Guide To Selecting A Wheelchair Cushion
What is the best wheelchair cushion? Actually there are many good wheelchair cushions on the market and the best approach will be different for everyone. This is an overview article about pressure sores and wheelchair cushions.
What causes pressure sores? Sitting upright focuses the body weight onto a very small skin area. This small area of skin is literally squeezed between the buttock bones (ischial tuberosities and the coccyx or tailbone, see photo) and the seat of the chair. When the skin is squeezed blood supply is pinched off. Decreased blood supply causes a lack of oxygen to the cells and tissue death. Once the tissue dies bacterial infection quickly develops. A pressure sore can develop very rapidly even within hours.
Pressure Sore Risk Factors An underweight person is at a higher risk of pressure sores. Being underweight means that there is less fat and muscle to act as a natural cushion between the bones and the skin.
Poor nutrition can cause anemia (decreased number of red blood cells) which leads to a lack of oxygen in the blood. Nutritional deficiencies can also depress the immune system which can lead to decreased healing of injured tissue.
Cigarette smoking can dramatically increase the problem. Smoking narrows the blood vessels and decreases the supply of oxygen to tissues.
Poor positioning in the wheelchair can increase the pressure on the skin. For example, if the foot rests are too high and the legs are not resting properly on the wheelchair cushion, the weight of the legs may be transferred to the buttocks putting increased pressure on the skin there.
If the wheelchair user is not stable in the chair, they can slide around and the buttock bones can damage the skin from the inside. This damage is known as shear.
Extreme vibration of the wheelchair can irritate or injure the skin.
Heat and moisture can promote chafing of the skin. Chafing causes the skin to breakdown more quickly and increases the likelihood of infection.
While pinching off the blood supply is the main cause of pressure sores, there are several factors that can increase the risk of pressure sores, for example:
There are many ways to decrease the risk of pressure sores. One way is to get the wheelchair cushion that is right for you. Other suggestions are discussed below.
A good wheelchair cushion will redistribute the occupant's body weight away from the skin directly under the buttock bones to a much larger area, including the thighs and the hips. This redistribution of weight decreases the pressure placed on these tiny patches of sensitive skin directly beneath the buttock bones.
Some wheelchair cushions (such as dynamic wheelchair cushions) attempt to frequently change the area of greatest pressure in order to limit the time that blood flow is pinched off to any one spot.
Certain wheelchair cushion materials may help to keep the skin cool and dry. This may minimize chafing and skin damage.
Wheelchair cushions may decrease the risk of pressure sores in several ways:
Where do you start? The first step, is to select the material that is right for you. Wheelchair cushions come in a variety of different materials and each has its advantages and disadvantages:
Foam Wheelchair Cushions are lightweight, inexpensive and compared to other wheelchair cushions, low maintenance. Foam can also be custom cut to fit the need of the user. If you have a particularly sensitive area of skin, a piece of foam may be cut out directly underneath in order to decrease the pressure on that area. However, foam wheelchair cushions can loose their shape in time and compress. This can cause the wheelchair cushion to 'bottom out' meaning that the wheelchair user is effectively sitting on the seat sling. For this reason foam wheelchair cushions should be checked often and replaced frequently. Foam wheelchair cushions also tend to hold in moisture like a sponge, which can promote skin chafing.
The advantage of Gel Wheelchair Cushions is that the weight is distributed well over a large area of the body which can very effectively diminish the pressure on anyone area. The disadvantage is that gel wheelchair cushions can bottom out, can leak and be less effective against vibration and impacts. Since Gel wheelchair cushions do not compress the way foam and air wheelchair cushions do, they do not have the shock absorption properties to absorb impacts such as when you hit a bump in the road. For this reason, gel is often combined with other materials in a hybrid type wheelchair cushion (see below). In addition, gel is quite heavy, though some ultra light gels are being developed.
Air Wheelchair Cushions are composed of many pockets of air which are interconnected so that the air can quickly shift from one pocket to the next. This allows the body weight to be distributed well over a large area and allows shock to be rapidly absorbed. Also, like foam, air wheelchair cushions can be modified in order to relieve pressure on a sensitive spot of the body. This is often done by tying off one cell of the wheelchair cushion directly below the sensitive area. The disadvantage of air wheelchair cushions is that they can be unstable making the occupant sway from side to side. Also air cells can easily leak and this type of wheelchair cushion tends to be expensive. Air pressure should be frequently checked to make sure that you do not 'bottom out'. This type of wheelchair cushion often has high maintenance requirements.
