Putting Powerchairs to the Test

The Hows & Whys of Power Chair Testing…& Why Results Should Matter to You

You’ve probably fielded the question before from payors or consumers, or maybe you’ve heard it second-hand via the occasional, not-very-well-informed newspaper article:

“Why do power wheelchairs cost so much?”

Of course, many factors contribute to the cost of a power chair, including complex electronics, positioning features, durable high-tech materials used in manufacturing and the need to customize some chairs to meet a client’s very specific medical needs.

But another significant power chair cost — in terms of dollars, engineering resources and time needed to bring a product to market — are the many performance and safety tests a chair must undergo and pass before a consumer, clinician or supplier ever gets to take it for a drive. Testing is largely a behind-the-scenes and highly proprietary process, but several power chair manufacturers agreed to share some of their details with Mobility Management.

What the FDA Requires

Wheelchairs are considered medical devices and are therefore regulated by the U.S. Food & Drug Administration, says spokesperson Peper Long.
“Each kind of wheelchair is classified as a Class I, II or III device, according to its level of risk,” Long explains. “Class III devices carry the highest level of risk and most often require FDA’s approval prior to being marketed in the United States. Class III devices require the most rigorous proof of safety and effectiveness from manufacturers.”

The sole Class III wheelchair on the market is Independence Technology’s iBOT Mobility System, best known for its ability to balance on two wheels to elevate and to climb stairs with physical guidance from its user. Independence Technology announced in December that it was halting sales and marketing of the iBOT.

“Class II devices represent the next level of risk,” Long says. “Class II devices often undergo the FDA’s pre-market notification process — since they may carry lower risk, they must demonstrate that they are ‘substantially equivalent’ to another device that has already been through the FDA pre-market approval or pre-market notification process. Most power wheelchairs fall into this classification.”

Class I devices, Long adds, “represent the lowest risk. These devices are subject to basic regulations, called ‘general controls,’ which include manufacturer registration and product listing, labeling requirements for that category of device, and perhaps other manufacturing and standards controls.”
Generally speaking, “Power wheelchairs are Class II medical devices,” Long says. “Manufacturers who wish to market a new power wheelchair must submit pre-market notification — some, more specialized power wheelchairs may require a premarket approval — along with other data.”

Testing from a Manufacturer’s Perspective

For obvious reasons, manufacturers typically guard their engineering details and testing procedures very closely. But several power chair manufacturers did share some information about their testing policies.

For instance, Dave Mahilo, director of corporate reliability for Invacare Corp., says, “We have a comprehensive product qualification testing lab in-house which performs mechanical and electrical testing. External testing is typically used for specialized test requirements, such as crash testing. There is typically a comprehensive test plan that covers subsystems (motors, controllers, frames, etc.) that progress up to completed unit testing. These tests include testing to standards such as RESNA/ISO, along with any particular company-required tests for durability/reliability/liability reasons.”

Says Julie Jacono, product manager/VP global power products for Sunrise Medical, “The policy for power chair testing at Sunrise Medical includes both meeting the FDA requirements as well as internal confidence testing to understand at which point the various products will fail. Sunrise has an in-house testing facility as well as utilizes independent testing labs where CMS (Centers for Medicare & Medicaid Services) requires.”

“PaceSaver has, from its inception, done testing to ANSI/RESNA standards on all our products,” says Jim Ernst, PaceSaver’s VP of product development. “As members of ANSI (American National Standards Institute)/ RESNA, we certainly subscribe to its relevance and importance in the medical field for all products. Several of our staff sit on the committees that help develop the standards, so we are keenly aware of what they are and how they work.”

Mike Zablocky, VP of engineering, and Walter Clark, VP of design quality & advanced technology at Pride Mobility Products Corp., gave a little insight into the specific types of testing that their power wheelchairs endure: “We test all of our power chairs within FDA requirements, meeting not only the RESNA 2008 standard, but also many international standards and performing testing to what we refer to as ‘real-world criteria.’ For example, we recognize that salt solutions, which can be corrosive, are commonly used in colder climates on walkways and ramps. As a result, Pride developed its own salt test. We treat products with a common salt solution for an extended period to confirm product integrity. In an effort to perform testing to the highest possible standard, we have a state-of-the-art, in-house testing lab, capable of testing to the RESNA standard and beyond. We also work with top independent laboratories for additional testing, including electromagnetic compatibility, flammability and crash testing. When it comes to design quality and product performance, testing is essential, so we commit extensive resources to our testing efforts.”

