Download Thiers, Bh "Preventing Pressure Ulcers: A Systematic Review."

Team Under Pressure Presents:
A Novel Approach
to Preventing
Pressure Ulcers
Biomedical Engineering Senior Projects I Final Report
Biomedical Engineers: Robert Karas and Corina Malone
UDM Mechanical Engineers: Bobby Lorenz, Frank McClosky, and Jacob
Dodman
UDM Nurses: Victoria Murad, Lydia Jacob, and Christina Osterhout
12/15/17
Table of Contents
Abstract ........................................................................................................................................... 2
Introduction ..................................................................................................................................... 3
Details of Design Concept .............................................................................................................. 8
Methods......................................................................................................................................... 13
Project Relevance/Broader Impact ............................................................................................... 16
Timeline ........................................................................................................................................ 17
Budget ........................................................................................................................................... 18
References ..................................................................................................................................... 20
1
Abstract
In collaboration with University of Detroit Mercy, our team at LTU has identified a need to
provide a cost-efficient device which is more effective at lowering risk factors of pressure ulcer
formation in patients confined to a wheelchair for an extended period of time. The goal of the
team is to use our engineering and collaboration skills to develop a product that will help people
who are at risk for pressure ulcer formation, and reduce the chance of developing or further
injuring a pressure ulcer. In the U.S. over 2.5 million people develop pressure ulcers annually.
Also, 25% of people who have suffered a spinal cord injury (SCI) develop a pressure ulcer.
There are 65,000 wheelchair bound individuals like our client, who suffer from a SCI, that have
an increased risk of forming ulcers. Our client is a Vietnam War veteran that was injured from a
gunshot wound leaving him paralyzed from the waist down. The idea was formed during a
meeting with the client whose chief complaint was that he experienced a lot of pain and
discomfort from pressure ulcers. Our client has expressed that he’s tried a variety of pads,
mattresses and other pressure relieving devices, however his pressure ulcers ultimately kept
progressing until they became a stage 4 pressure ulcer. Our team is proposing a device that will
alternate pressure to injured areas and offer a tilt feature to allow blood to circulate in the area
where pressure is relieved. The device will be a pad that is specifically designed for a
wheelchair to address main risks in pressure ulcer formation including pressure reduction,
moisture decrease and minimizing friction. The seat will alternate positions to relieve pressure
and recirculate blood to the area of interest. To decrease moisture the top layer will be a
moisture wicking material to prevent any fluids from seeping into the pad. Finally, a low friction
coefficient material, such as lyocell, will be ideal to prevent further injury and ultimately
decrease the chance of pressure ulcer formation.
2
Introduction
Our patient suffers from pressure ulcers due to his prolonged use of the wheelchair
throughout the day. He suffered a spinal cord injury due to a gunshot wound to his back that is
still lodged in his spine. After the war, our patient was also a victim of post-traumatic stress
disorder (PTSD) so it’s very important that the design of the device doesn’t evoke any abrupt
movements or loud noises that could potentially alarm him. The patient lost his lower limbs
after gangrene set in and stage four ulcers caused him to have several flap surgeries to help with
pressure ulcers. He is confined to a wheelchair to ambulate making him high risk of ulcer
formation so he has tried several pressure relieving pads and devices in earlier stages of the
disease. Our patient also lives with his grandson who cares for him and a wife who is also his
caretaker but suffers several illnesses herself. Therefore, our device needs to be mindful of the
caretakers and be effective in that no further injury occurs to his untreatable ulcers. Currently, he
is treating the pressure ulcers with pain medication and frequent massages from caretakers. Most
patients who spend 8 or more hours in a wheelchair tend to stay in the same position majority of
the time causing prolonged pressure to an area of the body. The area of the body which is in
contact with the surface will create friction and moisture increasing the risk of the formation of
pressure ulcers. Treatment is complicated and dependent upon the stage of the ulcer it is difficult
to determine if the skin will heal. Pressure ulcers are classified in 4 stages which regulate the
healing process and classifies the health of the tissue. Beginning with the first stage, the site of
the ulcer may be tender, painful, firm, soft, warm or cool compared with the surrounding skin.
