Intelli‑Gel® Evidence Pack

Transcription

w w w. k irt o n -he a l thc a r e .c o .uk
E: [email protected]
T: +44 (0)1440 705352
F: +44 (0)1440 706199
Intelli‑Gel Evidence Pack
®
Version: November 2011
The Kirton Healthcare Group Ltd, 23 Rookwood Way, Haverhill, Suffolk CB9 8PB
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2
Contents
Introduction3
Post Market Surveillance Statistics on the Intelli-Gel® Integral Cushion5
Research Report 1
Benchmark Tests to Determine the Intended Use Recommendation for the Intelli-Gel®
Contour and the Intelli-Gel® Low-Profile Cushions using XSENSOR Pressure Imaging
8
Research Report 2
Benchmark Tests to Determine a Maximum User Weight Recommendation
for the Intelli-Gel® Contour using an Instrumented Buttocks Indenter and
XSENSOR Pressure Imaging
25
Research Report 3
Clinical Evaluation of the Intelli-Gel® Integral Cushion in a Nursing Home
32
Research Report 4
Laboratory Bench Testing of the Intelli-Gel® Integral Cushion using an Instrumented
Buttocks Model
44
Research Report 5
Research and Development of Patient Support Surfaces using XSENSOR
Pressure Imaging
50
Case Study 164
Introduction
This document compiles the current evidence in support of the medical claims made by The Kirton Healthcare Group Ltd on the use of
Intelli-Gel® in various seat cushions. This is a live document to be updated when new evidence becomes available. There are three types
of evidence included:
1. Post Market Surveillance Statistics
A Post Market Surveillance Report describing all customer complaints relating to the Intelli-Gel® Integral cushion for
04/01/10–15/11/11. The document gives the reported incidence proportions of pressure ulcers during that period (sample of
4,000 users).
2. Research Reports
Five separate evaluations using different research methods both in-house and independently, lab based and clinically, are
reported for different stages of the design process. Research Reports 1 and 2 are the most recent reporting benchmark
testing of the Intelli-Gel® Contour and Low-Profile against other Class 1 Medical Device pressure relieving cushions. Research
Report 3 describes a clinical evaluation of the Intelli-Gel® Integral, Research Report 4 describes an independent lab study on
the Intelli-Gel® Integral and Research Report 5 describes in-house testing early in the design process evaluation 32 cushion
permutations.
3. Case Studies
One case study describes the success of Intelli-Gel® with a young girl suffering from Lichen Sclerosus. This case study
indicates that Intelli-Gel® is reducing the symptoms of Lichen Sclerosus due to both pressure redistribution and skin
temperature control. A version of this case study is being considered for peer review publication
Medical Claims
Based on the available evidence, and under the advice of the Tissue Viability Consultancy Services Ltd, The Kirton Healthcare Group Ltd
make the following medical claims:
1. The Intelli‑Gel® cushion can aid in preventing pressure ulcers for those at very high risk
2. The Intelli‑Gel® cushion can aid in the healing of pressure ulcers up to Grade 2 (European Pressure Ulcer Advisory Panel).
Based on these medical claims, and the supporting evidence, stand alone Intelli-Gel® cushions and chairs manufactured by The Kirton
Healthcare Group Ltd incorporating the Intelli-Gel® cushions are registered as Class 1 Medical Devices by the Medicines and Healthcare
products Regulatory Authority (MHRA).
3
Post Market Surveillance Statistics
on the Intelli‑Gel® Cushion
Period: 04/01/2010 – 15/11/2011
Quantity Sold: 4,000 into specialist seating, 500 into hospital patient chairs
Sample size: 4,000 individuals at risk of pressure ulcers
4
This report has been compiled by the R&D Department at The Kirton Healthcare Group Ltd, as part of ongoing post market surveillance
of the Intelli-Gel® Integral cushion. This is a requirement of the Medical Healthcare Regulatory Authority for Class 1 Medical Devices. The
information reported was supplied by the Customer Relations Department at The Kirton Healthcare Group Ltd.
Summary
Of the 4,000 cases there have been only 10 customer complaints that have been associated with the Intelli-Gel® Integral cushion. None
of these complaints give evidence of a link between the Intelli-Gel® Integral cushion and the onset of a pressure ulcer. It is reported that
one individual was uncomfortable, and that existing pressure ulcers in two individuals did not heal. For one other individual there was
a reported reddening in the sacrum area but this was resolved by repositioning the Intelli-Gel® cushion. In 4 cases a diamond pattern
was observed on the client’s skin and one of those cases reported discomfort. For one client discomfort was associated with the seam
between the Intelli-Gel and the foam surround.
Incidence proportions based on the first 22 months sales:
• In the 4,000 cases during the 22 month period, there was one reported incidence of a pressure ulcer however this was
followed up and no evidence was found to implicate the Intelli-Gel cushion
• Of those 4,000 cases, 0.0005% reported that existing pressure ulcers did not heal
• 0.0008% of cases associated the Intelli-Gel® with discomfort
• Diamond patterning was reported in 0.001% of cases however no link can be made between this and damage to the skin or
underlying tissues
Interpretation
Although the reported incidence proportions are extremely positive, they need to be interpreted with care. The cause and management
of pressure ulcers, whether superficial or deep, is complex and often involves multiple risk factors. The published risk factors are listed
below. Due to the nature of the specialist seating range by Kirton Healthcare, all users are considered to have reduced mobility and
therefore to be at risk of pressure ulcers. It is highly probable that a major proportion of this population sample involved multiple risk
factors with varying degrees of risk. Since each case of the population sample will differ in terms of risk level(s) and type(s) it is not
possible to statistically generalise the reported incidence proportions.
Intrinsic Risk Factors
•
•
•
•
•
•
•
•
•
Reduced mobility or immobility
Sensory impairment
Acute illness
Level of consciousness
Extremes of age
Vascular disease
Severe chronic or terminal illness
Previous history of pressure damage
Malnutrition and dehydration
Extrinsic Risk Factors (posture and movement)
•
•
•
Pressure
Shearing
Friction
Exacerbating Risk Factors
•
•
Medication
Moisture to the skin (continence, sweating)
Inherited Clinical Guideline B: Pressure ulcer risk assessment and prevention. Issue 2001. Review 2005. National Institute for Clinical Excellence
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Research Report 1
Benchmark Tests to Determine the
Intended Use Recommendation for
the Intelli-Gel® Contour and the
Intelli-Gel® Low-Profile Cushions
using XSENSOR Pressure Imaging
Introduction
The aim of this investigation is to determine whether it is suitable to position the Intelli-Gel® Contour and Intelli-Gel® Low-Profile
cushions at the same level as previous research has shown for the Intelli-Gel® Integral cushions. This level is for people with up to Grade
II pressure ulcers (EPUAP). The Intelli-Gel® Contour and Low-Profile cushions were benchmarked against other CE marked pressure
relieving cushions currently on the market using 2 volunteers and an XSENSOR Pressure Imaging system.
The data indicate that the Intelli-Gel® Contour cushion is more effective at off–loading the pelvis and has more contact area than the
Intelli-Gel® Low-Profile, resulting in lower Peak Pressure Index values. Both however outperformed the other CE marked cushions accept
for the air cushion.
Taking into account the claims made on the other CE marked cushions, trends in the data support a Grade II recommendation for
the Intelli-Gel® Contour and Intelli-Gel® Low-Profile cushions. It is important that with this recommendation, the manufacturer
acknowledge that a seating clinician should be involved with each individual user.
2
Materials and Methods
2.1Cushions
Table 1 and Figures 1-6 describe the cushions that were included in this evaluation. The size of the samples was kept as consistent
as possible, with seat widths close to 450 mm and seat depths close to 400 mm. The air cushion was selected because it is widely
considered to be the most effective static cushion for pressure reduction. The test-rig and XSENSOR Pressure Imaging system as
described in Section 2 of Research Report 5 in the Intelli-Gel® Evidence Pack (version November 2011) were used for this investigation.
Table 1. The cushions included in the investigation.
Intelli-Gel® Contour
Thickness
(mm)
90
Intelli-Gel® Low-Profile
50
Intelli-Gel® X
90
Air cushion
Intelli-Gel® Integral
Fluid cushion
Visco-elastic cushion
Visco-elastic & PU cushion
Reference foam 50
Reference foam 75
Reference foam 90
90
90
75
75
50
75
90
Cushion
Description
Manufacturers’ medical
claims/intended use
The new Intelli-Gel® component permanently fixed to a 3
dimensional anatomically profiled closed cell foam base
The new Intelli-Gel® component permanently fixed to a 2
dimensional anatomically profiled closed cell foam base
A prototype for a new Intelli-Gel® cushion design in
development
Inflatable air bladder cushion
Intelli-Gel® & foam composite
Fluid sack & visco-elastic foam surround
Visco-elastic foam
Visco-elastic foam & polyurethane foam composite
Polyurethane foam
Polyurethane foam
Polyurethane foam
Not specified
Up to Grade II
Up to Grade I-II
Up to Grade I-II
Up to Very High Risk
7
Figure 1. The Intelli-Gel® Contour cushion
Figure 2. The Intelli-Gel® Low-Profile cushion
Figure 3. The air cushion
Figure 4. The Intelli-Gel® Integral cushion
Figure 5. The Fluid cushion
Figure 6. The visco-elastic cushion
8
Figure 7. The visco-elastic & PU cushion
2.2Subjects
9
Two volunteers participated in this investigation. Volunteer 1 is a 61 year old male ectomorph weighing 70 kg, and Volunteer 2 is a 33
year old male mesomorph weighing 80 kg. Both volunteers were asked to wear lightweight trousers and to remove belts and items from
pockets prior to testing.
2.3Protocol
2.3.1Pilot test to determine the pre-measurement load duration for the visco-elastic materials
A pilot test was performed to ensure that the cushions with visco-elastic foams would have time to ‘warm up’ before taking
measurements. The visco-elastic cushion was chosen for analysis since this is the only 100% visco-elastic foam cushion included, and
Volunteer 1 was chosen to load the cushion. A 30 second measurement was taken immediately and then again every 2 minutes until the
change in pressure levelled off. During this period the volunteer kept as still as possible.
2.3.2Assessment of the cushion height after loading
Previous experience had shown that when seated, knee height has a significant effect on the interface pressures in the ischial regions.
In order to control this variation, each cushion was assessed and grouped based on the compressed height. Each group was assigned a
footrest height setting and an order in the protocol.
2.3.3Test protocol
Prior to testing, the footrest was adjusted to the predetermined setting for the first group of cushions. The first cushion from this group
was then placed onto the test-rig and the pressure mat was positioned. The volunteer then entered the test-rig in a controlled and
repeatable manner (hands on armrests, step onto footrest, make contact with backrest and lower steadily down onto the seat). The
volunteer then remained seated for a 3 minute stabilisation period before measurements were taken.
For those cushions containing visco-elastic foams, the volunteer first sat directly on the cushion without the pressure mat positioned
for a 20 minute ‘warm up’ period. After this the volunteer stood to have the pressure mat positioned and then commenced the 3 minute
stabilisation period as for the cushions not containing visco-elastic foams.
