Accessibility Considerations for Medical Devices Table of ......usability, performance, and most importantly, safety for all medical device users. Nearly 20% of the population over

Accessibility Considerations for Medical Devices – Winters, Story, Lemke

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Accessibility Considerations for Medical Devices

Table of Contents

1. Introduction………………………………………………………………………………………. 1

1.1 Scope……………………………………………………………………………………. 2

2. Design Considerations……………………………………………….………………………… 3

3. Guidelines……………………………………………………………………………………….. 7

3.1 Caveats & Limitations…………………………………………………………………. 7

3.2 General Guidance……………………………………………………………………... 8

3.3 Specific Guidance for Patient Support Surfaces…………………………………... 21

3.4 Specific Guidance for Telecommunications and Information Access Strategies for

WebBased, Mobile and HomeBased Healthcare Products............................... 26

4. Resources……………………………………………………………………………………….31


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Accessibility Considerations for Medical Devices

1. Introduction

While human diversity is discussed in the section on Basic Abilities, this section focuses specifically on medical device design strategies that serve the diverse needs of users who have disabilities, both as medical patients and as healthcare professionals. The goal of the guidance in this section is to improve access, usability, performance, and most importantly, safety for all medical device users.

Nearly 20% of the population over the age of 5 in the U.S. reports having a disability, and this percentage is projected to continue to increase annually (U.S. Census, 2000). This percentage also may be low because many older adults with limitations do not consider themselves “disabled,” just aging, and the market share of users with disabilities, for example home users and nurses, likely will continue to increase.

It is important to recognize that anyone could be a medical patient, and that many patients seeking healthcare have either permanent or temporary functional limitations. Regardless of disability, all patients need to be able to use medical devices easily, safely, and effectively, but many people with disabilities and older adults receive inadequate healthcare services because of factors such as inaccessible medical equipment, even though these populations are more vulnerable to some health problems (Grabois & Young, 2001; Gibson et al., 2003). More accessible medical devices can enable patients with disabilities to obtain the healthcare they need.

Although many medical devices need to be more accessible, it is recognized that every medical device will not be able to provide access to every user in every potential situation. However, there are several strategies that can help designers improve accessibility of medical devices. One strategy is to provide direct access. Sometimes small design changes can make big differences in accessibility, for example: making the height of exam chairs adjustable to a low of 19 inches can make it easier for wheelchair users to transfer; increasing font size, visual contrast and tactile cues on critical operator controls can make them easier for users with low vision to use. When direct access is not possible, medical equipment can provide indirect access by being compatible with auxiliary “assistive” equipment that is either available to all (such as a magnifying device) or supplied by the individual user (such as reading glasses or a screen reader). Such accessibility solutions often rely on multimodal interfaces.

Although many healthcare professions currently require specific skill sets and ability profiles, and it is unlikely that many specialized medical devices would be used by people with disabilities, accessibility is often still highly desirable. Some healthcare professionals do, in fact, have disabilities, although many would not


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use this label. Some practitioners enter their professions with functional limitations, others acquire them during the course of their lives, and many leave their professions due to ability decrements that are incompatible with the demands of the job. Of particular concern are individuals who develop disabilities through repetitive stress injuries or traumatic incidents on the job, such as back injuries from patient handling and carpal tunnel syndrome from extended manual exertion. Also, because overall the healthcare workforce is aging, more medical device users may have functional decrements associated with aging, including arthritis, decreased near vision and hearing loss.

Accessible medical devices are becoming more of an issue and a need for many members of our society, and accessibility is also a legal issue in the U.S. Several laws apply: the Americans with Disabilities Act of 1990 (ADA), which prohibits discrimination against or segregation of people with disabilities in all public facilities, activities, programs, or services, including public hospitals and healthcare facilities; Section 255 of the Telecommunications Act of 1996 (Section 255), which requires that telecommunications products and services be accessible to and usable by people with disabilities, if readily achievable; and where it is not, devices and services have to be compatible with peripheral devices and specialized customer premises equipment commonly used by people with disabilities; and Section 508 of the Amended Rehabilitation Act of 1998 (Section 508), which requires that Federal agencies that develop, procure, maintain, or use electronic and information technology have to make it accessible to people with disabilities. The US Access Board (http://www.accessboard.gov) implements guidelines associated with these laws, and a design is considered accessible if it meets certain guidelines.

The guidance that follows is intended to extend other sections in HE75 specifically to support designing for users with a diversity of abilities. For most medical devices, effective application of human factors practices will be synergistic with enhancing accessibility as long as designers recognize and include individuals with disabilities as potential device users in all stages of user interface design. Approaches are available for usability testing that systematically address accessibility by embedding inclusive design concepts into protocols, identifying use error and access barrier events for users with diverse abilities, and integrating postactivity user questionnaires into the device evaluation process (Winters et al., 2007).

1.1 Scope

This section provides general guidance based on the following: existing accessibility guidelines that address federal legislation, a consensus document called the Principles of Universal Design (Center for Universal Design, 1997) and its extension to medical devices (Story, 2007), and research findings of the Rehabilitation Engineering Research Center on Accessible Medical Instrumentation that is funded by the U.S. Department of Education to help address the need for more accessible medical devices (Winters, 2007; Lemke

http://www.access-board.gov/


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and Winters, 2007). This section does not include detailed descriptions of causes or types of functional limitations and disabilities, human skills and abilities (or disabilities) (see Section on Basic Abilities), or environmental access (see Section on Environmental Concerns). Specific guidance is provided for patient support surfaces and healthcare applications of webbased information technologies.

A summary of various strategies for providing access to medical devices for users with disabilities is presented, including direct access through universal design, multimodal interfaces and alternative formats, and indirect access through interfacing with commonly used assistive technologies (for example, text tospeech screen reader, pointing device, and wheelchair). An overview of interface requirements associated with using various assistive technologies in conjunction with medical devices is provided for both patient and provider users.

2. Design Considerations

In practice, designing the most accessible medical devices requires that devices accommodate the widest possible diversity and range of human abilities. When designing medical devices, it is important to consider the interactions between users with disabilities, for example medical professionals and patients, and the device, as well as the interactions of medical professionals without disabilities using devices while working with patients who have disabilities. Patient users also may participate in several possible roles when interacting with devices. Specifically, they can have a device used on them, they can be the primary user of a device, for example to determine their own blood pressure or temperature, or they can cooperatively work with others using a device. Accessibility is especially important for any devices that may be used in the home (see also Section on Home Healthcare). It is also important to consider assistive technologies, for example wheelchairs and hearing aids, that may be used in conjunction with medical devices, and the roles of caregivers or family members who may assist or become the primary users of medical devices.

There are often ergonomic tradeoffs related to designing more accessible devices that designers need to recognize; for example, increasing font size of a label may decrease information density. There are also many different design features that may be ideal for one user and not another; thus offering flexibility by providing options for different modes within one device (and interfacing with various assistive technologies) is good practice. It is recognized that safe use is the first priority for designers of medical devices. Designers are cautioned not to go so far in designing devices that are more accessible for some users that safety is decreased for other users. Separate products may also be designed for specific populations of intended users, including those with certain abilities or disabilities, although this is often impractical and generally not recommended for medical devices.


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To help designers understand which user populations to serve, Table 1 provides data on the incidence rates of common disabilities and examples of associated functional limitations that may affect the design of medical devices. Table 1 may be helpful for defining expected user characteristics and abilities. It also is important to consider the interactions of different disabilities because many people concurrently experience more than one type of disability, for example stroke may cause muscle paralysis, visual deficiencies, and speech impairment.