Stage 2 presents blisters which can be ruptured and if left untreated will accelerate to stage 3.
Stage 3 is the point where skin is compromised and fat can be exposed that can include yellowish
dead tissue with possible craters. For paralyzed individual’s injuries are more likely to advance
3
to stage 4 which usually results in surgery to remove damaged tissue and prevent infection. The
fourth stage is hardest to heal and is indicated by a large-scale amount of tissue loss which can
expose tendon, tissue, muscle or bone. If the injury is left untreated it could be classified as
unstageable where the surface is covered by yellowish, black, brown or dead tissue and the
severity of the wound is impossible to see. Spinal cord injury patients have a few extra factors
that make developing pressure ulcers easier for them. One factor is the inability to regulate heat.
Studies have shown an increase of one degree Celsius can increase the chance of getting a
pressure ulcer by as much as 10%. Another factor is that some spinal cord injury patients have a
compromised nervous system which affects fight or flight instincts and leads to increased
perspiration. Increased perspiration and wheelchair confinement lead to formation of pressure
ulcers near the bony areas of the body. When we heard about this undesirable problem that our
patient had, we knew that something had to be done in order to relieve his pain and try to help
reduce any further injury of his wound site. Another tragic state that he has to face is his PTSD.
Often times even his own wife feels unsafe around him, and the only thing that ever seemed to
calm anxiety was the water. If there is a way to incorporate water either by sound or by massage
into the design, he could not only have the benefit of pressure therapy but also therapy to help
with his devastating PTSD. It was easy to identify the need of pressure ulcers because it is a
major problem for many Americans however it was very difficult to govern how to address this
problem. Patients who are wheelchair bound usually are in the chair for over a period of 8 hours
and are more likely to be in the same position. The prolonged pressure causes irritation, friction,
and increased moisture to the injury site. Clinicians advise that patients who are in a wheelchair
for over 8 hours should change their position every 15 minutes to relieve pressure allowing blood
to re-circulate in that area. After conducting interviews with 10 patients of varying stages of
4
ulcer formation the answers were carefully analyzed and assisted with confirming the need for
prevention and treatment of pressure ulcers. Many of the patients described extreme discomfort
and pain in relation to pressure ulcers. Most of them treated the pain with oral medications and
physical therapy that was described as “temporary relief”. In an interview with a spinal cord
injury patient confined to a wheelchair expressed the interest in devices that provide more
independence and less reliance on the caretaker for weight shifting. There were a large
percentage of patients who were not managing their pressure ulcers with any medical devices
and when asked about previous treatment methods responses indicated there were none. There
were also questionnaires given to physical therapist, RN, and doctors that revealed a need for a
device that effectively redistributes pressure but allows that patient some level of comfort. An
RN working for Receiving Hospital discussed how she sees patients not receiving the proper care
due to a lack of staff available to reposition patients as needed based on severity. Having a
device that reduces the need of another individual to assist in the weight shifting process will
provide an environment for prevention of pressure ulcers. Currently there are several medical
devices on the market that offer pressure redistribution through air loss, patient turning and
pressure alternation. There are several beds that circulate air or water and use gel or foam pads
to alleviate pressure and obtain a more balanced pressure or monitor applied pressure. Many of
these existing solutions are primarily for beds and recliners that intends to redistribute pressure.
