Recommendations on Standards for the Design of Medical Diagnostic Equipment for Adults with Disabilities, Advisory Committee Final Report

Medical Diagnostic Equipment Accessibility Standards
Sub-Committee Recommendations
Weight Scales - Final Report
May 31, 2013

The Subcommittee’s technical recommendations for the weight scales have taken into consideration the following technical criteria proposed in Chapter 3, part 1195 to Title 36 of the Code of Federal Regulations. Specifically, section M303, patient positions equipment designed to support seated in a wheelchair.

Abbreviated Chart from Proposed Accessibility Standards for Medical Diagnostics Equipment Appendix to part 1195, Section M303.

 
Equipment Evaluated: Wheelchair weight scales with single ramps, dual ramps, stand-on scales and stow-a-weigh scales.

Types of Scales

Single Ramp Scale (Diagram provided by US Access Board)	Dual Ramp Scale (Picture provided by Scale –Tronix)
Portable Scales (Picture provided by Scale -Tronix)	Wall Mounted or “Stow-A-Weigh” (Picture provided by Scale – Tronix)

Sub-Committee Summary of Scope for Recommendations

Though sometimes avoided, all patients should have their weight taken as it is a basic screening measurement. It is sometimes difficult to take the weight of patients who have mobility or stability issues or for those who use wheeled mobility devices. However, without an accurate and current weight measurement, chances of missing diagnosis or incorrectly prescribing medications increase.

The goal of the sub-committee is to encompass the broadest range of individuals with mobility disabilities including wheeled mobility device users in the following recommendations. All standard size manual wheelchairs, powered wheelchairs, small to mid-range scooters and most bariatric size, extra wide manual chairs can be accommodated as it relates to the platform size recommendations; however, some of the larger roadside scooter models, typically a 4-wheeled base scooter, may not be accommodate by this platform size.

Rationale for including scooters in equipment evaluation: Scooter use is increasing as aging ‘Baby Boomers’ acquire mobility disabilities, etc. In 1994-95, 0.21% of elderly (65+) adults used scooters (64,000 people), according to our analysis of the NHIS-D published in 2000 in "Mobility Device Use in the United States." In 2011, 2.3% of elderly population 65+adults use scooters (about 800,000 people), according to data from the National Health and Aging Trends Study. Trend is more than 10 times as many people in 16 years use scooters.

Compare that to wheelchair usage among the 65+ elderly: 2.9% (900,000 people) in 1994-95, and 6.1% (2.1 million) in 2011. Double the usage.
Percentage of Scooter Users:
(Chart from NHIS-D published in 2000 in “Mobility devices Use in the United Sates”)

1 NHIS-D published in 2000 in "Mobility Devise Use in the United States"

2 National Health and Aging Trands Study

It is also acknowledged that not all scooter users can easily transfer from their scooters; transfers for scooter users may be just as difficult as those who are wheelchair users. Having an accessible weigh scale that can accommodate a wide range of patient populations and mobility devices is optimal as it saves the patient from having to transfer just to have their weight taken.

Rationale for including alternative equipment for taking weight: The Sub-committee acknowledges alternative types of equipment that have integrated scales to be an effective means of taking a patients weight. Alternative equipment with integrated scales can eliminate the need for unnecessary patient transfers to a weight scale just to capture a patient’s weight. For example, if a patient transfers onto an examination table that has an integrated scale, the healthcare provider can also capture the patient’s weight once the patient has made this single transfer. Such types of equipment with integrated scales may include; examination tables, stretchers, portable lifts and overhead ceiling lifts. The medical diagnostic equipment accessibility standards also apply to the alternative equipment for taking weight for each function if they include an integrated scale for the patient position it supports; prone, sitting, standing, seated in a wheelchair.

Proposed Recommendations and Sub-Committee Recommendations

M303.2.3 Wheelchair Spaces / Depth of Wheelchair Spaces for front or Rear Entry

• Sub-Committee Recommendation: The Sub-committee and Full Committee have decided not to act on the proposed recommendation by the Notice of Proposed Rulemaking (NPRM) and retain the proposed provision as is. Based on recent anthropometric data, NPRM proposes to increase minimum depth dimension from 48 to 58 inches – majority of members have no opinion or anticipation of a situation where requirement is needed.