Table 1: Incidence of Different Disabilities in the United States 1 : percentages are self reported, 1999 data (CDC, 2001)

Cause of Disability Total (%)

Men (%)

Women (%) Possible Functional Limitations

Arthritis or Rheumatism 17.5 11 22.4 Joint stiffness, joint contracture/deformity, joint pain, muscle weakness, joint weakness/instability (Arthritis Foundation, 2006)

Back or Spine Problem 16.5 16.3 16.6 Back stiffness, pain, limited side/forward reaching/bending

Deafness/Hearing Problem 4.4 6.7 2.6 Loss of ability to hear specific tones, inability to perceive sounds

Limb/extremity stiffness 4.2 4.7 3.9 Loss of fine and/or gross motor control, limited joint range of motion

Mental/emotional problem 3.7 4.1 3.5 Difficulty concentrating, indecisiveness, slowed or hazy thinking

Diabetes 3.4 3.4 3.4 Decreased tactile sensation, vision loss, hearing loss, limb loss, decreased mobility

Blindness/vision problems 3.3 3.5 3.1 Blurred vision, cloudy vision, double vision, difficulty with color discrimination, loss of central vision

Stroke 2.8 3.3 2.4

Dysphasia, loss of sensation, visual deficits, joint contractures, spasticity, muscle weakness or atrophy, changes in muscle strength, tone and response, loss fine and/or gross motor control, upper extremity flexion synergy patterns (Shumway Cook and Wollacott, 2000)

Broken bone/fracture 2.1 2.1 2.2 Limited strength, limited mobility, reaching difficulty Mental retardation 2.0 2.9 1.4 Limited memory Cancer 1.9 1.7 2.1 Fatigue Head/spinal cord injury 1.1 1.6 0.7 Limited memory, paralysis, spasticity, limited mobility Learning disability 1.0 1.4 0.6 Reading difficulties, limited memory Alzheimer/senility/dementia 0.9 0.6 1.0 Short term memory loss, speech impairment Paralysis 0.8 1.0 0.6 Limited mobility, reaching difficulty, skin pressure sensitivity Missing limbs 0.7 1.2 Balance, dexterity Epilepsy 0.5 0.7 Seizures 1 Some data may be underestimations of the percentages of patient and provider users of medical devices because of temporary disabilities, aging trends in the U.S., and onthejob cumulative trauma disorders that may cause disabilities.

Because providing compatibility with existing assistive technologies often is the easiest approach for making devices more accessible to people with disabilities, Table 2 provides summary information on a small sample of some commonly used assistive technologies and their functions, as well as brief descriptions of device interface characteristics that may be needed to work effectively with each assistive technology. Some of the assistive technologies included in the table are devices that are owned by individuals for their personal use: some of them are


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portable and people take them along when they leave home, for example wheelchairs, hearing aids, and mouth sticks; others tend to remain in the home or workplace, for example text telephones, speech recognition software, and a stepping stool. It is important to recognize that most of these technologies are also useful in medical facilities, particularly those types that are not portable.

Table 2: Examples of assistive technologies that a designer may need to interface with to provide indirect access to the device, or to accommodate for when providing direct access.

Assistive Technology

Function Interface

Text Telephone (TTY/TDD)

Enables users who are deaf, hard of hearing, or have speech limitations to communicate via telephone by typing and reading messages instead of talking and listening (or sometimes with intermediary voice relay operator). Letters typed into the machine are turned into electrical signals that travel over regular telephone lines, and are converted back into letters that appear on a display screen and/or are printed on paper.

May include phone jack, keyboard with 20 to 30 character keys, display screen, ring indicator (flashing light), telephone modem, printer

Assistive listening system

Used to transmit sound as directly as possible to a transducer in the ear of a user who is hard of hearing.

Includes small personal amplifier, microphone, and extension cord.

American Sign Language (ASL)

Enables users to communicate using signs made with the hands and other movements, including facial expressions and body postures.

Requires clear line of sight; if remote include visual display; may include tactile display for individuals who are deafblind

Braille Enables users who are blind (and deafblind) to read by touching with their fingers an array of raised dots that represent letters, numbers, and punctuation.

Involves tactile labeling; consider user reach range to such labels

Screen Reader Converts text into synthesized speech so users can listen and navigate through software content. The user can allow the screen reader to read everything from top to bottom, or one line at a time, or use the tab key to navigate from link to link, from one heading to the next, from one frame to the next, or by other methods.

Requires software, audio display, text based content

Magnification Enables displayed information, such as that on a computer screen, selfcontained monitor or a control, to be readable by a user who has low vision.

Consider approach space, clear line of sight, software or physical magnifier (may be carried by the user or embedded in the product)

Guide cane Enables users to detect objects and barriers in their environment while moving through space; for example, a user who is blind tapping for spatial orientation and object detection

Consider approach space, devices near floor may be tapped; devices on wall may not be detectable

Speech recognition/activation software

Enables use of voice commands as an input mode to devices; two categories: systems with limited vocabulary that are intended for many users, and systems that use learning algorithms and involve training that are customized to a specific user.

Requires user speech, microphone, software, compatible operating system; may involve a visual and/or audio display

Upper or lower extremity prostheses and/or orthoses

Through replacement, enhancement and/or constraint of body parts, affects user physical function, particularly manual and mobility capabilities

Consider accommodation for moderately different body anthropometry, lack of fine motor control, limited range of motion, onehanded manipulation, decreased balance and positioning capabilities


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Headstick, mouthstick, dowel

Enables users to activate buttons and keys without use of fingers. Often held in the mouth or strapped to the forehead or hand splint.

Buttons and keys need to be flat, or preferably, concave.

Cane, crutches, walker

Enhances user balance while standing or walking Consider approach space, reach space, one or nohand operation of controls, grab bar for balance aid, storage during device use

Wheelchair, scooter Enables users with limited mobility to move through the environment without bearing weight on their legs.

Consider clear path of travel, approach space, reach space

Stepping stool (with handrail)

Enables users with limited reach ranges or mobility to access taller or higher items

Consider clear space adjacent to device that needs to be accessed

Lift equipment Generally used to transfer a patient from one support surface, such as a wheelchair, onto another, such as an exam chair. May be portable, or ceiling or wall mounted. Includes a controller and mechanical interface (with a surface that supports the patient in a sitting or lying position).

The patient, perhaps with assistance, needs to get into the lift, the controls need to be operated, and the patient needs to safely exit the lift.

Table 3 provides a useful classification scheme for delineating between different types of sensorimotor, interface, and device modes. Note that there are three primary sensory modes – vision, hearing, and touching/manual – each of which can have varying degrees of ability, for example from users who have full vision to users who are blind. This table helps point out that designs that are ideal for one population of users may be suboptimal for another population. Also, appropriate solutions within a disability category may not lie on a smooth continuum. For example, individuals who are blind often require fundamentally different approaches than do people with a specific type of partial visual limitation, such as needing audio displays versus larger font size and more color contrast. Such degrees of ability are also true for motor abilities such as manual control and speech production. Table 3 also implies that even though a sensory or motor mode is often the focus of a particular design specification, the desired solution often involves integration of both motor and sensory capabilities because of the twoway nature of interfaces. For instance, a control device such as a keyboard may improve usability for all and enable access for some by having a tactile component, for example excursion and stiffness of keys, plus a visual component (labeling and motion of keys), and an audio component (sound associated with key depression or retraction).


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Table 3: Classification scheme for delineating between different types of sensorimotor, interface, and device modes Sensorimotor Modes and Major Categories of Functional Limitation Associated with Each

Vision (Visuomotor) Blindness Partial sight Visuomotor limitation Color vision limitation

Hearing Deafness Hearing limitation

Touching/Manual Loss of sensation, loss of motor capability Partial sensation, partial motor capability Biomechanical loss or joint contracture Gross sensorimotor, reaching Fine sensorimotor, dexterity Speaking

Interface Modes and Major Categories of Devices Associated with Each

Input Control buttons, knobs Keyboard Mouse pointer (e.g., standard, rollerball, touchpad, forcepointer) Touch screen Joystick Microphone/Speech recognition Head/mouth pointer

Output Display/captions Dial, gauge Magnifier Audio/speakers Vibration

Device Modes Conceptual modes associated with device use, often associated with groupings of functions, which a user needs to be able to easily understand, and switch between, in the process of using the device.

3. Guidelines

There are many ways to design products to be accessible, and strategies that improve usability and sometimes accessibility are integrated throughout this standard. The following General Guidance in Section 3.2 is based on adapting aspects of existing guidelines to medical devices. The Specific Guidance in Section 3.3 provides design approaches for specific types of medical equipment, based on research or technical specifications developed for the implementation of federal legislation for related products, such as webbased products.

3.1 Caveats & Limitations

It is important to acknowledge that it may not be practical to design every device to be accessible to all users, so the following guidance is provided with the caveat that each statement may not always be appropriate. Accessibility may not always be practical or “readily achievable” for the intended user population. Certain types of medical procedures, or certain types of devices, may require


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particular abilities on the part of the medical device user. For example, it is not likely that a CT workstation would be used by a medical professional who is blind, so it is impractical to expect designers to use audio or tactile features for all visual components of the design. On the other hand, these modes can be considered if they might increase usability or decrease use errors (see Risk Management section). Often, improving accessibility will decrease errors and increase usability, and it may also increase the size and diversity of the intended user population. As a general rule, devices that are used by patients, lay users, or outside the clinical setting need to follow the guidance in this section to the greatest extent possible (see also Home Healthcare section).

