People are usually familiar with pressure injury, but other types of skin injuries are concerning. Friction injury occurs when the epidermis or top layer of skin separates from the dermis or bottom layer of skin. This is what is often referred to as a ‘rug burn.’ Shearing is pressure and friction, injuring the skin at the same time. It happens more often than people realize because it is so easy to occur. Both can happen even in the best situation, by accident, just in the blink of an eye.
Although the skin is tough, both layers of skin need to move together as they interact together to keep us healthy. When the skin is dragged across a surface, it can separate between the two layers. Friction injury is a simple separation. Shearing is more complicated since it includes pressure downward as the bodyweight is still present on the internal layer of skin, but there is also friction which drags the top layer of skin. In both cases, the site of attachment of the two layers can separate, creating a discolored pigment on the skin, shearing typically being more severe.
Friction injury affects the epidermis or top layer of skin. The outermost surface skin is removed by dragging the body part across something like the bedsheets, wheelchair cushion or wheel, sliding board, or because of spasticity causing a body part to rub against something. Friction injury will look red, purple, or irritated or like a blister with the top layer of skin removed. If the top layer of the skin is removed, an opening in the protective barrier can allow bacteria or viruses to enter the body.
The friction area is extremely tender, which can lead to episodes of pain and increased spasticity. There may be a response from the autonomic nervous system (ANS), as expressed by autonomic dysreflexia (AD), which is a signal to the body that something is wrong.
In shearing injury, there is pressure as well as friction. Both are present in this injury. The pressure comes typically from a boney prominence, applying pressure to the inside of the skin from the weight of the body. At the same time, a friction injury is occurring where the two layers of skin separate.
The dermis or lower layer of skin feeds the epidermis or top layer. When these two layers are separated, the top layer cannot get the nutrients needed to support it. Dragging skin across surfaces can cause this separation of layers. Shearing appears as discoloration on the skin, much like a friction injury or pressure injury, but it is much deeper in the tissue. The body responds in the same way as with a friction injury with pain, spasticity increases, and AD.
Depending on the size and amount of injury, shearing of the skin layers can take a while to heal, leaving that area of skin vulnerable to skin cell deformation and cell death in the lower level of skin, the dermis. Shearing injury makes the skin susceptible to evolving into pressure injury.
Shearing most often comes from pulling or being pulled up in bed by the upper body without picking up the lower body, not lifting the body when doing pressure releases, when transferring or sitting, and from dragging an arm or leg when moving it. Shearing can also occur when an assistive device is rubbing against the body. It can be a result of spasticity moving a limb against something. Mostly shearing injury appears at an area where a bone point is prominent to create the pressure when moving causing the skin to separate. However, shearing can occur anywhere on the body.
There are some techniques that can be used to avoid friction or shearing injury. If you are moving yourself, be sure to pick up your body when moving, keeping it off surfaces. If you are in bed, lower the head of the bed before attempting to move yourself up. Bend knees to help release pressure on your bottom to push up. If transferring to a chair, toilet, commode, or shower chair, lift your body to move. Position your feet first to avoid dragging them behind. If you are unable to lift your body, a sliding board can help. Be sure the sliding board is polished, so your skin does not drag. When getting out of the shower or if you are a little damp for any reason, use corn starch on the sliding board for an easy slide, not a wet drag.
If someone is moving you, they will need to follow the same guidelines as above. The use of equipment for moving your body can be a valuable assistance in avoiding friction and shearing injury as the equipment can provide the lifting needed for position changes. Transfer equipment can be used to move you from one location to another. Even a bed sheet, carefully placed under your body, without wrinkles, can be used by two people to lift and pull your body up in bed.
Use of clothing and bed linen can make a difference in the development of friction or shear injury. Stiff or rough fabric is harsh against the skin. Clothing that moves with your body (if not too tight) can help reduce friction and shear injury. You will notice most pressure dispersing equipment like seats and headrests have a stretchy fabric covering that reduces wrinkles but also ‘gives’ when in use. The coverings are also a bit slick as fabric goes. High thread count sheets make a slightly slicker surface for movement in bed. Of course, you don’t want to fly out of your bed or chair due to slippery fabric or sheets, but less rough content is better.
Some parts of your body are particularly vulnerable to friction and shear injuries just by the nature of their use. In particular, elbows and heels can be areas of friction and shear because of how these body parts are located and used. People tend to rest on their elbows, especially if their upper body or core is weak or if they are just tired. Elbow protectors can help reduce friction. Arm supports can be used when attached to wheelchairs and are also effective. The heels are particularly vulnerable to injury either in attempting to get traction for moving in bed or as they get dragged along when moving the body. Heelbos, the foot equivalent of elbow padding, is especially valuable. Positioning so that there is no pressure on the heels is also important.
Friction and shear injuries can develop into a pressure injury; it is important to stay off the area, so additional pressure is not applied. Even though it can take time to heal this area, keeping off the friction or shear site in less time than it would take to heal a pressure injury, so it is to your advantage to do so.