9.2 Pressure Injury Stages, Staging & Prevention Protocols

Pressure Injury Stages, Staging & Prevention Protocols

Pressure injuries—historically termed decubitus ulcers, pressure sores, or bedsores—represent one of the most critical indicators of nursing care quality in long-term care facilities, hospitals, and home health environments. Under federal Centers for Medicare & Medicaid Services (CMS) regulations and Mississippi State Department of Health licensing guidelines, healthcare facilities are held to rigorous standards to prevent facility-acquired pressure injuries.

A pressure injury is defined as localized damage to the skin and underlying soft tissue, usually over a bony prominence or related to a medical or other device. The injury occurs as a result of intense and/or prolonged unrelieved mechanical pressure in combination with shear forces, friction, and excessive moisture.

Because Certified Nursing Assistants (CNAs) perform the vast majority of repositioning, hygiene, and skin inspections, their mastery of pressure injury staging criteria, anatomical vulnerability mapping, and evidence-based prevention regimens is vital to preserving resident skin integrity.

1. Pathophysiology of Pressure Injuries & Extrinsic Mechanical Forces

Pressure injuries are not merely superficial skin abrasions; they are ischemic necrosis events that develop from the inside out when external physical forces collapse microvascular capillary beds.

+-----------------------------------------------------------------------------+
|                      PRESSURE INJURY CAUSAL CASCADE                         |
|                                                                             |
|   [UNRELIEVED EXTERNAL PRESSURE]                                            |
|   - Pressure exceeds capillary closure pressure (~32 mmHg).                 |
|                                  |                                          |
|                                  v                                          |
|   [MICROVASCULAR COLLAPSE & ISCHEMIA]                                       |
|   - Blood flow obstructed; oxygen & nutrients cut off from tissue.          |
|                                  |                                          |
|                                  v                                          |
|   [CELLULAR TOXIN ACCUMULATION & HYPOXIA]                                   |
|   - Metabolic waste products (lactic acid) accumulate in cells.             |
|                                  |                                          |
|                                  v                                          |
|   [TISSUE NECROSIS & ULCER FORMATION]                                       |
|   - Cells die; tissue sloughs, creating open wound down to deep fascia/bone.|
+-----------------------------------------------------------------------------+

The Four Major Extrinsic Forces

1. Mechanical Pressure: The perpendicular downward force exerted by body weight against a supporting surface (bed mattress or chair cushion). Capillary blood pressure in healthy human skin ranges from $16\text{ to }32\text{ mmHg}$. When external interface pressure exceeds $32\text{ mmHg}$ over a bony prominence, local capillaries collapse, cutting off microvascular perfusion.
2. Shearing Force: The mechanical force pulling parallel to the skin surface while deeper skeletal and muscular structures shift in the opposite direction. For example, when a resident's bed is elevated to $60^\circ$ or $90^\circ$, gravity pulls the bony skeleton downward toward the foot of the bed while the outer skin remains stuck to the bed linens. This sliding shear stretches, kinks, and tears delicate subcutaneous blood vessels, causing extensive deep tissue ischemia.
3. Friction: The mechanical rubbing and scraping of superficial epidermal skin against an opposing surface (e.g., dragging an uncooperative resident across bed sheets rather than lifting them with a draw sheet). Friction removes the protective stratum corneum layer, creating painful abrasions and making the skin highly susceptible to deeper breakdown.
4. Moisture & Maceration: Constant exposure to urine, feces, wound drainage, or heavy diaphoresis over-hydrates and softens the epidermis—a process called maceration. Macerated skin appears white, waterlogged, and fragile, losing its natural tensile strength and dramatically multiplying the destructive impact of pressure and friction.

2. Anatomical Vulnerability Mapping: High-Risk Bony Prominences

Any anatomical area where a bony prominence lies directly beneath a thin layer of skin and subcutaneous fat without thick muscle padding is at extreme risk for pressure injury development.