The phrase “where readily achievable for the [intended] user population” applies to all of the following guidance. The term “readily achievable” is used to mean “easily accomplishable, without much difficulty or expense” (ADA, 1990) and it is important to recognize that the design recommendations that follow are readily achievable for many types of medical devices.

3.2 General Guidance

There are several approaches that can be used to achieve accessibility, and the following guidance makes use of one or more of these approaches. Two general approaches are described here:

a) Guidance on multimodal interface design based on the conceptual framework used in the U.S. Access Board’s regulations for providing access for users with various categories of functional impairment to both operation of and information retrieval for a device or product.

b) Guidance on device design based on universal and inclusive design strategies.

For many products, design strategies using conventional good human factors practices, augmented by sensitivity to testing with a diverse user population, may suffice to improve device accessibility. However, such strategies often have ceiling effects in that iterative solutions that improve the ease of use for most users can reach a limit that excludes certain subpopulations from full or even partial access without a fundamental change in approach. Occasionally, ease of use decisions made for the majority can have the unintended byproduct of diminishing access for some, exposing a conflict between collective ease of use and inclusive access. The focus of U.S. laws and regulations has been on the right of access to the benefits of a product, rather than directly on its usability. The guidance of this section builds on the “performance criteria” and mode based approaches for providing accessibility that have formed the foundation of most U.S. accessibility standards.

Most of the guidelines in this subsection emphasize the importance of support for redundant coding of display information, and for alternative means for finding and/or operating controls. Another key theme is that the options available to the


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device designer include both “direct access” (integration into product) and “indirect access” (support for product connection to or use with assistive technologies). This subsection uses as primary resources the U.S. Access Board’s regulations related to:

a) Accessibility standards for electronic and information technology to support implementation of Section 508 of the Rehabilitation Act. The material provided here is based on Subpart C: Functional Performance Criteria (Section 508, §1194.31, parts af).

b) Telecommunications Act Accessibility Guidelines (TAAG) for accessibility, usability and compatibility of telecommunications equipment that were formulated to support implementation of Section 255 of the Telecommunications Act of 1996. The material provided here is based on items related to input, control and mechanical functions (Section 255, §1193.41, parts ai).

Much of the guidance that follows identifies both “mode of operation” and “information retrieval” components, following the approach used in regulatory guidance for Subpart C of Section 508. Both need to be addressed for full consideration of access to a device or product. For instance, note that a sensory impairment like a visual impairment influences not only direct use of the sensory mode, such as obtaining visual information from the device, but also operation of the device, for example: reaching, locating, understanding, and then operating a control. Similarly, a motor impairment affects operation of a device, which in turn can affect information retrieval. Further, the statements adapted from existing regulatory guidance have been softened by using the word “consider” or “should,” in place of the word “shall.”

Some of the guidance that follows also draws on content from the Principles of Universal Design (Center for Universal Design, 1997). The term universal design was coined by the late Ronald L. Mace to describe the process of designing all products and environments to be usable by people of all ages and abilities, to the greatest extent possible (Mace, 1991). Its roots lie primarily in the disability and design communities. One resource for this guidance is a set of seven principles, the Principles of Universal Design, which were generated using a consensus process involving ten experts in the universal design field (Center for Universal Design, 1997). For each of the seven core principles (equitable use, flexibility in use, simple and intuitive use, perceptible information, tolerance for error, low physical effort, size and space for approach and use), four or five guidelines were articulated to help provide design process guidance for improving accessibility (Story, 2007). Another term that is popular in the U.S. is inclusive design (Wilcox, 2007; European Design for All eAccessibility Network, 2006). The preferred term in the European Union is design for all (European Institute for Design and Disability, 2002).


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It is useful to note that universal design differs from accessible design and interfacing with assistive technologies, and can be viewed as a key strategy (but not the only one) for enhancing the direct accessibility of medical products. Unlike designing to interface with assistive technologies or for multimodal operation, universal design seeks to design products to suit concurrently the needs of people of all ages, sizes, and shapes, and with a wide range of abilities and disabilities, and accessible features are integrated into these designs so that they look and function as integrated systems. While universal design may be difficult or impossible to achieve for many medical devices, it is often efficient and economically advantageous to approach it as closely as practicable when designing for diverse user populations.

3.2.1 For users who may be blind or have visual impairments, provide at least one mode of operation and information retrieval that does not require user vision, or provide support for assistive technologies used by these users.

Medical device users may be blind or have various uncorrectable visual limitations such as loss of visual field, or may suffer from temporary visual impairments such as low lighting or an obstructed line of sight. Thus it is important to design devices that do not overly depend (unnecessarily) on presenting information only in visual form. Lack of vision also impacts device operation. There are strategies and infrastructure that can help designers avoid overly depending on user vision. The most common multimodal alternative is to provide audio output for visual content, for example a tonal beep for turning on and off a device (with different tones for different binary operations). Directional tones or tactile cues can help a blind user safely operate controls. Multimodal presentation can sometimes improve a product for most users while providing access for some, for instance by representing an ultrasound blood flow or velocity signal in audio form, in addition to the standard visual graph, through a filter that maps the signal to changes in audio amplitude and frequency over time. Providing text descriptions, for example ASCII text, of visual information content such as images and video clips, enables access through use of auxiliary aids or users’ assistive technologies (Section 508 §1194.31(a) and Section 255 §1193.41(a)).

3.2.1.1 For users who may have visual impairments, provide text description of visual information and navigation assistance.

Text descriptions of visual information including images, graphs, charts, icons, and symbols are critical for gaining access to this information, and providing text descriptions is the most common approach for interfacing with assistive technologies such as screen readers that work with computer systems. The user’s assistive technology can then provide the information in an appropriate alternative format, such as audio or Braille or largefont text. Text descriptions can be considered for all images, and certain protocols for information layout and use of tab ordering for assistance with navigation through spatially presented


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information are provided in the Web Consortium Accessibility Guidelines 1.0 and 2.0 (World Wide Web Consortium 1999, 2006). For products that are not computerbased, such as vital signs monitors, one simple solution is to support use of audio to toggle through the displayed values, if the quantity of values is not too high.

3.2.2 For users who may have limited visual acuity, provide at least one mode of operation and information retrieval that does not require visual acuity greater than 20/70, or provide support for users’ assistive technologies.

This is relevant for products used by persons who have limited visual acuity (including many older adults who wear corrective glasses part of the time but may not always have them available), and/or products that present a lot of visual information (Section 508 §1194.31(b) and Section 255 §1193.41(c)).

3.2.2.1 To achieve direct access, strategies include using labeling (directly or as an option) in large fonts with good contrast, or providing an auxiliary magnifying tool with a product.

3.2.2.2 To achieve indirect access, strategies include providing support for electronic magnifier software, such as thirdparty products or a builtin magnifier similar to those available for some computer operating systems, or allocating physical space for provision of a mounted or handheld auxiliary magnifying tool.

3.2.3 For users who may be color blind, provide at least one mode of operation and information retrieval that does not require color vision.

While the primary goal is providing access for users with color blindness (such as greenred; Section 255 §1193.41(c)), this guidance is also good human factors practice (see also sections on Basic Principles and Displays). Redundant coding, such as labeling and position cueing, typically helps increase user performance and decrease use errors. A classic example is traffic lights, which cue with location as well as color (the red light is always on top and the green light, on the bottom). Labeling is another example to address this guidance, for example, a green power button can also have an “On” label on its face or alongside.

3.2.3.1 The means of conveying information, whether indicating an action, prompting a response, or distinguishing a visual element, should not use color coding as the only coding mechanism (Section 508, §1194.25(g)).

3.2.4 For users who may be deaf or hard of hearing, provide at least one mode of operation and information retrieval that does not require user hearing, or provide support for users’ assistive technologies.


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Providing redundant visual and tactile information for audio content is the most common approach for addressing this guidance. For example, a monitor alarm can present an audible tone, flashing visual display, and vibrating mechanism. It is also important to consider the assistive technologies that people with hearing impairments may use, such as hearing aids and text telephones. It is especially important to consider hearing aid use when designing wireless devices in order to eliminate any interference that could cause irregular or degraded sound quality with the hearing aid. This guidance is not to be interpreted as discouraging the use of audio in medical devices, and indeed Guidance 3.2.6 encourages such use (Section 508 §1194.31(c) and Section 255 §1193.41(b, d)).

