Deep tissue injury occurs when the blood supply to the muscle and connective tissue overlying a boney prominence such as the sacrum is interrupted by pressure on the small blood vessels or by shear stress. If the pressure or shear stress continues, the tissue will become ischemic and eventually infarct. As the tissue next to the boney prominence is deep to the skin, the tissue damage is not appreciated by the health care team until the damage extends to the skin surface. Early signs visible to the health care team include blanching of the involved area, or erythema. At that point, the underlying tissue has already gone on to irreversible tissue damage. Once the skin breaks down, bacteria in stool or urine can invade the area and lead to more tissue destruction. Bites from vermin in the area may also introduce bacteria into the wound.
Healing of deep tissue injury requires the patient to have adequate protein production. Accordingly, patients who are malnourished have impaired wound healing. The immune system depends on protein synthesis to fight off infection also and so is compromised in the malnourished patient. In addition, patients suffering from diabetes are more prone to infection as their immune system is compromised.
Both deep tissue injury and bug bites cause skin integrity breakdown which increases susceptibility to invasion by virulent bacteria which then cause further tissue destruction. This is especially true in a patient immunosuppressed from poorly controlled diabetes who is also incontinent of stool and urine.
Further adding to susceptibility is poor nutrition. When dangerously low, it reflects that the liver is unable to make proteins necessary for wound healing or proteins needed to fight infection. Albumen is a protein made by the liver. Poor protein intake results in the body not being able to heal wounds. Low protein levels also interfere with the body’s ability to fight off infection as the host response to infection depends on proteins such as antibodies. In short, poor nutritional state is another substantial factor that prevents healing and fighting infection.