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Analysis of Effective Interconnectivity of DegraPol-foams Designed for Negative Pressure Wound Therapy
Department of Materials, ETH Zurich, Zurich, Switzerland
ZMB, Center for Microscopy and Imaging Analysis, University of Zurich, Switzerland
Cardiovascular Surgery, University Hospital Zurich, Zurich, Switzerland
* Author to whom correspondence should be addressed.
Received: 10 January 2009; in revised form: 20 March 2009 / Accepted: 24 March 2009 / Published: 25 March 2009
Abstract: Many wounds heal slowly and are difficult to manage. Therefore Negative Pressure Wound Therapy (NPWT) was developed where polymer foams are applied and a defined negative pressure removes wound fluid, reduces bacterial burden and increases the formation of granulation tissue. Although NPWT is used successfully, its mechanisms are not well understood. In particular, different NPWT dressings were never compared. Here a poly-ester urethane Degrapol® (DP)-foam was produced and compared with commercially available dressings (polyurethane-based and polyvinyl-alcohol-based) in terms of apparent pore sizes, swelling and effective interconnectivity of foam pores. DP-foams contain relatively small interconnected pores; PU-foams showed large pore size and interconnectivity; whereas PVA-foams displayed heterogeneous and poorly interconnected pores. PVA-foams swelled by 40 %, whereas DP- and PU-foams remained almost without swelling. Effective interconnectivity was investigated by submitting fluorescent beads of 3, 20 and 45 mm diameter through the foams. DP- and PU-foams removed 70-90 % of all beads within 4 h, independent of the bead diameter or bead pre-adsorption with serum albumin. For PVA-foams albumin pre-adsorbed beads circulated longer, where 20 % of 3 mm and 10 % of 20 mm diameter beads circulated after 96 h. The studies indicate that efficient bead perfusion does not only depend on pore size and swelling capacity, but effective interconnectivity might also depend on chemical composition of the foam itself. In addition due to the efficient sieve-effect of the foams uptake of wound components in vivo might occur only for short time suggesting other mechanisms being decisive for success of NPWT.
Keywords: Degrapol®; polymer foams; pore interconnectivity; Negative Pressure Wound Therapy (NPWT)
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MDPI and ACS Style
Milleret, V.; Bittermann, A.G.; Mayer, D.; Hall, H. Analysis of Effective Interconnectivity of DegraPol-foams Designed for Negative Pressure Wound Therapy. Materials 2009, 2, 292-306.
Milleret V, Bittermann AG, Mayer D, Hall H. Analysis of Effective Interconnectivity of DegraPol-foams Designed for Negative Pressure Wound Therapy. Materials. 2009; 2(1):292-306.
Milleret, Vincent; Bittermann, Anne Greet; Mayer, Dieter; Hall, Heike. 2009. "Analysis of Effective Interconnectivity of DegraPol-foams Designed for Negative Pressure Wound Therapy." Materials 2, no. 1: 292-306.