+-----------------------------------------------------------------------------+
|               PRESSURE INJURY ANATOMICAL SITES BY BODY POSITION             |
|                                                                             |
|   [1. SUPINE POSITION (BACK-LYING)]                                         |
|   - Occiput (back of skull)    - Scapulae (shoulder blades)                 |
|   - Spinous processes (spine)  - Elbows (olecranon process)                 |
|   - Sacrum & Coccyx (tailbone) - Calcaneus (HEELS - EXTREME RISK)           |
|                                                                             |
|   [2. LATERAL POSITION (SIDE-LYING)]                                        |
|   - Ear / Temporal bone        - Acromion process (shoulder tip)            |
|   - Ribs & Lateral chest wall  - GREATER TROCHANTER (HIP - HIGHEST RISK)    |
|   - Medial & Lateral condyles  - Medial & Lateral malleoli (ankles)         |
|                                                                             |
|   [3. SITTING POSITION (WHEELCHAIR / CHAIR)]                                |
|   - ISCHIAL TUBEROSITIES (sitting bones - absorbs 75% of sitting pressure)  |
|   - Sacrum & Coccyx            - Scapulae (against chair back)              |
|   - Popliteal fossa (knee fold)- Plantar heels & metatarsals                |
|                                                                             |
|   [4. MEDICAL DEVICE PRESSURE SITES]                                        |
|   - Ears (nasal cannula tubing)- Nares (nasogastric tubes)                  |
|   - Inner thigh / meatus (Foley catheter tubing) - Casts / braces / splints |
+-----------------------------------------------------------------------------+

Clinical Vulnerability Ranking:

• The Sacrum/Coccyx and Calcaneus (Heels) account for over 60% to 70% of all pressure injuries in long-term care settings.
• Heels have minimal subcutaneous adipose tissue and poor collateral circulation, making them exceptionally vulnerable to rapid, full-thickness mummification and necrotic breakdown.

3. NPUAP / CMS 6-Stage Pressure Injury Classification System

The National Pressure Injury Advisory Panel (NPUAP), endorsed by CMS, classifies pressure injuries into six standardized clinical stages based on the depth of tissue destroyed.

+-----------------------------------------------------------------------------+
|                       NPUAP / CMS PRESSURE INJURY STAGING                   |
|                                                                             |
|   [STAGE 1]  --> Intact skin with NON-BLANCHABLE ERYTHEMA.                  |
|   [STAGE 2]  --> Partial-thickness dermis loss; PINK/RED MOIST wound bed or|
|                  intact/ruptured SERUM-FILLED BLISTER.                      |
|   [STAGE 3]  --> Full-thickness skin loss; SUBCUTANEOUS ADIPOSE (FAT) visible|
|                  Slough/eschar may be present. Undermining/tunneling.       |
|   [STAGE 4]  --> Full-thickness tissue loss; EXPOSED FASCIA, MUSCLE, TENDON,|
|                  LIGAMENT, CARTILAGE, or BONE directly visible/palpable.    |
|   [UNSTAGEABLE]-> Full-thickness loss covered by SLOUGH (yellow/tan) or     |
|                  ESCHAR (black/brown necrotic tissue) obscuring wound bed.  |
|   [DTPI]     --> Deep Tissue Pressure Injury: Intact/non-intact skin with   |
|                  persistent NON-BLANCHABLE DEEP RED, MAROON, or PURPLE      |
|                  discoloration, or blood-filled blister.                    |
+-----------------------------------------------------------------------------+

Detailed Analysis of Each Pressure Injury Stage

1. Stage 1 Pressure Injury: Non-Blanchable Erythema of Intact Skin

   • Skin Status: Intact skin with localized redness.
   • Blanching Test: When light fingertip pressure is applied, the reddened area does not blanch (does not turn white/pale); it remains red. In darkly pigmented skin, blanching may not be visible; instead, look for localized warmth, edema, induration (firmness), or a boggy, spongy texture with purple/blue hues compared to adjacent skin.
   • Clinical Importance: Stage 1 represents an early warning signal of microvascular ischemia. If pressure is immediately relieved, the tissue will recover without permanent ulceration.