A 30 second recording period followed the 3 minutes of stabilisation which was saved for further analysis. The volunteer then stood
from the test-rig while the pressure mat was removed and repositioned. The volunteer then sat back onto the same cushion for another
3 minute stabilisation. Each cushion was measured 3 times and averaged. Measurements of the air cushion were taken several times
throughout the test session with the inflation pressure readjusted each time. The test order was as follows:
Group A
1.
Air cushion (1st measurement set)
2.
Reference foam 50
3.Intelli-Gel® Low-Profile
4.
Air cushion (2nd measurement set)
Group C
5.
Reference foam 90
6.
Fluid cushion
7.Intelli-Gel® Contour
3
10
Group B
1.
2.
Reference foam 75
3.
Visco-elastic & PU cushion
4.Intelli-Gel® X
5.Intelli-Gel® Integral
Group A
6.
Air cushion (3rd measurement set)
Analysis
The analysis for this investigation is based on the research carried out by Sprigle et al. (2003) for the International Organization for
Standards (ISO) tissue integrity Working Group. In their research, various interface pressure parameters were evaluated for repeatability
and reliability.
The main pressure outcome from this investigation is Peak Pressure Index (PPI). PPI replaces single sensor peak pressures, which has
been found to be unstable and exhibit poor repeatability. PPI is defined as the mean value of the three data sets of the highest recorded
pressure values within a 9-10 cm² area under one of the load-bearing surfaces (ischial tuberosities, greater trochanters, and sacrum).
The XSENSOR mat has cells with 1.61 cm² areas, so 6 cells (a 3 x 2 array) were selected based on the arrangement that gave the highest
mean.
Average pressure shows good repeatability but according to Sprigle et al. has limited clinical relevance because it does not distinguish
between many cushions. Average pressure is included as a pressure outcome in this investigation for informational purposes. Average
pressure is defined as the mean value of the three data sets of the average of all nonzero pressure values.
Desirable pressure distributions are primarily achieved in two ways. High pressures can be off-loaded from the pelvis to the thighs
and/or reduced by increasing the surface area. There are two pressure parameters that are useful for assessing these mechanisms;
Dispersion Index and Contact Area Threshold.
Dispersion Index (DI) is defined as the mean value of the three data sets of the sum of the pressure readings in the coccygeal and ischial
zones and divided by the sum of all pressure readings expressed as a percentage. Figure 1 shows the mat areas for the XSENSOR Pressure
Imaging system.
Figure 8. XSENSOR Pressure Imaging mat areas
Contact Area Threshold is defined as the mean value of the data sets of the area of sensels with pressure readings equal to or exceeding
5 mmHg (the threshold used to define “contact”). For each data set the contact area C is determined from Equation 1 where C is the
contact area, Nmat is the total number of sensels in the mat, and n is the number of sensels with pressure readings ≥5 mmHg.
1
C=Ax
( )
n
Nmat
2
In addition to looking at the magnitude of pressure, the rate of change of pressure has been reported as contributing to tissue
damage presumably because of the associated shearing that may exist within the tissues. Sprigle et al. propose a pressure parameter
for evaluating pressure gradients, which provides a comparison of a resultant pressure distribution to that of an ideal homogeneous
distribution. Seat Pressure Index (SPI) is a single value representing this comparison. The ideal pressure distribution in a seated posture
is defined as a homogeneously distributed surface at 30 mmHg. A dimensionless SPI quantity is calculated which includes an average
of values exceeding a threshold (mean30¬), a measure of dispersion (standard deviation or skewness) of these same values, and the
relative amount of the mat loaded. Using skewness was found to be unreliable however reliability was found for SPI using standard
deviation as the measure of dispersion. SPI-sd was therefore included in this investigation and is defined in Equation 2, where SD30 is
the standard deviation of the values exceeding 30 mmHg . The average of three SPI-sd measures was used for the benchmarking.
2
SPI-sd =
[
(mean30 + SD30 )
30
]+[
2
number of mat sensels
(number of sensels ≥ 5)
]
2
To help understand the results from this investigation it was also considered useful to analyse the Total Force. This is defined as the
mean value of the three data sets of the sum of forces measured by the pressure mapping system (expressed in Newtons). For this, the
sum of pressure is converted to N/cm² (factor 0.013332239) and then to Newtons by dividing by the cell area (1.61 cm² for the XSENSOR
system).
4Results
Table 2 gives the results for the pilot test. Figures 9-32 give the benchmarking results. The results for the Intelli-Gel® Contour and
Intelli-Gel® Low-Profile are highlighted with a red outline. Trends in the data are illustrated with shading.
Table 2. Peak Pressure Index (PPI) and Average Pressure (AVG) for the pilot test for cushion stabilisation using Volunteer 1
and the visco-elastic cushion
Time (min)
PPI
AVG
0
2
4
6
8
10
12
14
16
18
210.34215.82 217.6 218.7 218.67219.54218.74219.02219.31219.92
81.8986.8587.9788.6289.0389.5189.7190.0190.3390.66
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Figure 9. Peak Pressure Index results for Volunteer 1, test 1. The dark
shading illustrates a group of consecutive cushions comprising of only the
Intelli-Gel® and air cushions. The Intelli-Gel® Contour and Low-Profile are
highlighted with a red outline.
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Figure 13. Average pressure results for Volunteer 1, test 1. Shading is used
to separate the cushions into two distinct groups based on the differences
of pressures. The red outline highlights the Intelli-Gel® Contour and LowProfile cushions
Figure 14. Average pressure for Volunteer 1, test 2. Shading is used to
separate the cushions into two distinct groups based on the differences
13
Figure 17. Contact Area Threshold results for Volunteer 1, test 1. The dark
highlighted with a red outline
14
Figure 21. Dispersion Index results for Volunteer 1, test 1. The dark
15
Figure 25. Seat Pressure Index results for Volunteer 1, test 1. The dark
16
Figure 29. Total Force results for Volunteer 1, test 1. Shading is used to
illustrate the relationship between Total Force and Average Pressure. The
red outline highlights the Intelli-Gel® Contour and Low-Profile cushions
17
5
Discussion
The results from the pilot test indicate that the visco-elastic cushion stabilised after 10 minutes. For the 18 minute load period of the
pilot test, 57% of the change in pressure was measured at 2 minutes, 76% at 4 minutes, 87% at 6 minutes and 96% at 10 minutes. Based
on these data a 20 minute pre-test loading period was considered adequate to stabilise the visco-elastic foams. It is interesting to note
that during the measurement period the interface pressures increased. This is counter intuitive as one would expect the pressures to
improve as the visco-elastic foam ‘warms up’. One possibility is that the cushion would require longer than 20 minutes for the viscoelastic properties of the foam to take effect however such a duration would seem unacceptable. The pressure reducing effect of viscoelastic foam may work better in mattress applications than seating where the weight of the body is shared across a much larger area. In
seating there appears to be little change over time that can be associated with visco-elastic properties of the foam, rather in this case
the increase in pressure is probably due to creep in the pressure sensors.
For the main part of the investigation, the results showed good repeatability although there was some natural variation between test
sessions which is attributed mostly to variation in posture. The use of the test-rig had significantly reduced this as it permitted control of
seat height (knee height), seat length, and pelvis and head position. Both volunteers were familiar with pressure mapping, so understood
the importance of consistent ingress and posture.
The pressure mat used in the investigation had not been calibrated immediately prior to testing. However, interpretation of the pressure
distributions are not based on absolute data but on relative comparisons, so reliability issues associated with any drift that may have
occurred since the last calibration are bypassed. It became evident when analysing the Total Force that the mat was over reading the
interface pressures however this would have been consistent across cushions so there is no change in relative differences.
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The aim of this investigation was to use Interface Pressure Imaging to inform the decision on the intended use guidelines for the
Intelli-Gel® Contour and Low-Profile cushions. The industry common practice for these guidelines is based on the grading system for
risk levels and pressure ulcers as defined by the European Pressure Ulcer Advisory Panel (EPUAP). The intended use guidelines and the
medical claims which qualify the products as Class 1 Medical Devices are interchangeable. Table 1 gives the known manufacturers’
claims for the cushions included in this investigation that are currently CE marked and available on the market. The Intelli-Gel® Integral,
fluid cushion and visco-elastic cushion are claimed to be suitable for people with pressure ulcers up to Grade II. The visco-elastic & PU
cushion is claimed to be suitable for people at very high risk of developing a pressure ulcer. The manufacturers of the air cushion do not
specify a grading; however it is widely accepted as the most effective pressure redistributing static cushion available on the market.
The PPI results show, consistently across the 2 test subjects and test sessions, a trend where all cushions containing Intelli-Gel® and the
air cushion form a group which outperforms all others (Figures 9-13). Taking into account the claims made on the other cushions, this
trend would logically support a Grade II recommendation for the Intelli-Gel® Contour and Intelli-Gel® Low-Profile cushions. The Grade II
recommendation is the upper threshold for a manufacturers’ claim on a static pressure relieving cushion.
Average pressure has also been used in the past to rate cushions, and has been shown to be reliable, but has been questioned in terms of
its volatility for comparing across cushions. In this investigation, average pressure has clearly differentiated the Intelli-Gel® Contour and
Low-Profile cushions from the other cushions tested (Figures 14-17), with reductions in average pressure ranging between 15-20%.
Contact Area Threshold and Dispersion Index (DI) are reported to understand the nature of the pressure distributions for the Intelli-Gel®
Contour and Low-Profile. Figures 17-20 give the results for the Contact Area Threshold and suggest that there is relatively low contact
with the cushions for both volunteers. Without increasing area, the only other way a cushion can lower high pressures is to redistribute
to low pressure areas. DI measures the share of pressures between the pelvis and the thigh, and therefore gives an indication into the
redistributing characteristics between these two areas. Low DI values can be seen for Volunteer 2 but not for Volunteer 1, so an offloading of pressure from the pelvis to the thighs does not fully explain the low pressures.
In a separate study by the Furniture Industries Research Association (FIRA), the material properties of the Intelli-Gel® Contour before and
after pounding were analysed using hysteresis curves measured with an instrumented buttock model indenter. The buttock indenter was
gradually forced in and out of the gel, during which time the distance travelled and the reaction force from the cushion were precisely
measured. Figure 33 gives an example of the hysteresis curves obtained. What is interesting here is the levelling off of the curves at just
over 600 N, which is indicative of the gel columns buckling under load. When the columns buckle their resistance to force is effectively
neutralised so the neighbouring columns assume the load. As the load on those columns increase they then in turn buckle and transfer
load to their neighbouring columns, and so on, so the buttocks continue to immerse into the gel without an increase in overall reaction
force.
Additional measurements were performed on the Intelli-Gel® Low-Profile to follow up these findings, but with a 300 mm diameter disc
indenter as opposed to the buttock model to isolate the column buckling property. Figure 34 shows the hysteresis curves and it can be
seen that the columns buckle at approximately 330 N (140 mmHg of pressure) with the curves levelling off after this point. Figure 35
shows the hysteresis curves for polyurethane foam (75 mm thick) for comparison which increases linearly after the initial indentation.