The issue with many of these devices is that they still show chances of forming pressure ulcers
because of ergonomics or the device main purpose being predictive pressure ulcer devices. The
devices currently on market are pads and coverings for mattresses and chairs which are no slip
covers trying to keep the body still but no concern for shear forces applied to the skin. There are
also microclimate controlled covers for chairs and beds in attempt to keep the body cool and dry
5
to prevent excess dampness from developing and leading to increased tissue damage. There are
some other treatment solutions to pressure ulcers such as special dressings, negative pressure
therapy, hyperbaric chambers, ointments and Band-Aid. Most technology on the market focus
on determining how where and how much pressure is applied to a given area. The main existing
solution for wheelchairs is the Geri Chair Alternating Pressure pad. It has air interwoven
channels that will inflate a set of alternating channels to relieve pressure and rotate the channels
that are blown up to relieve pressure. There is an opportunity to innovate existing solutions by
developing a cost-effective device that is effective and helps to reduce pressure ulcer formation.
We have identified the stakeholders as being primarily the patient but also nursing staff,
clinicians, hospitals, medical equipment companies, caregivers, insurance companies, wound
care facilities and home healthcare agencies. These influential stakeholders do not pose any
conflict of interest because all above mentioned will tend to benefit from this product. Our target
audience would be wheelchair bound individuals who are also the decision makers because they
will provide the demand. We have identified 3 market segments that include pre-hospital,
hospital, and post hospital which provides a map of the stakeholders. All segments include the
patient while also included in pre-hospital are caretakers and medical device companies where
the patient is treated and therapeutic devices are purchased in hopes of healing/preventing
pressure ulcer formation. In the hospital segment nursing staff, clinicians, and insurance
companies are concerned with treatment of pressure ulcers as well as preventing patients from
getting pressure ulcers once they were admitted. In post-hospital, medical device companies,
insurance companies, and caretakers search for wound care and treatment options in attempts of
preventing ulcers from progressing to further stages or preventing infection.
6
In the U.S. pressure ulcers cost anywhere between $9.1 and $11.6 billion per year and the cost
for an individual patient care ranges from $20,900 to 151,700 per pressure ulcer. In a 2015 study,
there were 2.5 million pressure ulcers in the U.S. alone where 25% of all people with spinal cord
injury develop pressure ulcers every year. Per a report by the Medicare services the average cost
of pressure ulcer treatment is $43,180 also reporting an estimated 65,000 individuals that are
wheelchair bound and develop pressure ulcers annually. The 65,000 people who suffer from a
spinal cord injury and are wheelchair bound multiplied by the cost of pressure ulcer treatment
gives a $2.8 billion market available in this product. The device that we are anticipating on
creating will help the pre-hospital, hospital and the post-hospital market. The device will prevent
the ulcer from worsening and will also slow the development of pressure ulcer formation
eliminating the main factors associated with pressure ulcers. The prevention of further injury is
the main goal of the project and to alleviate pressure at the injury site providing more comfort to
the patient.
7
Details of Design Concept
When coming up with a design, the first step was to see what the market already has on
it. When looking at the treatment or prevention of pressure ulcers there are two main categories,
hospital equipment and then at home equipment. Hospital equipment to treat and prevent
pressure ulcers mainly includes mattresses and mattress pads. Since hospitals are actively trying
to figure out how to stop pressure ulcer formation, there are quite a few options including low air
loss beds, alternating pressure mattress pads, and patient turn devices. Low air loss beds use a
simple idea that if air is circulating under the body, then the pressure will distribute evenly
throughout the body. Alternating pressure pads try to make sure that the pressure points that the
patient feels shift about every 15 minutes to alleviate the pressure. Also, patient turning devices
believe that turning the patient will result in reduced pressure and increased blood flow to the
injury site, resulting in less pressure ulcers. These forms of treatment are widely used in many
hospital settings, however are rarely used outside of the hospital. Wheelchair bound individuals
suffer a great risk for pressure ulcers due to the fact they have to be in a seated position for most
of the day putting pressure on both the hip bones and the tail bone. Many different seats are used
including pressure relieving pads and pressure alternating pads. Pressure relieving pads are
designed in an ergonomic manner to try and even out the pressure distribution of the patient.
