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

19 Inch Low Height

Although the subcommittee’s conversations were complex and far-reaching, the following points summarize the factors that lead to the selection of the 19 inch height recommendation:

• Ensures that such equipment is accessible to, and usable by, individuals with accessibility needs and will allow independent entry to, use of, and exit from the equipment by those individuals

• Carefully balances the costs to hospitals, physicians, and other health care providers of replacing or modifying existing equipment together with manufacturer costs of redesigning equipment

• Provides for the least cost to health care system of any option considered by the subcommittee

• Results in the most rapid rate of adoption of accessible equipment by health care providers and the benefits of that equipment to individuals with accessibility needs, particularly those who use wheeled mobility devices.

The memorandum explains why a requirement for a 19 inch lower adjustable height for tables and chairs is the most appropriate standard for the initial implementation of section 4203 of the Patient Protection and Affordable Care Act.

Current Situation: the Vast Majority of Examination and Procedure Tables are 32 Inches High

In the United States, approximately 82 percent⁵ of physicians, hospitals and other health care providers use examination and procedures tables with a 32-inch fixed height, as shown in Figure 1. Industry commonly refers to these tables as "box tables.” These tables provide an often-insurmountable barrier to health care for people with accessibility needs. Since 2001, the number of adjustable-height tables has steadily increased, but continue to represent a minority of examination tables in the United States.

Figure 1: Percentage of fixed height versus adjustable height medical tables

One of the primary objectives of the U.S. Access Board’s requirements should be to accelerate the growing trend of heath care providers to purchase adjustable height tables, which will reduce the number of fixed, 32 inch high inaccessible tables.

Figure 2: Illustration of the height difference between a fixed height and adjustable height medical table

Implications of a 19 Inch Minimum Standard for the Highest Point in the Lowest Adjustable Position

This memorandum presents the factors that support a minimum standard of 19 inches as the highest point on the transfer surface in a table or chair’s lowest adjustable position. However, shorthand references to 19 inches as the minimum standard as used in this memorandum should not be equated with a 19-inch transfer surface height, for two major reasons. First, as depicted in Figure 3, adjustable tables currently on the market generally feature contoured bolsters that provide greater security once an individual is seated or lying on the table or chair. A 19-inch standard means that any bolsters fit within the highest point standard, thereby making the front edge of the table/chair lower than the bolsters (by about ¾” based on currently marketed bolsters, or about 18 inches compressed at the transfer surface).

Second, as a minimum standard, establishing a 19-inch highest point standard does not mean that all newly manufactured tables and chairs will necessarily be fixed at a 19-inch height. Unlike fixed transfer surfaces such as toilets or non-adjustable tables, there is no reason to standardize at a single height based on broadest usability. In a marketplace of adjustable tables and chairs, increased range of adjustability will be advantageous to patients and caregivers alike. It is not unreasonable to expect that table and chair manufacturers will seek to compete by offering products with greater degrees of adjustability.

Figure 3. Illustration of measurement height at bolsters relative to lower transfer surface

Alignment of 19 Inch Recommendation with Access Board Proposed Rulemaking

The subcommittee’s recommendation of a lower adjustable height of 19 inches maximum is consistent with the U.S. Access Board’s proposed rule and supported by public comments. In its proposed rule, the Access Board proposed that the “height of the transfer surface during patient transfer shall be 17 inches (430 mm) minimum and 19 inches (485 mm) maximum measured from the floor to the top of the transfer surface” for both examination tables and chairs.⁶ The Access Board based its proposal, “on provisions in the 2004 ADA and ABA Accessibility Guidelines for architectural features that involve transfers (e.g., toilet seats, shower seats, dressing benches).”⁷ In addition, the Access Board recommended, “Where patient support surfaces are contoured or upholstered for patient comfort or to support patient positioning during diagnostic procedures, the height of the transfer surface measured from the floor may vary across the transfer surface. The highest and lowest points of the transfer surface on such equipment would have to be within the specified dimensions.”⁸ The Access Board proposed that the measurement should be taken from the “floor to the top of the upholstery under static conditions, without compression or deflection in the transfer surface ….”⁹ 

The Access Board’s proposal also explained that it 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. In support of the alternative proposal, it cites ANSI/AAMI HE75¹⁰ and the Wheeled Mobility Anthropometry Project.¹¹ The results of this study recommended adjustable heights, with an increased maximum height above 19 inches, be provided in order to better accommodate users of powered wheelchairs and scooters. During the committee hearings, the manufacturers accepted that this would be appropriate and offered 19-inch to 25-inch adjustable height through powered tables.

