Pressure Ulcer Prevention and Treatment Following Spinal Cord Injury - 21

CLINICAL PRACTICE GUIDELINE

(Yarkony, 1994). Initially following injury, prone
positioning may be contraindicated, secondary to
orthopedic or medical restrictions, yet should be
considered when spinal and respiratory stability
is established.
A change in body weight may make
previously prescribed wheelchairs and cushions
contributing factors to excessive pressure if they
become too small or large for the person's body.
Increases or decreases in weight could lead to
excessive pressure being exerted on cushion
surfaces, especially those that are filled with air,
fluid, and foam.

Individualized Pressure
Redistribution System
6. Provide an individually prescribed seating
system designed to redistribute pressure.


Employ a power weight-shift system
when manual pressure redistribution
is not possible.

(Scientific evidence-I, III, IV V; Grade of
,
recommendation-A; Strength of panel opinion-Strong)

Sitting interface pressures are significantly
greater than supine support interface
pressures due to smaller contact areas. Higher
intermittent pressures may be tolerated more
than uninterrupted continuous lower pressures.
Wheelchair cushion performance should be
evaluated in relation to the pressure-time effect
on tissue viability (Rithalia, 1997). Collectively,
these and other biochemical and biomechanical
observations (Claus-Walker et al., 1977;
Rodriguez and Claus-Walker, 1988) suggest that
tissue response to external load is controlled by
many factors, influencing microcirculation and
interstitial fluid flow (Bader, 1990; Reddy et al.,
1981). The deep tissue expression of surface
stresses is mediated passively by tissue stiffness,
connective tissue structure, and the collagen
matrix (Bogie et al., 1995; Reddy, 1990).
In addition to passive effects, muscular activity
(Schubert et al., 1995) will influence interstitial
fluid pressure, blood and lymphatic capillary flow
and the accumulation of metabolic end products,
hypoxia, cell rupture, and necrosis (Reddy, 1990).
Therefore, pressure-reducing strategies are best
when they follow an individualized approach
based on individual and caregiver characteristics
with the objectives of prevention, early detection,
ease of maintenance, and affordability (Remsburg
and Bennett, 1997).
Thorfinn et al. (2009) compared
subcutaneous tissue oxygen and glucose levels

in individuals without SCI sitting on a wheelchair
cushion and a hard surface. Both tissue
oxygenation and glucose levels were significantly
lower while sitting on a wheelchair cushion
as compared to not sitting, but were profoundly
reduced while sitting on the hard surface
consistent with the theory that subcutaneous
adipose tissue covering the ischial tuberosities
becomes ischemic during sitting.
In a study of persons with and without SCI
that measured the characteristics of seat loading
in manual wheelchair users, it was found that
individuals with SCI have a higher pressure
distribution over a smaller area, a much smaller
contact area, and a load distribution that is
asymmetrical in comparison to persons without
SCI, putting individuals with SCI at higher risk for
pressure ulcer development (Gutierrez et al.,
2004). Karatas et al. (2008), in studying the
relationship of dynamic sitting stability of persons
with and without SCI and its relationship to
pressure ulcer development, found that the
center-of-pressure displacements in unsupported
forward, backward, and right- and left-sided
leaning were smaller in persons with SCI than in
those without SCI. This can be attributed to loss
of function of the trunk, abdominal, hip, and
lower extremity muscles in individuals with
cervical and thoracic injuries. Based upon these
findings it can be hypothesized that improving
one's ability to shift in all planes could potentially
help in preventing pressure ulcers.
Reenalda et al. (2009) analyzed the sitting
position interface pressure distribution and
subcutaneous tissue oxygenation of persons
without SCI and found that subjects shifted
posture an average of 8 times per hour in the
sagittal plane (80%) and frontal plane (20%).
These posture shifts caused an increase of 2.2%
in the subcutaneous tissue oxygen saturation,
suggesting potential increased tissue viability.
Depending on a person's cognitive and
physical status, a variety of pressure relief and
redistribution techniques can be performed
including push-up lifts (commonly discouraged in
favor of other techniques due to stress on the
shoulders and wrists and risk of long term
musculoskeletal complications), side leans, and
forward leans. Use of a mechanical reclining or
tilting in space wheelchair feature can also
facilitate pressure redistribution. Tilt, recline,
and standing systems should be considered
as a means of achieving adequate pressure
redistribution for all wheelchair users (Sprigle et
al., 2010). The full range of tilt of a power
wheelchair should be utilized to maximize the

21
Pressure Ulcer Prevention and Treatment Following Spinal Cord Injury

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