Idea Transcript
THE IMPORTANCE OF SEATING
… with people in mind
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the importance of seating
Contents
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Pressure ulcer development
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06
Epidemiology
Biomechanics of seating
08
09
Abnormal postures
Seating: choices, design considerations and evaluation
15
Reviewing the evidence
17
Risk assessment and seating selection
20
Economics
22
Summary
22
References
23
the importance of seating
Research Ethics ArjoHuntleigh strives to protect the rights and dignity of individuals who take part in clinical studies by following the principles outlined in international guidelines and the Declaration of Helsinki. Research studies are subject to ethics committee approval and informed patient consent is an essential requirement for inclusion. For individual case studies, or retrospective reviews, consent is sought prior to the presentation of material. General product surveys and clinical audit data, which ensure the anonymity of the individuals screened, may be included with the permission of the healthcare facility.
acknowledgement The Tissue Viability Society reviewed and agreed the educational content of this publication and has been pleased to work in partnership with ArjoHuntleigh to create a valuable educational resource.
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the importance of seating
the importance of seating
INTRODUCTION Pressure ulcers represent a major yet largely avoidable risk to health. For some, this is a temporary situation which is dealt with conservatively but for others, perhaps confined to a chair for long periods, the risk of a pressure ulcer becomes a way of life and, as such, needs to be considered in parallel with other lifestyle choices.
In 1978 Keane1 observed that for many seated patients
both simple and innovative seating solutions developed
with non-healing pressure ulcers, there were two choices;
to complement the mattress and to give equitable therapy
either permanent bed rest or sitting on the wound.
over a 24-hour period 4.
However, evidence today strongly suggests prolonged bed rest can be detrimental, leading to secondary complications such as deep vein thrombosis (DVT), muscle atrophy, urinary and respiratory infection; conditions which increase morbidity and delay recovery 2. Thirty years on and sadly, despite an increasing number of options, the advice has changed little for the seated individual with some guidelines recommending a maximum sitting period of 2 hours3; clearly this does not take physiological needs, psychosocial needs, personal choice or quality of life into account and doesn’t differentiate between those who are temporarily or permanently chair bound. Perhaps a failure to take a humanitarian and pragmatic approach to seating is one reason why there is a relatively high occurrence and recurrence of pressure ulcers in people confined to chairs. A second, and equally important factor, is the failure to access the wide range of
Today, by taking a proactive approach to risk management and placing a greater emphasis on choice and quality of life, solutions can be found which assist posture and reduce pressure over bony prominences: when combined with an individualised repositioning schedule this may enable individuals to safely extend their seated time. The best formula for achieving optimum clinical outcomes involves the multi-disciplinary process of incorporating patient, carer and clinician education, clinical assessment in association with skilled prescription and care. With this in mind, this educational resource is designed to provide the healthcare professional with an overview of the physiological problems faced by a seated individual, a summary of the clinical evidence related to pressure redistributing seating surfaces and guidance towards the selection of an effective solution.
the importance of seating
PRESSURE ULCER DEVELOPMENT A pressure ulcer can be described as an area of localised damage resulting from the effects of PRESSURE, SHEAR AND FRICTION 5 usually working in combination (Figure 1).
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Contact pressures in seating In contrast to the supine position, pressures experienced at the cushion:body interface when seated are much higher, as 75% of the body weight is transmitted through approximately 8% of the body at or near the ischial tuberosities11 (Figure 2). Pressures in excess of 60 mmHg are common and will almost certainly occlude the tissue
The formation of pressure ulcers is complex and not
capillaries especially in vulnerable individuals12.
fully understood, however the basic process involves the constriction of small blood vessels as a result of external compression and/or distortion of the soft tissues. This
FIGURE 1
results in an insufficient supply of essential nutrients and oxygen, together with a build up of waste products from cell metabolism. Over time, tissue viability decreases and
Typical pressure ulcer
irreversible tissue breakdown and necrosis occur 6, with subcutaneous tissue and muscle more easily damaged by pressure than the overlaying skin7.
How pressure effects tissue Critical determinants of pressure ulcer development have been described as the intensity and duration of pressure
FIGURE 2
(typically measured in mmHg) which together, affect the health of soft tissue and its supporting structures8. Pressure ulcers may result from short periods of high contact pressure or long periods of comparatively low contact pressure9 by occluding the blood and lymphatic circulation.
