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Insights into mechanisms of action

Don Hudson began by challenging conventional understanding of the effects of negative pressure on perfusion in the peri-wound area. The widely held belief is that there is sub-atmospheric pressure adjacent to the wound, and that NPWT increases blood flow.1 At previous meetings Prof Malin Malmsjo has presented evidence that in defect wounds there is a hypo-perfusion zone close to the wound margin (0.5cm) and a hyper-perfusion zone further from the wound margin (2.5cm)2. By contrast, when the team at Cape Town used intracranial pressure transducers to measure the pressure on intact skin, they found that pressure was always slightly positive down to a depth of 1cm, and a reduction in tissue perfusion was observed using radioisotope perfusion imaging3.