Limitations of in vitro antimicrobial dressings study

Commentary: Response of Human Macrophages to Clinically Applied Wound Dressings Loaded With Silver

“…From there, the fluid is absorbed by the superabsorbent within the dressings and the dressing substrate itself (Cutting et al, 2015 ; Benskin, 2016b , 2018 ). Without a body to donate fluid, both the standard and the silver PolyMem WIC entrapped a part of the agar in the dressing, providing evidence of desiccation and a failure of the experimental model (Benskin, 2016a , b ; Varela et al, 2020 ). Desiccation as an unmeasured confounding variable would explain why Atrauman, with and without silver, the test dressings with the greatest ability to preserve wound moisture in vitro without a cover dressing, appeared to be less cytotoxic than the other test dressings, including the other two without silver (Atrauman, 2020 ; Varela et al, 2020 ).…”

“…As the authors noted, rather than distributing cytotoxic silver into the wound bed like the other silver test dressings, PolyMem Silver's continuous wound cleansing system interacts with the body to dislodge wound pathogens and pull them into contact with silver locked in the dressing (Burd et al, 2007 ; Benskin, 2012 , 2018 ; Varela et al, 2020 ). Rather, in vitro , PolyMem WIC had no body from which to draw new moisture to replace what was absorbed, impairing the ordinarily robust moisture-balancing system and leading to cell death by desiccation (Benskin, 2016a , 2018 ).…”

“…However, the study results are unlikely to be clinically meaningful because of two major design flaws: (1) Contrary to the Instructions for Use, the researchers did not provide secondary (cover) dressings to prevent desiccation with any of the six study dressings (Hess, 2020 ; Atrauman, 2020 ), and (2) The in vitro techniques used did not capture the multifunctional interactive attributes of polymeric membrane dressings (PMDs) such as PolyMem WIC and PolyMem WIC Silver, rending the results for these dressings clinically irrelevant (Benskin, 2012 , 2016a ).…”

Polymeric Membrane Dressings for Topical Wound Management of Patients With Infected Wounds in a Challenging Environment: A Protocol With 3 Case Examples

“…Silver PMDs pull microbes into contact with silver locked into the dressings, making them safer than other silver dressings. 37,39 The flexibility of PMDs was advantageous in this mobile area of the body. The patient was encouraged to move his hand to avoid contractures.…”

Methods used in the study,Evaluation of a polyurethane foam dressing impregnated with 3% povidone-iodine (Betafoam) in a rat wound model, led to unreliable results

“…The configuration of the PMD tested in this study, PolyMem Silver, is designed to keep the silver locked in the dressing, where it acts on microbes that are pulled from the wound bed by the above-described continuous cleansing system without the toxic effects to human cells that may be a problem for conventional foam dressings with silver [ 10 26 27 28 29 ]. Even in the artificial conditions of the study by Zou et al [ 30 ], cited by the authors, PolyMem Silver was the least toxic of all the silver dressings tested.…”