What is deep tissue injury (DTI)?
It is commonly thought that a pressure injury always starts on the surface of the skin and goes deeper step by step. Research has found, however, that there is another kind of pressure injury that forms from the inside out. It is called deep tissue injury (DTI).
In DTI, the deep soft tissue (the muscle and fat) over a bony prominence is damaged first, while the skin still looks intact or shows only slight changes. At first, purple or maroon patches may appear on the skin, or blood-filled blisters may form. These discoloured areas do not turn white when pressed (non-blanchable), and they may feel firmer, softer, warmer or cooler than the skin around them.
The hardest thing about DTI is that the skin surface looks fine while the tissue underneath may already have died over a wide area. Within a few days, skin discolouration that seemed minor can turn into a very deep wound.
Why is the deep tissue damaged first?
To understand the cause of DTI, it helps to know what happens to body tissue under pressure:
High-risk areas
DTI is most common where the bone sticks out and the soft tissue is thin:
When lying in bed
- Sacrum (tailbone area)
- Heels
- Back of the head
- Shoulder blades
- Hips (greater trochanter)
When sitting in a wheelchair
- Ischial tuberosities (sitting bones)
- Coccyx
- Back of the knee
- Ankles
People at higher risk
- People who have had a stroke or a spinal cord injury
- Older people who are bedbound for long periods
- People with diabetes
- People who are malnourished
- People with impaired sensation
In people with darker skin, the purple colour change of DTI is usually less obvious and harder to see early. Special attention should therefore be paid to whether the area feels soft or firm, warm or cool, and touch can be used to help the assessment.
How can DTI be found early?
Recognising DTI early prevents the wound from getting severe. Day to day, watch for the following signs:
Skin colour change
- Purple or maroon patches on the skin
- A colour clearly different from the skin around it
- The area does not turn white when pressed
Blisters
- Blood-filled blisters
- Dark red or purple blisters
- The skin around the blister may change colour
Temperature
- It may feel warmer than the skin around it (a sign of early inflammation)
- Or it may feel cooler than the skin around it (a sign of tissue death)
Firmness
- It may feel firmer than the surroundings (a sign of swelling)
- Or it may feel softer than the surroundings (a sign of tissue breakdown)
If DTI is suspected, take the pressure off that area at once and have a healthcare professional assess it as soon as possible. Do not massage or rub the area, because this can make the injury worse.
Prevention
The core of preventing DTI is to reduce continuous pressure and shear force:
- Turn regularly—People in bed should change position every 2 hours. People in a wheelchair should relieve pressure every 15–30 minutes.
- Use pressure-relieving equipment—Use a pressure-relieving mattress or an air mattress, raise the heels so they float free, or add a protective pad.
- Reduce shear force—Do not raise the head of the bed above 30 degrees. When moving the patient, lift the body and do not drag it.
- Make sure of good nutrition—Take in enough protein, and enough fluids and vitamins.
A home nursing servicechecks the patient's skin, teaches family members how to turn the patient and transfer them between bed and chair, and recommends suitable pressure-relieving aids, to lower the risk of pressure injury and DTI.
Is there a patient at home who is bedbound for long periods or has limited mobility? Our home nurses can visit for a skin assessment and care guidance.
Ask about home nursing