This results in a more even spread of pressure to try and normalize the pressure distribution to
alleviate any pressure points. The other type of wheelchair pad in the market is pressure
alternating pads. These pads try to change the pressure points every 5, 10, or 15 minutes to try
and stop pressure from building up on certain areas.
After reviewing these devices it became clear that little was being done on the market to
build a device that not only relieved pressure, but promoted blood to recirculate to the injury site.
8
Three design concepts were created including an inflatable pad that would be able to redistribute
pressure as well as make major adjustments to the patient to allow for blood to recirculate to the
injury site(s), a reclining wheelchair integrated with a pressure sensor to automatically adjust the
patient to relieve high pressure areas, and a water pad for a wheelchair that would feature cold
water as well as circulation to try and promote healing and injury site microclimate control. A
decision matrix was designed using what our group thought was the most important criteria, see
table below, and a design idea was then solidified.
Concept Decision Matrix
Concept 1
Concept 2
Concept 3
Inflatable Wheelchair Recliner Pad Wheelchair w/ Tilt Function Water Circulating Cushion
Concept
Description
Criteria
Weight
Patient Interest
Mobility
Comfort
Pressure Reducing
Temperature Reducing
Friction Reducing
Marketing Potential
Manufacturing Feasibility
Total
0.1
0.1
0.15
0.2
0.1
0.1
0.15
0.1
1
1
1
1
0
1
1
0.5
0.85
0
1
1
1
0
0
1
1
0.7
0
1
1
1
1
0
1
1
0.8
Table 1: Decision Matrix for three design concepts
The inflatable recliner pad was chosen due to the interest from our client. When deciding
between air, water, or gel to inflate the pad with we went with air because it is lightweight, easy
to use, and will not weigh down the wheelchair with a tank holding the liquid or gel. In order to
ensure that our idea was novel, we researched all sorts of cushions and found the area for
improvement. No matter what wheelchair/cushion combination someone chose they still
recommend the patient to do certain stretches like shown in the figures below to ensure proper
blood circulation and skin proliferation.
9
Images 1 & 2: Stretches to ensure blood circulation and prevent skin deterioration
Once this was realized, a design of the pad was made so that the patient wouldn’t have to
make these stretches a part of his routine. Many patients forget about doing stretches after about
a week or two post treatment. Our device will help the patient recirculate his blood to the injury
areas so the device should be more effective at preventing pressure ulcers than previously made
devices. To do this we brainstormed an idea that the pad can have eight pads, to ensure no
pressure points are created, that will not only alternate but lift up the patient in various directions
to ensure proper circulation to prevent further degeneration of the skin.
10
Images 3, 4, 5 & 6: CAD drawing of design at different inflation settings
These images show how we intend to inflate the balloons to ensure that pressure will not
only be redistributed, but the pad will allow the patient to have full recirculation during inflation
patterns designed to tilt the patient at a fifteen degree angle. This will ensure proper recirculation
and will occur every fifteen to thirty minutes depending on the user’s preference. To ensure
comfortability a very slim piece of foam will be placed above the inflatable balloons. This foam
will in no way hinder the effect of the balloons due to the thin aspect of the foam.
After the concept was designed we knew we had to figure out the outer material for the
seat. After deliberation with nurses of various specialties, we decided to go with a waterproof
material in order to prevent water from sitting on the seat which can increase the chances of
pressure ulcer development.
After all the materials and concepts were finished, the actual mechanics were taken into
account. In order to get our desired fifteen degree tilt, we need the balloons to raise about four
inches from the seat. The amount of pressure these balloons will feel will be a maximum of three
pounds per square inch. This was calculated by taking the highest weight allowed, 300 pounds
11
which a standard wheelchair is regulated for, and dividing by the area of balloons that will be in
contact with the patient. However, when looking at the tubes they will see a much higher
pressure due to the small area of the tube. This is why when we chose our valves and pump to
include in our design we had to make sure they can withhold a high PSI rating in order to work
for our application. We went with an air compressor, because most pumps will not allow the
balloons to inflate. Also, we went with solenoid valves because they will control each tube
independently. Lastly, we chose an Arduino to operate our system because we don’t need any
computing power like raspberry pie microcontrollers and the Arduino can control the compressor
and the valves to ensure proper function.