3.2.5 For users who may be hard of hearing, provide at least one mode of operation and information retrieval that enhances auditory volume, or provide support for users’ assistive devices.

This guidance is important for users with hearing impairments, and it may also be helpful for users who are “temporarily disabled” due to a noisy environment (Section 508 §1194.31(d)).

3.2.5.1 Products that have auditory output should provide audio signals at a standard level through an industrystandard connector such as a headphone jack that will allow for private listening.

It must be noted that, because the standard audio output jack commonly found on computers (and its corresponding input connector on headsets) is exactly the same size and shape of oxygen sensor connectors that are used in many medical devices, this guidance may not be appropriate for all devices. The product needs to provide the ability to interrupt, pause, and restart the audio information signal when functionally permissible (for example nonalarm) at any time (Section 508 §1194.25(e)). Some advantages of providing a standards compliant interface jack include: easier identification, private listening capabilities with reduced environmental noise from speaker output, minimal physical space requirement within design, ability for wireless control with use of a remote headset, and the ability for personalized filtering by use of a customized assistive listening device.

3.2.5.2 One strategy for enhancing auditory volume is to provide embedded speakers. While embedded speakers are not appropriate for all medical devices, they offer convenience for many users.

3.2.5.3 When products deliver voice output in a public area, incremental volume control should be provided with output amplification up to a level of at least 65 dB. Where the ambient noise level of the environment is above 45 dB, a volume gain of at least 20 dB above the ambient level should be user selectable (Section 508 §1194.25(f)).


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3.2.5.4 Auditory output volume level should reset to a default value (for example 65 dB) when a device is initially powered.

3.2.6 For users who may find interaction within the anticipated use environment challenging, integrate modes of hearing with modes of vision and/or touch.

This guidance is especially important for users with temporary or chronic hearing impairments (for example users in noisy environments and deaf users), because audio information could be degraded or missed altogether. The audio mode tends to integrate well with other modes, especially vision but also manual operation, for example sounds are often expected to be associated with certain operations, such as keyboard strokes or operation of certain monitor controls. This can make audio an effective multimodal option. As an example, videoconferencing standards purposely aim to maintain lipsynching by slightly delaying the lower bandwidth audio signal to be synchronized with video, as this is a clear user preference.

3.2.6.1 User performance advantages of audio channels should be optimized.

Multimodal interfaces with a mode for audio are encouraged, including interfaces for timebased signals. Audio redundancy may mildly improve user performance overall for those without hearing loss, while helping assure that the content is similar across modes. The advantages of audio as a singlechannel display mode are often overlooked. Audio often requires less attentional cognitive focus and fewer physical constraints than vision or touching. For applications where one channel of information is presented (for example a timebased signal), one potential advantage is that the reaction time associated with hearing a signal and making a simple response averages 150 milliseconds, which is about 50 milliseconds quicker than for vision. Another advantage is that the user can perform other tasks while listening to an audio channel, because the user’s body does not have to be oriented in a general direction as for video, or within arm’s reach as with tactile. Single channels can be coded by acoustic frequency or magnitude, though frequency is more common. Generally, humans have excellent relative tonal resolution but poorer absolute recognition, making hearing especially effective for dynamic signals or for hearing beats such as heart rate. For absolute values that change less frequently, it is better for a speech synthesizer to speak the value.

3.2.7 For users who may have limited tactile sensation, provide at least one mode of operation and information retrieval that does not depend on tactile sensation.

While there are clear cases where tactile sensation is integral for manual operations involving medical tool use that cannot possibly be replicated by audio or visual means, operation of controls and certain tools should not rely only on tactile information to identify or operate the control. An example is a medical


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pager, which has options for both a tactile (vibratory) mode and an auditory mode. Another example is a visible cursor on the screen for a mouse (pointing device).

3.2.8 For users who may have vision impairments, integrate tactile features into the interface surface.

While Guidance 3.2.7 emphasizes not depending only on tactile sensation, many individuals with disabilities, especially users who have visual limitations or are blind, make more use of tactile cues on controls and of surface features than designers might realize. Tactile variation can provide effective cues that can facilitate use of the interface. Many users who are blind or have visual limitations are also willing to learn or memorize the components of an interface, so the more distinguishable the controls or surface features are the better it is for the user. In highnoise areas or in cases where visual and auditory detection may be impaired, such as in the early stages of hypoxia and dark rooms, tactile features such as surface texture and vibration can offer significant advantages.

3.2.8.1 Textural transitions to a surface can help orient users or may organize related content into groups to facilitate navigation. This can involve surface textures, changes in plane, or raised ridges.

3.2.8.2 Functions of the device should be operable from controls that are tactilely discernable and that can be explored without activating the controls (Section 508 §1194.23k1).

3.2.8.3 Use controls that differ in their tactile representation; for instance, vary the control size or shape or use raised lettering or symbols.

3.2.8.4 Avoid user exposure to sharp edges or hot surfaces that could injure someone engaged in tactile exploration.

3.2.8.5 Use tactile vibration as a redundant mode for transmitting information such as an attentiongetting signal.

3.2.8.6 Place touch controls so that accidental activation is minimized.

3.2.9 For users who may have speech impairments, provide at least one mode of operation and information retrieval that does not require user speech, or provide support for these users’ assistive technologies.

An example is a homebased telehealth product that integrates vital sign monitoring and voicebased phone calls where the user periodically interacts with a telenurse to share information. Examples of assistive technologies to interface with to meet this guidance include providing an instant messaging or TTY


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interface, or a videoconferencing system (Section 508 §1194.31(e) and Section 255 §1193.41(h)).

3.2.10 For users who may have upper extremity motor impairments, use speech recognition as one of multiple redundant control input modes.

While Guidance 3.2.9 notes not to depend only on speech as a control operation mode, speech is often a very effective control mode (or the only control option for some users with disabilities). Speech recognition systems are often used by users with fine motor impairments for data entry and control purposes. There are two primary approaches that can be integrated with medical devices: general speech recognition systems that are intended for any user and usually support a small vocabulary, and personalized speech recognition systems that involve interactive training so that the system is tuned to the voice of a specific user. Personalized systems are worth noting, as many individuals with disabilities are willing to put in the time necessary for interactive training if it enhances access and performance. Speech control may not be suitable in noisy environments, with multiple users, or when users may speak multiple languages. Further, there are tradeoffs related to using speechbased interfaces that should be recognized; for example, concerns related to the privacy and security of information. Consideration of speechcontrolled systems, or the ability to interface with existing speech recognition software, is nonetheless encouraged as this can provide access for individuals who may otherwise lack it.

3.2.11 For users who may have upperextremity motor impairments, provide at least one mode of operation and information retrieval that does not require fine motor control or simultaneous actions.

Many people have motor disabilities that affect their potential interactions with medical devices, such as decreased fine motor control, decreased grip strength, inability to exert and maintain forces, and inability to perform twohanded tasks. Thus, it is important to minimize the motor demands of using a device. This guidance is especially relevant for homebased users of medical devices, but it does not necessarily apply for very skilled users who perform specialized procedures such as surgery. The following guidance can be used to increase the accessibility of mechanically operated controls that have to be reached and manipulated for users with disabilities (Section 508 §1194.31(f) and Section 255 §1193.41(e)).

3.2.11.1 The status of all locking or toggle controls or keys should be visually discernible, and discernible either through touch or sound (Section 508).

3.2.11.2 The device should be operable with one hand, when possible.

3.2.11.3 The device should be operable with either the right or left hand.


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3.2.11.4 For handheld devices, users should not have to use a positive grasp to keep the device in their hand. Using surface textures, contouring, or hooks can increase the friction between the user’s hand and the device.

3.2.11.5 Use controls for continuous channels that do not require users to perform twisting movements. Many users may have diminished abilities to perform twisting motions of the wrist, for example due to limitations in neuromotor coordination, arthritis, and carpal tunnel syndrome, so the preferred accessible interface for adjusting continuous (analog) controls such as volume is a sliding control, thumbwheel, or knob with a wedgeshaped pointer that can be turned by linear motion against the side of the knob (with a finger, the side of the hand, or a pointing device such as a dowel).

