Page 19 - Mobility Management, September 2017

ATP Series
t face value, immersion, envelopment and off-loading seem to be straightforward terms, even in the
complex realm of seating people with significant mobility impairments.
But combine those terms with the variety of materials used to create today’s wheelchair seat cushions, then
add clients with unique clinical needs. Suddenly, those common terms become much more complicated.
Starting with Definitions
Susan Wilson, VP of Supracor, said of the three terms, “According to the 2015 draft of RESNA national standards, ‘Immersion is the depth to which a body penetrates into a seat cushion from an uppermost plane; envelopment is the ability of a cushion to conform, so to fit or mold around the irregular shape of the body; and off-loading is the clinical practice of reducing or removing pressure from one area of the body to another in an effort to reduce risk to injury — e.g., reducing the pressure under the ischial tuberosities and increasing pressure on the thighs or other parts of the seated body.”
From those basic definitions, cushion strategies can become very diverse, in part because of the wide array of media that can be used to create wheelchair seat cushions.
For example, Wilson noted for Supracor products, “Stimulite
cushions achieve envelopment and immersion as a result of their cellular matrix. Unlike most cushioning materials — including foams, gels and air bladders, which are isotropic and have the same resistance from different angles — Stimulite is anisotropic with different degrees of resistance in its length, width and thickness. This varying resistance enables the cushion to naturally contour to the body. When sitting on the cushion, the cells flex, allowing the body to immerse into the cushion. Since Stimulite cushions provide uniform pressure distribution throughout the cellular matrix, off-loading is generally not necessary.”
Compare Supracor’s situation with that of Sunrise Medical, which uses a multitude of materials, including different types of foam, air cells and gels in its cushion line.
Jeff Rogers, senior product manager of pediatrics and seating, said of Sunrise’s strategy, “For us, the big [term] is immersion — when a person sits into a product, trying to evenly distribute pressure is our goal. When no two butts are the same, it’s always a challenge to conform around people. You can’t create
a cookie-cutter approach, so you’ve got to have products that can fluctuate. We have a full product line that tries to handle this in multiple different directions. We have cushions that
do off-loading and try to load where possible, like with the J3 [cushion]. We have cushions that fully plan to immerse, like the
Understanding & Distinguishing These Seating Strategies
By Laurie Watanabe
MobilityMgmt.com
MOBILITY MANAGEMENT | SEPTEMBER 2017 17
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