Figure 33. Hysteresis curve for the Intelli-Gel® Contour using a
buttock model indenter. The indenter is forced into the Intelli-Gel® for
approximately 15 mm and 30 mm. At these points the indenter is held
stationary while the gel relaxes and then lifted off. Measurements are
shown in both directions, for both distances and with several repetitions.
Figure 34. Hysteresis curves for the Intelli-Gel® Low-Profile using a 300
mm diameter disc indenter. The indenter is forced into the Intelli-Gel for
just over 20 mm. At this point the indenter is held stationary while the gel
relaxes and then lifted off. Measurements are shown in both directions.
19
Figure 35. Hysteresis curves for 75 mm standard polyurethane foam
using a 300 mm diameter disc indenter. The indenter is forced into the
foam for just over 20 mm. At this point the indenter is held stationary
while the foam relaxes and then lifted off. Measurements are shown in
both directions.
Seat Pressure Index (SPI-sd) has also been reported to check for large pressure gradients. Pressure gradients reflect the rate of change
of pressure and are believed to be a risk factor for tissue damage. Figures 25-28 show that the Intelli-Gel® Contour and Low-Profile fall
into a group comprising of only the air cushion and Intelli-Gel® brands having lower SPI-sd values than the group containing the other
cushions. This indicates that there should be no concern for high pressure gradients to be associated with Intelli-Gel®.
20
Although the low PPI values can be explained by the columns buckling and redistributing high pressures to neighbouring areas for the
Intelli-Gel® Contour and Low-Profile, this does not explain why the total average pressure and the total contact area are both measuring
low values when compared to the other cushions under the same load. To elaborate these findings further Total Force is reported. Total
Force should roughly measure the force that is generated from the proportion of body weight acting on the seat, and should therefore
be consistent regardless of the cushion that is in place. Figures 29-32 show variance for all cushions, with the lowest recorded force for
the Intelli-Gel® Contour and Low-Profile. Some variance can be attributed to the envelopment of the pressure map and consequently
the off-axis loading of the sensors. The XSENSOR system has capacitance sensors and, like other pressure mapping systems, are only
capable of measuring pressures from forces perpendicular to the electrodes. Off-axis loading therefore under-estimates the actual
applied force. This however does not explain the Intelli-Gel® Low-Profile which, on a hard base, is relatively flat and non-immersive.
Here, the pressure mat is likely to be underestimating Total Force because of its resolution and the heterogeneity of the gel surface.
Some of the sensors will be positioned over the gel columns whilst others will be overlaying the interspaces. Those sensors over the
interspaces could be responsible for the mat underestimating the Total Force. The important aspect though is how well the resultant
measured pressure distribution reflects the actual interface pressure affecting the skin. Compared to other systems, the XSENSOR
pressure mat has a relatively high resolution with 1296 sensors spaced 1.27 cm apart. The proportion of those sensors measuring over
or between the gel columns is random however the data show a low variance with coefficient of variations less than 5%. If hypothetically
all of the sensors were positioned directly over the gel columns, the Total Force may be more accurate however this would not give
a good representation of the pressure affecting the skin as it would be missing the important low pressure areas. Likewise, if all
sensors were overlaying the interspaces an unrealistic picture would also immerge. The measured pressure distributions are therefore
considered to give a reliable indication of the performance of the cushions.
6Conclusion
The results from this investigation would support manufacturer’s guidelines stating that the Intelli-Gel® Contour and Intelli-Gel® LowProfile cushions are suitable for users with up to Grade II pressure ulcers.
7.References
Sprigle, S., Dunlop, M.S., Press, L., 2003. Reliability of bench tests of interface pressure. Assistive Technology. 15: 49-57
21
Research Report 2
Benchmark Tests to Determine
a Maximum User Weight
Recommendation for the
Intelli-Gel® Contour using an
Instrumented Buttocks Indenter
and XSENSOR Pressure Imaging
Introduction
Benchmark testing was carried out at the Furniture Industries Research Association (FIRA) to determine a maximum user weight
recommendation for the Intelli-Gel® Contour cushion (Figure 1). Pressure distributions were collected from the Intelli-Gel® Contour
cushion, an air cushion, an air cell cushion, and a visco-elastic & PU cushion, under various loads applied with an instrumented buttocks
indenter. The results indicate lower interface pressures for the Intelli-Gel® Contour cushion in all test scenarios. Taking into account the
weight limits for the other cushions, a 30 stone (190 kg) user weight limit would appear to be a sensible recommendation for the IntelliGel® Contour. It is important that this recommendation is in the form of guidelines and that it is made clear that clinical consultation is
essential to ensure safety for those at risk of or with pressure ulcers.
22
Figure 1. The Intelli-Gel® Contour cushion. The new Intelli-Gel® component is
permanently fixed to a 3 dimensional anatomically profile closed cell foam base
2
2.1 Load tests
Load testing was carried out at the Furniture Industries Research Association (FIRA). The Kirton Healthcare Group Ltd provided the
XSENSOR Pressure Imaging System for data collection. Cushions were loaded using an instrumented buttocks indenter (Figures 2 and 3).
The following cushions were compared:
1. The Intelli-Gel® Contour (Figure 1)
2. The air cushion. An air bladder cushion where the inflation pressure of the cushion is customised to the individual
3. The air cell cushion. A cushion consisting of four compartments, each filled with air-filled cells, of which the two side
compartments have a higher cell density. Two of the air cells had been removed in the ischial tuberosity sites for greater
immersion.
4. The visco-elastic & PU cushion. The cushion has a 65 mm polyurethane base and a 25 mm visco-elastic topper.
Each cushion was first loaded to 600 N and allowed to stabilise for 3 minutes. During this stabilisation period the cushion tended to
relax so the indenter’s distance into the cushion was gradually increased to maintain a constant load of 600 N. This was followed by a 30
second recording of interface pressures. The load was then increased to 900 N and left for another 3 minutes to stabilise before the 30
second period of data collection. The protocol was then repeated to loads of 1200 N, then 1400 N and then 1600 N.
Figure 2. The instrumented buttocks indenter applying load to the
cushion with the XSENSOR Pressure Imaging System collecting interface
pressure data
Figure 3. Posterior view of the Intelli-Gel® Contour cushion in a loaded
condition
2.2 Analysis
The interface pressure variables selected for comparing all data are Peak Pressure Index (PPI) and average pressure. PPI is the mean of
the highest recorded pressure values within a 9-10 cm² area (approximately the contact area of an ischial tuberosity and other bony
prominences) under one of the load-bearing surfaces (ischial tuberosities, greater trochanters, and sacrum/coccyx). Analysing single
sensel peak pressures proves problematic because it is an unstable measure that exhibits poor repeatability (Sprigle et al., 2003).
Average pressure is the sum of all pressures divided by the number of all nonzero pressure sensels. Normally average pressure is not
sensitive enough to differentiate between cushions however given the range of loads in the current tests this was considered to provide
useful data.
3Results
The results from the testing are given in Tables 1 and 2, and Figures 4-7.
Table 1. Peak Pressure Index Results
Applied LoadIntelli-gel®
(N)
Contour
Peak Pressure Index (mmHg)
Air Cell
Air
Cushion
cushion
Visco-elastic &
PU cushion
600 157.76225.92171.18199.35
900 174.25245.2189.24221.6
1200
197.74/206.99
250
1400
213.77/218.12/
1600
227.3 /227.38/
Table 2. Average Pressure Results
Applied LoadIntelli-gel®
(N)
Contour
Average Pressure (mmHg)
Air Cell
Air
Cushion
cushion
Visco-elastic &
PU cushion
600 47.4660.2360.6475.11
900 64.4875.9279.597.27
1200
76.41/93.94
111.81
1400
83.98 /103.21/
1600
89.93 /111.43/
23
Figure 4. Peak Pressure Index Results
Figure 5. Average Pressure Results
24
Figure 6a. Intelli-Gel® Contour
600 N
Figure 6b. Intelli-Gel® Contour
900 N
Figure 6c. Intelli-Gel® Contour
1200 N
Figure 6d. Intelli-Gel® Contour
1400 N
Figure 7a. Air cushion 600 N
Figure 7b. Air cushion 900 N
Figure 7c. Air cushion 1200 N
Figure 7d. Air cushion 1400 N
4
Discussion
The results show that the Intelli-Gel® Contour performs better than all other cushions under all load conditions. There are several factors
which need to be considered however when interpreting these findings. Firstly the air cushion was adjusted once prior to testing and
unaltered for the different load conditions. The inflation pressure was determined when the cushion was loaded to 1400 N which is likely
to result in over inflation for the lighter loads. The performance of the visco-elastic & PU cushion could have been inhibited due to the
use of the indenter. With humans it could be expected that heat from the body would alter the visco-elastic properties of the foam and
improve the pressure relieving characteristics. Furthermore, although the indenter had been moulded to resemble the buttocks, it is
completely rigid so the resulting pressure distributions cannot be used to predict those from a human.
It is interesting to find that the air cell cushion has a 250 kg (2450 N) weight limit. Testing with this cushion was terminated after the 900
N (92 kg) test for fear that the pressure sensors might get damaged. The highest PPI values over all cushions were recorded for the air
cell cushion at loads of 600 N and 900 N, although the average pressures were higher for the visco-elastic & PU cushion at these loads.
The Intelli-Gel® Contour and air cushion resulted in similar PPI values. The Intelli-Gel® Contour resulted in lower values for the lighter
loads but as mentioned above the difference would likely diminish if the inflation pressure for the air cushion were adjusted for each test
condition. A much larger difference between these cushions can be seen though for average pressure. Lower pressures were recorded
from the Intelli-Gel® cushion, which is also visually apparent when comparing the images of the pressure maps in Figures 6 and 7. The
manufacturers of the air cushion do not give a maximum user weight limit.
The manufacturers of the visco-elastic & PU cushion do not specify a weight limit either, but the cushion has been used on chairs with
30 stone weight limits for many years with no known problems. The maximum PPI values that the pressure mat is capable of measuring
were recorded for the Reflexion™ foam at the 1200 N (122 kg) load. Neither the air cushion nor the Intelli-Gel® Contour approach these
values for any of the loads tested.
The aim of this investigation was to determine a maximum user weight recommendation for the Intelli-Gel® Contour by benchmarking
against equivalent pressure relieving cushions currently in use. Chairs used in hospital environments have weight limits up to 30 stone
(190 kg). In normal upright sitting with a backrest, approximately 75% of the body weight is transferred through the seat (Swearingen
et al., 1962). 75% of 30 stones is equivalent to 1400 N. At this load the average pressure for the Intelli-Gel® Contour was 20% less than
the air cushion. It can be expected that the air cushion was performing at its optimum at 1400 N because this was the load under which
the inflation pressure was determined. In addition to these findings, the 250 kg weight limit specified by the manufacturer of the air cell
cushion and the use of the visco-elastic & PU cushion on chairs with 30 stone weight limits would indicate that a 30 stone maximum
user weight recommendation for the Intelli-Gel® Contour would be appropriate.
Although it is acknowledged that there is a requirement for the cushion to be sold with a maximum user weight recommendation, it is
not possible to use body weight to predict the risk of an individual developing a pressure ulcer. Load transfer to a cushion will reflect
both mass and area. For example, people with little tissue can deform a cushion disproportionate to their body mass. Each individual
must be assessed and monitored when there is a risk of a pressure ulcer.
