Pressure Ulcer Prevention and Treatment Following Spinal Cord Injury - 64

PRESSURE ULCER PREVENTION AND TREATMENT FOLLOWING SPINAL CORD INJURY

control must be assessed due to the inherently
unstable nature of air cushions to horizontal
forces, affecting balance, function, and body
stability. Advantages of air-filled cushions include
being lightweight, easy to clean, effective for
many people, slower to deteriorate, and reduction
of shear and peak pressures. The disadvantages
are a possibility of puncturing, the need for
maintenance, difficulty of repair, and postural
instability enhancement of postural deformities
(Garber and Krouskop (1997)). Many factors
influence both the maximum pressure at the
buttocks/seat interface as well the overall
pressure distribution. Cushion geometry (size,
shape, air capacity, material, cover, actual air
pressure) and patient characteristics (body
weight; size and shape of buttocks; posture;
spinal deformities, such as scoliosis; sitting
balance; level; and completeness of the SCI) and
the wheelchair. Using an interface pressure
mapping system to change the cushion inflation
pressure individually for each patient may
optimize the effectiveness of the air-filled cushion
to reduce the risk of pressure ulcers. Hamanami
(2004) used a interface pressure mapping system
to determine the effectiveness of an air-filled
cushion, reporting that optimal reduction in
interface pressure was just before bottoming
out on the cushion.
F L U I D - F I L L E D CUS HIONS

Fluid-filled cushions tend to lessen horizontal
motion of the pelvis while conforming to body
contours and to reduce peak pressure over bony
prominences. When an individual with SCI is
sitting and actively moving, it is not unusual for
layers of buttock tissue to be sliding over one
another producing shear forces. Some researchers
believe that fluid-filled (gel) cushions are more
effective in reducing these shearing forces at the
buttock-cushion interface by conforming and
reducing the horizontal forces exerted on a
cushion. Fluid-filled cushions may not always
provide the lowest interface pressure, and
therefore the limitations must be considered in
the selection process (Nixon, 1985). These
cushions have good dampening and thermal
properties and provide a more stable base of
support. They may be affected by external
temperatures particularly cold weather
temperatures where they may freeze. Fluid-filled
cushions usually are covered by an easy-to-clean
material, are effective with a wide range of users,
promote more uniform distribution of pressure,
and provide better skin temperature control
(Garber and Krouskop, 1997). Viscous cushions
can be heavier than other cushion mediums

although recent technological advances in design
have addressed some of these weight issues. Fluid
encased within its container can flow to areas
under the pelvis where there is less pressure
being exerted on the cushion surface, therefore
allowing for a bottoming out condition to develop
under the areas of greatest pressure. This shifting
of the fluid from high to low pressure areas of the
cushion may lead to bony prominences coming in
contact with the harder cushion base that
supports the fluid pad. It is important for the
fluid to be kneaded and redistributed evenly
across the cushion base prior to its use in order
to avoid this occurrence.
GEL

Gel products are made of silicone, polyvinyl
chloride used alone or in combination with foam.
Gels have been found to be effective in preventing
shear. Gel surfaces are easy to clean, but they
tend to be heavy and difficult to repair. Because
they lack airflow for moisture control, they may
increase skin temperature after periods of
unrelieved sitting.
CEL L ULAR MATRI X ( HONEYCOMB)

Thermoplastic elastomer materials are seen in
"honeycomb-like" cushions, which flex when
pressure is applied to its surface to mold to the
person's shape. These cushions have good
resiliency and allows for good air flow between
the open cells of the cushion. This increased air
flow helps to wick moisture away from the bodycushion interface (Sprigle, 2001). The cushions
can be constructed with different amounts of
structural support and stiffness. They are
lightweight and easy to clean. They must be
visually inspected to detect collapse of the
honeycomb-like structures that indicate
deterioration with continued use.
COMBI NATI ON CUSHI ONS

Recently, a number of cushions have been
developed combining a variety of materials and
designs. Some use foams of various densities,
stiffness, and viscoelasticity. Others use
combinations of gel, air, viscous fluid and foam
materials. These designs may incorporate cutouts,
inserts, and modular components. The
combinations are usually intended for rapid
individualization of the cushion to the user in the
clinical setting. This category of cushions tends to
provide good envelopment and thermal
properties, pressure redistribution and enhanced
dynamic stability to the user. With the use of a
dense base with pressure redistribution modular
components imbedded, more postural asymmetry
can be addressed to attempt to normalize the

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