TIME FACTOR IS ACTUALLY MORE IMPORTANT THAN THE PRESSURE INTENSITY 10. When shear is also present (such as poor posture) vessels become narrowed and distorted and will occlude at lower pressures than when shear is not a significant factor.
Typical Pressure Area Index (PAI) image in supine and sitting positions. Note: red areas represent pressure in excess of 80 mmHg.
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the importance of seating
pressure ulcer development
Epidemiology and distribution of pressure ulcers
The anatomical location of pressure ulcers is closely related
The prevalence of pressure ulcers in the seated person is
shear and pressure within the tissue and is associated
poorly documented, with up-to-date data being scarce.
with the dimensions of the chair, as well as the supporting
Published figures range widely from:
cushion23. Collins reported a significant difference in
to posture, as a poor seated position can cause increased
pressure ulcer incidence when comparing the use of
l 15-60% in wheelchair users13,14
pressure reducing cushions and standard hospital chairs
l 7-28% in nursing home residents15
across two wards24. Another study reported a time-ulcer
l 8-33% in Spinal Cord Injury (SCI) patients16
relationship, with 7% of patients sitting for an average of
l 63% in orthopaedic patients17
2 hours developing pressure ulcers compared to 63% of
l Up to 60% in quadriplegic patients18
patients who sat for an average of 6 hours17. Heel ulcers may also occur when bed bound patients begin to sit out
FIGURE 3
and use their feet to improve stability such as when the Ischial ulcer
seat height is incorrect.
Routine audit identifies a gap between guidelines and practice In 2005, the National Institute for Health and Clinical Excellence (NICE) issued an evidence-based pressure ulcer Recurrence is also a real problem, as subsequent scar
prevention guideline which recommended that seating time
tissue over an ulcer site is vulnerable to repeat damage.
should be restricted and patients with superficial pressure
Even in extreme cases, where surgery is undertaken to
ulcers (grade 1 or 2) should, as a minimum, be placed on
smooth bony prominences and cover deep wounds with
a high specification foam mattress/cushion25. However,
myocutaneous/cutaneous flaps, reported outcomes may
despite this recommendation there would appear to be a
be poor. One study over an 8 year period recorded 69%
significant, and persistent, gap between guidelines and
of patients who underwent such surgery suffered recurrent
practice4.
ulceration within an average of 9 months19.
In 2006 an analysis of audit data covering 34,762 acute
While the distribution of pelvic wounds varies in the
care patients nursed within 43 UK facilities indicated there
literature, trends are similar with more than half of all
had been little practical response to the recommendations
wounds encountered occurring over the pelvic area
(Figure 4)4. These findings are not dissimilar in the USA
and approximately two thirds of wounds occurring over
and Europe 26 and show both prolonged sitting time, and
the ischial tuberosities (Figure 3), trochanters, heels
a failure to provide protection while seated for 3 out of 4
20
21
and coccyx . In one report even trochanteric ulcers, commonly associated with lateral rotation in bed, were present in 28% of wheelchair users22.
vulnerable patients.
the importance of seating
The NICE guideline was not introducing a new concept
As well as it being important to provide the seated patient
however; the need to provide adequate seating to
with an effective pressure-redistributing cushion, it is
vulnerable populations has long been recognised. In
also important to understand the negative impact of poor
27
1995 Malloy
showed a reduction in the prevalence of
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posture on tissue outcomes.
pressure ulcers from 19% to 9% following the introduction of pressure area care seating in a care of the elderly ward. In 2002, Zoller reported tissue damage prevention in 80% of surveyed wheelchair users who were provided with dynamic alternating therapy cushions instead of a static pressure redistribution cushion28.
SEATING PROVISION (ACUTE CARE)
% of patients who are without protection while seated yet are considered at sufficient risk to
Pre NICE
Post NICE
%
Guideline
Guideline
Improvement
80%
79% 1.25%
require a specialist mattress (alternating or low air loss) when in bed
% of patients who had no seat cushion even though they had a grade 2-4 pressure ulcer on their sacral region and who sat out of bed for up to 7 hours or more
FIGURE 4
Table showing the percentage of patients who sit out of bed with and without specialist seating equipment Data reports alignment with the clinical guideline based upon either ulcer risk (first measure) or ulcer grade (second measure).
