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Currently, surgical gauze and foam are primary dressings when used in wounds undergoing NPWT. Gauze and foam exhibit opposing physical structures; gauze being hydrophilic (absorptive) and foam being hydrophobic (water-repelling). A new dressing described as an antimicrobial, hydrophobic, wide-meshed material has shown promising results when used clinically in NPWT. It has been noted that gauze and foam dressings present both advantages and disadvantages. This new hydrophobic mesh dressing demonstrates a blend of traits associated with both gauze and foam, while perhaps eliminating several disadvantages associated with each.
Methods
The three materials (gauze, foam, and hydrophobic mesh) were compared in terms of fluid flow properties, density, wick time (drying time) and the amount of compression under negative pressure. The resistance to fluid flow of each material was determined by separately inserting an equivalent amount of each material inside a fistula model tube with attached vacuum pump. Passing fluid through the materials via suction resulted in saturation of each material. Flow rates were measured over a range of clinical NPWT pressures (50 to 120 mmHg).
Results
Gauze produced the highest resistance, impeding the flow of fluid through the fistula wound model. Gauze also demonstrated the slowest wick time (drying time). The hydrophobic mesh and foam had similar low resistances when fluid was separately passed through those materials, but the hydrophobic mesh exhibited a faster wick time.
Conclusion
This experiment suggests that gauze may prevent effective pressure distribution in wounds undergoing NPWT. Also suggested is that the hydrophobic mesh may perform similarly to foam in a NPWT environment regarding pressure distribution, and the faster wick time implies a more rapid egress of exudate from the wound when used with NPWT. This data should especially be considered for NPWT applications involving fistulas, and wounds with undermining or deep tracts.