Providing a resource for the prevention and treatment of pressure injuries
By Ana Endsjo MOTR/L, CLT
Beyond the Bed
Skin Changes that Increase Susceptibility
Extrinsic Factors
Pressure Redistribution
Offloading & Immersion
Summary & References
T
he purpose of this Wound Care Guide is to create a RESOURCE that fosters a more wholistic approach to the management of pressure injuries by simultaneously treating supine and seating postures. Our goal is to give a better understanding of the critical role appropriate wheelchair configurations and equipment choices play in the prevention and treatment of pressure injuries. After reading this guide, you as a Health Care Provider will be able to:
Identify the role wheelchair support surfaces play in the prevention and healing of a pressure injury
Ensure simultaneous consideration of BOTH supine and seated postures in the prevention and treatment of pressure injuries by addressing pressure, shear, and microclimate
Define each team member's role in prescribing and obtaining the appropriate wheelchair models, skin protection cushions, back supports, and accessories to minimize the risk of and assist in the healing of existing pressure injuries
Before we dive into the management of pressure injuries, let's go over
What is a pressure injury?
According to the NPUAP: "A pressure injury is localized damage to the skin and/or underlying soft tissue usually over a bony prominence or related to a medical or
In April of 2016, the National Pressure Ulcer Advisory Panel, or NPUAP, changed what we once knew as decubitus ulcer or pressure ulcer to pressure injury to have uniform terminology throughout the wound care world.
As health care providers—especially physicians, nurses, and specialized therapists in wound care—we understand bedside treatment well. We search for the most appropriate support surfaces and stay up-to-date with the most innovative technologies to promote healing and prevention of new pressure injuries.
However, too often we forgot a critical piece of the puzzle in the fight against pressure injuries: prevention and treatment at the wheelchair level!
The above words and concepts jump to mind when discussing pressure injuries and they are just as critical to understand from the seated posture as they are in supine.
Most patients that develop a pressure injury spend the majority of their time in bed or in a wheelchair, placing the skin and tissue under the bony prominences at risk. These "at risk" areas are almost identical bedside and in the wheelchair making it imperative to simultaneously prevent and treat pressure injuries from the supine and seated posture.
In the wound care world, we are in a constant battle against the extrinsic factors of pressure injury development.
The extrinsic factors and the threat they pose to the patient in relation to the bed is well understood, BUT...
Do we consider these factors in relation to the wheelchair?
WE SHOULD!
While seated, our weight goes directly through the pelvis and spine, leaving the bony prominences very susceptible to pressure, shear, and microclimate. This is the nature of a seated posture. With the constant compression of the skin and tissues:
a pressure injury can develop in four to six hours after sustained loading and at times in as little as an hour
and by allowing our patients to sit all day with low-quality cushions and back supports, we run the risk of "un-doing" the advancements we made with bedside treatments
Treatment at both surfaces need simultaneous attention to minimize the risk of development or assist in the healing of an existing pressure injury. Provide the best equipment possible for all support surfaces!
No matter if you are the doctor, nurse, therapist, or ATP, you play a critical role in the recognition, treatment, and prevention of a pressure injury. Take a look at the following flow chart to understand your role and how it fits in the big picture of providing every patient with the appropriate equipment.
Most wheelchair users are dealing with factors that compromise skin integrity due to:
Since changes occur at each layer of the skin through disease processes and/or natural aging, ALL the layers are compromised and make a patient more susceptible to a pressure injury.
It is our job to understand these skin changes in order to combat pressure injuries through our wheelchair configurations and equipment choices by:
Let's compare young/healthy skin to aged/diseased skin and see why our patient population is at higher risk for pressure injury.
Overall skin thickness decreases by 6.4% per decade, increasing:
○ the risk of skin tears with minimal pressure, trauma, and shear forces
○ the susceptibility of the deeper layers of skin to the extrinsic factors as the epidermal layer is broken open more easily
○ the amount of time needed to heal a pressure injury
Layers of skin changed: Epidermis, Dermis, Hypodermis
Fewer Sebaceous Glands
Less sebum (oil) production removes the oily coating from the superficial layer of skin, therefore:
○ breaking down the waterproof barrier that prevents excess moisture from entering the skin
○ reducing the natural lubrication that coats and protects the skin from drying out and becoming brittle, making it easier to break the skin open with pressure, trauma, and shear forces
○ allowing excess moisture to macerate the skin, increasing accessibility of the deeper layer to pressure and shear forces
Fewer Sweat Glands
○ Prevents perspiration with the exposure to excessive heat
○ Prevents the evaporation of sweat and the ability to cool the skin's temperature at the skin-seat interface
Weaker blood vessels and compromised blood flow make skin more susceptible to a pressure injury by increasing:
○ risk of ischemia and tissue death due to constant pressure under a bony prominence
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Loss of collagen and elastin fibers:
○ decrease skin's tensile strength and elasticity, making the skin unable to "snap back" to its original position after a load has been removed
○
Langerhans cells act as the body's warning against infection or high-pressure. The epidermal layer will redden and/or get warm as a warning sign to patient or caregiver to make a change!