55%
71%
-29%
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the importance of seating
BIOMECHANICS OF SEATING
In a correct seating position the pelvis should be in a
Normal sitting posture
the ischials and sacrum, and maximising the use of the
neutral, upright position promoting an upright posture and thus eliminating sacral sitting, minimising shear at
The pelvis is the main area of the skeleton which supports the body when sitting (Figure 5). It interacts with the spinal column, forms an interface with the lower limbs via the hip joints29 and is critical to the correct seated position.
FIGURE 5
Pelvis
femurs for weight bearing. Approximately 75% of the body weight is taken through the seated area (Figure 6), and the knees and hips should be level to ensure as large a surface area as possible over which to distribute weight. Ideally, the majority of weight bearing should be over the ischial FIGURE 6
Iliac crest
Correct seating position
Sacrum Coccyx
Ischial tuberosities
Important areas of the pelvis involved in seating include: l the iliac crests located near the top of the pelvis l the sacrum, a flat part of the vertebral column located
above the coccyx and close to the skin surface
l the spine, which supports the trunk of the body
against gravity
tuberosities and buttocks, and upper half of the posterior
l the lower limbs, which assist the buttocks in taking the
thighs, with the head in midline and balanced over the
body 31.
weight of the body
l the ischial tuberosities, which are small and rounded
and have the effect of rocking the body backwards
However, achieving a good posture is not simply a matter
and forwards: they form the ‘bony’ area beneath the
of position, it also demands a functional component.
buttocks placing them at greater risk of pressure
Individuals are inclined to adopt a posture that prioritises
damage.
When seated, the ischial tuberosities fall lower than the
thighs which contributes to an unstable seating
position and leads to a healthy seated individual
continually changing position30.
activity and comfort over concerns about tissue damage, which is why skilled assessment is recommended for anybody confined to a chair for prolonged periods.
the importance of seating
Abnormal sitting posture Posterior pelvic tilt
FIGURE 7
A posterior pelvic tilt is often seen in individuals who sit for long periods of time (Figure 7). l Weight is transferred to the sacrum, the ischial
tuberosities slide forward increasing friction and
shear force
Normal Seating Position
Posterior Pelvic Tilt
Normal and posterior pelvic tilt
l The hips move, the knee joint extends and the thighs
move forwards and off the chair
l The heels begin to support the weight of the feet
increasing risk of heel ulcers
l The pelvis and head move forwards, and kyphosis
(curvature of the spine) can occur; whereby the erect
spinal posture collapses and the upper back protrudes
outwards leading to a rounded lower back31, increasing
risk of pressure ulceration to the spine32 (Figure 8).
Causes of the posterior pelvic tilt Physical condition There are many reasons why a posterior pelvic tilt may occur which include: l individuals with a high muscle tone and extensive
spasms e.g. muscular sclerosis and cerebral palsy
sufferers l ataxia which can cause an individual to move
excessively as co-ordination and balance are affected
l a patient lying in the semi-recumbent position l a patient who has a poor state of consciousness l general malaise31
FIGURE 8
Spinal pressure ulcer
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biomechanics of seating
SeatinG
FIGURE 9
Poor seating plays a major role in the position an
The height and leg length of each individual is highly variable yet chairs are often a ‘standard’ size
individual sits and the following may all contribute to a posterior pelvic tilt ( Figure 9 ): l If the seat is too high, there will be no support for the
feet, restricting the blood flow at the back of the
thighs and placing the heels at risk as the patient
shuffles forwards
l If the seat is too low excess pressures are
concentrated under the coccyx and buttocks. The feet
push forwards for stability increasing heel pressure
l The length of the seat should be long enough to
provide full thigh support. This gives the largest
foundation over which to control the position of the
body l Too short or too long and the legs will pull the body out
of position
l An unsupportive backrest will allow and encourage
a slouched posture. Providing back support at the top
of the pelvis, will help hold the pelvis in a neutral
position and guide the spine along its natural curves
l An unsupportive seating surface i.e. sagging
upholstery could lead to poor pressure distribution,
poor positioning, excessive shear and build up of heat
and moisture
Anterior pelvic tilt An anterior pelvic position occurs when the pelvis moves
FIGURE 10
Normal and anterior pelvic tilt
forwards. The ischial tuberosities push backwards, shifting Normal Seating Position
Anterior Pelvic Tilt
the weight to the pubis area and placing it at risk of pressure damage. The hip angle decreases, shortening the hip flexors and hamstrings and the lower back muscles and abdominal muscles weaken contributing to lumber lordosis (forward curvature of the spine) and the head moves forwards31 (Figure 10).