The subcommittee’s recommendation appropriately balances the two proposed alternatives included in the Access Board’s proposed rule. Therefore, the Access Board should adopt the subcommittee’s recommendation provider for continuous adjustability of the height of the transfer surface between 19 and 25 inches.

A Minimum Highest Point standard of 19 Inches is Consistent with Existing Accessibility standards

Current accessibility standards and regulations generally consider a transfer surface height of 19 inches accessible. For example:

Nineteen-inch pool lift seats are accessible:

1009.2.4 Seat Height. The height of the lift seat shall be designed to allow a stop at 16 inches (405 mm) minimum to 19 inches (485 mm) maximum measured from the deck to the top of the seat surface when in the raised (load) position.

Nineteen-inch water closet and toilet seats are accessible:

604.4 Height. The height of water closet seats shall be 17 inches (430 mm) minimum and 19 inches (485 mm) maximum above the floor, measured to the top of the seat. Seats shall not be sprung to return to a lifted position.¹²

Likewise, 19 inch high benches are accessible:

903.5 Height. The top of the bench seat shall be 17 inches (430 mm) minimum and 19 inches (485 mm) maximum above the floor, measured to the top of the seat.¹³ 

Nineteen-inch high bathtub seats are accessible:

610.2 Bathtub Seats. The height of bathtub seats shall be 17 inches (430 mm) minimum and 19 inches (485 mm) maximum above the bathroom floor, measured to the top of the seat. Removable in-tub seats shall be 15 inches (380 mm) minimum and 16 inches (405 mm) maximum in depth. Removable in-tub seats shall be capable of secure placement. Permanent seats shall be 15 inches (380 mm) minimum in depth and shall extend from the back wall to or beyond the outer edge of the bathtub. Permanent seats shall be positioned at the head end of the bathtub.¹⁴ 

Nineteen-inch high shower compartment seats are accessible:

610.3 Shower Compartment Seats. The height of shower compartment seats shall be 17 inches (430 mm) minimum and 19 inches (485 mm) maximum above the bathroom floor, measured to the top of the seat. In transfer-type and alternate roll-in-type showers, the seat shall extend along the seat wall to a point within 3 inches (75 mm) of the compartment entry. In standard roll-in-type showers, the seat shall extend from the control wall to a point within 3 inches (75 mm) of the compartment entry. Seats shall comply with Section 610.3.1 or 610.3.2.¹⁵ 

Nineteen-inch high amusement park rides are accessible:

1102.5.2 Transfer Height. The height of amusement ride seats designed for transfer shall be 14 inches (355 mm) minimum and 24 inches (610 mm) maximum measured from the surface of the load and unload area.¹⁶ 

As mentioned above, a minimum standard of 19 inches at the highest point of a table or chair is not the same thing as the transfer surface height experienced by patients because the front edge of currently available tables is lower than the highest measured point. However, the fact that a nineteen-inch height is so widely accepted by existing accessibility standards for various types of benches and chairs strongly commends maintaining the standard for medical diagnostic equipment as the minimum standard for accessible examination tables and chairs. This is particularly the case because of the manner in which medical diagnostic equipment is used. Unlike toilets, bench seats, and bathtub seats, where usability may require constant contact of one’s feet with the floor for stability or require free use of one’s hands, in most cases medical examination tables and chairs will be raised substantially off of the floor to accommodate caregiver access to patients. Additional requirements of the proposed standards for arm supports provide additional security once an individual has made a successful transfer.

An Increasing Number of Health Care Providers are Transitioning to Adjustable Height Tables

In 2012, approximately 25 percent of examination tables sold in the U.S. are at about a 19-inch low height.¹⁷ This is a significant increase over the 17 percent of adjustable height tables sold in 2005. While manufacturers of tables and chairs understand that lower heights may be desirable, no manufacturer has been able to design and produce an examination table or chair that can reach a height lower than 19 inches uncompressed at the highest point on the table or chair. It is unclear when such a table or chair could be available.

If adopted by the Access Board, a recommendation of 19-inch maximum height will build on the growing percentage of providers voluntarily purchasing accessible, adjustable height tables, at 25 percent today.¹⁸ Conversely, if a new standard lower than 19 inches is established, thereby deeming all current adjustable tables inaccessible, the entire U.S. health system will be forced to begin at 0 percent accessible.

