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Is a friction injury pressure damage?

There is often confusion on when to report a blister caused by friction to a pressure ulcer presenting very similar caused by pressure or shear. It is important to understand the difference between Friction, Shear and Pressure as this may indicate separate care needs and prevention care planning.

Within this blog we will look at the definitions and clinical presentations, as well as how to minimise the risk of these injuries.

Pressure ulcers:

Pressure ulcers occur over predictable pressure points where bony protuberances are more likely to compress tissues when the patient is in prolonged contact with hard surfaces. These can occur on anyone but usually occur on those with an identified risk status and with prolonged immobility such as in a chair or confined to a bed.

‘Pressure ulcers can affect any part of the body that’s put under pressure. They’re most common on bony parts of the body, such as the heels, elbows, hips and base of the spine’.


A category 2 pressure ulcer where a blister is formed, especially on the heel can be the most confusing to identify as either a friction, shear or pressure injury. In some cases it may be a combination of all three. The reporting clinical is therefore left scratching their head as to what to report as.

See below definitions and guides I hope will help. Remember if in doubt report, photograph and investigate to help steer your decision on likely cause and future prevention planning. Where the patient has capacity they can advise of the history of any injury, e.g. I got a new pair of shoes that have been rubbing my heels = ? Friction injury.

Whereas if they have been in bed without offloading the heels and the heel is blistered but boggy and deep purple in colour with surrounding erythema, these may be an indicator of deeper tissue damage = ? pressure/shear, suspected deep tissue injury.

*Follow your pressure ulcer policy for treatment and management of pressure ulcers.

Friction injury:

Friction wounds are caused when the skin is rubbed against another object. These types of wounds can be caused when bed sheets are dragged across the skin.

Friction from catheter could be a medical device injury which similar to nasal may be seen as mucosal damage, again if sustained pressure here or rubbing of the device to the surface area may differ between pressure damage and friction.

Increased risk of intrinsic factors such as end of life, peripheral vascular shut down, neuropathy, reused sensation.

Due to these conditions where the resident may not feel the damage being done at a local level, we cannot be complacent in still identifying the risk. Educating the resident and informal carers is important so that they may self care/inspect and escalate if there is a concern. Friction injury where usually superficial in some cases can cause long term complications, especially with diabetic patients. Remember not all diabetic patients will be under a diabetic podiatrist until there is already an issue. Diabetic foot ulcers are notoriously hard to heal with severe consequences including amputation if unmanaged.

Ways to minimise friction injuries:

Identify risk, any loss of sensation to feet. 

Inform resident of risks and advise of prevention strategies, namely daily inspection, keeping the feet clean and dry and nails trimmed. Foot care leaflets are available and can be shared.

Ensuring the resident knows who to osculate to if there is a concern.

Assess footwear to ensure there are no lumps or bumps in them that may cause rubbing. Think of when you wore that new pair of shoes and the blister you had when you got home!

If the resident is diabetic ,ask the GP if they are under diabetic podiatry and require home visit.

For catheters, ensure the tip is not rubbing the tip of the penis, leg straps and clips can be provided to ensure the catheter sits comfortably.

For more complex patients ask your incontinence nurse specialist for advice.

For patients with uncontrolled spasms or tremors you may want to assess for offloading mattresses while in bed with in built heel slope (see OSkA Series5-V4L Lateral tilt mattress), use of dermal protection pads or use of prophylactic dressing such as mepilex border. NOTE: With prophylactic dressing the skin on the heel must still be monitored daily as the risk of the dressing being left in place and care staff leaving it can be an issue, so watch out for this.


Shearing wounds occur when forces moving in opposite directions are applied to tissues in the body. This can occur when the skin is stuck to a surface, such as a bed, while gravity forces the body downward on the bed.

As the bones move down due to gravity, blood vessels that are located between the skin and bones can become pinched, which can decrease blood flow to the area. With the lack of blood flow, tissue damage at a deeper level will occur and may start to present as a suspected deep tissue injury (SDTI). Shear injuries may be a result of combined pressure and shear forces.

How to minimise shear/pressure.

Follow your aSSKINg prevention planning and risk assessments including enhanced moving and handling assessment for risk of shear.

My advice as a rule of thumb is test if a SDTI occurred as a result of shear then treat as you would a deep tissue injury, although initially the skin may be intact, the level of trauma may greatly destabilise your resident and the need for complete offloading where possible is advised. 

These may be firstly seen as a category 1 pressure ulcer, so looking for that deep purple dark reddish appearance may indicate tissue damage is done at a deeper level.

Ensure while in bed the patient is not going to slide down the mattress, with hospital beds the knee break is often up and with static beds and decubitus cushion on the knees may be used.

The key here is to not allow the resident to slowly slide forward in the chair or bed.

Not using sliding sheets and repeated shifting up and down the bed without offloading the pelvis may cause shear.

Specialist sheets such as wendylett sheets are often used to help with residents in bed in long term care.

When do I report and investigate?

I think it must be accepted that all of the above samples may be open to subject views and as such the most recommended course of action is to investigate likely cause for either friction, shear or pressure damage through completing a root cause analysis. You may then as a MDT group decide most likely root cause and place actions in place to mitigate further damage whatever the cause.

Report all multiple Category 2, 3 & 4 pressure ulcers and SDTI’s to CQC. Although they are not requesting ungradable pressure ulcers to be reported for those suspected of being a SDTI with blister, I would report also as likely to deteriorate. 

Remember it can be very hard to correctly categorise  skin damage, with the research showing that even amongst senior nurses and wound care specialists there can be poor intra/inter rated reliability (agreement of category) so for long term care homes support in validating is often minimal. 

My advice is to photograph all skin changes so that you have a record and also you can ask professional colleagues to help with validating.

Don’t forget under duty of candour to include the residents’ next of kin in the process.

Taking a picture with consent or best interests is vital as this may be used to help you validate the categorisation of the injury with your multi-disciplinary team. 

For any advice on the above or should you like to discuss training in RCA and quality improvement in care ask OSKA.


Chronic wound repair and healing in older adults: current status and future research. Gould L, Abadir P, Brem H, Carter M, Conner-Kerr T, Davidson J, DiPietro L, Falanga V, Fife C, Gardner S, Grice E, Harmon J, Hazzard WR, High KP, Houghton P, Jacobson N, Kirsner RS, Kovacs EJ, Margolis D, McFarland Horne F, Reed MJ, Sullivan DH, Thom S, Tomic-Canic M, Walston J, Whitney J, Williams J, Zieman S, Schmader K

Wound Repair Regen. 2015 Jan-Feb; 23(1):1-13.