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

RECOMMENDED CHANGE

Revise the Section 5.4.11 recommendation as follows:

The Committee recommends transfer supports and connections contain the strength to resist vertical forces of 250 pounds and horizontal forces of 125 pounds at locations determined by the intended use of the equipment.

Rational for the change:

1. ANSI/BIFMA X5.1-2011 is widely recognized and used in the furniture industry. It specifies loading as percentage of patient weight (50% vertical and 25% horizontal). So for example, an examination table rated to support a 500 pound patient would be required to hold a weight of 250 pounds vertically, and 125 pounds horizontally.

2. ANSI/AAMI ES60601-1:2005, which is the safety standard most commonly used by medical devices, requires a similar instability test in section 9.4.2.3:

ME EQUIPMENT having a mass of 25 kg or more, other than FIXED ME EQUIPMENT that is intended to be used on the floor, shall not overbalance due to pushing, leaning, resting, etc. […]

The ME EQUIPMENT is placed on a horizontal plane and a force equal to 25 % of its weight, but not more than 220 N, is applied in any direction, except a direction having an upward component. […]

If the ME EQUIPMENT overbalances, it constitutes a failure.

Note that 220 N is equivalent to 49.5 pounds of force, significantly lower than BIFMA requirements.

3. Midmark has marketed a chair arm accessory for its examination tables for over 10 years that meets a load rating of 250 pounds vertically and 125 pounds horizontally. One of the intended uses of this chair arm is to assist with patient transfer (see image below). This chair arm has proven to be robust and reliable.

4. A horizontal force of 250 pounds is unrealistic. This far exceeds the force that a person can generate in the horizontal direction under any realistic transfer scenario (see figure below). Also, because MDE is not typically anchored to the floor, it is likely that the MDE would slide across the floor before a 250 pound force could be applied.

Source: FAA Human Factors Design Standard, Chapter 14
http://www.hf.faa.gov/docs/508/docs/hfdg/ch14.doc