11.3 Pressure Injuries & Wound Management
Key Takeaways
- NPIAP Staging classifies pressure injuries into Stages 1-4, Unstageable, and DTPI; Stage 3 exposes subcutaneous fat, whereas Stage 4 exposes fascia, muscle, tendon, or bone.
- Stable, dry, adherent eschar on heels or ischemic limbs must NOT be debrided, as it functions as a protective biological cover.
- Braden Scale scores range from 6 to 23; scores <= 12 indicate high risk requiring aggressive pressure-redistribution and turning protocols.
- Dressing selection matches exudate volume: hydrogels/hydrocolloids hydrate dry wounds, whereas calcium alginates/hydrofibers absorb heavy exudate.
National Pressure Injury Advisory Panel (NPIAP) Staging System
Pressure injuries are localized damage to the skin and underlying soft tissue, usually over a bony prominence or related to a medical device, resulting from intense and/or prolonged pressure or pressure in combination with shear. The National Pressure Injury Advisory Panel (NPIAP 2016) classifies pressure injuries into distinct clinical stages:
[NPIAP Pressure Injury Staging]
┌─────────────────────────────────────────────────────────────┐
│ Stage 1: Non-blanchable erythema of intact skin │
├─────────────────────────────────────────────────────────────┤
│ Stage 2: Partial-thickness skin loss with exposed dermis │
├─────────────────────────────────────────────────────────────┤
│ Stage 3: Full-thickness skin loss; subQ fat visible │
├─────────────────────────────────────────────────────────────┤
│ Stage 4: Full-thickness skin & tissue loss; exposed bone/ │
│ tendon/muscle/fascia │
├─────────────────────────────────────────────────────────────┤
│ Unstageable: Full-thickness loss obscured by slough/eschar │
├─────────────────────────────────────────────────────────────┤
│ DTPI: Persistent non-blanchable deep red/maroon/purple │
└─────────────────────────────────────────────────────────────┘
| NPIAP Stage | Clinical Definition & Anatomic Depth | Key Visual & Palpable Characteristics |
|---|---|---|
| Stage 1 | Non-blanchable erythema of intact skin. | Localized area of persistent redness; does not turn white when pressed. May differ in temperature, firmness, or sensation compared to adjacent tissue. |
| Stage 2 | Partial-thickness skin loss with exposed dermis. | Viable, pink/red, moist wound bed. May present as an intact or ruptured serum-filled blister. No adipose (fat) or deeper tissues visible. No slough or eschar. |
| Stage 3 | Full-thickness skin loss. | Adipose (subcutaneous fat) is visible. Granulation tissue and rolled wound margins (epibole) often present. Slough/eschar may be visible. No exposed muscle, tendon, ligament, cartilage, or bone. |
| Stage 4 | Full-thickness skin and tissue loss. | Directly visible or palpable fascia, muscle, tendon, ligament, cartilage, or bone. Slough and/or eschar may be present. Epibole, undermining, and tunneling common. High osteomyelitis risk. |
| Unstageable | Full-thickness skin and tissue loss in which extent of damage cannot be confirmed. | Covered entirely by slough (yellow, tan, gray, green, brown) or eschar (tan, brown, black). Removing slough/eschar reveals Stage 3 or 4. Exception: Stable dry eschar on heels. |
| Deep Tissue Pressure Injury (DTPI) | Persistent non-blanchable deep red, maroon, or purple discoloration. | Intact or non-intact skin revealing dark wound bed or blood-filled blister. Results from pressure/shear at bone-muscle interface. May rapidly evolve into Stage 3/4. |
Critical Clinical Rules:
- Stable, dry, adherent eschar on ischemic limbs or heels should NOT be debrided, softened, or removed. It serves as the body's natural biological cover; removing it risks severe bacterial invasion and limb-threatening osteomyelitis.
- Reverse Staging is Prohibited: A healing Stage 4 pressure injury does not become a Stage 3, 2, or 1. It is documented as a "healing Stage 4 pressure injury" because lost muscle and subcutaneous tissue are replaced by granulation/scar tissue, not original dermis/subcutis.
Risk Assessment: The Braden Scale
The Braden Scale for Predicting Pressure Sore Risk is a validated tool evaluated routinely in rehabilitation units. It consists of 6 subscales:
- Sensory Perception (1–4): Ability to respond meaningfully to pressure-related discomfort.
- Moisture (1–4): Degree to which skin is exposed to moisture (diaphoresis, incontinence).
- Activity (1–4): Degree of physical activity (bedfast, chairfast, walks occasionally/frequently).
- Mobility (1–4): Ability to change and control body position.