Polyurethane Honeycomb wheelchair cushions have great shock absorption properties. This material is very lightweight and allows air to circulate which helps to keep the skin cool and dry. It is also easily washable which many wheelchair users appreciate. The disadvantages are that the material may collapse under a heavy shock or load, it is expensive and some people complain that with time, the material loses its shock absorption properties.
Composite foams are being developed that are custom shaped and have many advantages over regular foam and other materials. This new material does not retain water, can be easily cleaned and is very lightweight. However, composite foam is much more expensive than regular foam.
Hybrid Wheelchair Cushion wheelchair cushions combine two or more of the materials above. The two materials combined means that one material's strength can compensate for the other material's weakness and vice versa. But they also may have the disadvantages of both materials. For example, a wheelchair cushion that is foam around the sides with a sheet of air cells built into the center may have better positioning and stability than an air wheelchair cushion and better shock-absorption than a fully foam wheelchair cushion. However, it will also have the negative properties of both and may need to be replaced when one of the materials breaks down. In addition, each type of material will have to be cleaned separately according to that material's requirements. In short, hybrids may function better but also may require more maintenance.
Dynamic wheelchair cushions combine hydraulics and other materials such as air to alternate pressure areas and minimize the amount of time that the pressure is pinching on any single area of the body. Disadvantage is that you may feel unstable because you are sitting on a moving object.
The second step to selecting the right wheelchair cushion for you is to consider the shape of the wheelchair cushion. Contoured Wheelchair Cushions provide postural support and help to hold the legs and body to keep them from moving around. This might be ideal for people who tend to slouch in their chair or for people whose legs move too much while riding. On the other hand, the contours minimize the area of the wheelchair cushion which is available for seating. If the wheelchair user feels best by moving around in the seat, a contoured wheelchair cushion may not be the best choice as the contours work to hold the user in place, usually bringing the body back to the same place every time.
The third step is to consider other features of your wheelchair cushion:
Durability: Wheelchair cushions will generally last 2-5 years, with air and foam probably the least durable. But experience varies greatly with this.
Weight: Foam and urethane honeycomb wheelchair cushions usually weigh approximately 3lbs (1.5kg), Air 5ibs (2.5kg) and Gel 8-12lbs (4-6kg). However, watch for lightweight gel cushions, as they will soon hit the market.
Guarantee: A typical guarantee is two years. Check with your dealer to understand their terms. This is particularly important for an air wheelchair cushion as leaks are a frequent hazard.
Maintenance: Air wheelchair cushions are often high maintenance, as you will need to check the air pressure frequently. In addition, ask about cleaning. All wheelchair cushions should be cleaned regularly but some are easier to clean than others.
Price: Typically wheelchair cushions range for $100(or euro 80) for a foam wheelchair cushion to over $300 (euro 250) for a hybrid wheelchair cushion.
The fourth step to selecting the right wheelchair cushion is to get your own experience and test different brands. While it is good to get suggestions from others, one person's needs or experience may not necessarily be the same as yours.
Other Tips to Decrease the Risk of Pressure Sores
Do not allow yourself to lose weight.
Shift weight frequently
Check your foot rest and wheelchair seating adjustments to be sure that it is set correctly for you. For example for those with a high spinal injury, a high seat angle (front seat height higher than back seat height) will help improve stability in the wheelchair. However, too great of a seat angle may transfer more body weight to the pelvis and this may put pressure on the skin beneath the bones in the buttocks. Similarly, if your foot rest is too high, the weight of your legs may be transferred to your hips putting increased pressure on the skin there. In most cases, foot rests should be positioned so that the legs are parallel to the ground. If you are having skin problems, discuss your wheelchair positioning with your therapist to see changing adjustment might be helpful for you.
If you change your wheelchair cushion make sure that your seating positioning has not changed. For example, if your wheelchair was designed for a wheelchair cushion that was 3 inches thick and you change to a wheelchair cushion that is 2 inches thick, your footrest should be lowered by 1 inch. If you do not do this, the thinner wheelchair cushion may cause your knees to be elevated and this could increase the pressure on the skin beneath your buttocks bones.
Keep skin cool and dry to minimize chafing.
Check your skin frequently and if you notice any injury at all, apply an antiseptic and consult your doctor immediately.
Finally, check your wheelchair cushion frequently and change your wheelchair cushion often. Wheelchair cushions age faster than you think. An old damaged wheelchair cushion is no wheelchair cushion at all.
If you are having problems with pressure sores, there are several things you can consider to improve the situation.
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