7.2 Risk Assessment Tools & Support Surface Selection

7.2 Risk Assessment Tools & Support Surface Selection

Preventing pressure injuries requires systematic risk identification paired with evidence-based support surface selection and individualized repositioning protocols. The Certified Wound Specialist (CWS) must master standardized risk assessment scales, understand the physics of tissue offloading, and appropriately prescribe support surface categories based on patient risk stratification and wound severity.

---

Pressure Injury Risk Assessment & The Braden Scale

Clinical judgment alone fails to identify up to 50% of patients at risk for pressure injury development. Standardized risk assessment tools must be completed upon admission, with clinical status changes, and at regular intervals (e.g., daily in acute care, weekly in long-term care for the first 4 weeks).

Structure of the Braden Scale

The Braden Scale for Predicting Pressure Sore Risk is the most extensively validated risk assessment tool worldwide. It consists of six subscales that assess key physiological and mechanical risk factors:

1. Sensory Perception: Ability to respond meaningfully to pressure-related discomfort (1 = Completely Limited, 4 = No Impairment).
2. Moisture: Degree to which skin is exposed to moisture (1 = Constantly Moist, 4 = Rarely Moist).
3. Activity: Degree of physical activity (1 = Bedfast, 4 = Walks Frequently).
4. Mobility: Ability to change and control body position (1 = Completely Immobile, 4 = No Limitation).
5. Nutrition: Usual food intake pattern (1 = Very Poor, 4 = Excellent).
6. Friction & Shear: Mechanical interaction between skin and support surface (1 = Problem, 2 = Potential Problem, 3 = No Apparent Problem).

Scoring & Risk Stratification

• Subscales 1 through 5 are scored from 1 to 4; Subscale 6 (Friction & Shear) is scored from 1 to 3.
• Total scores range from 6 to 23, with lower scores indicating greater risk for pressure injury development.

Clinical Cutoff & Subscale-Specific Interventions

• A Braden score of 12 or lower represents a critical clinical cutoff indicating high to severe risk. Patients with scores <= 12 require immediate initiation of comprehensive, aggressive pressure injury prevention protocols.
• Targeted Subscale Interventions: Clinicians must not rely solely on the total score. Individual subscale deficits guide specific care plans:
  • Sensory Perception <= 2: Inspect skin under medical devices twice daily; ensure heel suspension.
  • Moisture <= 2: Implement structured continence care regimen; apply dimethicone/zinc barrier protectants.
  • Mobility <= 2: Prescribe active repositioning schedule; deploy specialty support surfaces.
  • Friction & Shear = 1: Limit HOB elevation to <= 30 degrees; use slide sheets or transfer devices for repositioning.

---

Support Surface Classification & Selection

Support surfaces are specialized devices (mattresses, overlays, cushions) designed for pressure redistribution, microclimate control, and shear reduction. Centers for Medicare & Medicaid Services (CMS) and NPIAP classify support surfaces into three primary groups:

Group 1 Support Surfaces: Reactive Static Devices

• Description: Non-powered, reactive static overlays or mattresses composed of high-specification foam, gel, static air bladders, or water cells.
• Mechanism: Increases the total body surface contact area to redistribute interface pressure (immersion and envelopment).
• Indications:
  1. Patient is completely bedbound or chairbound, OR has a Braden score <= 18 with impaired mobility.
  2. Patient has a Stage 1 or Stage 2 pressure injury AND can independently change position sufficiently to relieve pressure.
• Limitations: Inadequate for patients who cannot turn independently or those with full-thickness (Stage 3 or 4) injuries.

Group 2 Support Surfaces: Dynamic Powered & Low Air Loss Devices

• Description: Powered, dynamic alternating-pressure mattresses/overlays or Low Air Loss (LAL) integrated bed systems.
• Mechanisms:
  • Alternating Pressure (AP): Sequentially inflates and deflates air cells to cyclically relieve pressure beneath tissues.
  • Low Air Loss (LAL): Provides continuous flow of air through porous fabric to control skin temperature and moisture (microclimate management).
• CMS Coverage Indications (Must meet criteria 1, 2, OR 3):
  1. Multiple Stage 2 pressure injuries located on trunk or pelvis while using a Group 1 surface for at least 30 days without healing.
  2. Large or multiple Stage 3 or Stage 4 pressure injuries on the trunk or pelvis.
  3. Patient is at high risk (Braden <= 12) AND unable to turn or shift weight independently.

Group 3 Support Surfaces: Air-Fluidized Beds

• Description: Advanced powered systems containing millions of silicone-coated ceramic/glass beads fluidized by warmed, pressurized air circulating through a permeable filter sheet.
• Mechanism: Simulates liquid flotation, creating minimal interface pressures (well below capillary closure pressure ~32 mmHg), near-zero shear, and optimal microclimate control through high air flow.
• Indications:
  1. Severe, non-healing Stage 3 or Stage 4 pressure injuries on the trunk or pelvis.
  2. Post-operative management of complex skin flaps, myocutaneous flaps, or large skin grafts.
  3. Patient has failed a trial of a Group 2 dynamic powered surface for at least 30 days.
• Contraindications: Unstable spinal cord fractures (due to fluid-like instability), severe congestive heart failure, or pulmonary edema (due to fluid shift and bed angle limitations).

---

Repositioning Protocols & Biomechanics

Support surfaces reduce interface pressure but never replace structured manual repositioning protocols.

Bed Repositioning & The 30-Degree Lateral Tilt

• Frequency: Reposition bedbound patients at least every 2 hours (q2h), alternating between left lateral, back, and right lateral positions.
• Biomechanical Positioning: Use a 30-degree lateral tilted position supported by foam wedges or pillows.
  • Avoid 90-Degree Side-Lying: Direct 90-degree lateral positioning places extreme interface pressure directly over the greater trochanter and lateral malleolus, leading to rapid deep tissue injury.
• Head of Bed (HOB) Elevation: Limit HOB elevation to 30 degrees or less unless medically contraindicated (e.g., aspiration risk, mechanical ventilation). HOB elevation > 30 degrees severely increases sacral shear and sliding forces.

Seated Repositioning

• Independent Patients: Teach wheelchair or chair-bound patients capable of weight shifts to shift weight every 15 minutes for at least 1 to 2 minutes (push-ups, forward lean, side-to-side lean).
• Dependent Patients: Reposition dependent chair-bound patients at least every 1 hour. Seated interface pressures over the ischial tuberosities can exceed 100 to 300 mmHg. Chair sitting should be limited to a maximum of 2 hours continuously.

Heel Offloading Standards

• The calcaneus has minimal subcutaneous tissue cushioning and is the second most common site for pressure injuries.
• Floating Heels: Heels must be completely offloaded (floated) off the mattress matrix by placing pillows lengthwise under the calves or by applying dedicated heel suspension boots.
• Contraindicated Devices: Synthetic ring cushions ("donut" pads) are strictly contraindicated. Donut pads constrict circumferential venous outflow, increase localized edema, and accelerate tissue ischemia in the center of the ring.