With all this in mind the final product will have to be made for our client and his manual
wheelchair. The design includes two loops at the top that will fit over the caretaker handles on
the back of the wheelchair. The pad will then tie into the armrests to ensure that the pad is
secure. Pressure is to be reduced at least every fifteen to twenty minutes according to the nurses
we interviewed, so we will have the user be able to adjust their position every ten, fifteen,
twenty, or thirty minutes depending on their preference. The thirty minute option is for those
who are without a pressure ulcer that are just trying to prevent one from forming. The sequence
of pressure redistribution will occur every five minutes regardless of user input to ensure no
pressure points are created, and then will shift them to the left, the right, forward, and backward
depending on the time step they indicate. With all of these pressure redistributive patterns, this
wheelchair pad should be more effective than any other pad designed to reduce the chance of
pressure ulcers, and should improve healing of pressure ulcers.
12
Methods
Not only is it important to have a great design that should accomplish the desired task,
but there needs to be testing already specified to make sure that the product can work for its
desired function. These tests would include usability testing, materials testing, pressure testing,
weight testing, and safety testing. All of these types of testing will ensure that our product will
meet not only our client’s needs, but any future investor’s needs as well.
The first step to usability testing would be to contact LTU’s IRB and get approval for
human testing. This will need to be done in order to let our patient try out our chair, and give us
feedback on our design. This step is crucial because the designers always know how they intend
their product to be used, but sometimes how to function the device isn’t clear to the user. Since
our project is very client based, it is essential that our client can be able to use our device
intuitively in order to reach our intended market.
After our device is tested by the user for function we will do materials testing. This is to
ensure that the outer material we chose is both low friction and water resistant. A simple
coefficient of friction can be done with a force sensor tied to a certain amount of mass in order to
obtain the coefficient of friction. Then we can compare our material to other known material on
the market to ensure our material has a lower coefficient of friction. If it is not, then some simple
surface modification can be done, or a new material can be chosen. To test the hydrophobicity a
contact angle measurement can be done on the fabric. If there is a contact angle than the fabric is
considered water resistant. If the water is able to be wiped off of the surface and there is no wet
residue, then the material can be classified as waterproof.
Pressure testing is another aspect of testing that we will need to do in order to classify our
product. This can be done with simple pressure sensors hooked up to the motion capture
13
equipment to see if the patient’s pressure is properly redistributed. If the pressure is noticeably
not shifting, then the size of balloon or pressure from the pump will have to be increased to meet
the required goal.
Since standard wheelchairs are standardized to accept any weight until three hundred
pounds, our pressure pad should be able to withstand the same amount of weight. To do this we
need to test one and a half times the maximum weight desired for the product to be rated for.
This means our pad will have to be tested with someone weighing four hundred and fifty pounds.
This can be done with the weights from the weight room to ensure proper function when the
maximum weight capacity is reached.
Throughout these steps safety is our number one concern. If there is any potential hazard
or possible are for error, our job is to correct the error. This includes making sure our circuitry is
closed and unable to shock the patient. Also, preventing kick back from some of our components
to protect the Arduino. Lastly, we need to ensure that our device is usable without a seatbelt. If a
seatbelt is needed, some slight modification to our design will get the desired effect and once
again our product will be easy to use for our patient.
Product testing is very crucial for the development of a product. If your product is either
not safe or not effective, then your product will not be able to make it to market. Below is a risk
assessment exercise to try and find any potential risks that could be associated with our design.
