What are the standard components of Negative Pressure Wound Therapy (NPWT) in the context of grafts?

Negative Pressure Wound Therapy (NPWT) in Graft Management

NPWT is a wound-dressing system that applies subatmospheric pressure to promote graft survival and wound healing through a standardized setup consisting of four essential components: a foam or gauze interface placed directly on the graft, a transparent occlusive drape creating an airtight seal, suction tubing connecting to a pump unit that generates the negative pressure, and a fluid collection system. 1

Standard NPWT Components in Graft Context

1. Foam or Gauze Interface

• The sponge/foam interface sits directly on the skin graft surface and serves as the primary contact layer that distributes negative pressure evenly across the graft 1
• Polyurethane foam-based systems are the most commonly used materials in clinical practice 2
• Low-adherence dressing options can be incorporated to reduce trauma during dressing changes, particularly important when securing grafts 3
• The interface material allows for drainage of extracellular inflammatory fluids while maintaining contact with the graft 1

2. Transparent Occlusive Drape

• A semiocclusive barrier is applied over the foam to create an airtight seal around the wound and graft site 1
• The transparent nature allows for visual monitoring of the graft without breaking the seal 1
• This drape is critical for maintaining the subatmospheric pressure environment necessary for graft adherence 1

3. Suction Tubing and Pump Unit

• The pump generates subatmospheric pressure, typically set at 125 mm Hg for standard NPWT, though lower pressures (75 mm Hg) can be used for graft management with comparable efficacy and reduced pain 3
• The tubing connects the foam interface to the pump unit, allowing continuous or intermittent negative pressure application 1
• After split-thickness skin graft (STSG) placement, NPWT is typically applied for 4 days to secure grafts and improve survival 3

4. Fluid Collection System

• The system includes a canister that collects wound exudate and inflammatory fluids removed from beneath the graft 1
• This drainage component is essential for preventing fluid accumulation that could compromise graft take 1

Mechanisms Supporting Graft Survival

NPWT promotes graft adherence through four key mechanisms 1:

• Macrodeformation of tissues brings the graft into intimate contact with the wound bed
• Drainage of extracellular inflammatory fluids prevents seroma formation under the graft
• Stabilization of the wound environment reduces shear forces that could disrupt graft adherence
• Microdeformation at the cellular level promotes angiogenesis and granulation tissue formation

Clinical Application Considerations

• NPWT has demonstrated efficiency specifically for skin graft management across various wound types 1
• The system can be used both for wound bed preparation before grafting and for securing grafts post-operatively 2
• Pain levels during therapy tend to decrease as treatment progresses, with moderate pain (4-5 on visual analogue scale) reported during dressing changes 3
• Complications are rare but include toxic shock syndrome, fistulization, bleeding, and pain—special care must be taken to prevent these events 1