3.2.11.6 The force required to activate controls and keys should be a maximum of 5 lbs. (22.2 N).

3.2.11.7 If key repeat is supported, the delay before repeat should be adjustable to at least 2 seconds, with key repeat rate of 2 seconds per character (Section 508, §1194.23(k3)). This pertains to actions associated with configuring the device as well as operating the device.

3.2.11.8 Where a product utilizes touch screens or contactsensitive controls, a redundant input method should be provided for mechanically operated controls or keys so that they can be tactilely explored without activating them (see Section 508, §1194.23(k)).

3.2.12 For users who may have physical disabilities, provide at least one mode of operation and information retrieval that enables effective user positioning and orienting relative to the medical device without requiring the user to stand or maintain unsupported postures, such as specific head, torso, arm, and leg positions.

Many functional limitations can be minimized by effective design planning, and good human factors practice dictates that products need to be designed to serve the needs of users. This guidance also reflects the importance of testing products with a diversity of users, because user orientation and body positioning relative to medical devices is especially critical for effectively using medical devices. Some examples of this guidance include: a mammogram where patients can sit in chairs or wheelchairs for the entire exam; a powered exam chair with controls for positioning the chair height, seatback angle, leg angle, and headrest position; and a medical workstation that provides adequate space for a user in a wheelchair.

To help determine whether reach ranges are appropriate for seated users that include people who use wheelchairs or scooters, consider the following guidance that is part of both the ADAAG and Section 508 standards. The reach ranges


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presented below relate to minimal spatial access, not necessarily optimal performance. For optimal user performance with medical devices, it is recommended that designers stay well within these limits unless usability testing indicates otherwise (Section 255 §1193.41(f)).

3.2.12.1 Forward reach If the clear floor space adjacent to a medical device allows only forward approach by a seated user (such as a user in a wheelchair), the forward reach height should be a maximum of 48 inches (1220 mm) and a minimum of 15 inches (380 mm).

3.2.12.2 Forward reach over an obstruction If the forward reach is over an obstruction, reach and clearances should be the following (ADAAG §4.2.5, see Fig. 1):

a) The dimension x (in Fig. 1) needs to be ≤ 25 inches (635 mm).

b) If x < 10 inches (255 mm), then the dimension y needs to be 15 inches (380 mm) minimum and 46 inches (1170 mm) maximum.

c) If x is 10 to 20 inches (255 to 510 mm), then y needs to be 15 inches (380 mm) minimum and 48 inches (1220 mm) maximum.

d) If x is 20 to 25 inches (510 to 635 mm), then y needs to be 44 inches (1120 mm) maximum.

Figure 1: Recommended forward reach dimensions for seated users (ADAAG §4.2.5).


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3.2.12.3 Side reach If the clear floor space adjacent to a medical device allows parallel approach by a seated user (e.g. a user in a wheelchair, see Fig. 2), the side reach should be a maximum of 54 inches (1370 mm) and a minimum of 9 inches (230 mm) above the floor (Fig. 2b).

3.2.12.4 Side reach over an obstruction If the side reach is over an obstruction, the reach and clearances should be as shown in Fig. 2c.

Figure 2: Recommended side reach dimensions for seated users (ADAAG §4.2.6).

3.2.12.5 Remote control A useful alternative strategy to direct reach is to support a remote control for a device, preferably operable with one hand and from a location of the user’s choice.

3.2.12.6 Sight lines The device should offer a clear line of sight to important elements for any seated or standing potential user, including users of wheelchairs. An example is video monitors in a hospital room, which may need to be easily visible for all healthcare personnel involved, including those who may be seated. This often requires use of multiple monitors or monitors whose positions can be adjusted.

3.2.12.7 Neutral body positions The device should allow users to maintain neutral body positions, with minimal sustained physical effort. An example is a backrest or armrests on a chair, which can improve comfort and reduce fatigue of healthcare practitioners during long procedures. A chair that provides chest support can reduce load on the lower back during sustained forward reaching tasks, such as when performing surgery.


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3.2.12.8 Access space Adequate space for physical access to a medical device should be provided to enable use of assistive devices or personal assistance. Welldesigned products and environments can suit users who use assistive devices such as wheelchairs, walkers or canes, or who have personal assistance from another person to operate a device. An example is an xray platform that has space underneath or along both sides to accommodate the horizontal support legs of portable mechanical lift equipment that may be used to transfer patients who cannot stand or walk.

3.2.13 For users who may have cognitive or memory impairments, provide at least one mode of operation and information retrieval that minimizes cognitive and memory requirements, and the language and learning skills required of the user.

This is good human factors practice (see especially Section on Home Healthcare), but it bears explicit mention for users with cognitive deficits (either temporary or permanent). For example, medical devices may provide full prompting for selected procedures during training periods to guide new users, which may be turned off for proficient users. For devices used by patients with limited ability to read or comprehend text in English, alternative modes (such as picture images, audio/video tape, or an alternative language) that relay the same content are encouraged. This guidance may also be helpful for highly trained medical professionals who may not use the device frequently or may be stressed, overworked, and pressed for time (Section 255 §1193.41(i)).

3.2.14 For users who may benefit from having more time for device operation, and for tasks that are not timecritical, provide at least one mode of operation and information retrieval that does not require a timed response.

Some medical device functions are timecritical. However, for some users access is the key issue and these users are willing to spend extra time to achieve it. For cases in which timing of device functions is not critical, the device should adapt to the user’s pace, to allow, for example, users with vision, reading, or movement limitations to operate the device successfully. This is especially true for devices used outside the clinical environment or in the home, because independence is greatly valued by many users with disabilities (Section 255 §1193.41(g)).

3.2.14.1 For electronic and information technologies, users should have the option of having up to 2 seconds to perform an action, such as keystrokes during text entry.

3.2.14.2 When users are expected to respond within a certain amount of time, they should have the option of changing or turning off any timeout setting or be able to indicate that they need more time. Ideally, when a timed response is required,


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users are alerted and given sufficient time to indicate that they need more time (Section 508 §1194.25(b)).

This guidance is particularly important from the perspective of medical device safety, as there is little reason to place, for instance, inhome users under time pressures that may result in use errors.

3.2.15 To maximize compatibility with electronic technologies and methods used by individuals with disabilities, use standard telecommunications protocols, operating systems, graphical user interfaces and monitors.

This guidance is motivated by the concept that device designers should take advantage of the advances in accessibility support for mainstream telecommunications and information technologies, and is applicable to users with various sensory and motor impairments. Consensus protocols for telecommunications, for example multimodal transmission of information and data compression, generally provide an accessible format for thirdparty products. The trend in some classes of medical devices toward standards and computerbased graphical user interfaces and monitors is often considered to be a positive development because of the collection of accessibility tools that are available for both developers and end users. Developers of the major computer software operating systems have long histories of adding accessibilitymotivated interface features, providing accessible software, and offering libraries and tools for developers that enhance product accessibility. As an example, Table 4 lists some accessibility features available in various operating environments (most often through an accessibility option within the control panel). Along with these suites of accessibility features that can be configured by users, a large number of third party products designed specifically for individuals with disabilities are also available, such as: screen readers, Braille printers, alternative mouse pointers and keyboards (see Table 2). For selected specific guidance in this area, see Subsection 3.3.2.

Table 4. Example of accessibility settings available on some operating systems, which help make the computer more comfortable, and easier to see, hear, and use.

Control or Display Mode

Accessibility Feature

Description Users

Keyboard Sticky Keys To use shift, control, alt, or logo key sequentially rather than simultaneously with another key

For users with limited arm/wrist/forearm strength, or neuromotor impairment

Filter Keys Ignore brief or repeated key strokes, or slow the repeat rate

For users with neuromotor impairments such as tremor

Toggle Keys To hear tones when pressing caps lock, num lock, and scroll lock

For users with functional limitations, including cognitive and hearing

Audio Sound Sentry To generate visual warnings when system makes sounds

For users who are deaf, or in noisy environments

Show Sounds / To tell programs to display captions For users who are deaf, or in


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Talking Alerts for the speech and sounds they produce

noisy environments

Display High Contrast To use colors and fonts designed for easy reading

Creates high contrast black background with white text, for users with limited visual acuity or in environments with poor lighting

Curser Options To change the speed that the curser blinks and the width of the curser

For users with low vision, or who have a risk of seizures

Magnifier / Zoom To magnify a region of text in proximity of the pointing device

For users with low vision, or in a poorly lit environment

Mouse MouseKeys To control the pointer with the numeric keypad on the keyboard

For users with limitations in neuromotor coordination

Pointer Top Speed

To control the highest speed that the mouse travels

For users with limited hand range of motion, or limitations in neuromotor coordination

Pointer Acceleration

To control the rate at which the mouse accelerates

For users with limitations in neuromotor coordination, especially tremor

3.2.16 To offer direct access for the largest possible number of users, provide the same means of use for all potential users: identical whenever possible, equivalent when not.