the importance of seating | 11
Causes of the anterior pelvic tilt Physical condition The anterior pelvic tilt can be seen in individuals with slow progressive neuromuscular diseases such as muscular
FIGURE 11
Normal spinal position and pelvic obliquity
dystrophy or spina bifida when sitting, as they orientate themselves into a forward sitting position in order to maintain an ability to function33.
Seating This position is naturally assumed when sitting forwards at a desk and is less associated with pressure ulcers, so if this position is a problem it tends to be associated with a physical condition rather than the seating.
Pelvic obliquity Pelvic obliquity is very common in individuals who sit for long periods of time and most people adopt a slightly oblique posture. The pelvis becomes skewed or rotated so it is no longer in a horizontal position and tilts, leading to sitting imbalances, shear and friction (Figures 11 & 12). As the pelvis tilts the affected side will take the extra weight through the ischial tuberosities. If pelvic obliquity is marked, this extra weight is also taken through the greater trochanter on the affected side, increasing the risk of pressure damage to these areas. The head will reposition itself over the pelvis forcing the spine to compensate and change shape and scoliosis can occur as a result 34, 35.
FIGURE 12
Wheelchair user leaning to one side
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biomechanics of seating
Causes of pelvic obliquity Physical condition
A person must be correctly seated for effective pressure
Pelvic obliquity is a progressive condition and is seen in;
seating used. This must include;
l scoliosis associated with neuromuscular disorders
l the dimensions of the chair, is the ground to seat
which in severe cases can lead to the dislocation of
the hip joint and pressure damage36
l are the arm rests the correct height?
management, so attention needs to be paid to all
height being altered by the use of a cushion?
l in individuals with hemiplegia who have poor trunk control
l the seat width, depth and back rest height should all
l in electric wheelchair users who to tend to lean to one
side in order to use the controls31
be considered as it will all affect posture
l The condition of the seating surface is also vital as
sagging seats, fixed backrests and deteriorated foams
Seating
can all contribute to pressure damage
In many cases seating is the main cause of pelvic obliquity;
A seating guide (Figure 14) which highlights these points
l if the seat is too wide, it will offer no support and
can be downloaded from www.arjohuntleigh.com
encourage slouching to one side (Figure 13)
l If the seat is too narrow, the weight is shifted to one
side in order to try and reduce the width of the body35 FIGURE 13
Problems associated with poor seating
Correcting poor posture Many of these postural problems can be corrected very simply by the thoughtful use of cushions (low cost), heightadjustable chairs (moderate cost) and client education; these are possible solutions for people temporarily confined to a chair, but for those with significant postural problems, existing tissue damage, or for long-term chair users, a permanent solution should be sought by referral to a specialist seating practitioner.
FIGURE 14
The Good Seating Guide
the importance of seating | 13
Managing the risk:
Physical repositioning requires a combination
Given a lack of contemporary research focused on
of the following faculties:
pressure ulcers and seating, evidence-based guidelines
l Upper body strength
need to refer to older, typically acute care studies, to formulate their recommendations17, 23, 24, 37; this is the
l Good postural stability
basis for restricting seated time. However, it may not
l Cognitive and
always be acceptable or desirable and it is important to
temporal
balance physiological and psychological well-being with
awareness
the management of risk.
l Discipline and
One strategy for pressure ulcer avoidance, and one which
determination
has been quite widely researched, is the prescription of
l Sometimes the
individualised repositioning schedules to regularly off-load
assistance of a
and reperfuse the tissue such as those described below.
carer or access
to mobility aids
FIGURE 15
Sara® 3000 standing and raising aid
Physical repositioning Over time, chair-bound individuals, their carers and
Push-ups
healthcare professionals have explored a number of
For those chair bound individuals who have sufficient upper
strategies in order to enable longer periods in a chair
body strength, push-ups can be used to achieve pressure
without incurring tissue damage. Such strategies are
relief from the buttocks, using the arm rests of the chair
intended to avoid prolonged and high pressure over any
or the wheelchair38 (Figure 16, see over). However, this
one anatomical area; the most commonly prescribed
method of pressure relief has been shown to be difficult for
method is an individualised programme of physical
newly injured patients due to recent surgical intervention or
repositioning which is usually accompanied by a pressure
severely decreased upper body strength and endurance39.