The strength and durability of the cushion should also be considered when determining the maximum user weight limit. For
people at risk of or with pressure ulcers, the reliability for the cushion to deliver a consistent performance is important to ensure safety.
The Intelli-Gel® Contour was pound tested to BS EN ISO 3385:1995 and the result was Class X, Extremely Severe Use. Recommended
applications for this class are heavy duty contract seats and heavy duty public transport seats.
5.Conclusion
The results from this investigation would support a 30 stone (190 kg) maximum user weight recommendation. This recommendation
should be given in the form of guidelines to inform the cushion selection process however body weight cannot ensure user safety so
clear instruction for clinical consultation should be included.
6.References
Swearingen, J., Wheelwright, C.D., Garner, J.D., 1962. An Analysis of Sitting Areas and Pressures of Man. Oklahoma City, Federal Aviation
Administration
25
26
Research Report 3
Clinical Evaluation of the
Intelli-Gel® Integral Cushion in a
Nursing Home
1
Fiona Collins MSc, 2 Stephen Young PhD, 3 David Wickett MA
Tissue Viability Consultancy Services Ltd, UK;
Independent Skin Science Consultant, UK;
3
The Kirton Healthcare Group Ltd, UK
1
2
Abstract
Aim of the evaluation
To evaluate the Intelli-Gel® Integral cushion in order to examine its effect on contributing to the prevention of pressure ulcer damage.
5 residents in a nursing home with existing pressure ulcers participated in a 4 week evaluation (mean age 89, range 78-96; mean
Waterlow Score 24, range 19-31). Intervention was exchange of the volunteers’ existing pressure relieving cushions with the Intelli-Gel®
Integral cushion. Clinical inspection of skin quality and high definition ultrasound measurements were carried out at the beginning of
the evaluation, after 14 days and at the end of the 4 weeks period. Data was collected from all volunteers at day 14, however only three
completed the evaluation.
Results
Both visual inspection and ultrasound measurements showed healing at day 14 for all cases, with particular significance for those with
Grade II pressure ulcers. At the end of the trial, there was no evidence of pressure damage for the 3 remaining volunteers. In addition,
volunteers and nursing staff reported that the cushion increased comfort, improved sitting posture and tolerance.
Conclusions
Based on this evaluation, the Intelli-Gel® Integral cushion has potential to be beneficial for individuals at very high risk of developing
pressure ulcers, and for those individuals who have pressure ulcers up to Grade II. It was envisaged that improvement in skin quality
would be due to the pressure redistribution characteristics of the material but the results indicate that the cushion is also acting as a
positional device preventing posterior pelvic tilt and unloading the sacrum.
Keywords: pressure ulcer; seating; cushions; prevention
27
1Introduction
The Intelli-Gel® Integral cushion is a new cushion designed to reduce the occurrence of pressure damage in people in long term care.
The cushion contains a unique gel component that has an open lattice design measuring 330 mm x 305 mm x 44 mm (Figure 1).
The Intelli-Gel® Integral cushion was bench tested at The Rehabilitation Engineering and Applied Research Lab, Georgia Tech University,
using an ISO buttock model (Figure 2). The Intelli-Gel® Integral cushion was evaluated against a standard polyurethane foam cushion,
a polyurethane foam cushion with a visco-elastic foam topper, and a commercially available air bladder wheelchair cushion that is
inflatable to be customised to the individual. The results indicated that the Intelli-Gel® Integral cushion has the potential to reduce high
pressures associated with the ischial tuberosities, exhibiting the lowest recorded pressures in this region at loads equal to or below 70
kg.
The purpose of this evaluation is to explore the effectiveness of the Intelli-Gel® Integral cushion in a small cohort in long term care.
28
Figure 1. Intelli‑Gel® cushion insert (330 mm x 305 mm x 54 mm)
Figure 2. The ISO buttock model used for bench testing at The Rehabilitation
Engineering and Applied Research Lab (REAR) at Georgia Tech University
2
2.1Volunteers
Volunteers were 5 residents in a nursing home who were considered to be at high risk of developing pressure damage, or who had
existing pressure damage (no greater than Grade II, EPUAP). All volunteers had profiling beds and alternating air mattresses but poor
seating provision. None of the participants were able to independently transfer, all requiring hoisting. All of the participants were
doubly incontinent. All of the participants had poor nutritional intake, despite taking supplements. Volunteers were visited prior
to commencement of the evaluation in order to collect demographic data (Table 1). Informed consent was provided by either the
volunteers or those responsible for their care. The research activity undertaken by the Tissue Viability Consultancy Services Ltd complies
with the Declaration of Helsinki, 1964.
Table 1. Demographic data at beginning of the evaluation
Volunteer Age
Sex
Waterlow
General health
score
Cushion prior
to the evaluation Number of hours
spent sitting
1
96
Female
19
Cardiac failure, general frailty
Propad
5-6
2
92
Female
21
Angina: CVA
Castellated foam
Variable, but normally 5-6
3
78
Female
25
Alzheimer’s disease: frailty
Propad
7-8
4
93
Female
26
CVA; frequent falls; immobility Medform-visco
Varies greatly between
2-8. Volunteer
normally very unsettled
5-6
5
85
Female
31
Alzheimer’s disease: frailty
Propad
2.2 High Definition Ultrasound
High frequency diagnostic ultrasound is a non-invasive method, which allows the clinician to obtain a high-resolution image of the
wound bed (Young and Ballard 2001, Chen et al., 2001, Mirpuri and Young 2001, Kerr et al., 2006, Quintavalle et al., 2006, Young et al.,
2008, Hampton et al., 2008, Hampton et al., 2009). The technique allows the clinician to measure oedama in the skin and underlying
tissues. The presence of oedema in the tissues is one of the main indicators of the development of a Grade I pressure ulcer. Oedema
will be present at any site that has incurred some sort of damage and is the body’s natural response to this damage. Measurements of
oedema are taken at both the pressure sore site and at neighbouring uninjured, normal skin for comparison. The ultrasound measures
from the skin surface to a depth of approximately 10 mm.
The scanner used (Figure 3) operates at a range of frequencies from 20MHz to 50 MHz (Episcan - Longport Inc.). This frequency gives an
axial resolution of 20 - 65µm.
29
Figure 3. High Frequency Diagnostic Ultrasound Scanner
30
2.2.1High Definition Ultrasound Scan Analysis
Each scan is analysed using a form of pixel distribution analysis whereby pixels below a certain intensity are classed as Low Echogenic
Pixels (LEP). The ratio of LEP’s to Total Pixel count (TP) has been shown to reflect changes in dermal water content (Gniadecka 1996,
Gniadecka and Quistorff 1996). Using this technique it is possible to get a quantitative assessment of the level of oedema present in
tissues. Figure 4 shows the scan of one volunteer’s normal skin and Figure 5 shows the scan of the pressure ulcer.
In order to show the extent to which each volunteer’s skin had returned to normal, the data were inserted into Equation 1, and presented
as a percent reduction of oedema towards normal skin. Here, the LEP/TP value for normal skin represents zero and the LEP/TP value for
the first assessment represents 100%. The percent of improvement within this range is then shown after day 14 and then day 28 for
each case.
% oedema reduction = 100[1-(lt-ln)/(l0-ln)](1)
Where,
ln = LEP/TP normal skin
l0 = LEP/TP day 0
lt = LEP/TP treatment (either 14 days or 28 days)
Figure 4. The ultrasound scan of one volunteer’s normal skin.
31
Figure 5. The ultrasound scan of one volunteer’s pressure sore. The images
shows that the deeper layers of the skin is saturated with oedema
2.3Protocol
2.3.1Day 0
All volunteers remained in bed prior to assessment. The skin of each participant was examined for signs of pressure damage.
Photographs were taken of any areas in the buttocks/sacral region that exhibited signs of pressure damage. A high definition ultrasound
scan was taken of each participant’s pressure ulcer and adjacent normal skin. The normal skin was scanned to establish a profile of what
the uninjured tissue looks like.
The volunteers existing pressure redistributing cushions were removed from their armchairs and replaced with the Intelli-Gel® Integral
cushions. The seat bases that supported the cushions were rigid. Volunteers were then mobilised in accordance with their care plan.
2.3.2Day 14 and 28
The above methodology was repeated, with the exception that the Intelli-Gel® Integral cushion remained in the armchair throughout the
period of the evaluation. Therefore none of the volunteers used their old cushion during the period of the evaluation.
3Results
3.1 Visual Inspection of Skin Quality
On day 0, the first assessment revealed that all of the volunteers had pressure ulcers up to Grade II (Table 2). The skin quality on all of
the volunteers showed marked signs of improvement in their sacral and buttocks regions after using the Intelli-Gel® Integral cushion.
The improvement was seen on both day 14 and day 28. Of particular note were volunteers 1 and 5. Both of these had Grade II pressure
damage noted at the initial assessment, but both volunteers’ wounds showed significant signs of improvement during the second
assessment on day 14, as evident by the photographs in Figures 6-10.
Unfortunately volunteer 1 developed a chest infection the week prior to the final assessment and died the day before this. Volunteer
5 also developed a chest infection in the week prior to the final evaluation and had remained in bed for that week. It was therefore
considered inappropriate to reassess her, as the results could not have been related to the cushion.
On day 28 volunteers 2, 3 and 4 were assessed for the final time. None of these volunteers showed any evidence of pressure damage.
32
Table 2. Results for the ultrasound measurements
LEP:TP Ratios
% reduction towards normal skin
Existing
Volunteer
pressure ulcer Normal skin
Day 0
Day 14
Day 28
Day 14
0.46
0.38
27%
1
Grade II
0.16
Day 28
2 Grade I
0.140.560.390.13 40% 102%
3 Grade I
0.190.520.31 0.3 64% 67%
4Grade I
0.190.370.30.23 39% 78%
5
Grade II
0.2
0.45
0.41
16%
Figure 6. Volunteer 1. Day 0. Marked erythema over sacral and buttock region
33
Figure 7. Volunteer 1. Day 0. Skin moved to reveal a Grade 2 pressure ulcer
Figure 8. Volunteer 1. Day 14. Significant improvement was seen in the
pressure ulcer, which was now superficial and commencing epithelialisation.
Erythema of the surrounding skin was no longer present.
34
Figure 9. Volunteer 5. Day 0. Grade II pressure ulcer and marked erythema
over the sacral area
Figure 10. Volunteer 5. Day 14. Significant improvement was seen in the
pressure ulcer, which was now superficial and commencing epithelialisation
35
3.2 High Definition Ultrasound
Table 2 gives the results from the ultrasound measurements. The results show that for volunteer 1, oedema had reduced by 27% towards
that of the normal skin. For volunteer two, this reduction was 40% at day 14, and 100% for day 28. For volunteer 3, this was 64% at day
14 and 67% at day 28. A reduction of 39% at day 14 and 78% at day 28 was measured for volunteer 4, and a 16% reduction at day 14
was measured for volunteer 5.
