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March 2005

By Lauren Rosen, PT, MPT, ATP

Recommending the correct wheelchair cushion is key to maintaining the health of patients

Finding the right cushion for a patient can be something like trying to find a needle in a haystack. There are many options, and each cushion is said to work well for clients with many different diagnoses. Knowing this, how does a practitioner decide which cushion is right for their client?

To make an educated decision, it is important to know the different types of cushions that are available. There are five main types of cushions: foam, gel/fluid, air, honeycomb, and sculptured. Each one has benefits for the appropriate client and can cause problems if prescribed improperly.

MANY CHOICES, MANY SOLUTIONS
Foam cushions range from basic to complex models. Because of the variability in the types of foam cushions, foam can work well for many individuals.

The basic two-inch foam cushion is best suited for individuals with good sensation who frequently move themselves in the wheelchair. These individuals usually do not spend their entire day sitting in the wheelchair. Because this cushion is so thin and is usually made of soft, comfortable foam, it is very easy to bottom out if the person is not careful.

Many companies manufacture foam cushions that are thicker and combine multiple layers of different types of foam. Usually, less dense and softer foam is positioned closest to the patient and more dense foam is underneath it. The softer foam helps the cushion feel comfortable and properly supports the client, while the more dense foam decreases the risk of bottoming out. This type of cushion can be appropriate for individuals with decreased sensation and who move themselves less frequently.

It is important to note that because these cushions use foam, they do not have good breathability. Foam cushions may provide adequate pressure distribution, but individuals who live in warmer climates may be at increased risk of developing pressure sores when using them because the poor heat exchange causes an increase in sweating and moisture. Additionally, if a client is incontinent, this can permanently damage the foam, which can decrease the weight-distributing ability of the cushion and cause odor.

Most gel or fluid cushions are constructed in combination with foam. The gel and fluid is positioned closest to the skin to provide a pressure-relieving surface while the foam provides the rigidity for the cushion. Generally, gel and fluid conform well to bony prominences, providing good pressure distribution and reduction. Gel and fluid are cooler seating surfaces than foam so this can decrease problems with moisture and sweating.

Clients who have poor sensation and do not move themselves frequently are appropriate users of gel and fluid cushions. These cushions work well with clients who do lateral scoot transfers because they provide a hard surface from which to transfer.

With gel and fluid cushions, it is important that the client or their family assess the cushion regularly. Because these cushions contain a substance that can move, over time, the gel or fluid can shift away from the areas of increased pressure so that the client bottoms out. Cushion manufacturers have worked to come up with ways to prevent this shift, but, so far, they have not been 100% successful. Nevertheless, it takes only a few seconds to move the gel or fluid back into the proper position.

Air cushions provide good pressure distribution. These cushions have multiple interconnected air cells that evenly distribute pressure when the client sits on the cushion. Some have air cells arranged in quadrants. By inflating one quadrant more than another, the pelvis and legs are positioned independently so the client is properly supported. This is especially important in individuals with any deformities such as pelvic obliquities.

Air cushions are frequently the cushion of choice for individuals who have a history of pressure sores. Clients who are at a high risk of developing pressure sores due to lack of sensation and a decreased ability to shift their position can also benefit.

Setting up and maintaining an air cushion properly take time. If there is too little air in the cushion, a client bottoms out. If there is too much air, the person does not sink into the cushion, and this can also cause bad weight bearing and can result in the development of pressure sores. It is important to add that overinflation is just as dangerous as underinflation.

For clients who independently transfer using a lateral scoot or sliding board technique, this cushion can be difficult to use. When the client pushes on the air cells for support during the transfer, the cells will deflate because they are designed to respond to increased pressure by deflating. With practice, most people can overcome this difficulty, but it is a consideration for weaker clients who have difficulty transferring.

For many individuals, a honeycomb cushion is the appropriate choice. This type of cushion has multiple layers of honeycomb, each with a different stiffness. These layers allow the client’s bony protuberances to sink into the cushion while supporting the surrounding anatomy. By doing so, this type of cushion is very effective at distributing pressure. The cushion weighs less than three pounds so it does not add much weight to the overall wheelchair.

Honeycomb cushions, like gel and air cushions, are used for clients who have poor sensation and do not move themselves frequently. These also work well for clients who perform lateral scoot transfers because they provide a hard surface from which to transfer.

Honeycomb cushions have very good ventilation. They have tiny perforations in the honeycomb cells to circulate air and evaporate moisture. Decreasing the moisture due to heat keeps the client cool and dry.

