Pressure ulcers (injuries) are localized areas of tissue necrosis that typically develop when soft tissue is compressed between a bony prominence and an external surface for a long period of time. Ulcers covered with slough or eschar are by definition unstageable. The base of the ulcer needs to be visible in order to properly stage the ulcer (though the ulcer will be at least a stage III, as slough and eschar do not form on stage I or II ulcers).
Figure 1: Sloughy heel pressure ulcer, unstageableFigure 2: Pressure ulcer, leg (unstageable)Figure 3: Slough covered pressure ulcer, unstageable
Pressure ulcers are accepted to be caused by three different tissue forces:
Prolonged pressure: In most cases, this pressure is caused by the force of bone against a surface, as when a patient remains in a seated or supine position for an extended period. When this pressure exceeds the tissue capillary pressure, it deprives the surrounding tissues of oxygen and can lead to tissue necrosis if left untreated.
Shear: This force is typically a result of the skin of a patient staying in one place as the deep fascia and skeletal muscle slide down, which can pinch off blood vessels and in turn lead to ischemia and tissue necrosis.
Friction: Friction is the opposing force to the shear force. This can cause microscopic and macroscopic tissue trauma, specifically when the patient is being moved across the support surface.
In addition, moisture from incontinence, perspiration or exudate can increase the coefficient of friction between the skin and the surface, making it more susceptible to friction damage. Increased moisture also can weaken the bonds between epitheleal cells, resulting in skin maceration, which also makes the skin more susceptible to pressure, shear, and friction damage.
- Immobility or limited mobility
- Spinal cord injury
- Diseases that affect blood flow such as diabetes or atheroscelerosis
- Fragile skin
- Urinary or fecal incontinence
- Poor nutrition or dehydration
- Decreased mental awareness
- Neurological disease
Infection is the most common major complication of pressure ulcers. If the ulcer progresses far enough, it can lead to osteomyelitis (infection of the underlying bone) or sinus tracts, which themselves can be either superficial or connect to deeper structures.
Treatments & Interventions
The goal of treatment of unstageable pressure ulcers is to safely debride them to the point where they can be properly staged and treated accordingly. However, in the case of stable, nonfluctuant heel ulcers with dry eschar covering the wound, debridement should not be performed for the sake of staging as this eschar serves as a protective cover.
The following precautions can help minimize the risk of developing pressure ulcers in at-risk patients and to minimize complications in patients already exhibiting symptoms:
- Turn patients every two hours.
- Keep the skin clean and dry.
- Avoid massaging bony prominences.
- Provide adequate intake of protein and calories.
- Maintain current levels of activity, mobility and range of motion.
- Use positioning devices to prevent prolonged pressure bony prominences.
- Keep the head of the bed as low as possible to reduce risk of shearing.
- Keep sheets dry and wrinkle free.
Merck Sharp & Dohme Corp. Pressure Ulcers. The Merck Manual. http://www.merckmanuals.com/professional/dermatologic_disorders/pressure.... Updated October 2008. Accessed August 22, 2012.
National Pressure Ulcer Advisory Panel. Pressure Ulcer Prevention Points. National Pressure Ulcer Advisory Panel. http://www.npuap.org/resources/educational-and-clinical-resources/pressu.... Accessed August 22, 2012.
Salcido R. Pressure Ulcers and Wound Care. Medscape Reference. http://emedicine.medscape.com/article/319284-overview#aw2aab6b2. Updated January 18, 2012. Accessed August 22, 2012.
Images copyright Medetec (www.medetec.co.uk). Used with permission.