Pressure Ulcers

Pressure ulcers are localized areas of tissue damage or necrosis that develop because of pressure over a bony prominence. (Other synonymous terms include decubitus ulcers and, colloquially, “bed sores”.) Pressure ulcers arise due to pressure on affected areas due to immobility for extended periods of time. The epidermis functions as the outer protective layer of the skin. It is easily damaged by sun or trauma. There are 5 layers of the epidermis (stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and the stratum corneum). Melanin is produced by the epidermis, namely the stratum basale. This layer is completely recycled every 60 days. The dermis is the skin layer under the epidermis. It secretes collagen and elastin proteins for tensile strength and skin recoil, respectively. It contains hair follicles, nerve endings (which are painful when exposed), and can regenerate when damaged. The dermis contains mast cells, macrophages, and lymphocytes to provide the integumentary system with immune system protection. The subcutaneous layer acts as a support for the dermis and the epidermis. It also provides insulation, cushioning to withstand stress and pressures, and storage of fat (adipose tissue). The pathogenesis of pressure ulcers is multifactorial and includes pressure over bony prominences for extended periods of time, shearing forces, friction, moisture (i.e. urinary incontinence), immobility, and nutritional status.

There are 6 different types of pressure ulcers. The following descriptions are adapted from the National Pressure Ulcer Advisory Panel:

• Stage 1: Stage 1 pressure ulcers are characterized by intact skin with non-blanchable redness of a localized area usually over a bony prominence. Darkly pigmented skin may not have visible blanching (turning white when pressed); color may differ from surrounding areas. The area may be painful, firm, soft, warmer, or cooler as compared to adjacent tissue. Stage 1 pressure ulcers may be difficult to detect in individuals with dark skin tones.
• Stage 2: Stage 2 pressure ulcers appear as partial thickness loss of the dermis layer presenting as a shallow open ulcer with a red pink wound bed without slough (necrotic tissue); they may also present as an intact or open/ruptured serum-filled blister. Stage 2 ulcers present as a shiny or dry shallow ulcer without bruising (which is implicated in deep tissue injury wounds).
• Stage 3: Stage 3 pressure ulcers are identified by full thickness tissue loss. Subcutaneous fat may be visible but bone, tendon, or muscle is not exposed. Slough may be present but does not obscure the depth of the tissue loss. Undermining and tunneling may be present. Wound undermining occurs when the tissue under the wound edges becomes eroded, resulting in a pocket beneath the skin at the wound's edge. Undermining is measured by inserting a probe under the wound edge directed almost parallel to the wound surface until resistance is felt. Tunneling wounds have channels that extend from a wound into and through subcutaneous tissue or muscle. They often are difficult to manage and may persist for long periods of time. The depth of a stage 3 pressure ulcer varies by location. The bridge of the nose, ear, occiput, and malleolus do not have subcutaneous tissues and stage 3 ulcers can be shallow. In contrast, areas of significant adiposity can develop extremely deep stage 3 ulcers. Bone and tendon are not visible or directly palpable.
• Stage 4: Stage 4 pressure ulcers are full thickness tissue loss with exposed bone, tendon, or muscle. Slough or eschar (is dead tissue that sheds or falls off from healthy skin; typically, colors are tan, brown, or black, and eschar may be crusted) may be present on some parts of the wound bed. Undermining and tunneling are often present as well. Exposed bone and tendon are visible or directly palpable. The depth of a stage 4 pressure ulcer, like a stage 3, varies by location. Osteomyelitis (bone infection) is a complication of stage 4 wounds due to extension of the wound into muscle, fascia, bone, etc. Diagnosis of osteomyelitis requires a bone biopsy and wound cultures. Treatment involves antibiotics for several weeks (ca. 6 weeks) via PICC line, often requiring discharge to sub-acute rehabilitation for administration.
• Unstageable: Unstageable wounds involve full thickness tissue loss in which the base of the ulcer is covered by slough and/or eschar. Until enough of the slough or eschar is removed to expose the base of the wound, the true depth (and therefore, the stage) cannot be ascertained.
• Deep tissue Injury: A deep tissue injury (DTI) is identified by a purple or maroon localized area of discolored intact skin or blood-filled blister due to damage of underlying soft tissue from pressure and/or shear. The area may be preceded by tissue that is painful, firm, boggy, warmer, or cooler to adjacent tissue. Evolution may include a thin blister over a dark wound bed. The wound may further evolve and become covered by thin eschar. Evolution may be rapid and expose additional layer of tissues even with optimal treatment.

It should be noted that reverse staging of pressure ulcers to assess healing is not done because healing ulcers do not progress serially in reverse. Healing involved granulation, wound contraction, re-epithelization, and scar formation. Healing should be described in terms of exudates, surface area (measurements), health of surrounding tissue, and the health of the granulation tissue. For treatment, stage 1 ulcers require no type of dressings. Stage 2 pressure ulcers are treated with moist or occlusive dressings to maintain a moist, healing environment. Stage 3 ulcers require debridement, usually with an enzymatic agent or wet-to-moist normal saline soak. Stage 4 ulcers are treated like stage 3 ulcers, or by surgical excision/debridement and grafting. Foley catheters are used for sacral wounds to prevent skin maceration and further breakdown as a result of moisture-associated skin damage. A Foley catheter is a thin, sterile tube inserted into the bladder to drain urine. Because it can be left in place in the bladder for a period of time, it is also called an indwelling catheter.

Review Questions

Questions 1-3: An 83-year-old bedbound patient is seen in the nursing home for evaluation of a new sacral decubitus ulcer. He is bedbound secondary to multiple sclerosis. His vital signs are stable. His physical exam is notable for a 3 cm x 4 cm x 5 cm sacral wound with full thickness skin loss that extends down but not through the underlying fascia. There is no eschar present. There is no undermining.

1. Which of the following descriptions is correctly paired?

A. Stage 1 – superficial partial thickness skin loss involving the dermis and epidermis
B. Stage 2 – altered intact skin which is non-blanchable
C. Stage 3 – full thickness skin loss that extends down but not through the underlying fascia
D. Stage 4 – a pressure-related injury to subcutaneous tissues under intact skin
E. Deep tissue injury – full thickness skin loss and extensive destruction and necrosis of muscle and bone

2. How do pressure ulcers develop?

A. Due to pressure on affected areas due to immobility for extended periods of time
B. Due to physical elder abuse
C. Due to excessive nutrition and hydration
D. Due to untreated skin or soft tissue infections
E. Due to severely dry skin

3. What is the best rationale for the placement of a Foley catheter during the treatment of a sacral pressure wound?

A. Most patients with pressure ulcers have obstructive uropathy and cannot adequately void.
B. To prevent skin maceration as a result of moisture-associated skin damage.
C. To prevent the introduction of bacteria in the urine into the sacral wound.
D. To relieve pressure from a distended bladder on the sacral wound.
E. Foley catheter placement should be avoided due to the risk of catheter-associated urinary tract infections.

Answers to Review Questions

1. C
2. A
3. B