redistributing cushion: these techniques tend to be
In addition to this, evidence exists to suggest lifts of 15-30
focussed on long-term chair users.
seconds are ineffective in raising transcutaneous oxygen
This programme is not easy to adopt or maintain as it has
tension for most individuals40 and the process may cause
a major impact on lifestyle. Many observational studies13, 37
‘over-use’ injury to the shoulders and wrists increasing with
show that, despite routine prescription, adherence to the
age38.
regimen is haphazard and poor concordance is frequently
Leaning forwards and/or side to side
associated with ulcer formation.
Pressure can be reduced by leaning forwards, bringing the chest close to the thighs, or leaning from side to side (Figure 16, see over). However, this technique may prove difficult for recently injured patients, those with respiratory
14 | the importance of seating
biomechanics of seating
problems or autonomic dysreflexia (over stimulation of the
and as you aged the skin became more resilient to pressure
autonomic nervous system leading to extreme hypertension:
damage, much like developing hard skin on the soles of the
associated with spinal injury). It can also lead to compression
feet: 60% of this study group had had a pressure ulcer37.
of the bladder and requires good trunk control to gauge the movement and return to the correct seated position39.
A further study in 2002 examined the behaviour of wheelchair bound individuals to assess perceptions of risk,
FIGURE 16
Side leaning, forward and push-ups
Wheelchair tipping
type and frequency of pressure relief and beliefs in levels
Where an individual is unable to independently recover from
of responsibility at personal and health professional levels.
the forward leaning position, or lateral shifts are ineffective,
This revealed that only 23% of participants performed
powered seating or carer intervention may be used which
off-loading exercises every 15 minutes, despite 80% being
allows the individual to tilt backwards past 35° to 65°39.
capable of performing them independently13.
It has been shown that the 35° tip is of little value, whereas the 65° tip does provide some pressure relief but possibly insufficient to ensure tissue reperfusion. During wheelchair tipping the individual may become poorly positioned in the chair, especially if significant spasticity is present16 and powered systems can be very expensive so are not
key points • Ulcers are most common in the pelvic area • A wide gap exists between guidelines and practice • Low concordance with self-directed repositioning schedules • Ulcer recurrence is common
commonly used.
Concordance
Summary 3, 25, 41
While repositioning every 15 minutes
is recommended,
evidence suggests these movements are not held for long 42
It is vital that posture and pressure management techniques are considered for each individual, as both play a major
enough to allow tissue perfusion . Concordance may be
role in pressure damage and, if understood and managed
low; although focussed education and the use of timed
correctly, the risk of pressure damage can be reduced.
audible prompts may be beneficial. A study of health
However, reliance on movement techniques have shown
education in a group of young wheelchair users showed the
variable results and ulcers continue to occur and recur,
average sitting time was 8.5 hours/day. A common belief
even when movement is complemented by foam, gel and
was that the use of a pressure redistributing cushion negated
air filled pressure redistributing cushions: this situation may
the need to perform pressure relieving movements and lifts,
be helped by the use of active (dynamic) seat cushions.
the importance of seating | 15
SEATING: CHOICES, DESIGN CONSIDERATIONS AND EVALUATION Design considerations
Cushion evaluation
A large variety of cushions exist to provide pressure
Clinicians selecting a cushion are faced with a large variety
redistribution and they fall into one of two categories:
of cushion types and it is not a straight forwards process. No single cushion satisfies the needs of all users and
n Static cushions such as air filled, foam and gel;
alone or in combination
These cushions passively reduce pressure exerted over bony prominences and may be referred to as ‘reactive’43 as the pressure remains constant in the absence of movement*. However, pressure is unlikely to be low
different cushions may be needed at different times such as for work, leisure and sport. A cushion needs to be able to reduce the amount and/or duration of pressure and shear, which can lead to tissue distortion, as well as be suitable for the environment it is to be used in, comfortable and user friendly.
enough to maintain sufficient tissue perfusion hence a high recurrence rate in some users: they are usually prescribed alongside an individualised repositioning programme.