14
Probability
Severity
Catastrophic
5
Severe
Not enough
Pressure
Distribution which
causes pressure
points
Unlikely
1
Remote
2
1. User
manual; user
testing
2. Design docs
3. Test tilt of
device
1
Acceptability
Pressure
Points
Triggered
Residual
Risk
20
Occurrence
4 Acceptable 1. limit the
amount of
inflation
2. possible
seatbelt
Broken Bone
Disease
state
progression
Disease
state
progression
Verification
1
Controls
4
Acceptability
Balloons inflate too Pain/Concus
much in back,
sion
causes patient to
fall out of chair
Risk
Occurrence
Severity
Harm
Degree of
Tilt being
exteme
Situation
Hazard
Line #
10
4 Acceptable
2. Possible
seatbelt
3
3
9
Possible
3
Caution
1. Better
materials
2. Higher
number of
balloons
1. Pressure
Test
2. User test
3. Design docs
1
3
Acceptable
Probable
4
Intolerable
Caution
Acceptable
4
Major
3
Minor
2
Negligible
1
Table 2: Risk assessment chart with risk criteria below for under pressure decubitus ulcer pad.
15
Project Relevance/Broader Impact
This project relates to many people because of its intent to heal pressure ulcers by reducing
friction, redistributing pressure and decreasing moisture. Per a report by Transparency Market
Research the pressure relief market is expected to experience a compound annual growth rate of
5.2 percent from 2014 to 2020. These numbers show that there is an identified need to prevent
pressure ulcer formation which can ultimately lead to death. It is important to understand the
broader impact this device will have on the medical industry due to the amount of people
suffering from pressure ulcers. Pressure ulcers can be acquired in the home setting, hospital or
even long term care facilities which is the reason prevention is so vital. Along with knowledge,
there is a need for medical equipment that reduces the risk factors in the formation of these
wounds. Our portable product which effectively prevents pressure ulcers will be an innovative
solution to the identified need. Patients confined to wheelchairs express awareness about the
importance of prevention and concern about the effect, if left untreated. This problem is a threat
to all patients who are subjected to a wheelchair or bedridden for a long period. The impact of
this condition results in many people being affected due to fatalities and decreased activities of
daily living for patients. The fatal environment for causes patients to get progressively worse
with time and increased lack of mobility which increases risk factors for pressure ulcer
formation. Stakeholders are equally interested and concerned with the pressure relief market and
how it will affect them directly.
16
Timeline
To successfully complete the project our team anticipates to complete all objectives and goals
within the structured time frame. Our first task is to meet with our faculty advisor to in the
beginning of the 2nd semester to receive feedback and guidance to help organize our efforts in
developing a prototype. This task will continue until the project is completed to ensure deadlines
are being met. Materials will be bought no later than February 1st and prototype build will be
begin no later than February 1st as well. The task will proceed until no later than March 1st to
guarantee testing will begin by March 1st. Testing will be completed no later than March 15th to
assure that modifications can be made if necessary. Modifications must be complete by April 1st
so that a robust prototype is achieved in time for the final deadline. This timeline is intended to
provide direction for the senior project, allow deadlines to be met and be conducive to a
prototype which delivers a solution to the identified need.
17
Budget
Item
Quantity Needed Price/unit (US$) Total Cost (US $)
RolAir FC2002 - Portable Air Compressor
1
70
70
Arduino Board & Accessories
1
78
78
Crydom DC Relay to Arduino
11
20
220
Batteries (9V & 12V)
1
30
30
Solonoid Valves
10
15
150
Pneumatic Tubes
4
5
20
Foam Pad
1
25
25
Material for Air Bladders
16
5
80
Outer Shell Material
1
100
100
TOTAL COST
773
The group decided on doing an Arduino based design because the Arduino has been used
in previous projects and wo do not need computing power that the raspberry pie gives. The air
compressor is used because pumps that were able to get to a high enough psi rating were very
expensive compared to the air compressors. These can all be controlled via relays to the Arduino.