Exceptions Considered for Wheelchair Spaces on Raised Platforms

M303.2.2 Proposed Exception: The exception to the minimum width in M303.2.2 would apply where ramped surfaces are provided on the opposite sides of the raised platform so that patients using wheelchairs can enter and exit the platform facing the same direction. The exception would permit the width of the wheelchair space between the edge protection to be reduced to 32 inches wide minimum at the platform level. This dimension is based on provisions in the 2004 ADA and ABA Accessibility Guidelines that allow accessible routes, which normally must be 36 inches wide minimum, to be 32 inches wide minimum for short distances such as at door openings. The exception would require a space 36 inches wide minimum to be provided outside the perimeter of the raised platform and above any edge protection so that patients using a manual wheelchair can extend their arms and elbows when they push on the wheel rims to maneuver onto and off of the platforms.

M303.2.3 Proposed Exception: The exception to the minimum depth in M303.2.3 for wheelchair spaces entered from the front or rear would permit a portion of the 48 inch minimum depth of the wheelchair space that accommodates the wheelchair footrests to extend beyond the raised platform and over any edge protection. For example, the wheelchair footrests would be allowed to extend beyond the depth of the raised platform and over any edge protection on wheelchair weight scales used by patients seated in a wheelchair.

• Sub-Committee Recommendation: Platform size shall be clear width of 32 inches minimum and clear length of 40 inches minimum.

(Figure 1 –Clear Platform showing the measurements of 32” wide x 40” inches length

Rationale: Clear platform size of 32 inchesminimum width x 40 inches minimum length accommodates non-powered and powered wheeled mobility devices including scooters; small and mid-size scooters. May not accommodate some larger roadside scooters with 4-wheeled based. This platform dimension is consistent with the recommendations of the IDeA Center Study recommendations for a minimum flat surface of 40 inches length for platforms accommodating wheeled mobility devices including scooters. This size platform allows for maneuverability on the platform for positioning and takes into consideration the operations of the wheelchair / scooter user to not always have the ability to stop precisely in the middle of the platform.

To have an accurate weight the wheelbase* 4 wheels and 3 wheels for some scooters must be on the platform (and make contact). The foot pedals, footrests, scooter deck and tip wheels can overhang or extend beyond the platform and still get an accurate weight.

*The IDeA Center Study defines wheelchair wheelbase as the distance from the center of the primary drive wheel to the center of the caster measured parallel to the floor.

*The IDeA Center Study defines scooter wheelbase as the distance from the center of the primary drive wheels to the center of the back or front wheels measured parallel to the floor.

*The IDeA Center Study findings indicate that a 36 inch length accommodates standard manual and motorized wheelchairs and most, if not all, bariatric size- extra wide manual chairs

IDeA Center Study at the University of Buffalo, New York): Summary analysis of wheelbase measurements on wheeled mobility devices

[Click image above to view HTML version]

IDeA Center (Buffalo Study) Recommendations for Platform Length:

• a minimum flat surface of 40 in. length for platforms accommodating wheeled mobility devices including scooters
• a minimum flat surface of 33 in. length for platforms accommodating wheeled mobility devices excluding scooters

Ramps M303:3.3, 3.3.1, 3.3.2

M303.3 Proposed Provision: Changes in Level at Entry to Wheelchair Spaces includes technical criteria for changes in level at the entry to a wheelchair space as may occur at wheelchair weight scales with raised platforms. The technical criteria are consistent with the 2004 ADA and ABA Accessibility Guidelines. Level changes up to ¼ inch high are permitted to be vertical. Level changes between ¼ inch high and ½ inch high would be required to be beveled with a slope not steeper than 1:2. Level changes greater than ½ inch high would be required to be ramped. Ramp runs would be required to have a running slope not steeper than 1:12 and a cross slope not steeper than 1:48. The clear width of ramp runs would be required to be 36 inches minimum. Ramps with drop offs ½ inch or greater would be required to provide edge protection 2 inches high minimum on each side to prevent users from inadvertently travelling off the sides of the ramped surface.

• Sub-Committee Recommendation: Steepest Slope permitted to be:

• Rise 0 to 1 ½ inches – 1:2 Slope
• Rise >1 ½ to 2 ½ inches – 1:8* Slope
• Rise >2 ½ inches – 1:12 Slope

Rationale: Based on Weight Scales Subcommittee recommendation with full Committee’s input and partly the 2004 ADA and ABA Accessibility Guidelines. *The rise of >1 ½ to 2 ½ inches - 1:8 slope is from section 405.2 Maximum Ramp Slope and Rise for Existing Sites, Buildings, and Facilities - [A steeper ramp for a limited rise is allowable].

A ramp, using a 1:2 slope, will allow for short rise ramps found on stow-a-weigh scales. Space constraints are of consideration in this recommendation, as medical equipment and adequate space in the acute care or in the medical office setting are often competing. Scales that can be wall mounted or that are portable would facilitate where there are space constraints. Patients are always supervised and assisted by a healthcare provider when taking weight.