4
Discussion
The result from this investigation indicate that the Intelli-Gel® Integral cushion can contribute to the healing of pressure sores up to
Grade II, as assessed by visual inspection and measured by high definition ultrasound.
Previous laboratory research had shown excellent pressure redistributing characteristics of the Intelli-Gel® Integral cushion.
Furthermore, gel has a high specific heat capacity and the Intelli-Gel® Integral insert has an open structure that would appear to be
beneficial in terms of moisture transport. Although these factors are known to contribute to reducing the risk of tissue damage, the
effects observed in the present investigation may be more closely linked to posture. It was observed that all of the volunteers’ sitting
posture was much improved using the Intelli-Gel® Integral cushion. Previously, their posture had tended to be asymmetrical and
unstable, with all volunteers tending to adopt a posterior pelvic tilt as they slid downwards in the chair. The pressure damage found in all
volunteers was consistent with sliding, as this tended to be over their sacrum. In the case of volunteer 1 and 5 in particular, the pressure
damage over the sacrum was attributed to friction and shear forces. When using the Intelli-Gel® Integral cushion the volunteers’
sitting posture was far more symmetrical and stable. They tended to remain upright in the chair, rather than sitting in a posterior pelvic
tilt and this could account for the improvement seen on the skin in the sacral area of all volunteers, as weight had been transferred
appropriately onto the ischial tuberosities.
It is possible that nursing staff were more motivated to better position the volunteers during the course of the evaluation. Since there
was no control group, the influence the investigation had on the care of the volunteers cannot be determined. The evaluation was done
in the same nursing home with the same nursing staff.
It is possible that the cushion architecture helped to stabilise the pelvis in an appropriate position. The Intelli-Gel® Integral material is
encased in polyurethane foam on all sides except the user interface surface. It is likely that there is more immersion into the Intelli-Gel®
than the foam border, resulting in increasing structure and support towards the edges of the cushion that could resist sliding, posterior
tilt and obliquity. This in turn could inhibit fidgeting. Not all of the volunteers were able to communicate their levels of comfort/
discomfort, but those who could, reported that the Intelli-Gel® Integral cushion provided improved comfort compared to their original
pressure reducing cushion. However, the nursing staff also reported that the volunteers appeared to be far more comfortable. Of
particular note were volunteers 3 and 4, whose agitation and restlessness when sitting was significantly diminished.
Probably for the reasons above, all of the volunteers were able to sit for longer periods of time in comparison to previously, particularly
volunteer 3. On average sitting tolerance was extended by two hours for each volunteer.
5Conclusion
Based on this evaluation alone, the Intelli-Gel® Integral cushion shows potential in contributing to healing pressure ulcers up to Grade II,
and as an aid to preventing pressure ulcers for those at very high risk. Furthermore, the use of the Intelli-Gel® Integral cushion enabled
all of the volunteers to sit more comfortably, with an upright and symmetrical posture, for longer. A larger control study involving a
modification to this protocol would be the next logical step towards understanding how these findings can be generalised to the wider
population.
36
6
Conflict of Interest Statement
The research lead of this investigation, Fiona Collins, is a Director of Tissue Viability Consultancy Services Ltd and was commissioned
by The Kirton Healthcare Group Ltd to conduct this investigation. The Kirton Healthcare Group Ltd has an ongoing professional
relationship with Tissue Viability Consultancy Services Ltd, having worked together to provide training days for Occupational Therapists.
Dr Stephen Young is an associate of Tissue Viability Consultancy Services Ltd and was employed to work on this project.
David Wickett, corresponding author, is the Design Manager of The Kirton Healthcare Group Ltd..
7Acknowledgements
The authors would like to thank the volunteers and nursing home staff who kindly took part in this evaluation.
Role of the funding source
This research was sponsored by The Kirton Healthcare Group Ltd. Kirton’s involvement in this evaluation is via the corresponding author
David Wickett, who is an employee of the company. His involvement was in the analysis and interpretation of the empirical data and in
contributing to the writing of the manuscript.
8
References
European Pressure Ulcer Advisory Panel
Chen, L., Dyson, M., Rymer, J., et al., 2001. The use of high frequency diagnostic ultrasound to investigate the effect of HRT on skin
thickness. Skin Research and Technology 7(2): 95-7
Gniadecka, M., 1996. Localization of dermal edema in lipodermatosclerosis, lymphedema, and cardiac insufficiency: high-frequency
ultrasound examination of intradermal echogenicity. J Am Acad Dermatol. 35:37-41
Gniadecka, M., Quistorff, B., 1996. Assessment of dermal water by high-frequency ultrasound: comparative studies with nuclear
magnetic resonance. Br J Dermatol. 135:218-224
Hampton, S., Young, S., Bree-Aslan, C., et al., 2009. Parafricta material: can it reduce the potential for pressure damage? Journal of
Community Nursing 23(4): 28-31
Hampton, S., Young, S., Kerr, A., 2008 Treating Sinus Wounds. Journal of Community Medicine 22(6):30-32
Kerr, A., Young, S., Hampton, S., 2006. Has packing sinus wounds become a ritualistic practice? British Journal of Nursing 15(19): S27-S30
Mirpuri, N., Young, S.R., 2001. The use of diagnostic ultrasound to assess the skin changes that occur during normal and hypertensive
pregnancies. Skin Research and Technology 7:63-69
Quintavalle, P., Lyder, C.H., Mertz, P.J., et al., 2006. Use of high-resolution, high frequency diagnostic ultrasound to investigate the
pathogenesis of pressure ulcer development. Adv. Skin & Wound Care 19(9):498-505
Young, S.R., Ballard, K., 2001. Wound Assessment: Diagnostic and assessment applications – Part 2. In: Electrotherapy-Evidence based
practice. Churchill-Livingstone (London) pp 308-312
Young, S., Bolton, P.A., Downie, J., 2008. Use of high-frequency ultrasound in the assessment of injectable dermal fillers. Skin Research
and Technology 1(14): 1-4
37
38
Research Report 4
Laboratory Bench Testing of the
Intelli-Gel® Integral Cushion using
an Instrumented Buttocks Model
1Introduction
A new pressure relieving seat cushion for long term care had been developed by The Kirton Healthcare Group Ltd. In-house testing using
XSENSOR Pressure Imaging had shown potential for the new Intelli-Gel® Integral cushion to be positioned next to the market leaders
for pressure redistribution. Although very positive, there was concern that the results could be biased since the testing was carried out
internally at The Kirton Healthcare Group Ltd. Furthermore, a recent study showed that pressure mats exhibit poor repeatability (Pipkin
and Sprigle 2008). To verify the in-house findings, the Rehab Engineering and Applied Research Lab (REAR) at the Georgia Institute of
Technology were commissioned to undertake independent tests using a more repeatable method involving an instrumented buttocks
model.
The data from REAR corroborate the data collected using the XSENSOR system. The new Intelli-Gel® Integral cushion resulted in
lower interface pressures under the ischial tuberosity (IT) region than the air cushion at loads equal to or below 70 kg (11 stones). At
these loads, pressures at the IT site were approximately 33% lower than the visco-elastic cushion; and 47% lower than the standard
polyurethane cushion. The data from REAR indicated relatively high pressures at the greater trochanter site for the Intelli-Gel® Integral
cushion however the buttocks model does not include the thighs where pressures would normally be shared. The Intelli-Gel® Integral
cushion was assessed in a follow-up test using the XSENSOR Pressure Imaging System and a human volunteer side leaning. No signs of
high pressures at the greater trochanters were observed. Higher pressures towards the outer margins of the buttocks could be beneficial
in terms of sitting stability.
2
A prototype Intelli-Gel® Integral cushion wrapped in a fire retardant barrier fabric, a visco-elastic foam cushion (with a polyurethane
core), a single valve air cushion and a standard polyurethane foam cushion were compared. Pressures were measured at multiple
locations along the midline of an instrumented buttock model (Figure 1). The cushions were measured five times a day, over three days,
for three loading conditions corresponding to body masses: 56, 70 and 84 kg. The inflation pressure of the air cushion was readjusted for
each loading condition. All testing was carried out independently by technicians at REAR.
Figure 1. The REAR instrumented buttocks model showing pressure sensors
39
3Results
The mean pressure for each test day, and average of all days are given in Table 1 for the IT sensor with an 84 kg load. Table 2 and 3
present the IT sensor pressures for a 70 and 56 kg load respectively.
Table 1. IT sensor pressure data (mmHg) loaded to 84 kg
Day
Polyurethane cushion
Visco-elastic
foam cushion
Intelli‑Gel®Air
cushion
cushion
1
144.46
86.74
79.6
68.06
2
155.07
100.68
84.22
68.17
3 138.4187.3263.12
50.97
AVG
145.9891.5875.6562.4
40
Day
Visco-elastic
foam cushion
Intelli‑Gel®Air
cushion
cushion
1 95.0366.1947.68
42.39
2
106.31
79.3
51.96
79.3
3 92.9767.0644.37
39.39
AVG 98.170.8548.01
53.69
Day
Visco-elastic
foam cushion
Intelli‑Gel®Air
cushion
cushion
1 61.8453.5330.55 46
2 72.8365.8144.16
42.27
3 60.7554.6336.65
39.43
AVG65.1457.9937.12
42.57
4
Discussion
The data from REAR suggest that for an 84 kg load, the visco-elastic foam cushion reduces IT pressure relative to the standard
polyurethane foam by 37%, for a 70 kg load there is a reduction of 28% and for a 56 kg load there is a reduction of 11%. REAR supplied
the polyurethane foam cushion which had a 76 mm thickness. The visco-elastic foam was 90 mm thick so the reduction in IT pressure
could result in part from the additional thickness. The Intelli-Gel® Integral cushion was also 90 mm thick so comparisons are made to the
visco-elastic cushion.
The data indicate that for an 84 kg load, the Intelli-Gel® Integral cushion reduces IT pressure by 17% when compared to the visco-elastic
foam cushion. For a 70 kg load the Intelli-Gel® Integral cushion reduces IT pressure by 32% and for a 56 kg load IT pressure is reduced by
36%.
Under an 84 kg load, the air cushion reduces IT pressure relative to the visco-elastic foam cushion by 32%, under a 70 kg load by 25%
and for a 56 kg load 27%.
Taken over all load conditions, these data suggest that when compared to the visco-elastic foam cushion, both the Intelli-Gel® Integral
and air cushion result in similar reductions of IT pressures (27% and 28% respectively). At loads equal to or lower than 70 kg, the IntelliGel® Integral cushion appears to be more effective in reducing IT pressures than the air cushion.
