Pressure Ulcers
Summary
Pressure ulcers are localized injuries to the skin and underlying tissue, usually over a bony prominence, resulting from sustained pressure (ischemia), often in combination with shear and friction. They are a major cause of morbidity in immobile patients (elderly, spinal cord injury, ICU). Prevention is the cornerstone of management, as established Grade 3/4 ulcers can take months to heal or may require complex surgical reconstruction. The Waterlow Score or Braden Scale are essential for risk assessment. [1,2]
Key Facts
- Mechanism: Pressure > Capillary Closing Pressure (32 mmHg) -> Occlusion of blood flow -> Tissue Ischemia -> Necrosis.
- The "Iceberg Effect": A small break in the skin often hides a large cavity of necrotic fat/muscle underneath, as muscle is more sensitive to ischaemia than skin.
- Hospital Acquired: Development of a Grade 3 or 4 pressure ulcer in hospital is often considered a "Never Event" or serious incident requiring investigation.
- SSKIN Bundle: The universal care bundle:
- Surface (Mattress).
- Skin Inspection.
- Keep Moving.
- Incontinence/Moisture.
- Nutrition.
Clinical Pearls
The "Bottoming Out" Test: Slide your hand under the mattress while the patient is on it. If you can feel the patient's sacrum resting on your hand through the mattress foam, the mattress is useless. They need a better one (Dynamic/Air).
Heels: The second most common site. "floating heels" (using pillows under calves) is the most effective prevention.
Unstageable: If an ulcer is covered in black eschar (scab) or yellow slough, you cannot grade the depth. It is classified as "Unstageable". Do not guess Grade 3 vs 4 until debrided.
Risk Factors
- Immobility: Stroke, Spinal Injury, Coma, Fracture.
- Sensation Loss: Neuropathy (Diabetes).
- Moisture: Urinary/Faecal Incontinence (Maceration weakens skin).
- Poor Nutrition: Low Albumin/Protein impairs healing.
Mechanism
- Pressure: Vertical force compresses vessels.
- Shear: Sliding down the bed causes skin to stay put (friction) while bone slides down. This stretches and tears the perforating blood vessels in the deep fascia.
- Reperfusion Injury: When pressure is relieved, free radicals damage tissue.
Grading (EPUAP / NPUAP)
- Inspect: Sacrum, Heels, Ischial Tuberosities (if sitting), Greater Trochanter (if lying on side), Occiput (children/ICU).
- Test: Blanching test (Glass test).
- Measure: Length x Width x Depth.
- Probe: Check for sinus tracts or bone.
Microbiology
- Swab: Often contaminants. Only swab if spreading cellulitis or systemic sepsis.
- Bone Biopsy: If Osteomyelitis suspected.
Bloods
- Albumin/Pre-albumin: Nutritional marker.
- CRP: Infection?
- HbA1c: Diabetic control.
Imaging
- MRI: To diagnose Osteomyelitis in Grade 4 ulcers.
Management Algorithm
PRESSURE ULCER IDENTIFIED
↓
REMOVE PRESSURE (Offload)
(Repositioning schedule)
↓
OPTIMISE HOST
(Nutrition + Glycaemic control)
↓
┌─────────────┴─────────────┐
SUPERFICIAL DEEP / NECROTIC
(Grade 1-2) (Grade 3-4)
↓ ↓
DRESSINGS DEBRIDEMENT
(Films/Foams) (Larvae / Sharp)
↓
VAC THERAPY
↓
PLASTIC SURGERY
(Flap Reconstruction)
1. Prevention (The Best Cure)
- Repositioning: Every 2-4 hours. 30 degree tilt (avoid 90 degrees on throchanter).
- Surfaces:
- At Risk: High specification foam.
- High Risk / Existing Ulcer: Alternating Pressure Air Mattress (APAM).
- Barrier Creams: Protect against moisture (Cavilon).
2. Wound Management
- Debridement: Removing dead tissue is essential for healing.
- Sharp: Scalpel (bedside or theatre).
- Biological: Larval Therapy (Maggots) - very effective for slough.
- Autolytic: Hydrogels.
- Dressings:
- Exudate: Foams / Alginates.
- Granulating: Hydrocolloids.
- NPWT (Negative Pressure Wound Therapy / VAC): Sucks out fluid, increases blood flow, promotes granulation. Excellent for large cavities.
3. Surgical Reconstruction
- For Grade 3/4 ulcers in patients who can withstand surgery and rehabilitation.
- Flaps: Rotation or Advancement flaps (e.g. Gluteal fasciocutaneous flap) to bring healthy vascularised tissue/muscle over the bone.
- Strict Bed Rest: Required for weeks post-op to prevent flap dehiscence.
- Sepsis: Source often missed (check the back!).
- Osteomyelitis: Requires 6 weeks antibiotics +/- surgery.
- Marjolin's Ulcer: SCC developing in chronic wound.
- Healing is slow. A Grade 4 ulcer may take 3-6 months or never heal.
- Associated with 2-4x increase in mortality in elderly.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| CG179 | NICE (2014) | Use Waterlow/Braden score. Reposition every 6 hours (at risk) or 4 hours (high risk). |
| EPUAP | Euro Pressure Ulcer Panel | The Gold Standard for grading. Do not use "reverse staging" (a healed Grade 4 is a "Healed Grade 4", not a Grade 0). |
Landmark Knowledge
1. The "Debridement" Rule
- You cannot stage a wound until you debride it.
- Exception: Dry, stable necrotic tissue (eschar) on Heels should NOT be debrided. It acts as a natural biological cover. Leave it alone unless infected.
What is a Bed Sore?
When you lie in one position for too long, the weight of your body squeezes the blood vessels in your skin against the bone. If the blood stops flowing, the skin dies.
How can we stop it?
Movement is medicine. We need to turn you every few hours to let the blood flow back. We also use special air mattresses that inflate and deflate to massage your skin.
Can it be fixed?
Yes, but it takes a long time. It's like digging a hole - easy to make, hard to fill. We have to clean out the dead tissue and encourage new flesh to grow from the bottom up.
Primary Sources
- NICE Guideline CG179. Pressure ulcers: prevention and management. 2014.
- European Pressure Ulcer Advisory Panel (EPUAP). Prevention and Treatment of Pressure Ulcers: Clinical Practice Guideline. 2019.
- Lyder CH, Ayello EA. Pressure Ulcers: A Patient Safety Issue.
Common Exam Questions
- Nursing: "Non-blanchable erythema. Grade?"
- Answer: Grade 1.
- Plastics: "Black eschar on heel. Management?"
- Answer: Leave it alone (if dry/uninfected). Offload.
- Pathology: "Deepest layer involved in Grade 3 vs 4?"
- Answer: Grade 3 = Fat. Grade 4 = Muscle/Bone.
- Geriatrics: "Tool for risk assessment?"
- Answer: Waterlow or Braden.
Viva Points
- Reactive Hyperaemia: The normal redness seen after pressure is removed. It should blanch (turn white when pressed) and disappear within 30 minutes. If it doesn't blanch, it's a Grade 1 ulcer.
- Maceration: White, soggy skin from sweat/urine. Makes skin weak and prone to tearing.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.