6.1 Pressure Injury Prevention: Bundles, Turning Schedules, & Heel Floating

Pressure Injury Prevention: Bundles, Turning Schedules, & Heel Floating

Pressure injury prevention requires a systematic, multi-faceted approach grounded in evidence-based guidelines established by the National Pressure Injury Advisory Panel (NPIAP), European Pressure Ulcer Advisory Panel (EPUAP), and Pan Pacific Pressure Injury Alliance (PPPIA). Hospital-acquired pressure injuries (HAPIs) represent significant patient morbidity, prolonged hospitalizations, and increased healthcare costs. A structured prevention strategy integrates validated risk assessment, standardized skin care bundles, strict mechanical repositioning schedules, shear reduction techniques, specialized calcaneal offloading, and individualized support surface technology.

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Etiology & Pathophysiology of Pressure Injuries

Pressure injuries (PIs) develop from sustained external mechanical loading applied to the skin and underlying soft tissues, particularly over bony prominences. Two primary biomechanical forces drive tissue degradation:

1. Direct Pressure: Compressive force applied perpendicular to the skin tissue interface. When localized external pressure exceeds normal capillary perfusion pressure (typically $20\text{--}32\text{ mmHg}$), capillary collapse occurs, causing localized microvascular ischemia, cellular hypoxia, metabolic waste accumulation, tissue acidosis, and ultimate cell necrosis.
2. Shear Forces: Mechanical deformation generated when skin and superficial fascia remain fixed against an external surface (e.g., bed sheets) while deep skeletal structures and underlying fascia slide downward due to gravity. Shear stretches, twists, and angulates dermal and subcutaneous blood vessels, resulting in deep tissue tearing and ischemic necrosis that begins at the muscle-bone interface before manifesting superficially.
3. Friction & Microclimate: Friction represents resistance to motion between two surfaces, removing protective stratum corneum layers. Microclimate refers to the local temperature and moisture environment at the skin-support surface interface. Elevated tissue temperature increases cellular metabolic oxygen demand, while excessive skin moisture (sweat, urine, wound exudate) causes maceration, softening the stratum corneum and lowering the mechanical threshold for pressure and shear damage.

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Structured Pressure Injury Prevention Bundles

A prevention bundle combines evidence-based interventions that, when executed together consistently, deliver superior clinical outcomes compared to individual, uncoordinated care steps. The widely recognized SSKIN Bundle serves as the clinical foundation:

• S — Surface: Selection of appropriate pressure-redistributing mattresses or cushion overlays tailored to patient weight, mobility, and risk score.
• S — Skin Inspection: Comprehensive head-to-toe skin assessment conducted at least daily (and every shift in intensive care units), focusing on bony prominences (sacrum, heels, ischium, trochanter, occiput, elbows, malleoli).
• K — Keep Moving: Implementation of a strict, individualized repositioning schedule in bed and chair.
• I — Incontinence & Moisture: Moisture management utilizing pH-balanced cleansers, skin protectant moisture barriers, and breathable absorbent pads.
• N — Nutrition & Hydration: Nutritional screening, protein supplementation ($1.2\text{--}1.5\text{ g/kg/day}$), and hydration management to support tissue integrity.

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Repositioning Protocols & Biomechanical Positioning

Repositioning redistributes pressure, restores tissue perfusion, and prevents ischemic tissue injury. Unrelieved pressure for as little as 1 to 2 hours can induce irreversible muscular and subcutaneous ischemia in high-risk patients.

Bed Repositioning Schedule & 30-Degree Lateral Tilt

• Frequency: Bedbound patients must be turned at minimum every 2 hours (q2h) around the clock. High-risk patients on static surfaces may require turning every 1 hour.
• 30-Degree Lateral Tilt: Patients should be positioned in a 30-degree lateral tilted side-lying position rather than a traditional 90-degree side-lying position. In a 90-degree side-lying position, direct compressive force is concentrated over the greater trochanter and lateral malleolus, leading to rapid breakdown. The 30-degree tilt uses angled foam wedges placed behind the back and hip to tilt the torso, distributing body weight across the fleshy muscular gluteal mass while avoiding direct pressure on both the sacrum and the greater trochanteric prominence.
• Supine Alignment: When supine, place pillows beneath the head, lower back, and lower legs to maintain natural spine curvature and offload bony contact points.

