Pressure Injuries

Background

By definition, a pressure injury is localized damage to the skin and underlying soft tissue, usually over a bony prominence or related to a device. Importantly, the National Pressure Injury Advisory Panel (NPIAP) emphasizes that preferred terminology for these wounds is “pressure injury” instead of “pressure ulcer”.

A number of factors are involved in the complex pathogenesis of pressure injuries:

  • Pressure (perpendicular force applied to the skin)
  • Shear (displacement or deformation of tissue, usually in a diagonal direction)
  • Friction (resistance to movement between surfaces such as the superficial layers of skin and the adjoining support surface)

A prolonged period of pressure leads to decreased (or cessation of) capillary blood flow to tissue, which deprives the tissue of oxygen and nutrients, leading to cell death and tissue necrosis.

Risk factors for pressure injury include immobility, malnutrition, reduced skin perfusion, and sensory loss, among others. The Braden score can be used to identify patients at risk for pressure injuries.

Staging

Accurate staging requires us to evaluate areas of skin damage in various ways:

  • Measurements (length, width, and depth)
  • Evaluating color, temperature, tenderness, bogginess, fluctuance, etc.
  • Checking for the presence of sinus tracts, necrotic tissue, or exudate
  • Checking for signs of healing such as granulation
  • Photographs are always helpful!

The NPIAP staging system is a commonly used approach to staging pressure injuries.

StageDescription
1Non-blanchable erythema of intact skin
Intact skin with a localized area of non-blanchable erythema, which may appear differently in darkly pigmented skin. Presence of blanchable erythema or changes in sensation, temperature, or firmness may precede visual changes. Color changes do not include purple or maroon discoloration, which may indicate deep tissue pressure injury.
2Partial-thickness skin loss with exposed dermis
The wound bed is viable, pink or red, moist, and may also present as an intact or ruptured serum-filled blister. Adipose is not visible. Deeper tissues are not visible. Granulation tissue, slough and eschar are not present. These injuries commonly result from adverse microclimate and shear in the skin over the pelvis and shear in the heel.
3Full-thickness skin loss
Adipose is visible in the ulcer. Granulation tissue and epibole (rolled wound edges) are often present. Slough and/or eschar may be visible. The depth of tissue damage varies by anatomical location; areas of significant adiposity can develop deep wounds. Undermining and tunneling may occur. Fascia, muscle, tendon, ligament, cartilage and/or bone are not exposed.
4Full-thickness skin and tissue loss
There is exposed or directly palpable fascia, muscle, tendon, ligament, cartilage or bone in the ulcer. Slough and/or eschar may be visible. Epibole (rolled edges), undermining and/or tunneling often occur. Depth varies by anatomical location.
UnstageableObscured full-thickness skin and tissue loss
If slough or eschar is removed, a Stage 3 or Stage 4 pressure injury will be revealed. Stable eschar (i.e., dry, adherent, intact without erythema or fluctuance) on the heel or ischemic limb should not be softened or removed.
Deep pressure injuryPersistent non-blanchable deep red, maroon or purple discoloration
Pain and temperature change often precede skin color changes. Discoloration may appear differently in darkly pigmented skin. This injury results from intense and/or prolonged pressure and shear forces at the bone-muscle interface. The wound may evolve rapidly to reveal the actual extent of tissue injury, or may resolve without tissue loss. If necrotic tissue, subcutaneous tissue, granulation tissue, fascia, muscle or other underlying structures are visible, this indicates a full thickness pressure injury (Unstageable, Stage 3 or Stage 4).
Source: NPIAP

  • Staging is used to describe the initial appearance of an area of skin damage, and does not imply progression or regression (i.e., staging does not imply that pressure injuries progress from one stage to another). The 3 most common pressure injuries are Stage 1, Stage 2, and Unstageable
  • NPIAP staging does not apply to mucosal injuries because anatomical tissue comparisons cannot be easily made
  • A pressure injury should be staged according to its deepest extent (i.e., based on deepest tissue present)
  • External appearance may be just the tip of the iceberg–the superficial skin is less susceptible to pressure-induced damage than deeper tissues, thus the external appearance may underestimate the extent of damage
  • Skin injury may not present as erythema in patients with dark skin tones, and instead may appear as hyperpigmentation in comparison with the surrounding skin
  • The majority of suspected deep pressure injuries occur on the heels
  • Slough is non-viable tissue (most often yellow, tan, gray, green or brown), which is usually moist, soft, stringy, and mucinous in texture. It may adhere to the base of the wound or present in clumps throughout the wound bed
  • Eschar is dead or devitalized tissue that is variable in texture, usually black, brown, or tan, and may appear scab-like. It usually firmly adheres to the wound

Examples:

Pressure injuries by stage. First row: Stage 1, Stage 2, Stage 3. Second row: Stage 4, Unstageable, Deep Pressure Injury

Differential

It’s essential to distinguish pressure injuries from other diagnoses, including skin tears, moisture-associated skin damage (MASD), and ulcers related to diabetes, arterial insufficiency, or venous insufficiency, noting that lesions may be multifactorial in etiology.