Loss of Langerhans cells from disease or age:
○ slows the natural immune response of skin reddening and/or temperature change that acts as the initial warning signs of injury to the skin with pressure and/or trauma
○ increases susceptibility to prolonged pressure without an obvious warning sign to take precaution
The dermal-epidermal junction is the communication channel between the dermis and the epidermis, allowing nutrients, O2, and blood to feed the epidermis and maintain skin integrity.
The dermal-epidermal junction is joined by wavy, finger-like projections called Rete Ridges. Rete Ridges increase the surface area to allow the flow of
With age, the dermal-epidermal junction flattens by 35%, decreasing blood flow, O2, and nutrient exchange between the dermis and epidermis,
○ Results in the thinning of both layers of the skin
○ Prevents the natural keratinization needed for maintenance and healing of the skin after injury
Thinner epidermal and dermal layers:
○ causes a reduction in the barrier between the bony landmark and the pressure source
○ increases the susceptibility of the epidermis to break open at the bony prominences with pressure or trauma with shear forces
Age causes nerve endings to lose their effectiveness to perceive and react to stimuli, decreasing the ability to perceive input from pressure, heat, and cold.
Did you know that loss in effectiveness of nerve endings decreases the ability to perceive pain from pressure build-up under bony prominences? This results in decreased reaction time in performing pressure relieving techniques, which can result in a pressure injury.
There is a reduction in the thickness of the hypodermis (fatty layer) due to:
○ the redistribution of fat cells
○ the loss of connective tissue
We never lose the number of fat cells we have. With age, fat cells are redistributed to areas of greater surface areas such as the stomach and thighs, leaving the areas under bony prominences more susceptible to the extrinsic factors of a pressure injury. Redistribution of fat cells to areas of great surface areas such as the stomach and thighs reduces the insulation and protective "cushion" the hypodermis normally would provide. A loss in connective tissue causes skin to be less firm. The skin then:
○ loses its strength and shape, becoming more susceptible to prolonged pressure at the bony prominences
○ loses fibrous bands that connect the skin to deeper tissues, making the deep tissue more susceptible to shear forces with movement in the wheelchair system
○ has diminished thermoregulation and absorbs more heat than it dissipates, making tissue more susceptible to the effects of pressure, shear, and microclimate
Patients are susceptible to pressure injuries in a seated posture due to the effects of intrinsic and extrinsic factors of a pressure injury.
Factors stemming from within the body that make an individual more susceptible to a pressure injury, such as:
○ Limited mobility
○ Impaired sensation
○ Age-related skin changes
○ Postural deformities
○ Poor nutrition and dehydration
○ Urinary and fecal incontinence
○ Obesity
○ Being underweight
○ Limited alertness
○ Muscle spasms
○ Smoking
○ Medical conditions affecting blood flow
Factors that stem from the outside environment and/or seating surface. Pressure, shear, and microclimate are the extrinsic factors of a pressure injury.
The therapist can prevent harmful effects of extrinsic factors through proper wheelchair positioning and equipment choices.
Let's take a look at the extrinsic factors and threat they pose to our patients while seated!
Pressure is a continuous force applied on or against an object by something that it is in contact with. In seating, equipment such as the seat and/or back support surface are in constant contact with the body creating peak pressures.
Shear is defined as a combination of downward pressure AND friction and occurs while a patient is in movement in the wheelchair system.
Tissue death can occur with both pressure and shear, but the mechanism is quite different.
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Patient sits in a static posture for prolonged periods of time. |
Peak pressures develop at the bony prominences caused by the downward pressure from gravity plus the upward pressure from the seated surface. |
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The skin/soft tissue between the bony prominences and the seat surface is constantly being compressed. |
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The lack of blood flow, O2, and nutrient delivery results in ischemia. |
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Result in tissue death. |
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Gravity causes downward pressure from prolonged sitting. |
The patient moves/slides in the chair, causing friction. |
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The skin/tissue at the seat surface DOES NOT move while the underlying bone structure DOES. |
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The skin/tissue is strained by the combined pressure and friction. |
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Permanent cell deformation and distortion occurs at the deeper layers of tissue. |
Blood vessel damage decreases oxygen delivery. |
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Ischemia. |
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Result is tissue death. |
Microclimate is the climate of a very small or restricted area that differs from the climate of the surrounding area. It usually occurs under the bony prominence where pressure is at its peak, creating excessive heat and/or moisture build-up at the seat and/or back support surface.
Increased body temperature at the skin surface, increased tissue temperature, and/or increased moisture at the skin surface due to:
○ sweat
○ urinary or fecal incontinence
○ drainage from wounds
○ sitting on a non-breathable seat surface preventing ventilation
A decreased number of sweat glands.