Figure 4: Sales percentages of fixed height versus manual medical tables

Available Data do not Support Departing from the Currently Accepted Standard of 19 Inch Transfer Surface Height

The Medical Diagnostic Equipment Technical Advisory Committee appropriately tried to determine what the optimal accessible transfer surface height is based on available data. In particular, the Advisory Committee spent a great deal of time discussing the Wheeled Mobility Anthropometry Project.¹⁹ In that study, which the U.S. Access Board commissioned, Dr. Steinfeld served as the lead investigator. The Wheeled Mobility Anthropometry project did not study optimal transfer surface heights or the ability of wheeled mobility device users to transfer independently from their mobility device onto an examination table or chair. Instead, the study measured the physical characteristics of people who use wheeled mobility devices and some of the characteristics of those devices.

In evaluating data about seat height, we must be sure to take into account the relevant transfer height from the wheelchair. Dr. Steinfeld’s study measured the rear compressed seat height of the wheeled mobility device with the user seated in it. For transfer purposes, however, the most relevant height is the wheelchair front edge. Unfortunately, Dr. Steinfeld did not measure the height of those same users' front wheelchair edges.

There is a recognized international standard defining various measurements of wheelchairs: ISO 7176-7:1998 Wheelchairs — Part 7: Measurement of seating and wheel dimensions. Figures 6 and 7 below are selected screenshots from this international standard. These illustrations identify several key measurements. The most important illustrations for present purposes are "seat plane angle," "effective seat depth," and "seat surface height at the front edge." The standard focuses on measurement procedure so it does not prove any actual measurements. However, as the images below make clear, the seat reference plane and effective seat depth will dictate the difference between the seat surface height at the front edge and the height of the seat at the rear of the wheelchair. Note further that wheelchair height measurements generally do not take into account the height of the cushion, which the consumer will need to clear at the front edge to enable a successful transfer.

In addition, section 4 of the Paralyzed Veterans of America’s Guide to Wheelchair Selection²⁰ also illustrates the distinction between the following heights:

…the seat surface height at the front edge (which excludes the effect of a seat cushion, typically measuring 2-4" in depth), the seat height at the rear of the seated surface, and the relevant transfer surface height for clearing the seat cushion.²¹

Therefore, the U.S. Access Board should not infer the seat surface height at the front edge is the same as the seat height measured in Dr. Steinfeld’s study. However, these illustrations used in measuring individuals for manual wheelchairs indicate that the U.S. Access Board cannot use the Steinfeld data to make a direct assessment of the table height needed to accommodate wheelchair users effectively.

Based on figures 5-7 below, a 17-inch rear compressed height measured by Steinfeld could easily correspond with a 20- or 21-inch uncompressed seat surface height at the front edge. This could in turn mean that individual users that Steinfeld measured below 19 inches would be able to transfer comfortably to a table surface for which the highest uncompressed surface is 19 inches.

Note further in figure 5 that the rear seat height is considerably lower than the height of the wheelchair wheels, which typically measure 22-26 inches. Any transfer from the rear of the chair would require the user to transfer up and over the wheelchair wheel, again, well above a minimum low-range height of 19 inches.

In addition, a second study commissioned by the U.S. Access Board and evaluated by the Advisory Committee (the Pittsburgh study²²) determined that manual wheelchair-users, who are generally the users most likely to have the lowest seated heights, are generally able to accommodate a 2-inch difference in height between one’s wheelchair and a transfer surface. Consequently, even if one posited that the Steinfeld study finding of 17 inches at the rear of the seat compressed corresponded to an uncompressed height of 17 inches at the front edge of the wheelchair, the maximum height of 19 inches at the highest point of a table or chair transfer surface would still fall within the 2-inch differential identified by the Pittsburgh study as accessible to most manual wheelchair users.

Figure 5: Adapted diagram from the “Paralyzed Veterans of America’s Guide to Wheelchair Selection” showing difference in measured height between Steinfeld report, wheelchair manufacturer’s height per ISO 7176-7, and the uncompressed upholstery measurement height.

Figure 6: Wheelchair manufacturer’s height and seat construction types (showing variation in compression when person’s weight is applied) per ISO 7176-7

Figure 7: Wheelchair manufacture standardized measurements per ISO 7176-7

Chairs with/without Footrests:

With a 17” transfer height, chairs with footrests, which the patient rests their feet on, such as those used in Otolaryngology, Ophthalmology, Plastic Surgery and others would not be comfortable to sit in for a large number of patients. Domestic UL and international IEC standards dictate a 2” clearance from the floor to the bottom of the footrest. And, with a minimal 1” thick footrest plate, the distance from the top of footrest to the top of the seat would be just 14”. Anthropometric data suggest the heel to popliteal dimension, without shoes, of males is 17.5” and that of females is 15.9” in the 50th percentile. Contact with the back of the thigh and/or the rear of the knee with the top front portion of the seat is vital for patient comfort and is especially important for maintenance of knee and thigh position of a disabled person who may lack control of his/her legs.