Current weight cell load technology that exists, allows for a low platform profile between ¾” to 1½”. As the height of the platform decreases, the length of the ramp can also decrease. The trend for the industry is towards lower weight cell technology development; however, this existing low weight cell profile may represent the limits of technology.

• Sub-Committee Recommendation: Edge Protection

o Single ramp scales: 2 inch edge protection absolute is required opposite the entry ramp on the platform as a safety feature to prevent wheeled mobility device drivers from over-shooting the platform as not all devices stop immediately when braking.

o A 2 inch maximum height is recommended so the edge protection does not obstruct the footrest from hanging over.

o Edge protection is required for either side of the platform (front edge and rear edge) and ramp. This is an additional safety recommendation.

 Single and dual ramp scales: 2 inches minimum required on both sides (front edge and rear edge) of platform
 Single and dual ramp scales: 2 inches minimum required on both sides of entry ramps
 Not required where platform is ≤ 1½ inches

Rationale: Edge protection provides additional safety features so user of wheeled mobility devices do not inadvertently drivel off ramp and/or platform.

Single Ramp Scale with 2” Edge Protection

Opposite the ramp entry and on both sides of the platform and ramp

Figure 2: Picture of single ramp scale showing the 2” edge protection at the opposite side of the platform and showing the 2” minimum edge protection on both sides of the ramp and platform

Dual Ramp Scale with 2” Edge Protection

On both sides of the platform and ramp

Figure 3: Picture of a dual ramp scale showing the edge protection on both sides of the platform and ramp

Standing Supports (M304.3 and M305.3)

M304.3 Proposed Provision: Would require standing supports to be provided on each side of the standing surface on diagnostic equipment used by patients in a standing position. M305.3 would require the standing supports to provide continuous support throughout the use of the diagnostic equipment and to not rotate within their fittings.

M305.3 Proposed Provision: Also provides technical criteria for standing supports in horizontal and vertical positions. Standing supports can be provided in a horizontal position, vertical position, or a combination of horizontal and vertical positions, as long as the minimum length of gripping surface is provided for the support position used on each side of the standing surface. Standing supports that adjust from horizontal to vertical positions and at angles in between, such as a bar that folds up and locks into multiple positions, can be used. These kinds of adjustable supports are not required but would accommodate a broad range of patients with disabilities, particularly where a patient needs to assume multiple body positions for a diagnostic procedure or needs to step up onto a surface and then maintain balance afterwards.

• Sub-Committee Recommendation: Standing Supports – Location
• (scales serving both wheelchair and standing users).

o 1 side of platform for dual ramp entry of platform
o 2 sides of platform for single ramp entry with 34” minimum width between standing supports
o The standing supports need to be tied in to the weighing platform for weight accuracy.

Rationale: Standing supports required on one side of dual ramp has relevance for users being able to access either side for entry – user may only have one usable side due to condition such as a stroke, or right or left side paralysis or weakness etc.

Standing supports required on both sides for single ramp entry to assist user to gain access to weight platform.

A 34” minimum width between the supports allows for adequate elbow space to push wheels onto platform and does not infringe on the 32” platform.

Standing Supports (scales serving both wheelchair and standing users)

• Sub-Committee Recommendation: Standing Supports - Length

The length of the standing supports to be 32” minimum for single ramp scale and 40” minimum for dual ramp scale.

o Single Entry Ramp - On both sides of single entry platform for a length of 32 inches minimum starting at platform entry edge.

o Dual Entry Ramp – On one side of dual entry platform for a length of 40 inches minimum.

Rationale: Having standing supports for 80%, or 32 inches minimum length at the platform entry edge on the single entry ramp allows for enough coverage in length to assist the patient for stability to grab on both sides, to gain access to the platform for this one way entry and exit. Standing supports on the dual entry ramp, allows for the full length of the platform to have a standing support available on one side for the patient to provide stability when entering onto the platform and exiting off the platform - a user may select which side of the platform to enter given the limitation of having one strong side due to conditions such as stroke or right or left side paralysis or weakness etc.

Standing Supports - Single Ramp Scale

Figure 4: picture of standing supports on both sides of a single entry ramp scale showing the 80% coverage (or 32” length) starting at the platform edge and the 34” minimum space between supports

Standing supports – Dual Ramp Scale

Figure 5: picture of standing supports on one side of a dual ramp scale of the platform length of 40” minimum

References:

NHIS-D published in 2000 in "Mobility Device Use in the United States."

IDeA Center (Buffalo Study) wheelbase measurements on wheeled mobility devices