Disclaimer: The contents of this series are for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. You should always consult with your healthcare professional before starting a new treatment or changing or stopping the current treatment.
This post covers the following topics; you can read more through the links provided within the text.
- Skin structure
- What is a pressure injury, how it occurs
- Common sites of pressure injuries
- Risk factors for pressure injuries
- How to detect and assess pressure injuries
- How to prevent pressure injuries: Follow “SSKIN”
1. Skin structure
Our skin has two layers: epidermis and dermis (Figure 1). Below that we have our muscles and the bone.
Epidermis: The skin we see
Dermis: It contains very thin blood vessels, nerve endings, hair follicles, oil, and sweat glands.
Fat tissues: It lies below the dermis.
Muscles: Those lie below the fat tissues.
Bone: Muscles attach to bones through tendons.
2. What is a pressure injury?
It is damage to the localized area of the epidermis and/o dermis and underlying structures; it begins as an injury to the small skin area but can go deeper up to the level of bone. One of the most common pressure injuries is bedsores.
2.1. How does a pressure injury occur?
Normally, while sitting or sleeping/lying down, we shift our position every few minutes with or without our knowledge to take off the pressure on our skin. It so happens because the delicate smaller blood vessels are compressed in-between the outside pressure and our bony prominences such as behind our head, hip bone, and heels, etc. The nerve endings on these areas identify this problem and send pain signals to our brain to make a move so that blood supply to the skin can be restored.
Some outside forces can disturb this process and as a result a pressure injury occurs. It can happen due to three modes of pressure.
Due to mechanical pressure
However, whenever the skin is trapped between an outside surface and inside bony prominence, the resulting mechanical pressure may compress very thin blood vessels depriving oxygen and nutrients to the skin cells; as result cells die. If the pressure continues the injury may run deeper until it meets the bone.
Due to shear pressure
In addition to the mechanical pressure, skin injury can occur due to another type of pressure: Shear pressure. Shear refers to a force that occurs when two surfaces rub against each other when the forces move opposite directions to each other. It occurs when the skin rubs against a rough sheet and any other surface. It can create damage to the skin and tissues under the skin resulting in stage 2 ulcer. When a person moves up on the bed, underlying bone can move against the bed surface while skin pressed in-between.
Due to friction
Friction is a mechanical force; it damages both the epidermis and dermis and occurs while we reposition the person. Both shear and friction may occur together.
However, if our nerve endings do not work, such as in diabetes and we are unable to move such as in paralysis, the pressure continues jeopardizing the skin’s blood supply. This results in skin cell death. This external pressure not only cause skin cell death but it affects its deeper structures too; fat cells and muscles.
How long does it take to develop a pressure injury?
The time can vary from few minutes to hours depending on the intensity of the pressure, age and health of the person, and the site of the body.
3. Common sites of pressure injuries
When someone is bedridden,
When someone is on a chair,
Other areas at risk
- Genitals of those sitting long hours in a wheelchair
- The areas that are constantly under a medical device such as leg bags, catheters, slings, belts, etc.
4. Risk factors for pressure injuries
The risk for pressure injuries becomes higher when,
- moving ability is lost,
- the sensation ability is lost such as in long-term diabetes and unconscious situations
- the communication and cognitive ability is lost
- aged, because with age the skin becomes thinner
- Ill, because the disease conditions and poor nutrition makes the skin thinner and unhealthy
- the skin is too dry
- the skin is too moist
- using medical or other devices: catheters, leg bags, belts, slings
- sheets and clothing are crumpled
- Improper sitting posture
- Incorrect methods of moving someone
- Inappropriate mattresses, cushions
5. How to detect and assess pressure injuries
Finger pressure as a test on the suspected area
The NICE 2014 guidelines recommend applying gentle finger pressure on a reddish skin area; if the reddnes disappears upon pressure (blanchable), that area is healthy; if not (non-blanchable) it is the first stage of a pressure injury. This is difficult to see among those with darker skin; their skin color becomes darker than its surrounding.
Other than the color change the area may feel tender, warmer than the surrounding, and either softer or harder. It may be a blister filled with fluid. There could be a deep wound also.
Any non-blanching areas need re-assessments every 2 hours until resolved according to the NICE guidelines.