What Test Results Mean

Next question: What do power chair test results mean? In other words, what are the goals behind power chair testing, and what should that testing accomplish? On the flip side, what should testing NOT be expected to accomplish?

“Minimally,” says Jacono, “these tests must ensure that the production design can fulfill the performance specifications as deemed appropriate by the FDA and CMS. This provides a common starting point for all products sold into the various codes. Additional internal testing can allow the manufacturer to make additional claims for performance above that required in the code.”

“The intent of the wheelchair testing was to provide a few comparison- basis tests that can be used when selecting a particular model of wheelchair for a user,” Mahilo says. “These tests are typically baseline tests and are not comprehensive of all the potential failure modes a wheelchair will encounter.”
Multiple manufacturers agreed that even passing performance and safety tests doesn’t mean a power chair is invincible in every extreme situation.

“When Pride tests our power chairs,” says Zablocky and Clark, “we’re confirming many aspects, including product safety, reliability, performance and functionality. We recognize that power chairs serve a complex role in a consumer’s life. We strive to account for diverse mobility needs and safety in our testing.

“For example, we recognize that consumers use their power wheelchairs year round, so we also perform climatic testing. In one test, we place a power wheelchair in a climate-controlled chamber for three hours at -25° C to confirm operation in colder climates. In these ways, we believe that testing should encompass the depth of a power wheelchair’s intended use in the real world to a reasonable extent. Still, it’s important to recognize that power chairs, as mobility devices, have limitations. They’re not intended for use in harsh or dangerous conditions. So testing occurs within the practical intended use constraints of the product.”

“Most consumers,” Jacono says, “still believe and use these products in a way to support an outdoor community environment, while the minimum specifications of these codes communicate a level of performance that is reduced from the historic, and representative of the primary ‘in-the-home’ use. Passage of these tests simply means that the definition of use follows the CMS definition, not that the consumer can continue to use the product in a heavy outdoor environment without issue.”

Because the consumers who use power chairs have such a wide range of medical conditions and needs, Ernst added that generic testing has its limits.
“(Testing) cannot establish the overall usability of the product for a specific individual,” he noted. “Tests assume certain ‘givens’ as to the user, and in a great many cases, those are not correct. We find that the vast majority of our products are ‘customized’ to better fit the patient and enhance their experience. While a ‘one-size-fits-all’ approach will work, it is not in the best interest of the patient and often not in the interest of safety.”

How Can You Use Test Results to Your Benefit?

But how can you use power chair testing results to facilitate your purchasing decisions and to choose the best-fitting equipment for your clients?
Mahilo suggested providers use test results as a starting point: “The current testing results are baseline comparison values that would be used in selecting a particular product based on user needs.”

“The ability of a unit to pass certain test — and this assumes the test was run correctly and in a certified U.S. lab — helps to assure that (providers) will be getting a quality product AND that they will be indemnified from liability down the road,” Ernst says. “Since the standards are all the same, the most important factor would be to assure that the tests were done in a U.S. lab and to the proper criteria.”

“As the testing bar is reflective of the CMS definition of use, providers should review this use profile with their consumers and in the cases that they know a user will exceed the CMS definition, consider a product with more capability,” Jacono advised. “Though it may be at a higher price, the amount of post-sale support will be drastically reduced.”

“DME (providers) should consider a power chair manufacturer’s dedication to testing when purchasing and supplying power chairs,” says Zablocky and Clark. “A fully-tested product — including formal lab testing and field trials — is the first sign of product integrity, quality and reliability. If a DME (provider) knows that a power wheelchair has not only excelled in rigorous RESNA testing, but also meets the real-world demands of field trials, they can feel much more confident about placing a client in that product.

“Along these lines, (providers) should not only confirm with the power wheelchair manufacturer that the product has met RESNA standards, but he or she should also inquire about any field trials and testing… Providers should evaluate all costs within their business models to maximize not only efficiency, but quality as well. Again, tested, tried and true make for the safest, most functional power wheelchairs.”