When comparing the pressures at the most distal sensor between the Intelli-Gel® Integral cushion and the visco-elastic foam cushion
it can be seen that the Intelli-Gel® Integral cushion results in higher pressures by a factor of approximately 2.5. These sensors could be
considered to represent the greater trochanters. Tables 4 and 5 show the pressure data for the IT and greater trochanter sensors for the
different load conditions and the difference between these two sites for the Intelli-Gel® Integral cushion and visco-elastic foam cushion
respectively. These data show that for the Intelli-Gel® Integral cushion, there is more pressure at the greater trochanter than in the IT
area, whereas there is more pressure in the IT area and less at the greater trochanter for the visco-elastic foam cushion. An explanation
for why the Intelli-Gel cushion is redistributing pressure to the outer margins of the buttock could be in the claims made by the inventors
of the Intelli-Gel® material. They claim that Intelli-Gel® redistributes pressure due to the ‘column buckling’ principle. For areas of high
pressures (in this case the ITs) the gel columns buckle and pass the loading onto larger surface areas where the pressures are lower
(in this case the surfaces surrounding the ITs). In these lower pressure areas, the gel column do not buckle and support the body. Low
pressures are associated with the buckled columns because they have low spring-back forces. The ability of the Intelli-Gel® Integral
cushion to redistribute interface pressure to the outer margins of the buttocks could be beneficial when considering sitting stability by
‘framing’ and securing the buttocks.
Table 4. Pressure data (mmHg) for the IT and greater trochanter sensors at different load
conditions for the Intelli-Gel® Integral cushion
Load
84 kg
70 kg
56 kg
IT
Trochanter
75.65
48.01
37.12
92.2
86.09
72.91
Difference
+16.56
+38.09
+35.79
41
Table 5. Pressure data (mmHg) for the IT and greater trochanter sensors at different load
conditions for the visco-elastic foam cushion
Load
84 kg
70 kg
56 kg
IT
Trochanter
91.58
70.85
57.99
47.51
30.4
19.98
Difference
-44.07
-40.45
-38.01
The instrumented buttocks model developed at REAR is capable of producing repeatable results to help to differentiate between
cushions. REAR have explained that they switched to this method of testing from using commercially available pressure mapping
systems because they found it was not possible to gain repeatable results in equal conditions with pressure mapping systems. Caution
is needed however when interpreting the data from the buttocks model. The model represents the pelvis of the body only (Figure 1). The
thighs are not represented in this model. The results of this laboratory study have shown redistributing characteristics of the Intelli-Gel®
Integral cushion, probably due to column buckling at the high pressure regions of the ITs. Since the thighs are not represented in the
buttock model the only area where pressure can redistribute to is the outer margins of the buttocks and the greater trochanter sensors.
With the human body, these pressures would be shared across the thighs so they could be lower.
Follow up measurements were made to test this hypothesis. Interface Pressure Imaging data were collected from one 58 year old
ectomorph male (BMI 19.4) in normal sitting, side leaning to the left and side leaning to the right. These data were collected at The
Kirton Healthcare Group Ltd and the intention was to deliberately load the greater trochanters. Figures 2 – 4 show the resulting pressure
maps which show no signs of high pressures at areas that could be associated with the greater trochanters.
Figure 4. Normal sitting on the Intelli-Gel®
Integral cushion
42
Figure 5. Side leaning to the left on the Intelli-Gel®
Integral cushion
Figure 5. Side leaning to the right on the Intelli-Gel®
Integral cushion
5Conclusion
The data from REAR verify the results from the in-house tests and indicate that the Intelli-Gel® Integral cushion reduces IT pressure to a
similar magnitude to air cushions, and could therefore be positioned alongside the market leaders for pressure relief. The data show that
the Intelli-Gel® Integral cushion redistributes pressure to the distal margins of the buttocks which could be advantageous in terms of
cushion stability. Subsequent in-house interface pressure imaging showed no evidence of any risk of tissue damage around the greater
trochanters.
It is recommended that a clinical study using volunteers representative of the intended end users be carried out to validate the
effectiveness of the cushion and to determine what medical claims are appropriate.
6References
Pipkin, L., Sprigle, S., 2008. Effect of model design, cushion construction, and interface pressure mats on interface pressure and
immersion. Journal of Rehabilitation Research and Development 45(6): 875-882
43
44
Research Report 5
Research and Development of
Patient Support Surfaces using
XSENSOR Pressure Imaging
1Introduction
The R&D team at The Kirton Healthcare Group Ltd carried out research to source current and future materials for seat cushions that
could help to reduce the risk of pressure ulcers. The first part of this report evaluates those materials in varying combinations and with
different types of base supports using the XSENSOR Pressure Imaging System and one test subject. The findings indicate a trend where
all material combinations that involve the Intelli-Gel® material result in the lowest Peak Pressure Index values.
The second part of this report describes the process of developing a cushion that incorporates Intelli-Gel® for seating in long term care.
Data were collected from two adults (one mesomorph and one ectomorph) and two children over the course of the cushion development
using the XSENSOR Pressure Imaging System. The final cushion specification is benchmarked against a visco-elastic pressure relieving
foam cushion and a single valve air cushion that is customised to the individual’s weight.
The results indicate that the final cushion specification has superior pressure redistributing qualities when compared to the visco-elastic
foam cushion, and exhibits similar pressure characteristics to the air cushion. It is recommended that the final specification be tested in
an independent laboratory to verify these results.
2
2.1 Research into current and future materials
The criteria for the selection of materials included cost, the ability to provide a therapeutic effect over a relatively large surface area (as
opposed to a specific site such as directly under the ischial tuberosities), a performance unaffected by seat tilt (fluid bags for example
were rejected because they pool when tilted) and no need for set-up or adjustment for multiple users. In addition to redistributing
pressure, the ability of the materials to reduce shear, maintain a dry interface and to preserve skin temperatures were important
functional parameters. A list of the materials collected is given in Table 1, with accompanying images in Figures 1-10. The materials
were tested in various combinations, and are described as having a core material and one or more toppers. Variations in the cushion
support were investigated with a rigid flat base, a rigid contoured base and a contoured elastomeric mesh base (Figures 11). Table 1
gives scores for the likely benefit of each material in terms of vapour permeability and specific heat capacity. Specific heat capacity
relates to the amount of energy required to heat a material, i.e. materials with a low specific heat capacity heat up easily. An air cushion
that can be customised to the individual is also included for benchmarking data as this was considered a market leader for pressure
redistribution in static cushions (Figure 12). All cushions were evaluated on a multi-adjustable test-rig (Figure 14).
45
Table 1. Selection of materials, with scores for vapour permeability and specific heat capacity
46
Material/technology
Thickness
(mm)
Phase 1
research
Topper
Core
Other complete cushions
Base
Flat gel
Castellated gel
Soft spacer fabric
Firm spacer fabric
Red Intelli‑Gel®
Blue Intelli‑Gel®
Yellow visco-elastic foam
Blue visco-elastic foam
Core spacer fabric
400 density polyurethane foam
Water-cell cushion (manufactured in 2003)
Water-cell cushion (new foam)
100% blue visco-elastic foam
100% yellow visco-elastic foam
Commercial visco-elastic cushion
Rigid flat
Rigid contoured
Flexible contoured (elastomeric mesh)
Phase 2
research
Topper
Core
Base
Other complete cushions
Red Intelli‑Gel®
Soft spacer fabric
Firm spacer fabric
Dacron
Deep Intelli‑Gel®
Rigid flat
Inflatable air cushion
Figure
Vapour High Specific
Permeable Heat Capacity
✗
15-18
1
20
2
✗
15
3
3
10
4
33
305 3
256 3
25
3
25
3
40
7
333
40
3
40
3
90
8
3
90
3
90
3
90
3
80
3
10
11
✓33
333
✗
✗
333
333
✗
✗
✗
✗
✗
✗
✗
✗
✗
✗
305 3
15
3
3
10
4
33
25
3
609 3
40
3
40
3
12
3
333
✗
✗
✗
333
✗
✗
✗
Figure 1. Flat gel
Figure 2. Castellated gel
47
Figure 3. Firm spacer fabric
Figure 4. Soft spacer fabric
Figure 5. Red Intelli‑Gel®
Figure 6. Blue Intelli‑Gel®
Figure 7. Core spacer fabric Figure 8. Water-cell cushion
Figure 9. Deep Intelli‑Gel®
Figure 10. Commercial visco-elastic cushion
Figure 11. Flexible contoured (elastomeric mesh)
Figure 12. Air inflatable bladder cushion
48
49
Figure 13. Test-rig and XSENSOR Pressure Imaging system
2.2 XSENSOR Pressure Imaging System
The XSENSOR Pressure Imaging System was used to measure seat interface pressures (Figure 13). The system consists of a pressure
mat and an X3 sensor platform to provide a communication relay function and power for the pressure mat. The XSENSOR 4.3 Industrial
software was used for operating the system and collecting data.
The pressure mat is thin and flexible, and contains capacitive sensors. The mat consists of a 36 x 36 array of sensors (1296 measuring
points in total) and covers a sensing area of 457 x 457 mm. The sensor spatial resolution is 12.7 mm, with no gaps between sensors. The
advantages of capacitive sensors are high repeatability, high accuracy, low hysteresis, and no need for frequent calibration, as is the
case for resistive sensors (Mootanah & Bader, 2006). In addition, the study by Pipkin and Sprigle (2008) suggested a low perturbation
error with the XSENSOR mats. The pressure range is 10–200 mmHg, and the manufacturer claims an accuracy of 10%. Prior to the
testing, the sensor mat was sent to the manufacturer for calibration.
2.3Protocol
2.3.1Stage 1
Thirty two cushion permutations were measured during the first stage of this research. Data were collected from one subject only due
to the time required for completion. Once the cushion and sensing mat had been fitted to the test-rig, the subject sat for a 10 minute
stabilisation period prior to data collection. This was to allow for creep in the cushion, sensors and body tissues to stabilise. 10 minutes
was found to be necessary since visco-elastic foams had been included which require ‘warming up’ to reach their maximum benefit.
Immediately following the stabilisation period, data were recorded for 36 seconds with the subject remaining as still as possible. This
recording period was then repeated twice, with a 5 minute recovery period between measurements. Each data set therefore contained 3
recordings.
2.3.2Stage 2
The second part of this research focused down on developing a cushion built around the Intelli-Gel® material. More samples of
the Intelli-Gel® material varying in gel type, wall size, grid density, column height and manufacturing techniques were supplied for
further investigation. The pressure distributions of material combinations incorporating these Intelli-Gel® samples, visco-elastic and
polyurethane foams, and spacer fabrics were compared in an iterative process to filter down towards a final specification. This final
specification was then benchmarked against a standard polyurethane foam cushion, a commercially available visco-elastic foam
cushion (with a polyurethane core) and a commercially available air cushion. The results of the benchmarking tests are reported here.
The protocol underwent modifications during this second stage of research depending on the temperate and creep characteristics
of the materials being compared. The base support was standardised to flat plywood. Two adult males, one mesomorph aged 30 and
one ectomorph aged 58, and two children participated at different stages of this process. The benchmarking data on the final cushion
specification are from the 30 year old male. The first comparison had a 5 minute stabilisation period for each cushion, with the subject
repositioning between measurements. Each data set contained 3 recordings which were then averaged. A different protocol was used
for the visco-elastic foam cushion. This had a 10 minute stabilisation period and the subject did not reposition between measurements.
This was in an attempt to ‘warm up’ the visco-elastic foam. The Intelli-Gel® and air cushions were compared again in two subsequent
test sessions. Interface pressure data is also reported for the air cushion where it was first maximally inflated, and then for each deflation
level until eventually bottoming out.