  • MASD is inflammation and erosion of the skin caused by prolonged exposure to various sources of moisture, including urine or stool, perspiration, wound exudate, mucus, or saliva. Unlike pressure injuries, MASD tends to occur over a large skin area in contact with moisture; lesions are superficial, blanchable, and have irregular edges

Prevention

The first step in managing pressure injuries is preventing them in the first place. A number of factors are important to consider:

  • Patient repositioning
    • Every 2 hours, if possible
    • Pair repositioning with documentation and other frequent checks
  • Pressure reduction
    • Air-fluidized beds, foams, gels, overlays, etc.
    • Preemptive dressings in high-risk areas
  • Improving mobility
    • Less sedatives
    • Physical and occupational therapies
  • Skin care
  • Avoiding/minimizing risk factors
    • Moisture
    • Malnutrition
    • Poor perfusion
  • Educating caregivers

Management

Wound healing has 4 phases:

  1. Hemostasis (immediate–coagulation cascade leads to clot formation)
  2. Inflammatory phase (days–neutrophils/macrophages remove debris)
  3. Proliferative phase (2 weeks–collagen synthesis and granulation formation)
  4. Maturation/remodeling phase (months–scar tissue forms)

General measures:

  • Positioning, positioning, positioning!
  • Pain control
  • Wound care (see below)
  • Treatment of infections, if present (pressure injuries can be a reservoir for resistant organisms!)
  • Nutritional optimization
  • Prevent contamination
  • Healing evaluation (e.g., PUSH scale)

Wound care:

A number of dressings are available for managing pressure injuries:

Dressing TypeContentAdvantagesDisadvantagesClinical Applications
GauzeCottonAbsorbent, permeable, can perform mechanical debridement, cost-effectiveRequires frequent dressing changes and does not retain moistureMultiple, including wound packing
FilmsPolyurethaneFlexible, transparent, water-resistant (i.e., retains moisture), semi-permeable (allows gas exchange while impeding external bacteria)May cause maceration, cannot be used on grossly infected/exudative woundsShallow/minor wounds, IV access sites, secondary dressings
AlginatesBrown algaePorous, very absorptiveMay adhere to wound when dry (requires secondary dressing), color and odor may mimic purulenceWounds with heavy exudate
FoamsPolyurethane foamRequires infrequent dressing changes, absorbs exudates, semi-permeable, thickness allows for extra protection from external traumaCannot monitor wounds on a daily basis, wounds can dry outMultiple, including moderate to heavy exudative wounds
HydrocolloidsCarboxymethylcellulose, gelatin, pectinProgressively absorbent by forming a gel, lowers pH (reducing bacterial growth), may be placed across joints or fill wound cavitiesCannot be used on grossly infected or exudative wounds, not transparentMultiple, but not in presence of heavy exudate
HydrogelsMethylacrylate polymersImparts moisture to dry wounds, has cooling effect, helps clear necrotic tissue / microorganisms, often transparentPoor absorption, must be protected with a secondary dressingVenous/arterial ulcers and surgical wounds; hydrogels also prevent tissue desiccation
Source: StatPearls

  • Stage 1 pressure injuries should be covered for protection, often using a foam dressing
  • Stage 2 pressure injuries generally need little debridement and require a dressing that maintains a moist wound environment
  • Stage 3 and 4 pressure or deeper injuries generally require debridement of necrotic tissue, treatment of infection (if present), and a selective approach to dressing type
  • Dryness: Hydrogels can provide hydration to the wound. Dry eschars can also benefit from enzymatic debridement, such as collagenase. 
  • Exudate: Heavy exudate can be managed with foam, hydrocolloid, or alginate dressings. Low exudate can be managed with hydrogel, hydrocolloid, or film dressings. 

Debridement

In general, pressure injuries that are stage 3 and above require debridement. There are 3 types of debridement: surgical, chemical (e.g., collagenase/Santyl), and biologic (maggots).

Chronic wounds frequently form biofilms that should be removed as part of debridement. If superficial, options include topical antiseptics such as silver sulfadiazine as well as honey-based and iodine-based preparations.

Nutrition

A pressure injury should prompt a nutrition consult! Both protein-calorie malnutrition and specific micronutrient deficiency should be addressed to optimize healing, noting that protein and energy requirements for healing may be significantly higher than baseline. Vitamins A, B, C, D, and zinc are particularly important for the inflammatory/immune cascade and collagen production.

Blog post based on Med-Peds Forum talk by Tamara Lhungay, PGY3, and Laura Schwartz, PGY3

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