One other feature about this cushion is that it is ideal for individuals with incontinence. It is antifungal and antibacterial, and the cushion naturally resists odor. Both the honeycomb cushion and its cover are machine washable and can even be placed in the dryer. This makes cleaning it very easy.

Of the pressure-relieving cushions, this one requires the least maintenance: nothing to inflate, nothing to readjust, and cleaning it is easy.

When a client has a pelvic obliquity or other deformities that cannot be accommodated by any of the above cushions, sculptured cushions are used to provide them with the proper support. The cushions are custom molded to the individual and assure that there is equal weight bearing. Frequently, these cushions are used in combination with sculptured back supports because many individuals with significant pelvic deformities also have back deformities.

The benefit to this system is its customizability. When needed, gel, honeycomb, or air cells can be added to sculptured cushions. If there are spots that are particularly susceptible to breakdown, the other materials can be placed in these areas to provide relief. By doing this, the risk of developing pressure ulcers can be significantly decreased.

MAT EVALUATION

An air cushion is light, but inflation needs to be just right for it to be effective for patients.

Now that you know all the types of cushions, it is time to decide which one will work best for your client. When deciding on a cushion, the first step is to complete a thorough mat evaluation to assess pelvic obliquity, pelvic tilt, scoliosis, and lower extremity range of motion. This is an important first step for all seating and positioning.

The first question posed to the client should always be about skin condition. Does your client currently have a skin sore and have they had one in the past? Previous skin sores are important because after a skin sore, the skin is at best 80% as strong as it was before the sore developed.¹ If the client has skin issues, then one of the more pressure-relieving cushions is indicated. The next question should be about sensation. Does the client have decreased sensation? If so, then choosing a more pressure-relieving cushion is important. If the client has good sensation, then a more basic cushion can work.

When deciding on an appropriate cushion, regardless of sensation, the client needs to sit on the recommended cushion. Sometimes cushions do not position the client properly, despite being an appropriate style of cushion on paper.

The client’s functional level should be determined. Does the client spend all day in the wheelchair or do they walk for most of the day and use the wheelchair only for long distances? How does the client transfer? Some of the best pressure-relieving cushions require extra effort to transfer using a lateral scoot technique.

The evaluation is the appropriate time to discuss the client’s funding source. Although there is not significant difference in the cost of most pressure-relieving cushions, some funding sources have policies regarding the type of cushions that they will fund. This is important information to have when making the final cushion selection.

PRESSURE MAPPING
While a pressure mapping system can be useful, it is important to note that the correct cushion decision can be made without one of these systems. However, there are times when pressure mapping can be especially beneficial. The client with repeated pressure sores despite cushion changes can benefit from the use of pressure mapping to identify the most effective cushion. Additionally, the objective data from pressure mapping can be helpful with payor sources when justifying why a client needs a certain cushion.

There have been many studies showing the benefits of using pressure mapping.^2,3 However, the most commonly used systems have limitations. They do not stretch or conform when the client is seated on them. This prevents the client from sinking appropriately into the cushion. Consequently, it may incorrectly show that a cushion does not work properly for a client or it may incorrectly show that a cushion does work for a client. Either mistake can lead to pressure sores.

One manufacturer has recently released a revolutionary new system for interface pressure mapping. The mat is made from a different material than those previously available. It stretches and conforms, which allows for better and more accurate results because it shows the true relationship between the body and the seating surface. With a system like this one, interface pressure mapping will be more helpful for many clients because it is more accurate.

Regardless of the techniques that you use to assess your clients, the end goal should always be that they are comfortable, positioned properly, and pressure ulcer free. There is no cushion that is perfect and that will work for all clients and all disabilities. The knowledge of the many types of cushions and for whom they are appropriate will help you to make correct decisions.

Lauren Rosen, PT, MPT, ATP, runs the Motion Analysis Center and the seating clinic at St. Joseph’s Children’s Hospital in Tampa, Fla. She can be reached at .

REFERENCES

Sarvis C. Course #907: wound management in the elderly. Sacramento, Calif: CME Resource; 1999.
Geyer MJ, Brienza DM, Karg P, Trefler E, Kelsey S. A randomized control trial to evaluate pressure-reducing seat cushions for elderly wheelchair users. Adv Skin Wound Care. 2001:14(3):120-129.
Apatsidis D, Solomonidis S, Michael S. Pressure distribution at the seating interface of custom-molded wheelchair seats: effect of various materials. Arch Phys Med Rehabil. 2002;83:1151-1156.

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