- Nutrition (1–4): Usual food consumption pattern.
- Friction & Shear (1–3): Assistance required for moving in bed/chair.
- Scoring Range: Total score ranges from 6 to 23.
- Risk Stratification:
- No Risk: 19–23
- Mild Risk: 15–18
- Moderate Risk: 13–14
- High Risk: 10–12
- Very High Risk: $\le 9$ Clinical Utility: A lower Braden score indicates higher risk and mandates immediate implementation of preventive interventions (e.g., Q2H turning schedules, specialized pressure-redistribution mattresses/cushions, moisture barrier creams).
Wound Debridement Strategies
Debridement removes necrotic, devitalized tissue and bacterial biofilm to convert a chronic wound into an active healing wound.
| Debridement Type | Mechanism of Action | Clinical Indications & Advantages | Contraindications & Limitations |
|---|---|---|---|
| Surgical / Sharp | Removal of devitalized tissue using scalpel, scissors, or curette by a clinician. | Fastest, most efficient method. Essential for severe infection, sepsis, or extensive necrosis. | Contraindicated in severe arterial insufficiency or dry stable heel eschar. Painful; requires analgesia. |
| Enzymatic | Topical application of exogenous proteolytic enzymes (Collagenase / Santyl). | Selective; digests collagen fibers anchoring devitalized tissue to wound bed. | Slower than sharp; requires daily application; deactivated by silver/heavy metals. |
| Autolytic | Body's own endogenous enzymes (macrophages/neutrophils) digest necrotic tissue under moist dressings. | Highly selective, painless, easy to apply. Uses hydrocolloids, hydrogels, or transparent films. | Slowest method; contraindicated in actively infected or grossly purulent wounds. |
| Mechanical | Physical force to detach necrotic tissue (e.g., wet-to-dry dressings, pulsed lavage, whirlpool). | Widely available; effective for large slough volumes. | Non-selective; can tear viable granulation tissue and cause significant pain. |
| Biological | Medical maggots (Lucilia sericata larvae) secrete digestive enzymes. | Selective; rapid liquefaction of necrotic tissue and bacterial ingestion. | Patient psychological aversion; specialized dressing required. |
Dressing Selection Matrix
Selecting the appropriate wound dressing depends primarily on exudate volume, wound bed depth, and presence of infection.
| Wound Characteristics | Primary Dressing Goal | Recommended Dressing Categories | Examples & Mechanism |
|---|---|---|---|
| Dry Wound / Minimal Exudate (e.g., Stage 2/3 with dry bed) | Rehydrate and provide moisture balance. | Hydrogels, Hydrocolloids, Transparent Films. | Hydrogels donate water to dry wound beds; Hydrocolloids maintain moist autolytic environment. |
| Moderate to Heavy Exudate (e.g., Stage 3/4 exuding ulcer) | Absorb excess moisture and prevent maceration. | Calcium Alginates, Hydrofibers, Polyurethane Foams. | Alginates (seaweed extract) & Hydrofibers absorb up to 20x weight, turning into gel; Foams absorb and cushion. |
| Infected / Malodorous Wounds | Reduce bacterial load and manage bioburden. | Silver-Impregnated Dressings, Cadexomer Iodine, Honey. | Sustained release of antimicrobial silver ions or iodine to destroy bacterial membranes. |
| Deep Cavity / Tunneling Wounds | Eliminate dead space and absorb exudate. | Alginate / Hydrofiber Ropes, Gauge Packing. | Loosely pack ropes into cavities to prevent superficial bridging and abscess formation. |
A 58-year-old male with complete T10 paraplegia presents with a deep ischial ulcer. Physical examination reveals full-thickness skin loss with visible subcutaneous adipose tissue, granulation tissue, and rolled wound edges (epibole). Gluteus maximus muscle fascia and ischial bone are not exposed or palpable. Slough covers approximately 15% of the wound bed. How should this pressure injury be formally staged according to NPIAP criteria?
An 82-year-old bedbound female with severe vascular dementia and peripheral artery disease is evaluated in the rehabilitation unit. On exam of her left heel, there is a 3 cm x 3 cm dark brown, dry, hard, fully adherent intact eschar without erythema, warmth, fluctuance, or purulent drainage. Which of the following is the most appropriate management plan for this heel wound?
A physical therapist asks for assistance selecting a dressing for a Stage 3 sacral pressure ulcer that measures 4 cm x 3 cm x 1.5 cm deep. The wound bed has red granulation tissue but produces large amounts of yellow, serosanguinous exudate that is macerating the surrounding peri-wound skin. Which of the following dressings is most appropriate to absorb excess exudate and manage peri-wound maceration?