Fewer sweat glands:
○ prevent perspiration with the exposure to excessive heat
○ prevent the evaporation of sweat and the ability to cool the skin's temperature at the skin-seat interface
A decreased number sebaceous glands.
Less sebum (oil) production removes the oily coating from the superficial layer of skin:
○ breaking down the waterproof barrier that prevents excess moisture from entering the skin
○ reducing the natural lubrication that coats and protects the skin from drying out and becoming brittle, making it easier to break the skin open with pressure, trauma, and shear forces
○ allowing excess moisture to macerate the skin, increasing accessibility of the deeper layer to pressure and shear forces
Raised skin temperature and excessive moisture weaken the outermost layer of skin, making the deeper layers, tissue, muscle, and bone more susceptible to pressure and shear forces.
Elevated body temperature:
○ increases metabolic rate, in turn increasing the demand of O2 to be delivered to the tissues
○ however, pressure and shear cut off O2 supply
○ so, as demand increases but supply decreases, ischemia occurs more quickly than when the body temperature is normal
Elevated moisture:
○ increases the skin's coefficient of friction, making the skin and deeper tissues "stick" more easily to the seat surface when shear forces are applied
○ weakens the collagen fiber connections between the dermis and the epidermis and increases the risk of maceration
○ increases risk of maceration of the superficial layers of skin, which exposes the blood vessels in the deeper layers. This makes the blood vessels more susceptible to tearing and damage from shear and pressure
When a referral comes in due to falls from a wheelchair system, the development of a pressure injury or even a patient sliding into abnormal postures more frequently, our minds immediately jump to the seat surface as the culprit. “What cushion are they currently on? Is it the wrong style or is it worn out and need to be replaced?” However, when considering the optimal seating system we need to understand that cushions alone cannot solve all seating issues! We need to consider the interplay between the seat surface- the cushion, the back support and the wheelchair model and configuration in order to reduce the risk of:
○ A pressure injury
○ Falls from the seated posture
○ Decrease in function
○ Serious health complications that may arise due to poor posture in the wheelchair system
When we replace the cushion alone, we are simply putting a band aid on, masking the real issue that will eventually “fall off” leading to repeat referrals until we fix the root cause!
When we think of trying to heal an existing pressure injury or reduce the risk of the development of a new pressure injury, one rule of thumb should come to mind:
“The greater the surface area making contact with the seat and back support surfaces, the less risk of peak pressures”.
Through wheelchair configuration and by choosing the appropriate construction of both the wheelchair seat cushion and back supports, even pressure redistribution over the greatest area of the body can be created to reduce the risk of harm to the at risk patient.
The principle of offloading is one method of pressure redistribution. Partial or complete offloading can be achieved depending on the cushion’s construction. Partial offloading is most commonly seen. The cushion manufacturer uses contours in the cushion to produce “shelves and leg troughs” where the greater trochanter will sit and to delineate where the lower extremities will be for better alignment and contact with the seat surface. These contours redistribute pressure from the small surface area right under the sacrum to the larger gluteal surface and down the femur. As a result of the greater trochanters sitting “higher on the shelves”, the high risk areas of the sacrum, coccyx and ischial tuberosities are partially suspended and are prevented from making full contact in the pelvic well of the cushion. This is known as partial offloading and can be an effective way to add stability and relieve the high risk areas from constant pressure under the bony prominences.
Immersion is another method of pressure redistribution. By allowing the body to immerse or “sink into” the medium of the cushion or back support, more contact is made over a larger part of the body. If you want to take it one step further, look for a cushion and back support that not only will “sink the body in” but will also wrap around it fully, capturing its “normal or abnormal” shape, known as envelopment. When the cushion or back support allows for both immersion and envelopment, even pressure of the gluteal surface and along the spine will be created, reducing the risk of pressure injury development.
• Understand the critical role addressing the seated posture plays in the wholistic approach to the prevention and treatment of a pressure injury.
• Recognize your role, no matter what discipline, in obtaining the appropriate skin protection equipment for the wheelchair system.
• Educate yourself in the skin changes that make a wheelchair user more susceptible to a pressure injury.
• Understand the extrinsic factors of a pressure injury in relation to the seated posture.
• Acknowledge all the components in the simple equation that will result in an optimal seating system.
• Learn the methods of pressure redistribution, the benefits and considerations of each method, and the importance they play in the construction of a cushion and back support to prevent and treat a pressure injury.
When we as healthcare providers understand these key principles and attack pressure injuries from all support surfaces, then and only then do we have a chance to win the battle against pressure injuries!
About Ana
Ana Endsjo has worked as an occupational therapist since 2001 in a variety of treatment settings. She has mainly worked with the geriatric population, dedicated to the betterment of the treatment of the elderly in LTC centers. Her focus has been on seating and positioning and contracture management of the nursing home resident. With this experience, her hope is to guide other therapists, rehab directors, nurses, and administrators through educational guides, blogs, webinars, and live courses in her role as Permobil's Clinical Education Manager of the Long Term Care Division.
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