Chairs with no footrest plate and only a breaking knee legrest have similar problems with a short legrest portion also. Patient comfort in the entry/exit position can be compromised even after the chair is raised and the back lowered because of the length of the chair top in the supine position. Even with the addition of a flip-up or slide out footrest/legrest extension, the total length of the average knee break chair is estimated to be 60“, and only be able to be a maximum of approximately 68” with extension. We estimate the addition of a manual extension of the footrest could add as much as $750 (15%). An electrical or automatic extension could be a $1300 (26%) addition to the net cost of either a chair with a footrest plate or to one without the plate, which only extends the legrest or calf portion. These chairs would have to have an electrical interlock installed in them to protect the chair and patient from the chair being lowered with the legrest extended. These kinds of additional adjustments and added protection controls tend to discourage the operator from using them and thus the patients could instead be forced to endure a medical procedure in uncomfortable positions.

Adoption of a 19 Inch Height Minimizes Costs to Health Care Providers

In the absence of clear data commending a departure from the existing broadly accepted transfer surface height maximum of 19 inches, information related to costs is especially critical to take into account in determining the minimum standard for medical examination tables and chairs. We estimated the costs of various examination table heights under consideration by the Medical Diagnostic Equipment Technical Advisory Committee using third-party data that represents approximately 80 percent of all distributed examination tables sold in the United States.²³ 

To determine the total number of examination rooms in the United States, we reviewed the CDC National Ambulatory Care Survey, and found that there are approximately 639,000 exam rooms in the United States today.

From this total number, and based on historic trends, we estimate that physicians will build new, or remodel existing, exam rooms at a rate of 4 percent each year, but the total number of examination rooms will remain unchanged from year to year.

Also based on historic trends, we estimate that physicians will replace equipment in 7 percent of their examination rooms each year, including new and replacement medical tables. We also estimate that the average annual inflation rate will be 3% over the next ten years.

Benefits and Costs: Overview

Based on our analysis, we determined that transfer surface height requirements lower than 19 inches would increase the cost of designing and manufacturing examination tables, reduce the rate of adoption of accessible equipment, and increase the health provider’s cost of purchasing accessible equipment.

While we estimate that adopting a lower-range requirement of 19 inches, health care providers will experience a 24 percent price increase. This means that a $5,000 adjustable-height examination table purchased today would cost approximately $6,200 after the Access Board adopts the requirements for knee-crutches and transfer supports because health care providers will need to retrofit existing tables and chairs with the required equipment. The price of that same table would be 39 percent higher than the cost of today’s examination tables if the height standard were lower than 19 inches.

Cost of Equipment

Costs to Lower Minimum Table Height

To be useful for its intended purpose, examination tables and chairs must maintain a high height of at least 32 inches, so that the health care provider has clinical access to the patient. In fact, 37 inches is the standard high height today for OB/GYN examinations. The need to reach heights above 32 inches interferes with efforts to lower the transfer surface height. The mechanical system necessary to raise the table are located in the base of the table, beneath the seating surface. As the difference between the required low-height and the necessary high-height for health care providers’ increases, the mechanics necessary to achieve that adjustable range become more complex and expensive.

Figure 8: Range of medical table heights

In addition, we took the costs of other requirements that the Access Board is likely to adopt into account. Based on currently marketed products, we estimate the following costs:

• Transfer Supports (TS): $500 - $1,000 (M301.3.1)

• Leg Supports (LS): $700 - $1,100 (M301.3.2)

Therefore, the average “upgrade” cost to add transfer and leg supports would be approximately $1,650.

Scoping Scenarios: Range of Possibilities

We do not know what mandates may be put in place in the future to require Access Board standards. However, the U.S. Access Board’s decisions regarding technical requirements for equipment will significantly affect the costs on health care providers and examination table and chair manufacturers.

To illustrate this effect, we considered a broad range of scenarios. For example, if a national mandate were to require one accessible table per physician work area of five exam rooms (a typical physician practice set-up today), that would require a 20 percent adoption rate. We also considered a 100 percent adoption rate to show the full range of potential costs.