2. Stage 2 Pressure Injury: Partial-Thickness Skin Loss with Exposed Dermis

   • Depth: Involves the epidermis and superficial dermis.
   • Appearance: The wound bed is viable, pink or red, moist, and free of slough or eschar. It often presents as an intact or ruptured fluid-filled (serum) blister or a shallow, open crater.
   • Exclusions: Does NOT include skin tears, moisture-associated skin damage (MASD / incontinence-associated dermatitis), or tape burns.

3. Stage 3 Pressure Injury: Full-Thickness Skin Loss

   • Depth: Extends entirely through the epidermis and dermis into the subcutaneous tissue.
   • Tissue Visibility: Subcutaneous adipose (fat) tissue is visible in the ulcer crater. Granulation tissue (beefy red, bumpy healing tissue) and epibole (rolled wound edges) are commonly present.
   • Slough & Undermining: Slough (stringy yellow/gray dead tissue) and/or eschar may be present but do not obscure the depth of tissue loss. Undermining (tissue destruction under intact skin edges) and tunneling may occur.
   • Exclusions: Fascia, muscle, tendon, ligament, and bone are NOT visible or palpable.

4. Stage 4 Pressure Injury: Full-Thickness Skin and Tissue Loss

   • Depth: Catastrophic, deep tissue destruction extending through all skin, adipose, and deep fascia layers.
   • Tissue Visibility: Directly exposed or palpable muscle, tendon, ligament, cartilage, or cortical bone.
   • Complications: Slough and eschar may be present; epibole, deep tunneling, and extensive undermining are almost always present. Carries an extreme risk of osteomyelitis (bone infection), joint sepsis, and fatal systemic bacteremia.

5. Unstageable Pressure Injury: Obscured Full-Thickness Skin and Tissue Loss

   • Definition: The true depth and clinical stage of the ulcer cannot be determined because the base of the wound bed is completely covered by necrotic tissue: either slough (yellow, tan, gray, green, or brown) or eschar (tan, brown, or black leathery crust).
   • Clinical Rule: Until enough slough or eschar is surgically or enzymatically removed (debrided) by licensed medical staff to expose the wound bed, the injury is classified as Unstageable. Once debrided, it will reveal either a Stage 3 or Stage 4 pressure injury.
   • Special Heel Eschar Exception: Stable (dry, adherent, intact, non-erythematous, and non-fluctuant) eschar on the heels serves as the body's natural biological barrier and should never be softened, soaked, or removed unless infection develops.

6. Deep Tissue Pressure Injury (DTPI): Persistent Non-Blanchable Deep Red, Maroon, or Purple Discoloration

   • Definition: Intact or non-intact skin with localized, persistent non-blanchable deep red, maroon, or purple discoloration, or epidermal separation revealing a dark wound bed or blood-filled blister.
   • Pathophysiology: Originates from intense shear and compressive forces at the bone-muscle interface deep beneath the skin. The surface skin may feel painfully boggy, mushy, warmer, or cooler than adjacent tissue.
   • Evolution: DTPIs can evolve rapidly, opening to expose massive underlying Stage 3 or Stage 4 muscle necrosis even with optimal wound care.

Clinical Comparison Matrix: Pressure Injury Stages

4. Evidence-Based Prevention Protocols & Repositioning Regimens

Preventing pressure injuries is infinitely more effective, humane, and cost-effective than treating advanced necrotic wounds.