Integrating accessibility features into medical devices reduces stigma to users who may need some of the device’s “special” features, and can sometimes reduce the cost of the device. An example is a weight scale with a large platform that is recessed into the floor (see Fig. 3). All patients, regardless of size, can use the same scale, whether they walk or use a wheelchair.

Figure 3:Weight scale recessed into floor of medical facility

3.3 Specific Guidance for Patient Support Surfaces

The guidance that follows pertains to patient support surfaces, such as examination tables, examination chairs, hospital beds, xray platforms,


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MRI/CT/PET scan platforms, and other similar devices. This device category was selected (along with Section 3.4 below for telecommunications and information access strategies) from numerous possible categories because data are available in this area, the guidance can be applied to a wide variety of different medical devices, and it is not possible to provide guidance for all devices.

The following guidance focuses on the needs of healthcare providers (engaged in work tasks) as well as of the needs of patients (for example, in hospital environments) and consumers (for example, in home environments). Much of the guidance in this subsection is based on a series of studies conducted by the Rehabilitation Engineering Research Center on Accessible Medical Instrumentation (RERCAMI), funded by the U.S. Department of Education’s National Institute on Disability and Rehabilitation Research (NIDRR). These studies included a national survey of patients with disabilities (Jill Winters et al., 2007), a series of focus groups with patients with disabilities (Story et al., 2005) and usability testing that documented the biomechanical accessibility and usability of various medical devices (such as hospital beds, examination tables, weight scales, and dental chairs) by individuals with various disabilities (Lemke, 2005). Where noted, this guidance is also extracted from the Americans with Disabilities Act Accessibility Guidelines (ADAAG), which were written primarily for architectural access to a wide range of public spaces, including healthcare facilities.

3.3.1 The base of the device should not extend horizontally beyond the edge of the support surface.

The base of the device should not impede the ability of patient users to orient a wheelchair next to the support surface. When wheelchair users perform manual transfers (for example using a transfer board), they need to place the wheelchair next to the transfer surface (for example an exam table) with a minimal horizontal gap between the wheelchair seat and adjacent surface.

3.3.2 The base of the patient support surface should provide clearance for lift equipment.

Many people with significant motor impairment such as paralysis are transferred from one surface to another using patient handling devices such as Hoyer lifts. Because this lift equipment is essential for many healthcare providers to allow safer and more efficient patient handling, it is important that patient support devices provide adequate clearance for optimal interaction between the device and lift equipment. The base of the patient support device needs to have space underneath or along both sides of the base, if the equipment is narrow, to accommodate the legs of portable mechanical lift equipment so that the patient can be suspended over the support surface before being lowered onto it.


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3.3.3 The height of the support surface should be easy to adjust to suit the needs of potential healthcare professionals and patients.

The support surface height should be easily adjustable (ideally with automatic power) to different heights. The support surface should adjust to a position high enough to accommodate tall healthcare providers and the range of medical procedures that may occur, and low enough (19 inches maximum) to accommodate patients who need to transfer on and off, even from a chair or wheelchair alongside.

3.3.4 The support surface should make patient transfer on and off safe and easy, as appropriate to the application.

3.3.4.1 The support surface should not be slippery.

3.3.4.2 The support surface should be stable at all times (i.e., should not move while the patient gets on or off), and have no sharp edges. A stable platform is important for helping patients maintain their balance while using the platform, including while they are transferring on and off.

3.3.4.3 The type of patient transferring that will occur onto and off the support surface should be considered when selecting the stiffness of the surface padding so there is a balance between comfort and functionality. For example, platforms that require frequent transfers and short position maintenance times should have stiffer padding (especially so that patients who perform manual or selftransfers can get sufficient leverage).

3.3.5 A nonobstructed path should be available for transferring.

Any side rails, arm rests, leg supports, control unit cords, or other auxiliary equipment should be positioned or be able to be moved out of the way so as not to interfere with the ability of users to transfer onto and off the platform.

3.3.6 The device should have integrated handholds to facilitate transferring.

The platform should have handholds such as recesses, handles, railings, and straps integrated into the device and placed at locations most appropriate for the intended tasks: for safety, and for assisting patients with transferring on and off, positioning or repositioning their bodies, and maintaining static positions (see example in Figure 4 below).


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Figure 4: Highcapacity weight scale with side rails (Detecto).

Many people with disabilities rely heavily upon grab bars and handrails to maintain balance and prevent serious falls. Many people brace their forearms between railings and walls to give them more leverage while maneuvering and stability while maintaining balance. Handholds can also help patients transferring onto and off the device, and many patients use them to help maintain a stable position while on the platform.

As an example, two different weight scales are presented below: a traditional standing scale (Figure 5a), and a wheelchair platform scale with a foldup seat (Figure 5b). In a formal study, each scale was used by 12 consumers with various disabilities such as paralysis, arthritis, and low vision (Lemke, 2005). During testing, each patient subject was asked to get onto each weight scale, measure their own weight, obtain the weight readout, and get off the scale.

(a) (b) Figure 5: (a) Traditional standing scale and (b) platform scale with a foldup seat.


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One of the most significant task requirements for patient users of weight scales relates to maintaining a stable and static position on the scale while their weight is determined. The weight scale shown in Figure 5a has a narrow and unstable platform and there are no handholds present, and this device proved to be very difficult for many users to balance on during usability testing. The weight scale shown in Figure 5b accommodates wheelchairs and provides a very large platform for users to stand on. The side railings are especially noteworthy because the weight readout is not affected by patients holding onto the railings, so patients can be encouraged to use the handholds for increased safety without compromising device accuracy.

The following considerations for handrails are extracted from the ADAAG standard (§4.26, Handrails, Grab Bars, and Tub and Shower Seats):

3.3.6.1 The diameter or width of the gripping surfaces of a handrail or grab bar should be 11/4 inches to 11/2 inches (32 mm to 38 mm). If a noncylindrical shape is used, it should provide an equivalent gripping surface.

3.3.6.2 If handrails or grab bars are mounted adjacent to a wall, the space between the wall and grab bar should be 11/2 inches (38 mm). Handrails may be located in a recess if the recess is a maximum of 3 inches (75 mm) deep and extends at least 18 inches (455 mm) above the top of the rail. This clearance is a safety measure to prevent injuries resulting from arms slipping through the gap between the rail and the wall.

3.3.7 The support surface contact surfaces should be safe and comfortable for the patient to assume and maintain positions.

3.3.7.1 The support surface should have sufficient padding and thermal insulation for the patient to be safe and comfortable.

3.3.7.2 The support surface should be wide enough to enhance patient safety and comfort. For platforms on which patients lie down, a patient should be able to roll to a side or prone position with minimal need to lift and shift their center of gravity. For platforms on which patients stand, platforms that are wide enough for patients to assume a wide stance position increase the overall accessibility and safety of these devices, because often users who have balance impairments can overcome their limitations if they can stand with their feet relatively far apart and/or use their upper bodies to help them balance.

3.3.7.3 For support surfaces that require the patient user to assume a seated position, armrests should be provided to enhance patient comfort, stability, and ease of transferring.

3.3.7.4 For patients with limited leg strength and control, instead of stirrups that support only the foot and require active user leg strength, leg supports that


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support both the foot and the leg should be used to assist patients in keeping their legs in an appropriate position.

3.3.7.5 The support surface needs to be adjustable or have adjustable support features, for example for the head, neck, back, lumbar region, leg, knee, and foot (as appropriate) to support patients in various body postures and positions in a manner that optimizes their comfort. This is particularly important when patients need to maintain a static position, such as for imaging procedures. While these adjustments are normally controlled by the healthcare professional, for some applications, patients ought to be able to make adjustments themselves if no professional is present, such as the arm rest position and head rest position.

3.3.7.6 In case the patient experiences muscle spasms or loss of balance, if the patient is expected to sit or lie independently on the support surface, straps or safety rails should be available.