2.4 Interpretation of interface pressure data
50
The interface pressure variable selected for comparing all data was Peak Pressure Index (PPI). PPI is the mean of the highest recorded
pressure values within a 9-10 cm² area (approximately the contact area of an ischial tuberosity and other bony prominences) under one
of the loading-bearing surfaces (ischial tuberosities, greater trochanters, and sacrum/coccyx). Analysing single sensor peak pressures
proves problematic because it is an unstable measure that exhibits poor repeatability (Sprigle, et al., 2003). Average pressure is reliable
but not very volatile because a lot of body weight is concentrated on only a portion of the surface area of the mat. Hence, calculating a
mean pressure value loses much meaning (Sprigle, et al., 2003).
3Results
The means and standard deviations for the stage 1 part of this research are presented in Table 2 and Figure 14. The data from the final
cushion specification resulting from stage 2 are given in Table 3 and Figure 15. Figure 16 gives data on the effect of different inflation
pressures for the air cushion on interface pressure.
Table 2. Mean Peak Pressure Index (mmHg) and Standard Deviations from Stage 1
Ref Topper
A1
B1
C1
D1
E1
F1
G1
H1
J1
K1
M1
N1
O1
P1
Q1
R1
S1
T1
U1
V1
W1
X1
Y1
Z1
A2
B2
C2
D2
E2
F2
G2
H2
Red Intelli‑Gel®
Firm spacer fabric + red Intelli‑Gel®
Red Intelli‑Gel®
Red Intelli‑Gel®
Blue Intelli‑Gel®
Firm spacer fabric + red Intelli‑Gel®
Red Intelli‑Gel®
Water-cell cushion (used)
Castellated gel
Firm spacer fabric + red Intelli‑Gel® + soft spacer fabric
No topper
Red Intelli‑Gel® + soft spacer fabric
Water-cell cushion (new)
Red Intelli‑Gel®
Water-cell cushion (used)
Soft spacer fabric
Firm spacer fabric
Water-cell cushion (new)
Castellated gel
Soft spacer fabric
Red Intelli‑Gel® + soft spacer fabric
Firm spacer fabric
100% blue visco-elastic foam
Commercial visco-elastic cushion
Flat gel
100% yellow visco-elastic foam
Core
Base
Mean PPI
STDEV
400 PU
400 PU
Core spacer fabric
400 PU
400 PU
400 PU
650 PU
400 PU
400 PU
400 PU
400 PU
400 PU
400 PU
Core spacer fabric
400 PU
Core spacer fabric
400 PU
650 PU
Core spacer fabric
Core spacer fabric
650 PU
650 PU
650 PU
400 PU
400 PU
Flexible Contoured
Flexible Contoured
Flexible Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Rigid Flat
Rigid Contoured
Rigid Contoured
Rigid Flat
Flexible Contoured
Rigid Contoured
Rigid Contoured
Rigid Flat
Rigid Contoured
Flexible Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Rigid Contoured
Flexible Contoured
Flexible Contoured
Rigid Flat
Rigid Contoured
Flexible Contoured
63.74
65.97
67.42
67.82
69.55
70.96
72.52
73.05
74.25
74.35
74.78
75.05
76.65
75.91
76.67
77.52
77.77
77.81
78
78.91
79.55
79.97
80.14
80.92
81.24
81.35
82.52
82.91
85.52
89.43
90.19
96.95
2.33
3.99
3.69
4.31
3.18
4.21
3.72
1.8
2.32
1.49
4.76
1.91
1.9
1.23
1.08
1.04
4.32
2.48
1.56
1.55
3.48
5.07
3.87
1.79
2.55
3.57
1.62
3.11
4.33
1.69
7.36
5.23
51
105.00
100.00
95.00
90.00
85.00
80.00
75.00
70.00
65.00
52
60.00
A1 B1 C1 D1 E1 F1 G1 H1 J1 K1 M1 N1 O1 P1 Q1 R1 S1 T1 U1 V1 W1 X1 Y1 Z1 A2 B
2 C2 D2 E2 F2 G2 H2
Cushion types
Figure 14. Mean Peak Pressure Index (mmHg) and Standard Deviations from Stage 1
Table 3. Mean Peak Pressure Index (mmHg) and Standard Deviations from Stage 2
Average
STDEV
Comparison 1
Comparison 2
Comparison 3
Air cushion
Intelli‑Gel® cushion
PU foam (650)
Air cushion
Air cushion
169.1
163.41
193.26
199.24
159.13
166.26
178.81
169.71
0.8
1.53
3.01
1.02
2.11
1.36
4.77
3.19
220
200
180
53
160
140
120
n
sh
cu
el
us
rc
In
te
lliG
Ai
io
hi
on
n
io
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cu
us
hi
on
el
tic
el
as
Vi
sc
o-
In
te
lliG
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m
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a
Ai
rc
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io
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(6
5
io
sh
PU
cu
el
In
te
lliG
Ai
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on
n
100
Cushion type
Figure 15. Mean Peak Pressure Index (mmHg) and Standard Deviations from Stage 2
195
190
185
180
54
175
170
165
160
155
150
145
9
8
7
6
5
4
3
2
1
Air cushion inflation level (9=maximum pressure, 1= miniumum pressure)
Figure 16. Peak Pressure Index values for an air cushion at various inflation levels
4
Discussion
Interface Pressure Imaging has been used by the R&D team at The Kirton Healthcare Group Ltd to help guide decision making through
the development of advanced pressure redistributing seat cushions for long term care. Although Pressure Imaging provides useful data,
there are limitations that need to be acknowledged when interpreting the results.
Firstly, the presence of the pressure mat at the body/support interface has an effect on the true pressures that would exist normally.
This is known as the perturbation error. Pipkin and Sprigle (2008) evaluated the perturbation error for a number of different pressure
mats using two artificial buttock models to collect data. They found that all pressure mats affected the readings, and in general most
underestimated the baseline data which supports Diesing’s conclusions (2002). The perturbation error was different for each mat
depending on the cushion type, which suggests that different pressure mapping systems could rank cushions in different orders. Pipkin
and Sprigle (2008) found that the two pressure mats that had the least perturbation error were the ConforMat and the XSENSOR mat.
The authors also found pressure mapping to have limited repeatability.
During stage 2 of this research, data was collected from subjects that differed in body type which meant that inter-subject comparisons
could not be made statistically (Swain and Peters 1997). It was considered important however to evaluate the cushion with a
heterogeneous group in order to develop the best understanding of the cushion’s characteristics with the resources available at the
time. In addition to this the protocol was modified several times during stage 2 depending on the expected rate at which the cushion
would stabilise which again made it not possible to draw statistical comparisons between different test sessions. Only the benchmarking
on the final cushion specification is reported.
The results of stage 1 suggest that a trend may exist where all cushion combinations incorporating the Intelli-Gel® material result in
the lowest Peak Pressure Index values. In addition to the pressure redistributing potential of this material, it appears to be beneficial
for controlling skin temperature and moisture build up. Previous studies have shown that gel wheelchair cushions maintain a constant
skin temperature (Fisher et al. 1978, Stewart et al. 1980) whereas foams and visco-elastic foams have been demonstrated to increase
skin temperatures by 3.4C and 2.8C respectively (Stewart et al. 1980). Increasing skin temperature is undesirable because there is an
accompanying increase in metabolism (Bruetman and Gordon, 1971). It has been shown that a 1° increase in temperature increases
tissue metabolism by 10% (Ruch and Patton, 1965). Increasing tissue metabolism results in an increased demand for oxygen. If tissue
demand for oxygen is not met cell necrosis can happen. This supply and demand relationship is central to pressure ulcer development.
Therefore, the high specific heat capacity of gel makes it a very suitable material for use in seat cushions designed to reduce the risk of
tissue breakdown. A problem with gels that are commonly available on the market is that they are impermeable to vapour. The study
by Stewart et al., (1980) demonstrated that relative humidity at the skin/cushion interface increased by 22.8% with gels compared to
10.4% with foams. Increased humidity could compromise skin strength making it more prone to mechanical damage from shear stress
or abrasion. Furthermore, dry skin offers less risk of infection. The Intelli-Gel® material is different from conventional gels in that it has
an open lattice design which permits moisture to transport away from the skin/cushion interface and through the gel columns.
The manufacturers of Intelli-Gel® claim that the material is beneficial because of the ‘column buckling’ principle. Here, it is said that the
gel columns buckle under areas of peak pressure such as bony prominences but under other areas where pressure is evenly distributed
the columns remain structural and support the body. Thus, the Intelli-Gel® is said to eliminate high pressures. The R&D team at The
Kirton Healthcare Group Ltd found however that the Intelli-Gel® did not always respond the same way under applied load. On some
occasions the gel columns buckled as expected, but on other occasions there was more of a toppling over which can be likened to falling
dominos. Intelli-Gel® had been previously used in bed mattresses where this problem may not exist due to a much larger surface area
supporting the body when lying. However, in a seat cushion it appeared that the Intelli-Gel® needed some surface tension to help control
how the columns responded to the higher pressures. This was achieved by inserting the Intelli-Gel® into a foam border and fusing a light
weight non-stretch fabric to the face surface of the gel and foam surround. A foam base was also included which built up the cushion to
the require 90mm thickness, and gave the additional cushioning necessary for occasions when the Intelli-Gel® began to bottom out. An
additional advantage of this cushion design is that the foam border can be easily modified to produce a cushion of practically any size,
which is particularly beneficial for supplying the extensive range of seat sizes common in long term care.
The results from benchmarking the final specification are presented in Table 3 and Figure 15. Here, it can be seen that there is a
significant difference between the polyurethane and visco-elastic foam cushions compared to the Intelli-Gel® and air cushions. Of
the three comparisons between the Intelli-Gel® and the air cushions, the Intelli-Gel® cushion scored better in two. The reason for the
differences in these three comparisons is the inflation pressure of the air cushion. Figure 16 shows how the interface pressures change
as the inflation pressure changes. This suggests that the air cushion has the potential to produce very low interface pressures but that it
is difficult to hone in on the correct inflation pressure. During the benchmarking tests, the air cushion was tested three times but in only
one of those three tests was the cushion inflated to its optimum for that subject.
5Conclusion
Based on the work carried out by the R&D team at The Kirton Healthcare Group Ltd, the final specification for the Intelli-Gel® cushion
showed potential to exhibit similar pressure redistributing characteristics to adjustable air cushions, and could therefore be positioned
alongside the market leaders for pressure relief. An independent laboratory study would be the next logical step towards verifying these
findings, before moving to a clinical study.
55
6References
Bruetman, M.E., Gordon, E.E., 1971. Rehabilitating stroke patients at general hospitals. Postgrad Med. 49: 211-215
Diesing, P., Hochman, D., Boenick, U., 2002. Numerical accuracy of pressure mapping systems - a comparative evaluation. European
Pressure Ulcer Advisory Panel, ed.
