - Example with ISO 62366”, European System, Software & Service Process Improvement & Innovation (EuroSPI 2013)

  3. Flood, D., Mc Caffery, F., Casey, V., Regan, G.,(2013) “MeD UD - A Process Reference Model for Usability Design in Medical Devices”, South CHI 2013 International Conference on Human Factors in Computing & Informatics, Maribor, Slovenia.