3.3.8 Controls for support surfaces should be easy to use.

Controls for adjusting the support surface, for example the height and back rest angle, should be easy to reach, view, understand, and operate for all intended users, including patients and care providers. The controls should be located as appropriate for the support surface, patient, and situation (i.e., different locations for individuals not intended to get out of bed versus individuals who use hospital beds in their homes).

3.3.9 Devices should provide access to continuous communication between patients and providers.

A continuous method of communication between the patient and provider, such as an intercom system and visual cues, is important for patient safety and security during procedures. This is especially important when the provider is located in another room or when the patient has hearing or visual limitations.

3.4 Specific Guidance for Telecommunications and Information Access Strategies for WebBased, Mobile and HomeBased Healthcare Products

As in section 3.3 (patient support surfaces) above, the guidance that follows was selected from numerous possible categories of medical instrumentation because data are available in this area, the guidance can be applied to many different medical devices, and it is not possible to provide guidance for all categories of devices. Where noted this guidance is based on Section 508 of the Rehabilitation Act as well as the W3C Web Content Accessibility Guidelines, as targeted to healthcare applications.


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With the emergence of telehealth and ehealth products and services, and of Internetenabled web services infrastructure, many medical devices have become (or soon will become) webenabled and/or part of integrated telecommunicationsenabled healthcare services. Multiple forms of wireless infrastructure have also emerged, and computing capabilities are becoming ubiquitous within environments such as the home (and in hospitals and clinics when HIPAA considerations can be addressed). The emerging vision of universal access has been defined as addressing not only the area of interface accessibility but also access barriers related to distance and cost; interestingly, all three have historic claims to this concept, with different federal agencies involved in implementation (Winters, 2007). There are also other areas of technological convergence, most notably between the traditional consumer electronics and medical device industries for certain classes of home and mobile products, and between the aging of the “baby boomer” generation and the push for better usability engineering for consumer electronics and webbased home products. It is reasonable to assume that consumers will demand more accessible products in the future, and that the risk associated with “old style” interfaces that are less accessible will be problematic if they proliferate.

These trends affect when and how medical devices are used, and indeed the nature of the interface, especially as related to home and mobile use. This in turn has human factors implications. Interfaces for medical products can and should take advantage of an existing, and growing, infrastructure of protocols and processes that relate to, for instance, accessible web design. Telecommunications and webbased capabilities can change the nature of interaction by opening up new alternatives for timely access to healthcare products and services (Winters, 2002), which can have significant effects on medical devices used for diagnosis and therapy. Guidance is needed to help navigate through the maze of possible design solutions to assure that accessible and usable design principles are followed.

Recently revised guidance from the FDA for medical device software makes such software subject to a regulatory premarket review by the FDA if the software impacts any medical diagnosis, therapeutic intervention, lifesupporting or life sustaining functions, or delivery of potentially harmful levels of energy in a way that is considered a major or moderate level of concern to health and safety (FDA, 2005). Telecommunications and information technology that is integrated with (or into) medical devices needs to follow a similar process.

This subsection provides specific guidance on telecommunications and information access design strategies. Whether the interface “solution” is universally designed (suitable for nearly anyone) or personalized (to an individual), the designer of the future will have a greater repertoire of tools with which to address access barriers, which in turn implies new human factors considerations. The guidance that follows builds on the considerable amount of usability analysis and ad hoc guidance that is available for designing web pages,


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consumer products that often include a wireless remote, and teleconferencing systems that are accessible to people with disabilities.

3.4.1 The W3C Web Content Accessibility Guidelines (WCAG) should be satisfied for all webbased medical products.

There has been a trend towards wider use of softwarebased interfaces for medical devices (see also Section on Software). The World Wide Web Consortium (W3C) Web Content Accessibility Guidelines (WCAG) Version 1.0 (W3C, 1999) have been successfully implemented on a broad scale by federal government web pages, including those of Department of Veterans Affairs and those associated with federal health programs such as Medicare; these guidelines should also be fully implemented for all webenabled medical products. Of note is that the W3C is in the final stages of implementing the Web Accessibility Guidelines Version 2 recommendation (W3C, 2006); the reader is encouraged to consult these newest recommendations for guidance. Also of note is the considerable collaborative effort that is underway to have the Version 2 guidelines adopted by governments around the world; thus these guidelines have international applicability. Dr. Judy Brewer, coordinator of the W3CWeb Accessibility Initiative (WAI), envisions innovative possibilities for using the WAI principles for designing future medical devices and interfaces that are both more accessible and usable (Brewer, 2007). While initially developed for web accessibility, the authors of the W3C Web Content Accessibility Guidelines encourage use of the guidelines for making all softwarebased interfaces more usable and accessible.

3.4.2 Existing videoconferencing and multimedia standards should be supported to the greatest extent possible.

Since the International Telecommunications Union (ITU) introduced the H.32x suite of videoconferencing standards in 1996, their impact has been considerable: dramatic reductions in cost have been realized, with considerable improvements in both product usability and quality. These standards address issues such as conferencing protocols, voice and audio codecs (compression algorithms), remote device control, security/encryption, shared whiteboards, support for data channels (including medical device data), and so on. In a parallel development coming from the information technology software community, since the late 1990’s the Internet Engineering Task Force (IETF) has been systematically developing a multimedia infrastructure that builds on the lighter weight Session Initiation Protocol (SIP). Collectively, these standards span both the classic phone line infrastructure (H.320 for moderate and higher bandwidth, H.324 for lower bandwidth videophones) and the packetbased Internet Protocol (IP) infrastructure (H.323, SIP), and apply to video, voice, images and data. Compression algorithms, audio and video protocols, and security continue to improve and get embedded into these standards. The approach toward consensus also helps assure that these protocols provide telecommunications


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information in an accessible format. Additionally, video feeds that include audio that are compliant with common multimedia standards helps to assure lip synching, as well as to accommodate the transfer of video feeds to larger displays.

Often these capabilities can be extended into the home, and a number of phone or webenabled conferencing/multimedia telehealth products are on the market, with digital phones (originally commonly called Voice over IP) now commonplace. Instant messaging “chat” programs also use these standards, usually either H.323 or SIP. Importantly, such multimedia is inherently multimodal, because it transmits audio (voice), video and data. Data includes text exchange (standard instant messaging, which is important for many people with disabilities), shared whiteboards, and shared signals. Standardsbased capabilities include control of zoompantilt of a remote camera, which is often a requirement for Medicare reimbursement of a telehealth encounter.

Designers who use these standards provide the user with multimodal flexibility. As an example, there are many possible strategies for augmenting an existing vital signs monitoring device with videoconferencing capabilities, including ad hoc approaches. This guidance strongly encourages the designer to consider implementation paths that take advantage of and support one or more of the existing circuitbased (H.320, H.324) or Internetbased (H.323, SIP) standards.

3.4.3 Existing consumer electronics and wireless standards should be supported and applied to the greatest extent possible.

Proprietary medical device electronic and information technology capabilities tend to lag about 35 years behind consumer technologies; for instance, many medical devices have been slow to support the USB port, and few, if any, medical device manufacturers are involved in the development of emerging standards such as Universal Plug and Play (UP&P, see http://www.upnp.org), the various World Wide Web Consortium working groups (see http://www.w3.org for various W3C activities), or the various wireless standards. While some of this may be related to regulatory issues, the effect of this is that many medical devices are technologically outdated and are not able to take advantage of the latest accessibility features that tend to be available in current consumer and business products.

In recent years there has been profound improvement in technical protocols and infrastructure for wireless communications, such as provided by the IEEE 802.11x standards (for example WiFi is 802.11b) for local area networks (LANs), the Bluetooth and ZigBee (IEEE 802.15.4) protocols for personal area networks (PANs), cell phone protocols for widearea networks (WANs), and IRDA for infrared lineofsight transmission. All of these are in use for current medical products. Note that these medical products may integrate with, and potentially even use, homebased consumer products such as using a television as a

http://www.upnp.org/

http://www.w3.org/


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monitor (subject to addressing HIPAA considerations and FDA regulatory approval). In contrast, from both an innovation and accessibility perspective, the medicalspecific Wireless Medical Telemetry Service (WMTS) network, where companies write their own proprietary code for connectivity rather than building on the multibillion dollar societal investment in wireless standards, is best avoided. For instance, hospital informatics systems use the consumeroriented wireless LAN (IEEE 802.11x), and therefore have access to better commercial technology for robust signaling and security, and also standardsbased wireless products commonly used by persons with disabilities; ideally, medical devices would as well.