How to assess the progression of a pressure injury
Healthcare professionals describe the natural history of a pressure injury progression in four stages. If you are interested in knowing more detail about this, you can read an excellent description with pictures on the Nursing Times through this link. Here is the summary;
|I||Unbroke skin, reddish that does not disappear on light finger pressure; the area is darker than the surrounding among those with darker skin; may complain of pain, tingling, numbness, and tenderness on touch; may feel warm.|
|II||An open wound or a blister|
|III||A deep wound; the damage has gone beyond the epidermis and dermis level.|
|IV||The wound has damaged the muscle and extends up to the bone.|
|unstageable||the wound is covered with dead tissue.|
6. How to prevent pressure injuries: Follow “SSKIN”
The “SSKIN” is an acronym that captures the key aspects of pressure injury prevention. It is as follows;
|S: Surface||minimal layers of clothing; not leaving slings under the buttocks after the transfer; make sure the correct support material; make sure catheters and straps of devices are not trapped; smooth out the clothing and other materials |
Use support surfaces: Read about it later in this post
|S: Skin care||daily look for signs and symptoms of stage I; minimize risk factors; keep not either too dry or too moist; do not rub, only pat. Use barrier cream to avoid moisture.|
|K: Keep moving/|
|While in bed: |
Reposition every 6 hours and every 4 hours those at high-risk; (NICE guidelines); should not be on the reddened area. The recommended standard is the 30 degrees tilted side-lying position at a time; the position needs to change from right, back and left. When sitting in bed, the head of the bed should not be elevated since it raises the pressure and shear forces over the lower back and buttocks. When sitting the amount of sitting time should be limited and the feet should be supported with a stool if they do not reach the floor. When re-positioning, the person should not be dragged.
While in a chair:
Repositioning every 30 minutes for 30sec. for those who can do it independently (side relief; tilt forward and full forward); should not remain seated more than 2 hours those who are at risk (NICE guidelines); should not sit those with a pressure ulcer; frequent standing when possible.
|I: Incontinence||Keep the skin clean and dry – it should not be too moist or too dry|
|N: Nutrition||Good nutrition and enough fluids|
Adhere to chair standards
Stephens and Bartley (2018) have tabulated the factors we should consider to prevent pressure ulcers when sitting on a chair long time. You can read the full article through this link (you can have free access because it is under a Creative Commons license. I will summarise it in the following table;
|seat width||at least 2.5 cm (two-fingers width) space between the hip and the side of the chair||if too narrow, it exert more pressure on the hip, buttocks, and genital area; more space makes difficult to fix lap belts, cushion supports.|
|seat height||Th feet should be able to place on the floor/foot plate.||If the seat is too high, the person is likely to slide down to touch the floor exerting undue pressure on the tailbone area.|
|seat depth||two-fingers width between the seat edge and the back of the knees.||If the seat is too long, the person is likely to slide forward to keep the feet on the floor/footplate.|
|chair backrest||the height and width to maintain a comfortable posture||If too low, it can create postural problems and pressure ulcers; if too high, it may restrict shoulder blade movements.|
|armrest height||The person should be able to place the arms comfortably.||If it is too high, the person will feel pain and discomfort on the bent elbow joint. If too low, it can create postural problems.|
|foot plate||The feet should rest on the plates.||If the rest length is too long, it creates pressure on buttocks and thighs; if too short, more pressure on calves and heels.|
adapted from the Stephens and Bartley (2018) article published in the Journal of Tissue Viability; 27: 1, 59-73).
under the Creative Commons license
Support surfaces help prevent pressure injuries. They include chairs, mattresses, cushions, heel/foot supports, pressure moving devices.
|Mattresses||Use high-specification ones (not foam mattresses) for high-risk ones (NICE guidelines); use active support surfaces for those already have a pressure injury. Read more through this link.|
|Cushions||Cushions are made of either foam, gel, air, or water; this article written by Stephens and Bartley (2018) compares advantages and disadvantages of different kinds of cushions.|
|Heel support devices||This article written by Jackie Fletcher provides an excellent account of heel support surfaces.|
|Synthetic sheepskin pads, rings, doughnut style devices||Avoid|
- National Pressure Injury Advisory Panel
- React to red skin
- Tissue Viability Society
- Stop the pressure
- Nursing Times article series on pressure ulcer education
- Pressure injury stages visuals
- Preventing pressure ulcers Youtube presentation
- Care at home series from WoundsCanada
- Selection and use of support surfaces
- How to prevent pressure injuries by the UHN