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

5.2.1.1 Transfer Surface Width Recommendations for M301

The Committee recommends a transfer surface of 28 inches minimum width for equipment used by patients in a supine, side-lying, or prone position.

Rationale for final recommendation

The Committee considered the initial proposal of 30 inches and ultimately decided to decrease the width proposal by two inches. Currently, the only equipment existing with a 30-inch transfer surface width is bariatric equipment.

At the Committee’s December 2012 meeting, Dr. Edward Steinfeld, Director of the Center of Inclusive Design and Environmental Access at the University of Buffalo, gave a presentation on the Wheeled Mobility Anthropometry Project (AWM Project).^GG He provided a brief analysis of measurements of the width and depth of seating surfaces for individuals using wheeled mobility devices. This study obtained data from subjects seated in their mobility devices. The results of the AWM Project indicated that a seating surface could have a width of 28 inches and accommodate the 95th percentile of the population of wheeled mobility device users studied.

As part of the deliberations, Committee members examined tables and chairs from various manufacturers during its meetings. The equipment was present and members could sit on, look at, and operate equipment during the meeting and breaks. This allowed members to experience tables that were 28 inches wide along with the other elements of the equipment.

Some supported the 28-inch dimension noting there is little gain in usability by increasing the transfer surface width to 30. The significant gain in numbers of persons able to use the equipment is at the width of 36 inches. The discussion of transfer surface width triggered the decision to set aside the issues of equipment for very large or obese patients. The Committee members expressed concern about the need to assure that persons of larger size receive care but there is incomplete data to determine specific criteria at this time.^HH

In order to have equipment with a wide enough transfer surface to accommodate very large or obese patients, the transfer surface width would need to be at least 36 inches. Since the needs of very large or obese patients are not included in this round of recommendations, the Advisory Committee agreed that either a 28 or 30 inch width would be appropriate. The Committee decided to reduce transfer surface width to 28 inches, with a future determination of equipment dimensions for very large or obese patients.

During the discussion, healthcare providers with experience in assisting patient transfers pointed out that too wide a transfer surface is challenging to smaller sized persons. Making all equipment wide enough for a 36-inch transfer surface would create difficulty for many smaller persons to transfer. For persons needing to reach across the table and pull themselves onto the transfer surface, a wider table becomes a chasm, which will impair the ability of many to grasp the side facilitating transfer. The width measurement is from the center-point of each side of the transfer surface as shown in Figure 5.2.1.1.

Figure 5.2.1.1 Measurement of Depth and Width from Center-Point of Transfer Surface Sides
(SOURCE: Midmark Corporation)

Notes

^GG Analysis of Seat Heights for Wheeled Mobility Devices. The study is available at http://udeworld.com/analysis-of-seat-height-for-wheeled-mobility-devices.

^HH Of note, the committee also decided by consensus that extreme obesity was not within the scope of the committee’s work, but to instead use the data provided by Dr. Steinfeld’s study in determining their recommendation. See section 8.1 of this report for further discussion of extreme obesity, and its recommendation for future topics of research.