Different types of evaluation data can be used to help in the decision process. In an ideal world, clinical trial data would always be available to inform cushion selection.
Consideration: Physical repositioning requires both cognitive and physical ability, alongside discipline and commitment from both the cushion user and, in many cases, the assistance of a carer.
Unfortunately, in reality, well designed studies are rare and confounded by low recruitment, high cost and long duration. However, evaluations performed within the laboratory using techniques based on existing pressure ulcer knowledge is readily accessible44 and widely used in
n Active cushions i.e. alternating pressure
the prescription of seating by physical therapists. These
techniques include;
(dynamic) therapy
Active* therapy has been designed to mimic spontaneous body movements through periodically off-loading the seated area and encouraging tissue reperfusion41. They may enable the user to extend seated time or may be a useful aid to reduce the risk of tissue injury in those who are unlikely to follow a repositioning programme.
Maximum, minimum and average interface pressure (IP) Maximum and minimum IP is commonly used to evaluate cushions and is performed with a single point sensor or more commonly a cushion-sized sensor mat. This is
Consideration: While these cushions may provide
particularly useful for static cushion evaluation44 and gives
a greater opportunity for reperfusion than a passive
the therapist a clear indication of where pressure is highest
cushion, they should still be used in association with an
(red area, Figure 17, see over). This enables immediate
individualised programme of repositioning. Also, active
corrective measures to be taken e.g. trying a different
pressure-redistributing cushions may not be suitable for
cushion, different inflation pressure (air-filled cushions) or
those with severe postural or anatomical abnormalities.
correcting abnormal posture. *The terms ‘active’ and ‘reactive’ have arisen from an international consensus group hosted by the NPUAP; this terminology may be adopted as an international standard: www.npuap.org/NPUAP_S3ITD.pdf
16 | the importance of seating
seating: choices, design considerations and evaluation
FIGURE 17
Map of the seated area indicating pressure in mmHg
A
B
Pressure Area Index (PAI) is expressed as the % of sensors recording pressure below a given threshold e.g. 40 mmHg and can be used to compare the pressure redistributing properties of static cushions Image A on the left shows poor pressure distribution with high pressures over the ischial tuberosities: this gives a low PAI Image B on the right follows corrective action (cushion) providing better weight distribution and lower pressures over the bony areas: this gives a high PAI
PAI technique is not suitable for mapping an alternating
FIGURE 18
system so a Pressure Redistribution Index (PRI) is PRI graphic of a typical alternating system
calculated by measuring pressure over time: specifically the percentage during each cycle when pressure is held below a series of nominal thresholds i.e. 60 mmHg, 40 mmHg and 20 mmHg (Figure 18). For more detail of this technique please refer to the Principles of Alternating Pressure; www.arjohuntleigh.com
Laser Doppler Fluxometry (LDF)
Evaluation data can be used to support clinical decision
This technique is used to assess skin blood
making, with interface pressure mapping becoming a
flow or perfusion. It is a non invasive technique
standard tool in seating clinics45 to identify which cushion
which examines the microcirculation of the
may provide the optimum pressure management for each
superficial skin using a highly flexible probe
individual. Mapping highlights asymmetries between
which conforms to the skin surface44.
the left and the right ischial tuberosities and greater trochanters.
FIGURE 19
Laser Doppler flexible probe
It should be noted that IP measurements are taken in a clinical or research setting with the seated individual in various, fixed positions. This provides a useful baseline but does not account for the fact pressure changes throughout the day due to normal activities of living; few studies have examined this area46.
the importance of seating | 17
REVIEWING THE EVIDENCE Although static cushions remain the most commonly
l 40 mmHg threshold: PRI = 46% equivalent to pressure
prescribed support surface, some users develop new
or recurrent tissue damage when seated, while others
relief for 28 mins/hr
l 20 mmHg threshold: PRI = 34% equivalent to pressure
continue to sit on non-healing wounds; for these
relief for 20 mins/hr
individuals an alternative solution should be explored such as the prescription of an ‘active’ cushion which periodically off-loads the tissue to complement a regimen
Audit data, Huntleigh Healthcare
of physical repositioning.
