Negative pressure wound therapy (NPWT/VAC) promotes wound healing through multiple mechanisms. Which of the following is NOT a recognised mechanism of NPWT?

• A Increasing interstitial oedema by raising capillary hydrostatic pressure in the wound bed ✓
• B Macrodeformation — drawing wound edges together by mechanical tension
• C Microdeformation — cell stretching at the foam-tissue interface stimulating angiogenesis and granulation
• D Removal of exudate and reduction of bacterial bioburden

Explanation

NPWT works by macrodeformation (mechanical wound closure), microdeformation (cell proliferation stimulated by mechanical stretch at the foam interface), removal of excess exudate (reducing wound oedema and bacterial load), and improving perfusion by reducing wound oedema. It REDUCES, not increases, interstitial oedema by creating a negative pressure gradient that draws excess fluid away from the wound into the canister. Increased capillary hydrostatic pressure would worsen oedema and is not a mechanism of NPWT.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.