Educación y Transmedia, de entretener a estudiar

Poor posture in the wheelchair will not only affect the patient’s func-tion and comfort, it will also affect the distribufunc-tion of pressure and thereby increase the risk of pressure problems.

Apart from meeting the patient’s need for postural support, the cushion must also be able to distribute the pressure over as wide an area as possible. The more the cushion can conform to the body’s contours, the better it will achieve this. Measurements of the pressure between the patient’s body and the seating surface in sitting can be taken by using either simple hand-held pressure transducer systems as described by Rothery (1989) and Dover et al (1992) or more sophisticated (and more accurate) computerized systems as described by Bar (1991), Henderson et al (1994) and Bogie et al (1995). Single cell transducers can help to identify peak pressures. However, inter-face pressure monitors which are able to map the entire seating area via a series of interconnected cells will give a more complete impres-sion of the distribution of pressure. The cushion should distribute the pressure evenly throughout the contact area with no peaks and troughs. The pattern of distribution is of primary interest, not merely the absolute value of pressure measured at a certain point. Capillary closure pressure of 32 mmHg is frequently quoted as a threshold for tissue viability and hence interface pressures above this level are thought to produce ischaemia (Kosiak 1961, Daniel et al 1982).

However, the length of time that an individual can withstand a certain pressure over bony prominences varies greatly from person to person. A guideline is given by Reswick & Rogers (1983). If shear-ing forces, e.g. through bad posture or transferrshear-ing, as well as vertical pressure are applied to the tissue, the process of tissue necrosis will be accelerated. More recent studies show that deeper tissue such as muscle is more susceptible to pressure and that deep ulcers, e.g. as a result of bruising after a bad transfer or a fall, can develop very fast without significant superfi cial signs of tissue breakdown (Bouten et al 2003).

Whatever system is used, it is important that the therapist takes into consideration the degree to which the pad used to measure the pressure may interfere with the pressure-distributing properties of the cushion being assessed. Interface pressure measurements are an

Ch06-F10180.indd 85

Ch06-F10180.indd 85 5/9/2006 6:49:01 PM5/9/2006 6:49:01 PM

extremely useful adjunct to a full clinical assessment, but as most only demonstrate the pressure distribution at the moment of use, they should never be used as the sole indicator of a cushion’s suitability.

Cushions

A wide variety of cushions is available worldwide ranging from simple easy-to-use cushions to highly sophisticated ones. No one cushion will be appropriate for every patient, but all wheelchair users must have at least a foam cushion. Where there is a choice of cushions other than foam, the therapist will need to examine and assess not only the patient’s posture and skin care needs, but also comfort, the method of transfer, the patient’s balance and stability in sitting and his degree of independence. Some cushions, for example, may cause difficulties when transferring, may be too heavy for the patient or relatives to handle, or may not be available in the appropriate size.

The climate in which the cushion is used can also affect the durability of the cushion. A hot, humid climate will make certain types of foam deteriorate faster. The patient and anybody involved in his care after discharge need to understand how the cushion works and how to look after it. Where the patient has more than one wheelchair, it may be necessary for the cushion to be used in both. This also applies to any special back supports which may be used. Trial periods with more than one cushion may be necessary.

Cushions are made from different substances, including foam and gel emulsion. Some are a combination of a contoured, fi rm base with a fluid-fi lled pad on top, such as the Jay (Fig. 6.2) and Flo-tech ranges.

Some are air-fi lled, e.g. the Roho dry fl otation cushion (Fig. 6.3) and

Figure 6.2 Jay 2 base and Flolite pad separated.

87

PRESSURE – EFFECTS AND PREVENTION

Vicair (Fig. 6.4), or a combination of air and foam, e.g. Varilite.

Many cushions are now contoured and designed to lower the ischial tuberosities into the cushion while lifting the distal end of the femur, promoting a more upright position of the pelvis (Green & Nelham 1991). This design of cushion also helps to reduce the interface pres-sures under the ischial tuberosities (Gilsdorf et al 1990). Cushions that are in sections (right/left, front/back) tend to offer greater stabil-ity and postural control. The Jay range of cushions has several options for modifications (Fig. 6.5) which can be employed either for assessment or for permanent use. Depending on the material of the cushion and the way it is used, it may last for anything from 6 months to several years. The patient must know the likely lifespan of the cushion, how to assess the wear and how to organize a replacement.

Most cushions come supplied with an outside cover. Although the cover needs to be well-fi tting, it must not detract from the conform-ing properties of the cushion, as the patient will then be supported by the cover rather than the cushion itself. This is a common problem with PVC-type covers. The best material for a cover is a two-way stretchy cotton based material, e.g. terry towelling.

Where access to a range of cushions is limited, the use of what is available and some imagination can go a long way to make a rela-tively simple cushion more effective. A foam cushion with ischial cut-outs fi lled with bags of air or water will offer a far greater degree of pressure relief than the foam on its own. A cushion made from

Figure 6.3 (left) Roho Quadtro cushion. It has four intercommunicating compartments, allowing for greater stability and postural control.

Figure 6.4 (right) Range of Vicair cushions.

Ch06-F10180.indd 87

Ch06-F10180.indd 87 5/9/2006 6:49:01 PM5/9/2006 6:49:01 PM

bicycle inner tubes and plastic balls has been described as being more effective than a foam cushion (Guimaraes & Mann 2003).

Whatever the sophistication of the cushion used, the need for regular pressure relief and checking of skin must never be forgotten.