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Human Factors Points To Consider for IDE Devices |
U.S. FOOD AND DRUG ADMINISTRATION
CENTER FOR DEVICES AND RADIOLOGICAL HEALTH
Purpose
This enclosure is intended to help sponsors of an Investigational
Device Exemption (IDE) determine how much attention to pay to
human factors during the premarket review and analysis process
and future device design and development. Included in this document
is a brief explanation of human factors engineering and the human
factors engineering process.
The extent to which human factors is considered, both by the sponsor
and the Office of Device Evaluation (ODE), for any device should
be governed by the complexity of the device and the risks associated
with its use. The goal is to assure that the device meets the
users' expectations, both stated and implied, so that the likelihood
of user error is minimized. To be effective, human factors must
be an integral part of the product development process from concept
through production. The objective is to produce a device with
an effective, efficient and safe user-device interface.
For more information, please contact one of our human factors
specialists at 240-276-3238 or by FAX at 240-276-3232.
Background
In the premarket review, ODE will verify that a manufacturer adequately considered the user and the use environment in the design and development of its medical device. The recently published Quality System Regulation (formerly known as Good Manufacturing Practices) requires most medical device manufacturers to "maintain procedures to control and verify the design of the device in order to ensure that specified design requirements are met. Manufacturers are required to establish and maintain procedures:
This will require that manufacturers have in place a process
that ensures adequate consideration of human factors in the design
and development of medical devices. The premarket review will
examine the products of this process, for example the results
of task analyses and usability testing, to verify that the device
design adequately addresses the users' needs and intended uses.
Human Factors Engineering
Human Factors is the science of human-machine interaction. Human
Factors Engineering is the application of this science to improve
this interaction, or more specifically, the user-device interface.
Three key areas to consider during the premarket review and analysis
process and future device design and development are:
Users and the Use Environment:
A device may have many users. The operator is one of the users;
other users include the patient, the prescriber of the device,
clinicians who interact but do not operate the device (e.g., take
readings, check status), hospital personal who support the device,
and personal who install and maintain the device.
Medical devices are being used in a wider variety of environments;
including operating rooms, emergency rooms, patient units, critical
care facilities, clinics and homes. There are also many external
environmental factors that influence device use - including light,
sound levels and other devices in close proximity.
Some questions to ask yourself:
1. Who is the user?
2. Can operator (use) error lead to death or serious injury?
3. How busy will the user of the device be?
4. How likely is the user to be distracted?
5. What is complexity of the use environment?
6. What is the user's level of cognitive stress?
7. How skilled is the typical user?
8. How diverse are the users of the device?
9. What is the user's understanding of the device?
10. How important to safe use are the user's vision, hearing,
dexterity and strength?
The User Interface:
The user-device interface is the link between the designer's intended
use of the device and the user, who ultimately decides, either
intentionally or unintentionally, how the device will be used.
The user interface includes all aspects of a device that users
operate, read, use or come in contact with in the course of interacting
with the device. The user interface includes the device's controls
and displays, alarms, operating logic, and all manuals, labeling
and training necessary to install, operate and maintain the device.
For each of the questions below, ask yourself, Can the design
be simpler, more intuitive, less demanding or more forgiving of
user error?
1. How much user adjustment or manipulation is required?
2. How many variables does the user have to interact with?
3. How rapidly and accurately does the user have to interact?
4. How complex are the displays and controls?
5. How complex or varied are the alarms?
6. Can alarms/feedback detect errors/fault conditions?
7. Can the device be misassembled/misattached?
8. How much training will the user need to operate the device?
9. How much maintenance will the device require?
10. How difficult is the device to maintain/service?
Device Design:
Relying on the user to adjust and compensate for problems presented by a poorly designed user interface is the least desirable alternative, and one that is bound to fail in time. The designer has a responsibility to produce a device that:
The goal is to design devices that are easy to use (user-friendly)
and minimize the chance for users to make mistakes. In addition,
since it is not possible to predict and prevent all errors, the
design must also be error tolerant.
The most common cause of human factors problems is the failure
of the device designers and developers to anticipate and deal
with the characteristics of the people who interact with the device
and the nature of these interactions. Including:
Human Factors Engineering Process
Human factors engineering is part of a systematic, iterative process
which must be properly coordinated and integrated into a structured
engineering design and development process to ensure that the
resulting product can be demonstrated to be safe and effective
and adequately addresses the user's needs and intended uses.
The Quality System Regulation will require most medical device
manufacturers to establish and document procedures for the control
of design input and output, design review, verification and validation,
design transfer into production specifications and design changes.
At a minimum human factors engineering activities will need to
be identified in the general design control plan and in the procedures
governing design input through design validation.
Human factors methods and tasks used during device design and
development include:
Information Review:
A review of the literature, incident report and recall data on
similar devices, and applicable codes, standards and regulations
will help identify the necessary information for the other design
processes. The literature review should include human factors
articles, technical reports and textbooks, and a thorough and
critical review and analysis of the appropriate medical literature
to uncover the problems reported by users. A review of reports
from the Medical Device Reporting (MDR) system as well as hospital
incident reporting systems will often uncover user problems that
have not been reported in the medical literature.
User Studies:
Designers should know their users firsthand. It is critical for
those involved in the design to spend time in typical environments
in which the device will be used. This includes visiting a number
of facilities that span the range of the use environments (e.g.,
hospitals, nursing homes, home-use) to see how the device will
be used and talking to users to understand their priorities, skills
and limitations. In addition, valuable information can be gained
by conducting interviews, holding focus groups, using questionnaires
or conducting usability tests of early prototypes. Those who
supervise and train users can be an especially valuable source
of information on the users needs. The use environment must be
closely evaluated, defined and understood.
Analyses:
A structured and critical examination of the device functions,
the tasks the user needs to perform and the procedures to set
up, check, use and service the device along with an analysis of
the hazards and risks resulting from possible user error are essential
human factors tasks. Analysis of the device functions, the users
tasks and hazards of user error can often be carried out as a
single integrated activity. Medical devices are becoming increasingly
multi-functional to accommodate a wider range of users and to
provide additional utility. The added device complexity, if not
carefully designed to address the users' capabilities, can adversely
impact ease of operation, increase the possibility of user error
and effect patients safety.
Usability Testing:
The proof that the design actually meets users' needs and intended uses can only be verified by observing typical users operating the device under real use (or closely simulated) environments. Most significant user interface problems can be found by conducting usability tests with representative users to observe how quickly, easily and safely they can set-up, check and operate the device. This testing should be conducted as early in the development cycle as practical. Limited usability tests can begin even before the first prototype has been constructed by employing mock-ups and computerized models. As design and development progresses, and the prototypes increase in fidelity, the usability tests can be more confidently relied on to validate that the design will meet the users' needs and intended uses.
Updated January 17, 1997
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