Choose your wheelchair cushions wisely

Friday, April 24, 2015

Typically, when wheelchair cushions are selected, pressure ulcers are not top of mind—despite the fact that they are very common and can be deadly. Current standards for wheelchair seating and cushions are inadequate in delivering appropriate protection from pressure ulcers. Even cushions categorized as “adjustable skin protection cushions” are not categorized by how well they minimize tissue deformations. Given this country’s significant wheelchair user population (about 3.6 million Americans over the age of 15) and the high healthcare system cost of treating pressure ulcers (over $11 billion annually), a change in direction toward prescribing better and safer seating solutions is increasingly essential. 

New research from the laboratory of Dr. Amit Gefen at Tel Aviv University in Israel, as well as other leading international labs, is providing a much better understanding of a particularly dangerous and difficult-to-detect kind of pressure ulcer—the sort caused by deep-tissue injury, or DTI. The primary cause of DTI-based ulcers is tissue and cell deformation rather than ischemia, or lack of blood flow, which acts as a secondary factor. Dr. Gefen’s lab recently performed a study that revealed important insights about the best ways to prevent such deformations—and, consequently, the DTIs they produce—in wheelchair users. 

The new study offers the first tissue deformation comparison between two commonly used cushion technologies—namely, foam-based (representing the largest number of cushions in use) and air-cell-based (ACB) technologies—to help guide clinicians in recommending the best cushion to protect their clients.

Using a sophisticated analytical tool called “finite element (FE) modeling,” the researchers were able to evaluate internal soft tissue loads in the buttocks to provide detailed performance comparisons of an ACB cushion and two flat, foam-based cushions with varying stiffness properties (7 kPa and 10 kPa) as used by individuals with spinal cord injuries (SCIs). SCI patients represent a key segment of the wheelchair user population. Many face entire futures in wheelchairs. Yet, roughly one in 10 of these patients will die from a pressure ulcer, and many more will be affected by such an ulcer and will consequently suffer a reduced quality of life.

The results of the study were dramatic. For the ACB cushion, immersion was consistently in the 91% to 93% range; for the foam cushions, the range was 58% to 65%. Consequently, all of the peak stress components were four orders of magnitude (i.e., 10,000 times) lower for all three kinds of tissues in the ACB cushion than for the foam models. Additionally, the ACB cushion showed lower peak stresses on muscle tissue from bone flattening and substantially decreased muscle atrophy than was present with the foam cushions. Further research is needed to understand how body movements, positions, and other common risk factors affect internal tissue deformations and stresses, but these findings clearly suggest that the ACB cushions provide much longer safe-sitting times than foams for wheelchair cushion users. 

Many clinicians view cushions as mere commodities and make recommendations solely on the basis of price, with the well-intentioned but erroneous belief that all cushions are essentially equal. Clearly, a policy of simply steering patients toward the cheapest solution without evaluating the ulcer risk to the patient is not only extremely shortsighted but also dangerously irresponsible. This approach can lead to needless maladies and suffering, and even to life-threatening conditions. In addition to the physical strain on the patient, there are significant financial impacts to consider: The total cost of managing a single, full-thickness pressure ulcer can be as high as $70,000.

The new and groundbreaking research from Dr. Gefen provides evidence for a critically needed change in direction toward prescribing better and safer sitting solutions through the use of ACB cushions.

Kara Kopplin is senior director of efficacy research, standards and compliance at ROHO, Inc. She can be reached at