If the market adoption rate of adjustable tables were to match a requirement that one table of every five tables meet a 19 inch lower adjustable range when facility construction occurs, there would be a drop in patient access to compliant examination tables of 17% and a savings of $420 million over ten years. However, if the market adoption rate were to match a requirement that ALL new tables meet a 19-inch lower adjustable range when new construction or remodeling occurs, then accessibility would increase by 17% at a cost to health care providers of $1.38 billion over a ten-year period.

By contrast, if the market adoption rate matched a requirement to make one table of every five tables meet an adjustable range lower than 19 inches, there would be a reduction in availability of accessible tables by 35% for a savings of $530 million over ten years. However, if the requirement were to make ALL new tables meet an adjustable range lower than 19 inches when new construction or remodeling occurs, then accessibility would decrease by 1% at a cost to health care providers of $1.52 billion over a ten-year period.

The table and chart below illustrate these examples.

Table 2: Costs of Scoping Scenarios

Figure 9: Summary of cost and implementation scenarios of Table 2

Therefore, while establishing these requirements will result in significant costs to health care providers, establishing a lower adjustable height requirement of 19 inches will maximize the percentage of accessible tables and will cost less than requiring an adjustable height lower than 19 inches.

 

Notes 

^5. Medical table install base derived from U.S. medical distribution sales data, as provided by Global Healthcare Exchange (GHX), found at http://www.ghx.com/product-pages/solutions/supplier-solutions/sales-data-analytics.aspx

^6. See M301.2.1 and M302.2.1.

^7. See Architectural and Transportation Barriers Compliance Board. Notice of Proposed Rulemaking: Proposed Accessibility Standards for Medical Diagnostic Equipment. February 8, 2012.

^8. Ibid.

^9. Ibid.

^10. Ibid, citing ANSI/AAMI HE 75, section 16.4.4. ANSI/AAMI HE75 recommends that the height of patient support surfaces "should be easy to adjust (ideally, powered) to suit the needs of health care professionals and patients." ANSI/AAMI HE75 further recommends that the height of patient support surfaces "should be adjustable to a position high enough to accommodate tall health care providers and the range of medical procedures that could occur . . . [and] to a position low enough [19 inches maximum] to allow for the comfort of providers who choose to work in a seated position, to enable patients to keep their feet on the floor while seated, and to accommodate patients who need to transfer laterally between the platform and a chair or wheelchair alongside."

^11. See Analysis of Seat Heights for Wheeled Mobility Devices at: http://udeworld.com/analysis-of-seat-height-for-wheeled-mobility-devices. The seat heights ranged 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. Seat heights for males were typically higher than for females. Thirty (30) percent of male manual wheelchair users and 6 percent of male power wheelchair users had seat heights equal to or less than 19 inches. 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. Thus, transfer surfaces that are adjustable from 17 inches minimum to 25 inches maximum during patient transfer accommodate significantly more patients who use mobility devices.

^12. See Accessible and Usable Buildings and Facilities, ICC/ANSI A117.1-2009.

^13. Ibid.

^14. Ibid.

^15. Ibid.

^16. Ibid.

^17. Medical table install base derived from U.S. medical distribution sales data, as provided by Global Healthcare Exchange (GHX).

^18. Some tables may require installation of a modified top to meet the 19” standard but would not require changing out the installed base.

^19. See Analysis of Seat Heights for Wheeled Mobility Devices at: http://udeworld.com/analysis-of-seat-height-for-wheeled-mobility-devices. The seat heights ranged 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. Seat heights for males were typically higher than for females. Thirty (30) percent of male manual wheelchair users and 6 percent of male power wheelchair users had seat heights equal to or less than 19 inches. 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. Thus, transfer surfaces that are adjustable from 17 inches minimum to 25 inches maximum during patient transfer accommodate significantly more patients who use mobility devices.

^20. Available at http://www.wheelchairnet.org/WCN_ProdServ/Docs/PDF/AXbook_Sec4a.pdf

^21. Ibid.

^22. Human Engineering Research Laboratories, University of Pittsburgh, The Impact of Transfer Set-Up on the Performance of Independent Transfers: Final Report. Available at: http://herl.pitt.edu/ab/transfer_assessment_report.pdf (visited May 22, 2013).

^23. Medical table install base derived from U.S. medical distribution sales data, as provided by Global Healthcare Exchange (GHX), found at http://www.ghx.com/product-pages/solutions/supplier-solutions/sales-data-analytics.aspx