(Data on file 2006)48
Alternating systems – are composed of (usually linear)
l Between 1998-2001, 94 patients across 55 acute and
air-filled cells which inflate and deflate30 alternatively
loading and off-loading tissues. The degree of pressure
l All patients were elderly, at high-very high risk of
relief achieved is related to many variables including; cycle
time, air pressure in the cells and the cover material
44
and
they often complement an alternating mattress system, providing 24 hour care.
Is dynamic seating a modality worth considering in the prevention of pressure ulcers? (Stockton L et al 2008)41 l Alternating therapy was shown to stimulate similar or
significantly better tissue perfusion than the static
devices combined with periodic lift offs, in an
investigation of 3 cushions; air, gel and an Alternating
Pressure Air Cushion (APAC)
l IP and tissue perfusion were recorded over the
ischial tuberosities
community settings were audited
pressure damage or had existing wounds
l Cushions were used for an average of 19 days with
clinicians reporting wounds ‘not deteriorated’ or
‘improved’ in 93% of the patients surveyed
L’utilisation dans l’aide à la prévention et au traitement des escarres (Phillips L et al 2005)49 l Tests showed an alternating cushion device (AURA
logic) provided regular intervals of pressure below
30 mmHg, approximately 23% of each cycle
l Where concordance with personal off-loading
regimens is doubtful, this may be be more reliable than
side leaning or forward leaning 3 times/hr
l The APAC reduced pressures to less than 30 mmHg
for 16 mins/hr compared to either of the passive
cushions which remained above 60 mmHg
Huntleigh Healthcare (Product focus 2007)47 l The Aura Freedom cushion was tested on 3 separate subjects
FIGURE 20
Aura® logic cushion
18 | the importance of seating
reviewing the evidence
Pressure sores: and incurable malady? (Zoller J 2002)
28
l Survey of wheelchair users provided with an active
cushion (for an average of 271 days) instead of their
usual static system combined with prolonged bed rest
l Chair time was increased from an average of 3.8 hrs to
8.5 hrs improving quality of life
Initial clinical observations of the role of a new alternating pressure cushion in the healing of established pressure sores (Donald J et al 1993) 51 l 12 patients were recruited to evaluate an active
system, the ProActive cushion; 9 subjects completed
the study
l 56% of users reported ulcer improvement with 18%
reporting wound closure
l New wounds were reduced from 80% (based on past
history) to 9%
l 5 subjects showed complete healing of their wounds l Of the remaining subjects, 3 presented with multiple
wounds and all showed complete healing of 1 or more
of these ulcers
l 91% felt concerns about pressure ulcer risk
was reduced
l For 4 of the subjects, sitting time increased from less
than 1 hour or not at all to an average of 5.5 hours
l 84% felt the cushion reduced or eliminated concerns
about work, life and social activities
l The RCT demonstrated even severe wounds can start
l 24% reported their pain was reduced or eliminated
healing while the normal activities of life can be
maintained
l 30% reported their overall outlook on life improved
A comparison of healing rates on 2 pressure relieving systems (Russell L et al 2000) 50 l Randomised Controlled Trial (RCT) of two different
alternating mattress and seat cushion systems; Aura
seat cushion and ProActive® cushion
l Both systems were found to be useful in providing
24 hour care for the seated patient, with wounds
progressing to healing and no deterioration observed
FIGURE 21
Airtech® cushion
Cushions may also have a battery powered pump for wheelchair users52, which may enhance the users quality of life by enabling them to undertake many of the activities associated with normal daily living, as well as being affordable.
A descriptive evaluation of pressure reducing cushions (Banks S et al 1995)53 l Evaluation of three pressure reducing cushions
– Vaperm®, Multitec® and Supratec®
l Results showed that irrespective of the total time the
patient spends sitting per day, all three cushions could
be used effectively as part of a pressure ulcer
prevention strategy plan
the importance of seating | 19
Reduction of sitting pressures with custom contoured cushions
Gel/Fluid cushions – low viscosity gels work on the
(Sprigle S 1990)54
cushion when the seated individual shifts position
l Body contours and mean pressures on 2 flat and
2 contoured foams
principle that there is a gradual movement within the
and they offer a stable sitting position with maximum conformity. The cushions may be heavy due to the density of the gel and are often incorporated with foam30, 38.
l Load deflection characteristics were compared l Contoured foam resulted in lower pressure distribution
than flat foam (p