Case Study: Quantum Rehab Q600Z

Submitted by Mike Zablocky and Walter Clark

The Quantum Q6000Z began as a design project in June 2006 and was launched in November 2007. It is specifically intended to offer exceptional rehab capabilities while maintaining excellent coverage in the Group 3 and Group 4 Standard, Single Power, and Multiple Power codes and meeting the funding guidelines required for providers to remain competitive.

Beta testing occurred throughout the spring and summer of 2007, leading to the fine-tuning of such areas as suspension, component aesthetics, and overall performance characteristics.

FDA-required testing occurred throughout the development cycle and was performed both in-house and at independent laboratories based upon the particular area of testing.

Results of FDA testing as reported to the SADMERC/PDAC, including:

Control Type: Q-Logic
Patient Weight Capacity: 300 lbs.
Seat Type: High-Back
Seat Width & Depth Range: 18” wide x 16” deep
Seat-to-Floor Range: 21.5” to 23.5”
Chair Length: 36”
Pivot Turn: 22.5”
3-Point Turn: N/A
Minimum Range including Theoretical and Maneuvering Miles: 18.1 miles
Minimum Obstacle Height in mm from Standing Start and Runup: 74.93mm
Dynamic Stability (degrees of incline); Highest Degree Tested with Passing Score: 10 degrees

Case Study: PaceSaver BOSS 6

Submitted by Jim Ernst

The Boss series of chairs goes back more than six years, when we realized the market needed a good heavy-duty chair to meet the needs of bariatric patients. At that time and to this day, many units that call themselves “bariatric” are nothing more than base units with a few additional supports. This DOES NOT qualify a chair as bariatric, or meet the true needs of this population. We started from the ground up to design a chair that would meet the rigorous requirements of the typical bariatric patient.

No units left the factory till those tests concerning safety and stability were complete.
Tests took place at our testing facility at our main plant. We have over the years assembled quite an array of test apparatus, including a dedicated drum (or double drum) tester to specs; a drop-test frame capable of handling up to a 600-pound chair; a freezer large enough to place the largest unit inside; a water-test apparatus, plus a full range of electronic gear, including the equipment to do our own EMI testing (though that is not what we use to certify; we merely test beforehand so we are sure it will pass at the official lab); adjustable ramps and other devices to test angles and inclines; and dedicated, calibrated spaces to measure unit performance.

Results of FDA testing as reported to the SADMERC/PDAC:

Control Type: Fully programmable; basic non-expandable is standard. Basic expandable is optional.
Patient Weight Capacity: 600 lbs.
Seat Type: Com-for-back; sling/solid
Seat Width & Depth Range: 24-30” wide x 20-23” deep
Seat-to-Floor Range: 19.3-22.3”
Chair Length: 48” with footplate
Pivot Turn: 44”
3-Point Turn in inches: 44”
Minimum Range including Theoretical and Maneuvering Miles: 19 miles theoretical; 17 miles maneuvering
Battery type: Group 24 AGM Sealed Lead Acid (75AH)
Minimum Obstacle Height in mm from Standing Start and Runup: 60mm standing; 80mm with runup
Dynamic Stability (degrees of incline): 8 degrees
Highest Degree Tested with Passing Score: 10 degrees

Case Study: Invacare TDX Spree

Submitted by Julie Jackson

The Invacare custom power engineering and marketing team began designing the TDX Spree with concept models in early 2006. The chair is targeted for smaller clients who need a compact base with performance capabilities to climb over a 2” obstacle, achieve a low seat-to-floor height, have the ability to elevate to gain access to areas otherwise not previously reachable and also have the need for weight-shift tilt.
The chair launched to the market in February 2008.

SADMERC testing was conducted in August 2007 in the Corporate Reliability Test Lab at Invacare Corp. The results of the testing meet the Medicare Group 3 coding requirements.

More Information on FDA Policies

To learn more about how the U.S. Food & Drug Administration (FDA)
classifies various medical devices, visit the FDA’s “Device Advice” page at www.fda.gov/cdrh/devadvice/313.html.
If you’d like more specific information on wheelchairs, such as the product codes used to classify the devices, and are willing to type in a longer Web address, try www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFR-Search.cfm?CFRPart=890. You’ll find the FDA’s official definitions and descriptions of various wheelchairs and accessories: The wheelchair categories are 890.3850, 890.3860, 890.3890 and 890.3900.

This article originally appeared in the February 2009 issue of Mobility Management.

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