Seated Repositioning & Weight Shifts

• Seated individuals experience concentrated pressure over the ischial tuberosities ($>100\text{ mmHg}$). Seated patients capable of independent movement must perform micro-shifts or weight shifts every 15 minutes (leaning side-to-side or forward push-ups for 15 to 30 seconds).
• Dependent seated patients must be repositioned or returned to bed at minimum every 1 hour (q1h).
• Seat tilt-in-space wheelchairs providing a backward tilt of at least $30^\circ\text{--}45^\circ$ effectively redistribute ischial pressure to the backrest.

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Shear Reduction & Head of Bed (HOB) Management

Shear stress over the sacrum and coccyx increases exponentially as the head of the bed (HOB) is elevated. When HOB exceeds 30 degrees, gravity pulls the skeleton downward while the skin adheres to the bed linen, creating severe deep tissue shear.

• HOB Elevation Limit: Maintain HOB elevation at $\le 30$ degrees except during active tube feeding, meals, or severe respiratory distress (e.g., acute heart failure or COPD exacerbations). Following meals, lower HOB back to $\le 30$ degrees within 30 to 60 minutes.
• Knee Gatch Adjustment: When HOB elevation is clinically required, elevate the knee gatch (foot of bed) by 10 to 15 degrees before raising HOB. This creates a anatomical cradle that prevents the pelvis from sliding forward.
• Safe Patient Handling Devices: Never drag or pull patients across bed sheets. Utilize low-friction slide sheets, air-assisted transfer devices, or mechanical ceiling lifts for all lateral transfers and repositioning maneuvers.

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Calcaneal Offloading: Heel Floating Protocols

The heels (calcaneus) represent the second most common site for pressure injuries. The heel anatomy is exceptionally vulnerable due to a thin subcutaneous fat pad, minimal overlying muscle, poor collateral arterial supply, and high mechanical pressure against mattress surfaces.

Heel Floating Protocol

• Complete Elevation: The gold-standard recommendation is heel floating, defined as elevating the heels entirely off the mattress surface so that zero pressure is exerted on the calcaneus.
• Pillow Placement Technique: Place pillows under the full length of the lower legs (calves and Achilles tendon region), extending from below the popliteal fossa down to above the ankle. Ensure knees are slightly flexed ($5^\circ\text{--}10^\circ$) to prevent popliteal vein compression or hyperextension of the knee joint.
• Suspension Boots: In high-risk patients or those with limb contractures, pre-formed heel suspension boots (foam or air-filled boots with calcaneal cutouts) provide secure offloading while maintaining neutral foot dorsiflexion ($90^\circ$) to prevent foot drop contractures.

Critical Warning: Ring cushions, donut devices, and tight heel cups are strictly contraindicated. Donut cushions restrict surrounding venous outflow and arterial blood flow, creating a circumferential ring of ischemia that accelerates tissue necrosis.

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Support Surface Classification & Clinical Selection

Support surfaces redistribute pressure, manage microclimate, and reduce shear. NPIAP categorizes surfaces based on powered status and dynamic capabilities:

1. Non-Powered (Reactive) Surfaces: High-specification pressure-redistributing foam mattresses, gel overlays, or static air surfaces that conform to body contours to increase total contact area, thereby lowering average pressure over bony prominences. Indicated for moderate risk (Braden 13-14).
2. Powered (Active) Dynamic Surfaces: Alternating-pressure air surfaces (APAM) with motorized pumps that sequentially inflate and deflate adjacent air cells in cycle times (typically 10-15 minutes). This periodically relieves pressure completely over specific anatomical areas. Indicated for high/very high risk (Braden ≤12) or existing Stage 1/2 injuries.
3. Microclimate & Low-Air-Loss (LAL) Surfaces: Feature continuous airflow through permeable top covers to cool the skin and evaporate perspiration/moisture. Indicated for patients with excessive sweating, maceration, or moisture management challenges.
4. Air-Fluidized Therapy (AFT): Specialized beds filled with silicone-coated glass beads suspended by warmed, pressurized continuous airflow, creating a fluid-like state. Provides maximum flotation and minimum pressure/shear. Indicated for severe Stage 3/4, unstageable, or deep tissue pressure injuries, multiple turning surface breakdown, or post-flap reconstruction surgery.