Pressure injuries

For operative pressure injuries, see separate topic under 'Operating theatre'

Lesions caused by unrelieved pressure that results in damage to the underlying tissue

Risk factors

• Immobility
• Older age
• Obesity
• Malnutrition
• Ischaemia
• Sensory loss
• Medical comorbidities and frailty
• General anaesthetics
• Poor skin
• Presence of implants (joint replacements etc.)

Pathophysiology

• Generally the result of soft tissue compression between a bony prominence and an external surface for a prolonged period
• Complex pathogenesis, with consideration to interaction between injury characteristics and local tissue characteristics, rather than just pressure. The deformity produced locally by pressure is likely important.
  • Pressure
  • Friction (less important)
  • Shearing forces - such as when patients are on an incline
  • Moisture (less important)
• Pressure to the skin in excess of arteriolar pressure (32mmHg) may lead to local hypoxia and accumulation of metabolic waste products
• Muscle is the most susceptible to injury, followed by fat, and then skin - so deep injury can occur without much visible change. High-grade injuries can start with deep injury that subsequently becomes evident on the skin. It is less likely that there is a uniform progression from grade 1 to grade 4.

Prediction

• Norton or Braden scales can be used to predict
• Specificity and sensitivity 60-80% and low interobserver reliability

Staging:

• NPIAP system - describe the INITIAL appearance of the area. Not useful to guide treatment progress, just what it looks like initially.

Staging of pressure-induced skin and soft tissue injuries[1]

Stage	Description
1	Skin intact but with non-blanchable redness for >1 hour after relief of pressure.
2	Blister or other break in the dermis with partial thickness loss of dermis, with or without infection.
3	Full-thickness tissue loss. Subcutaneous fat may be visible; destruction extends into muscle with or without infection. Undermining and tunneling may be present.
4	Full-thickness skin loss with involvement of bone, tendon, or joint, with or without infection. Often includes undermining and tunneling.
Unstageable	Full-thickness tissue loss in which the base of the ulcer is covered by slough and/or eschar in the wound bed.
Deep tissue pressure injury	Purple or maroon localized area of discolored intact skin or blood-filled blister due to damage of underlying tissue from pressure and/or shear.

Management

General:

• • Pain control
    • Topical anaesthetics have limited evidence - probably don't use
    • Topical opioids have shown some small benefit in trials
    • Mostly will require systemic analgaesia
    • Reconsider wound management techniques if pain is bad
  • Treat infection only in clinically infected wounds. Evaluate for osteomyelitis.
  • Assess and improve nutrition
  • Reposition every two hours. Use support surfaces to offload pressure from the area. Consider air-fluidised beds for patients that are difficult to position due to multiple pressure areas.
  • Prevent contamination
    • Little evidence for IDC/rectal tube
    • Consider colostomy if site is prone to faecal contamination
  • Daily monitoring with wound care nurse.

Wound care:

• • General principles:
    • Debride necrotic tissue
    • Appropriate dressings or wound packing to promote healing
    • Wound coverage
  • Specific regimens:
    • Stage 1: cover for protection
    • Stage 2: generally need little debridement. Require a dressing to maintain a moist wound environment.
    • Stage 3 and 4: require debridement of necrotic tissue and possibly treatment of infection. Following wound bed preparation, coverage may involve skin grafting or other tissue transfer procedures.
      • If the wound is small and relatively clean, can try to manage on the ward with debriding dressings such as Prontosan

Surgical

• • Debridement
    • Debride all necrotic tissue, preferably in OT in most cases
    • Obtain tissue culture
    • Bone biopsy, if involved, for confirmation of OM
    • Meticulous haemostasis is necessary, because these wounds have a propensity to bleed
    • Use outside-to-inside approach, starting from skin
    • Usually apply a VAC - quite good evidence for it in this setting
  • Diversion
    • Consider for patients with longstanding and deep sacral and ischial pressure injuries
    • Can end up being permanent
    • In selected patients, can improve healing times
  • Reconstruction
    • Need a stable wound bed, free of infection, with optimised medical factors before considering
    • Padding of pressure points with full thickness, well-vascularised skin
    • Fasciocutaneous flaps are often used for closure

Prognosis:

• One study looked at >1000 nursing home patients to assess the proportion that were ulcer-free at six months:
  • Stage 2 - 70%
  • Stage 3 - 50%
  • Stage 4 - 30%
    • 77% of stage 4 ulcers followed for two years eventually healed