+-----------------------------------------------------------------------------+
|                     CORE PRESSURE INJURY PREVENTION RULES                   |
|                                                                             |
|   [REPOSITIONING REGIMEN]                   [HEEL OFFLOADING ("FLOATING")]  |
|   - Bedbound: Turn at least EVERY 2 HOURS.  - Elevate heels completely off  |
|   - Chairbound: Shift at least EVERY 1 HOUR.  the mattress surface.         |
|   - Use 30-DEGREE LATERAL TILT.             - Pillows under calves only;    |
|   - NEVER place directly on trochanter 90°.   zero pressure on Achilles/heel|
|                                                                             |
|   [SHEAR & FRICTION REDUCTION]              [SKIN HYGIENE & MOISTURE]       |
|   - Head of Bed <= 30 DEGREES.              - Cleanse immediately post-void.|
|   - Use DRAW SHEETS with 2 caregivers.      - Pat dry; apply barrier cream. |
|   - NEVER DRAG a resident across linens.    - NEVER MASSAGE REDDENED BONY   |
|   - Use dynamic air mattresses & cushions.    PROMINENCES (causes necrosis)!|
+-----------------------------------------------------------------------------+

The 30-Degree Lateral Side-Lying Tilt

When placing a bedbound resident in a lateral side-lying position, never turn them directly onto their side at a $90^\circ$ angle. A $90^\circ$ turn concentrates the resident's entire body weight directly over the greater trochanter of the femur—the single most pressure-sensitive site on the hip.

+-----------------------------------------------------------------------------+
|                        THE 30-DEGREE LATERAL TILT                           |
|                                                                             |
|   [STEP 1: POSITIONING]  ---> Roll resident slightly to the side (~30°).   |
|   [STEP 2: BACK SUPPORT] ---> Place a supportive pillow behind the back to  |
|                               maintain the 30° angle off the trochanter.    |
|   [STEP 3: KNEE/ANKLE]   ---> Place a pillow between knees and ankles to    |
|                               eliminate bone-on-bone friction.              |
|   [STEP 4: ARM SUPPORT]  ---> Support upper arm with pillow across chest.   |
+-----------------------------------------------------------------------------+

Heel Offloading ("Floating Heels") Protocol

Heels have the highest risk of rapid necrosis. Standard hospital mattresses provide inadequate pressure redistribution for the calcaneus.

• Correct Technique: Place a pillow longitudinally beneath the resident's lower legs (calves), extending from below the knees to above the ankles. This elevates the feet and suspends the heels completely in mid-air ("floating heels") with zero contact against the bed sheets.
• Common Dangerous Error: Placing a pillow or folded towel directly under the Achilles tendon or heel. This focuses intense mechanical pressure on the Achilles tendon and fails to relieve calcaneal pressure.

Specialized Support Surfaces, Hygiene & The Massage Prohibition

1. Pressure-Redistribution Mattresses & Seating Cushions:

   • Static Foam Overlays / High-Density Foam: Distribute body weight over a broader surface area.
   • Dynamic Alternating-Pressure Air Mattresses: Sequentially inflate and deflate alternating air cells to periodically relieve interface pressure completely across anatomical zones.
   • Wheelchair Gel/Air Cushions (e.g., ROHO): Must be placed in every wheelchair for non-ambulatory residents. Donut-shaped ring cushions are strictly prohibited because they constrict venous blood flow and create intense circular ring pressure that accelerates tissue ischemia.

2. Incontinence Management & Barrier Protection:

   • Incontinence of urine and feces exposes skin to caustic urea and bacterial digestive enzymes (lipase and protease).
   • Cleanse the perineum promptly after every incontinent episode with warm water and a pH-balanced, no-rinse perineal cleanser; gently pat dry with a soft towel.
   • Apply a thick layer of moisture barrier ointment containing zinc oxide, dimethicone, or petroleum to shield the skin from moisture maceration.

[!WARNING] The Absolute Prohibition on Massaging Reddened Bony Prominences: In past decades, caregivers mistakenly rubbed or massaged reddened skin over hips and tailbones to "stimulate circulation." Extensive clinical research has proven that massaging reddened bony prominences causes massive shearing and ruptures fragile ischemic capillaries, transforming a reversible Stage 1 injury into deep subcutaneous necrotic damage. NEVER massage reddened bony areas.