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Hello all!
Often when I go into hospitals and other facilities – places that have equipment pools for seating and mobility, but limited budgets for replacement items – I am asked "How can you tell if a cushion is worn out?" Because of the frequency of that question, I thought it would make a great topic for Clinical Corner. It is also a topic that is applicable for evaluating an individual wheelchair user's cushion to determine when a replacement cushion may be needed if there are no provincial funding guidelines.
So, how can you tell if a cushion is worn out? Visual inspection will give a lot of information. Starting with the cushion cover, look for signs of wear, such as tears on the material or splitting at the seams. Also look for thinning of the cover material or obvious wear patterns on the material. With respect to the actual cushion, the cover must come off to complete the visual inspection. Cushions are made with different materials and each material will wear differently over time.
The wear of a foam cushion will depend in part on whether the foam is open cell or closed cell and will depend upon the density of the foam. Recall that foam with greater density will have greater durability. (See Skin Protection and Cushion Materials for more information on cushion materials.) Visual inspection of foam involves checking for foam granulation or brittleness. Discolouration is not necessarily a sign of wear as some foams will become a darker yellow with extended exposure to air1. Mould, caused by an exposure to moisture, however, is a sure sign that the cushion should be replaced.
Tactile inspection also will reveal information on the wear of the cushion. For an open cell foam, check the amount of springiness that is available in the material and ensure that it is an even amount of springiness throughout the material by pressing your fingers into the cushion at different sites2 (i.e. check that the springiness of the foam in the pelvic area matches the springiness at a different part of the cushion to ensure that the foam is working as intended).
To determine the wear of a fluid or gel cushion, visual and tactile inspection can be employed. Look for damage to the seams of the segmented areas or for visible tears or punctures in the fluid pack. Check the level of fluid in the cushion by immersing your fingers into the fluid pack to see how easily your fingers push down into the fluid before you feel the foam base of the cushion2. Also check to ensure that the fluid/gel has sufficient viscosity, or flow, and sufficient homogeneity of the material, to continue to offer skin protection.
Visual inspection also will tell you a lot about the wear of a cushion with an air bladder. Check for any signs of damage to the valve(s) or to the seams of the chambers. Ensure that once the valve is closed, the cushion maintains its inflation. Also, look for any cracks or "stress lines" across a chamber, which indicates that the material has been stretched too far, leading to a slow leak1.
Visual and tactile inspection can tell us a lot about the wear of a cushion, but what are some of the factors that influence wear? Activities and environmental factors influence the wear of wheelchair cushions. The actual use of the cushion will have an impact on its wear. For example, the frequency3 and type of transfer may affect wear. A sliding board transfer may cause more wear to the cushion cover due to friction1 or may cause some damage, such as a puncture, to the material of the cushion4. A transfer that is not completed in a controlled fashion (i.e. the client "plops" onto the cushion) may cause greater wear – the springiness of foam can be affected over time and other materials, such as air or fluid/gel have the potential to "pop" with the force of a great load coming onto the cushion4. In addition, use in sports will affect the wear of the cushion over time3. The frequent loading/unloading and weight shifting on the cushion will impact its wear.
Moisture is an environmental factor that will affect wear. Moisture, such as through incontinence, can lead to degradation of a foam, or even mould. Weather conditions, such as temperature, humidity and precipitation, also can affect cushion materials. For example, some types of fluids may freeze if left outdoors in a frigid environment. Air will expand or contract depending upon temperature (i.e. air expands with heat)4 so a cushion that is used outdoors a great deal may have a different wear pattern than a cushion that is used primarily indoors.
What we can see from this discussion is that age of a cushion is not the sole predictor of wear of a cushion. So many other variables affect the wear of a cushion, including the material of the cushion and the environment and actual use of the cushion over time.
References
- Watanabe, L. (2012). Time to Make a Change? Mobility Management 11(3), 24 – 30.
- Boucher, S. (2012). Advising Your Client on the Wear and Tear of a Wheelchair Cushion. Downloaded April 25, 2012 from https://www.sunrisemedical.com/education-in-motion/blog.
- Sprigle, S. (2012). Changes in Wheelchair Cushion Performance Over Time. Proceedings of the 28th International Seating Symposium.
- Boucher, S. (2012). What affects a cushion's expected lifespan? Downloaded April 25, 2012 from https://www.sunrisemedical.com/education-in-motion/blog