3.4.4 Builtin multimodal capabilities should be recognized and used.

Multimedia technical capabilities continue to improve. For many computer based, inhome and mobile products, a multimodal infrastructure is available that includes intrinsic support for voice, video, text exchange and timebased signals. Additionally, many of the security/confidentiality challenges of the past have been addressed. This can make support for multimodal interfaces that can help address guidance provided in Section 3.1 more readily achievable.

3.4.5 Basic electronic and information technology accessibility requirements should be integrated into medical devices that use homebased technologies.

Although many individuals still lack these devices, homebased infrastructures such as televisions, computers and wireless networks offer ready platforms for providing inhome telehealthcare. For example, if televisions are used as a monitor display, because of Section 508 most television tuners are likely already equipped with secondary audio program caption decoder circuitry which appropriately receives, decodes, and displays closed captions from broadcast, cable, videotape, and DVD signals (Section 508 §1194.24 (b)). Most televisions also come with wireless remote controls that include volume control.

3.4.6 Medical devices with audio interfaces should consider compliance with existing laws related to use of telecommunication products with hearing aids.

The compatibility problems between hearing aids used by persons who are hard of hearing and audiobased technologies such as telephones have been address by Access Board regulations, and solutions are readily achievable. For medical devices with such interfaces, the specific guidance provided in Section 508 under the title Telecommunications Products (1194.23) may be helpful (see http://www.accessboard.gov/sec508/guide/1194.23.htm).

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3.4.7 Modern infrastructure with accessibility capabilities should be used for training and informational materials.

To ensure access, all training, documentation and other informational materials should be accessible in multiple formats. Note that in meeting such a requirement, the designer can take advantage of modern infrastructures for direct access, and also common assistive technology products for indirect access. For instance, the following guidance is based on existing development tools:

3.4.7.1 All training and informational video and multimedia productions, regardless of format, that contain speech or other audio information necessary for the comprehension of the content, should be open or closedcaptioned (based on Section 508 §1194.24 (c)).

3.4.7.2 All training and informational video and multimedia productions, regardless of format, that contain visual information necessary for the comprehension of the content, should be able to be audio described (based on Section 508 §1194.24 (b)).

3.4.7.3 Display or presentation of alternate text presentation or audio descriptions should be userselectable unless permanent (based on Section 508, §1194.24 (e)).

4. Resources

1. Americans with Disabilities Act (ADA, 1990), http://www.usdoj.gov/crt/ada/adahom2.htm.

2. Americans with Disabilities Act Accessibility Guidelines for Buildings and Facilities (ADAAG, 2002), U.S. Architectural and Transportation Barriers Compliance Board (Access Board), as amended through September 2002.

3. Arthritis Foundation (2006), http://www.arthritis.org/resources/gettingstarted/what_is_arthritis.asp, accessed March 30, 2006.

4. Brewer, J. (2007). Access to Medical Instrumentation: The Role of Web Accessibility, in Medical Instrumentation: Accessibility and Usability Considerations (Winters, J.M. and Story, M.F., eds.), Boca Raton: CRC Press.

5. CDC (2001). Prevalence of disabilities and associated health conditions among adultsUnited States, 1999. MMWR, 50: 1205.

6. Center for Universal Design (1997). Principles of Universal Design, v. 2.0., Raleigh: N.C. State University.

7. European Design for All eAccessibility Network (2006). Glossary of Terms. Available online: http://www.education.edean.org.

8. European Institute for Design and Disability (2002). Why Design for All? Available online: http://www.designforall.org/.

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9. FDA (2005), Document 337 , http://www.fda.gov/cdrh/ode/guidance/337.html 10.Gibson, M.J., Freiman, M., Gregory, S., Kassner, E., Kochera, A., Mullen, F., et al.

(2003). Beyond 50 2003: A report to the Nation on Independent Living and Disability, Washington, DC: AARP.

11.Grabois, E. and Young, M.E. (2001). Managed Care Experiences of Persons with Disabilities, Journal of Rehabilitation, 67, 3; 13.

12.Lemke, M.R. (2005). "The Evaluation of Three Alternative Methods for Understanding Biomechanical Aspects of Medical Device Accessibility" (MS Thesis, Marquette University), 104105.

13.Lemke, M.R. and Winters, Jack M. (2007). Comparison of Accessibility Tools for Biomechanical Analysis of Medical Devices: What Experts Think, in Medical Instrumentation: Accessibility and Usability Considerations (Winters, J.M. and Story, M.F., eds), Boca Raton: CRC Press.

14.Mace, R.L., G.J. Hardie, and J.P. Place (1991). Accessible Environments: Toward Universal Design, Center for Accessible Housing: Raleigh, NC. p. 32.

15.Section 508 of the Rehabilitation Act (1998), http://www.access board.gov/sec508/guide/act.htm

16.ShumwayCook, A. & Wollacott, M.H. (2000). Motor Control Theory and Practical Applications. Baltimore: Lippencott Williams and Wilkins. 127160, 497516.

17.Story, M.F. (2007), Applying the Principles of Universal Design to Medical Devices, in Medical Instrumentation: Accessibility and Usability Considerations (Winters, J.M. and Story, M.F., eds), Boca Raton: CRC Press.

18.Story, M.F., Winters, Jill M., Premo, B., Kailes, J.I. Schwier, E. & Winters, Jack M. (2005). Focus Groups on Accessibility of Medical Instrumentation. Proceedings of the RESNA 2005 Annual Conference, Atlanta, GA.

19.Telecommunications Act (1996), http://www.access board.gov/about/laws/telecomm.htm

20.Telecommunications Act Accessibility Guidelines (TAAG), Architectural and Transportation Barriers Compliance Board, Federal Register, 36 CFR Part 1193, RIN 3014AA19, February 3, 1998, available online at: http://trace.wisc.edu/docs/access_board/telfinal.htm

21.U.S. Access Board, http://www.accessboard.gov/telecomm/background.htm. 22.U.S. Census (2000), Economics and Statistics Administration 23.Wilcox, S.B. (2007). Using Ethnographic Research to Develop Inclusive Products, in

Medical Instrumentation: Accessibility and Usability Considerations (Winters, J.M. and Story, M.F., eds), Boca Raton: CRC Press.

24.Winters, Jack M. (2002). TeleRehabilitation Research: Emerging Opportunities, Annual Reviews of Biomedical Engineering, 4:287320.

25.Winters, Jack M. (2007). Future Possibilities for Interface Technologies that Enhance Universal Access to Healthcare Devices and Services, in Medical Instrumentation: Accessibility and Usability Considerations (Winters, J.M. and Story, M.F., eds.), Boca Raton: CRC Press.

26.Winters, Jack M., Rempel, D., Story, M.F., Lemke, M., Barr, A., Campbell, S. and

http://www.access-board.gov/sec508/guide/act.htm

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Danturthi, S. (2007) The Mobile Usability Lab Tool for Accessibility Analysis of Medical Devices: Design Strategy and Use Experiences, in Medical Instrumentation: Accessibility and Usability Considerations (Winters, J.M. and Story, M.F., eds.), Boca Raton: CRC Press.

27.Winters, Jill M., Story, M.F., Barnekow, K., Kailes, J.I., Premo, B., Schweir, E., Danturthi, S. and Winters, Jack M. (2007). Results of a National Survey on Accessibility of Medical Instrumentation for Consumers, in Medical Instrumentation: Accessibility and Usability Considerations (Winters, J.M. and Story, M.F., eds.), Boca Raton: CRC Press.

28.World Wide Web Consortium (1999). Web Content Accessibility Guidelines 1.0, Available online at http://www.w3.org/TR/WAIWEBCONTENT/

29.World Wide Web Consortium (2006). Technical Reports and Publications. Available online at http://www.w3.org/TR.

30.World Wide Web Consortium (2006). W3C Web Consortium Accessibility Guidelines (WCAG) 2.0, Working Draft 27, April 2006. Available online at http://www.w3.org/TR/WCAG20/guidelines.html

31.World Wide Web Consortium (2006). Web Content Accessibility Guidelines 2.0. Available online at http://www.w3.org/TR/WCAG20/.

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Accessibility Considerations for Medical Devices Table of ......usability, performance, and most importantly, safety for all medical device users. Nearly 20% of the population over