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

5.1 Transfer Surface Height Recommendations

Description: The transfer height is set above the finished floor surface to permit transfers form mobility devices onto the transfer surface. This height is also critical for patients who use mobility aids such as walkers and canes and may find it difficult to get up onto or down from an examination chair or table or imaging bed platform, and for facilitating assisted transfers. The height provision is the same for MDE used by patients in supine, prone, or side-lying positions (M301) and patients in seated positions (M302).

NPRM Proposed Provision: M301.2.1 and M302.2.1 Height. The height of the transfer surface during patient transfer shall be 17 inches minimum and 19 inches maximum measured from the floor to the top of the transfer surface.

Advisory M301.2.1 and M302.2.1 Height. The transfer surface position may be outside of the specified height range when not needed to facilitate transfer.

NPRM Preamble Discussion: The technical criteria allow the height of transfer surfaces to be either fixed or adjustable within the 17 inches minimum and 19 inches maximum range. Based on the information discussed below (see NPRM discussion), the Access Board is considering requiring in the final standards that the height of transfer surfaces be adjustable from 17 inches minimum to 25 inches maximum during patient transfer.

5.1.1 Transfer Surface Height Adjustability Recommendation for M301 and M302

The Committee recommends adjustable height in small, virtually continuous increments.

Rationale for final recommendation

The Committee agreed that adjustability greatly increases the overall accessibility of equipment for all persons. Adjustable height MDE, such as exam tables, imaging tables and chairs, will make it possible to position the transfer surface near the height of the seat of the mobility device. For some, independent transfers are only possible when there is minimal or no change in vertical height between the seat of the mobility device and the transfer surface. People may prefer or, in some cases, require, transfer to a slightly lower surface moving the transfer surface lower than the seat of the mobility device; then adjusting the transfer surface to above the seat for the return transfer.

The Committee sought information on the range of seat heights of persons using mobility devices for this recommendation. The research documented a wider range in the seat heights of mobility devices than existed in the past. The Wheeled Mobility Anthropometry Project found a range of occupied seat heights from 16.3 inches to 23.9 inches for manual wheelchair users;16.2 inches to 28.9 inches for power wheelchair users; and 18.8 inches to 25.3 inches for scooter users. In determining these heights, project researchers measured the seat heights from underneath the buttocks at the center of the occupied seats, a spot likely to be lower than the front of the seat where a person transfers.^FF Some Committee members pointed out that this likely made the seat height measurements lower than the actual spot from where a person actually transfers. The adjustability of medical diagnostic equipment will facilitate transfers for all types of patient populations by providing the ability to “pair” the transfer surface of diagnostic equipment at or near the height of the mobility device. People who use wheelchairs, most of which have no adjustability, will directly benefit from medical diagnostic equipment that moves up or down; as will people who use scooters, some of which have height adjustable seats that swivel to assist with alignment for transfers. Persons who are older, have stability/balance issues, and use a walker or cane, will also benefit from adjustability of the equipment when getting on and off the equipment. Industry experts noted that adjustability is readily available in many existing products. Both electronic and manual pump chairs have the ability to stop at any position and are not limited to set points within the range. Thus, the committee adopted a standard of adjustability in small, virtually infinite increments.

Figure 5.1.1 Adjustable Height Medical Table/Chair
(SOURCE: Midmark Corporation)

The Committee recognized that some types of imaging equipment do not allow adjustability with today’s technology. Specific types of imaging equipment, DXA and some x-ray systems, have the imaging hardware below the table underneath the patient. Imaging industry members acknowledged, as new technologies develop, future generations of equipment might find a way to incorporate adjustability. In the meantime, industry proposed creating a System Accessibility Configuration to provide a means to achieve accessibility where equipment’s current design is limited or achieving accessibility is not technically feasible despite best efforts to redesign imaging equipment (see Section 7).

5.1.2 Transfer Surface High Height Recommendations for M301 and M302

The Committee recommends an adjustable height range with an upper height measuring at least 25 inches.

Rationale for final recommendation

The anthropometric data referenced above in the Wheeled Mobility Anthropometry Project shows seat heights for people who use mobility devices are above 19 inches. For manual wheelchair users seats measured up to 23.9 inches; for power wheelchair users up to 28.9 inches; and for scooter users to 25.3 inches. Seat heights for males were typically higher than for females. All the male manual wheelchair users and 92 percent of the male power wheelchair users had seat heights equal to or less than 25 inches. Therefore, transfer surfaces that are adjustable to a 25 inches maximum during patient transfer accommodate most patients who use mobility devices.

Since one key factor in ease of transfer is locating the transfer surface near or at the same height as the seat of the wheeled mobility device, moving the minimum high point for adjustability of transfer surfaces, improves access for many. This particularly benefits persons using powered mobility devices and scooters with higher seat heights.

5.1.3 Transfer Surface Low Height Options for M301 and M302

The Committee did not agree on a final low height recommendation.

Rationale for final recommendation (more detail provided in Section 6)

The Committee was unable to reach consensus regarding the transfer surface low height. The Committee considered various anthropometric data from research, clinicians, and Committee expertise but was never able to agree on a recommendation. The Committee shifted focus from a fixed height range between 17 to 19 inches as adjustability was accepted. Members focused on determining a specific low height absolute measurement.

A portion of the Committee recommended a height range of 17 inches to 25 inches.

A portion of the Committee recommended a height range of 18 inches to 25 inches.

A portion of the Committee recommended a height range of 19 inches to 25 inches.

The Stretcher Subcommittee recommended considerations for the height range of stretchers.

The Imaging Subcommittee recommended deferring this issue to the Table and Chairs Subcommittee.

5.1.4 Transfer Surface Height Measurement for M301 and M302

The Committee recommends capturing the transfer surface height at the highest point of the seat in an uncompressed state, inclusive of bolsters.

Rationale for final recommendation

Having an accessible transfer surface height is critical to facilitate independent patient transfers to equipment used by patients both in a supine, side-lying, or prone and seated position. To determine compliance, it is necessary to have a consistent point of measure. Since many transfer surfaces are not perfectly flat, measuring to the highest point in an uncompressed state provides this consistent point of measure. Identifying the highest point on the transfer surface will assure that all points on the transfer surface comply with the height criteria. This recommendation applies to exam tables and chairs and this measurement may not necessarily be at the centerline of the seat where there are higher points on the seat.

Figure 5.1.4 Illustration of Height Measurement
(SOURCE: Midmark Corporation)