The relays is the most expensive item and if we need to cut our costs, then the relays can be
wired in differently, but may not be as effective. The batteries are 9V to power the valves and the
Arduino, and 12V to power the air compressor. The solenoid valves are chosen because they
allow for control over each bladder separately in order to get the proper balloons inflated to
achieve the desired task. Only ten are needed, eight can control the bottom and two will control
the top. Pneumatic tubes are chosen because they were recommended for the air compressor and
they are relatively low cost. The foam pad needs to be a slight foam pad that can provide
ergonomics, so a relatively cheat piece. An air mattress material can be used for the balloons and
they will hold up to the weight that we expect to put on the pad. Lastly, the outer shell is a
waterproof material that surrounds the device in order to allow the patient to be separate from
our device, as well as lower friction and water that will gather on the surface. The funding source
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for this project will be the UDM budget of one thousand dollars, which allows us to purchase all
of the above items with about two hundred and twenty five dollars left for incidental needs and
items that were not intended.
19
Appendix
Block Diagram of our design
Cross sectional view of the seat cushion
Solidworks Drawing of our Initial Idea
20
Tenative Schedule for the Senior Projects II
TEAM UNDER
PRESSURE
UDM NURSES
Disease State
Fundamentals
Background
Information
UDM
ENGINEERS
LTU ENGINEERS
Design
Parameters
Methods
Design
Ergonomics
Market
Research
Fabrication
Methods
Manuafacturing
Team Structure
21
References
Fu, Jicheng, Yih-Kuen Jan, and M. Jones. "Development of Intelligent Model to Determine
Favorable Wheelchair Tilt and Recline Angles for People with Spinal Cord Injury." 2011
Annual International Conference of the IEEE Engineering in Medicine and Biology
Society (2011): n. pag. Web.
Graves, Nicholas, Frances A. Birrell, and Michael Whitby. "Modeling the Economic Losses
from Pressure Ulcers among Hospitalized Patients in Australia." Wound Repair and
Regeneration 13.5 (2005): 462-67. Web.
Jan, Yih-Kuen, Maria A. Jones, Meheroz H. Rabadi, Robert D. Foreman, and Amy Thiessen.
"Effect of Wheelchair Tilt-in-Space and Recline Angles on Skin Perfusion Over the
Ischial Tuberosity in People With Spinal Cord Injury." Archives of Physical Medicine
and Rehabilitation 91.11 (2010): 1758-764. Web.
Janssen, Thomas, Christof Smit, and Maria Hopman. "Prevention and Treatment of Pressure
Ulcers Using Electrical Stimulation." Pressure Ulcer Research (n.d.): 89-107. Web.
Krapfl, LA, and M. Gray. "Does Regular Repositioning Prevent Pressure Ulcers?" Journal of
Wound, Ostomy and Continence Nursing 36.1 (2009): 34. Web.
Moore, Zena, and Seamus Cowman. "A Systematic Review of Wound Cleansing for Pressure
Ulcers." Journal of Clinical Nursing 17.15 (2008): 1963-972. Web.
Moore, Zena Eh, and Seamus Cowman. "Repositioning for Treating Pressure Ulcers." Cochrane
Database of Systematic Reviews (2008): n. pag. Web.
Reiber, Gayle E., and Joseph W. Lemaster. "Epidemiology And Economic Impact Of Foot
Ulcers And Amputations In People With Diabetes." Levin and O'Neal's The Diabetic
Foot (2008): 3-22. Web.
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Sen, Chandan K., Gayle M. Gordillo, Sashwati Roy, Robert Kirsner, Lynn Lambert, Thomas K.
Hunt, Finn Gottrup, Geoffrey C. Gurtner, and Michael T. Longaker. "Human Skin
Wounds: A Major and Snowballing Threat to Public Health and the Economy." Wound
Repair and Regeneration 17.6 (2009): 763-71. Web.
Thiers, B.h. "Preventing Pressure Ulcers: A Systematic Review." Yearbook of Dermatology and
Dermatologic Surgery 2007 (2007): 295-96. Web.
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