Abstract
Aims: A previous study demonstrated that negative pressure wound therapy (NPWT) increases tissue pressure. This conflicts with the understanding that these dressings increase perfusion. This randomised case control study investigates the effects that circumferential NPWT has on perfusion in humans and how different suction pressures influence this.
Methods: Ten healthy volunteers were recruited into the study and sequentially randomised to receive suction pressures of either −400 mmHg or −125 mmHg. With both hands placed in circumferential NPWT dressings, suction was only applied to one hand. Perfusion of both hands was then analysed simultaneously using radioisotope perfusion imaging. After allowing one week for complete excretion and decay of the isotope, an identical experiment was done on the same volunteers’, this time using the contralateral hand as the test hand. A total of 20 scans were carried out. Data were analysed using the Wilcoxon and Mann-Whitney tests.
Results: In the hands that received suction pressures of −400 mmHg, there was a highly significant mean reduction in perfusion of 40% (SD 11.5%, p< 0.0005). In the hands that received suction pressures of −125 mmHg there was also a highly significant mean reduction in perfusion (mean 17%, SD 8.9%, p< 0.0005). The reduction in perfusion of the group undergoing NPWT at −400 mmHg was significantly greater than the group undergoing NPWT at −125 mmHg (p< 0.015).
Conclusion: Tissue perfusion beneath circumferential NPWT dressings is significantly reduced when suction is applied, regardless of whether suction pressures of −125 mmHg or −400 mmHg are utilised. There is a significantly greater reduction in perfusion at suction pressures of −400 mmHg, compared to −125 mmHg. This implies that circumferential NPWT should be used with extreme caution, if at all, on tissues with compromised perfusion. This finding represents a paradigm shift in our understanding of the mechanism of action of NPWT.
Correspondence should be addressed to: EFORT Central Office, Technoparkstrasse 1, CH – 8005 Zürich, Switzerland. Email: office@efort.org