Fisher, S.V., et al., 1978. Wheelchair cushion effect on skin temperature. Arch Phys Med Rehabil. 59: 68-72
Pipkin, L., Sprigle, S., 2008. Effect of model design, cushion construction, and interface pressure mats on interface pressure and
immersion. Journal of Rehabilitation Research and Development. 45(6): 875-882
Mootanah, R., Bader, D., 2006. Pressure sensors in biomedical engineering. In Wiley’s Encyclopaedia of Biomedical Engineering. John Wiley
and Sons, New York
Ruch, R.C., Patton, H.D., (eds) 1965. Physiology and Biophysics. ED 19, Philadelphia, Saunders. p 1046
Swain, I.D., Peters, E., 1997. The effects of posture body mass index and wheelchair adjustment on interface pressures. Evaluation Report
MDA/97/20. Medical Devices Agency
56
Stewart, S.F.C., Palmieri, V., Cochran, V.B., 1980. Wheelchair cushion effect on skin temperature, heat flux, and relative humidity. Arch
Phys Med Rehabil. 61: 229-233
Case Study 1
This case study describes the effect of Lichen Sclerosis on Anna, a six year old girl and how her symptoms were greatly alleviated by the
provision of an Intelli-Gel® cushion and mattress.
Anna is a vibrant six year old girl who was diagnosed with Lichen Sclerosus (LS) a disease considered to be rare, two years ago, following
numerous visits to paediatricians. Following diagnosis, she commenced a regime of creams and steroids in order to manage the disease
and alleviate her symptoms.
Lichen Sclerosus
LS is a chronic inflammatory, usually itchy dermatosis which usually affects the skin of the anogenital region in women and the glans
penis and foreskin in men (Powell & Wojnarowska, 1999). Women are more commonly affected than men (10 to 1 ratio), particularly
around and after menopause, but younger women or girls may also develop the disease. It is not an infection and is not contagious.
It occurs less commonly in extra-genital areas. It does not cause any systemic disease outside the skin. The most common groups to
be affected by it are middle aged and older women but it can occur in children. The cause of LS is unknown. Several risk factors have
been proposed, including autoimmune diseases, infections and genetic predisposition (Yesudian et al. 2005, Regauer, 2005). There is
evidence that LS can be associated with thyroid disease.
Aetiology
Although it is not clear what causes LS, four theories have been hypothesised:
•
•
•
•
Autoimmunity: In case of LS, specific antibodies have been found. Furthermore, there seems to be a higher prevalence of
other autoimmune diseases such as diabetes mellitus type 1, vitiligo and thyroid disease
Infection: Both bacterial as well as viral pathogens have been implicated in the etiology of LS.
Hormones: Since LS is primarily found in women with low estrogen levels, hormonal influences have been suggested, but
there is very little evidence to support this theory.
Local skin changes: Some findings suggest that LS can be initiated through scarring or radiation, although these findings were
sporadic and very uncommon.
Signs and Symptoms
Depending on the severity of the disease there may be absent or severe symptoms. For the majority of cases, early in the disease, small
white spots appear on the skin, which are shiny and smooth in appearance. Later, the spots grow into larger patches; this may be patchy
or involve the entire vulva extending down to the anus. Itching is the most common symptom and some people experience soreness and
burning. The skin may fissure or blister, causing stinging and pain. Small purplish/red areas may be seen on the white background. These
are due to tiny areas of bleeding into the skin, often because of scratching. There may also be thinning and shrinkage of the genital area
that may make coitus, urination and defecation painful.
Frequently, scar tissue develops. There may be scarring that causes loss of vulvar tissue (e.g. clitoris) or shrinkage of the vulvar areas,
which can cause pain and interfere with sexual intercourse and even cause problems urination. However, LS does not involve the vagina.
Children usually complain of itching and are constantly scratching and rubbing at their vulva. They may develop burning or pain with
urination and with bowel movement and may even develop constipation (Dalziel and Shaw, 2010).
The disease often goes undiagnosed for several years, as it is sometimes not recognized and misdiagnosed as thrush or other conditions.
It is not normally correctly diagnosed until the patient is referred for specialist intervention. It is estimated that lichen sclerosus affects
about 1 in 1,000 women. However, it may be more common due to misdiagnosis.
57
Treatment
There is no permanent cure for lichen sclerosus. However, treatment with a topical steroid usually controls the symptoms of itch and
soreness; it often prevents the condition from getting worse and prevents scarring (Neill et al, 2002). Occasionally, the condition clears
away for good for no apparent reason. This is more common in young girls when the condition often goes during puberty.
Introduction to Anna
Anna is a vibrant eight year old girl, who has a passion for Dinosaurs! She lives at home with her parents, brother and sister and tries to
lead a normal life. In the several months prior to referral to the seating therapist, Anna had experienced particularly severe symptoms.
Her LS had moved down to and around her anus, making it difficult for her to pass stools without pain; she required admission to hospital
for faecal impaction, for which she received a phosphate enema. (Anna takes Movicol every day and has for the last 2 years.) Anna
receives ongoing care from the dermatology department at her local District General Hospital. She uses an emollient and a topical
steroid every day, but although some days her skin appears asymptomatic, the following day the LS has returned. As a consequence
Anna has learnt to avoid things that hurt her ‘bottom’, like bike riding and swimming, preferring to pursue other interests. Anna’s pain
score has never been below 2- 3 (0 = no pain & 10 = unbearable pain), even on a day when her skin is apparently asymptomatic.
58
Anna’s severe pain was having an enormous impact on her ability to perform well as school. She found it impossible to sit properly on her
school chair, resorting to placing one foot under her bottom in order to lift her pelvis and soft tissue off the seat surface. This position
allowed her skin to breathe and remain as cool as possible. However, it was not comfortable for her and as a result, she was constantly
fidgeting in class. Anna was also absent from school at least two days per month due to her pain. Both of these factors were having a
detrimental effect on Anna’s schooling.
One of the most incapacitating effects of LS is disturbed sleep. As soon as Anna gets into bed the itching and irritation starts. The
summer months are particularly bad as the heat at night also seems to aggravate her symptoms.
Reason for Anna’s Referral to the Eastbourne Wound Healing Centre
Anna’s mother contacted the Eastbourne Wound Healing Centre in order to ask for independent advice on seating, as it had proven
impossible to obtain advice and help from other sources. Anna’s paediatric OT had neither seating experience nor a budget for
equipment provision and neither did her School Nurse. Anna’s mum had also approached the district nursing team for help, but as Anna
was under 18, they were not able to provide with either advice or equipment. Luckily a work colleague knew about the Wound Healing
Centre and suggested that she contact them; Anna’s mum was keen to purchase whatever equipment was required, but she was at a loss
to know what would be most appropriate. At this point in time, Anna was experiencing severe pain when sitting and as discussed above,
her attendance and performance at school placed her and her parents under severe duress.
Seating Assessment
Whilst Anna received a comprehensive seating assessment, it was clear that as she was an otherwise active child, she did not require
any form of specialist seating for either pressure relief or postural stability and support. Therefore the main goals of intervention were
identified as follows:
•
•
•
•
To provide comfort
To facilitate a cooling sensation on the buttocks and anogenital region
To promote a flow of air where possible
To maintain an appropriate seat to ground height for Anna when sitting on the school chair
The ultimate goal however was to enable Anna to participate more fully in school activities and if possible, reduce her absence.
Impact of the Intelli-Gel® Cushion on Anna
By pure chance, the seating therapist had in her possession a 1” thick Intelli-Gel® cushion from The Kirton Healthcare Group Ltd, which
she took with her for Anna to try. This just happened to be the correct size for the school chair and, due to the slim nature of the cushion,
allowed Anna to maintain contact with the floor. Anna immediately stated how comfortable the cushion was and was able to sit for over
10 minutes without fidgeting. Therefore it was agreed that she could keep the cushion on a trial period at school. In order to make the
cushion portable, Anna’s mum constructed a cotton drawstring bag. Anna therefore carried the cushion from class to class within the
school day, returning home with the cushion available to use in the evening. This cushion made a considerable difference to Anna at
school; she reports being much more comfortable and wherever she goes, “Mr Squidgy” (as she has named the cushion!), follows her.
Her teachers have observed a marked difference in her ability to concentrate in class; Anna has had fewer absences from school since
having the cushion because she feels more able to cope at school on ‘sore days’. When Anna was asked whether her school friends were
interested in her cushion and if she had had any questions, she replied that she had. When asked what she replies to her friends she
answers ‘because’!! Anna’s mum has witnessed a tremendous change in Anna and this has had a significant impact on family life. The
family is now able to go on days out and go on holidays, simply because Anna can now cope with sitting on long journeys.
Impact of the Intelli-Gel® Mattress on Anna
Following the success of the Intelli-Gel® cushion, Anna’s mum asked if it would be possible to try the Intelli-Gel® in a mattress to reduce
Anna’s symptoms during the night and to help her sleep. Anna’s symptoms during the night were understood to be triggered by heat. The
summer months were the worst for Anna and sometimes Anna’s mum would use a fan to blow air into her bed to try to keep her cool. The
Kirton Healthcare Group Ltd responded by supplying Anna with a specially made mattress. Anna is doing really well on the mattress and
has gone nearly 8 months without a serious outbreak. She had one period of bad skin and irritability at night with disturbed sleep and
scratching etc... but the family were away on holiday! Anna said how hot she got and that she could not wait to get home to her own bed!
Conclusion
The impact of the Intelli-Gel® cushion on Anna’s life both at home and at school has been life changing to both her and her family. Anna
now has an additional cushion for use at home and an Intelli-Gel® mattress to sleep on at night. During the last 8 months that Anna has
been using the cushions and mattress she has been largely asymptomatic. She is a happy little girl who takes her Mr Squidgy cushion
everywhere with her. It even went abroad on holiday! For Anna and her family getting on with everyday life is made easier by the help
of the Wound Healing Centre Ltd and The Kirton Healthcare Group Ltd. Anna’s family are hoping that puberty will help her skin too,
although they are not looking forward to a moody teenager!
References
Dalziel, K., Shaw, S., 2010. Lichen sclerosus. BMJ. 340: c731
Neill, S.M., Tatnall, F.M., Cox, N.H., 2002. Guidelines for the management of lichen sclerosus. Br J Dermatol. 147: 640-9
Powell, J., Wojnarowska, F., 1999. Lichen sclerosus. Lancet. 353: 1777-83
Regauer, S., 2005. Immune dysregulation in lichen sclerosus. Eur J Cell Biol. 84(2-3): 273–277
Yesudian, P.D., Sugunendran, H., Bates, C.M., O’Mahony, C., 2005. Lichen sclerosus. Int J STD AIDS. 16(7): 465–473.
Author
Fiona Collins MSc DipCOT SROT
Tissue Viability Consultancy Services Ltd
10 Gildredge Road, Eastbourne, BN21 4RL, UK
Tel: 00 44 (0)1323 735588
Fax: 00 44 (0)1323 737132
Mob: 00 44 (0)7801 784214
Email: [email protected]
Web: www.tissueviability.org
59
T: +44 (0)1440 705352
F: +44 (0)1440 706199
The Kirton Healthcare Group Ltd
23 Rookwood Way
Haverhill
Suffolk CB9 8PB
UK
+44(0)1440 705352
+44(0)1440 706199
E-mail: [email protected]
Telephone:
Facsimile:
Customer Helpline:
0800 212709
www.kirton-healthcare.co.uk
www.ajway.co.uk

Intelli‑Gel® Evidence Pack

Transcription

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