Efficient Silver Release From Ion Exchange Silver Dressings in Biologically Relevant Media.

INTRODUCTION: Silver-containing wound dressings commonly are used when there is a risk of infection. These commercial antimicrobial silver dressings have various compositions that use different substrates and/or silver sources. Common silver sources are ionic silver (Ag+) and metallic silver (Ag0). A third source of silver is ion exchange silver compounds (Ag+ complex), in which silver ions are encapsulated in an inorganic carrier to moderate the availability of the silver ions and are released via an ion exchange mechanism. OBJECTIVE: In this study, silver release of different types of silver dressings (Ag+, Ag0, Ag+ complex) in biologically relevant media is investigated. MATERIALS AND METHODS: Simulated wound fluid (SWF) and SWF in combination with 5% bovine serum albumin were used as the extraction media. RESULTS: The composition of the extraction media was found to strongly affect the release of silver. The silver released from most silver dressings peaked at ca 0.5 ppm of soluble silver without any protein in the extraction media. Apparent equilibria established between silver and the salts used for SWF were disrupted by the presence of the protein. This resulted in a dramatic increase in silver release over ionic solutions in the absence of the protein. Dressings differed dramatically in their silver release efficiency. The nature of the silver played a more significant role than the silver content in the dressings. CONCLUSIONS: The ion exchange (Ag+ complex) silver dressing was shown to be the most efficient among all the dressings tested for silver release.

MRI compatibility of silver based wound dressings.

As silver dressings gain more widespread use, it is more likely that patients with silver-based dressings will also undergo magnetic resonance imaging (MRI). In current practice, these dressings are removed prior to imaging due to concerns over heating and image distortion. As dressing changes can be painful, the need to remove dressings simply for MRI may increase pain and contribute to opioid dependency. To examine the need for dressing removal, American Society for Testing and Materials International standards for assessing device deflection and torque were performed on 5 silver containing and 3 non-silver control dressings. Magnetically induced heating and image distortion were examined in a porcine hind limb wound dressed with control and test dressings. The limb was scanned in a clinical high field 3T MRI scanner using a series of standard MRI sequences (Survey, T1-weighted SE, T1-weighted IR TSE, T2-weighted TSE, DUAL TSE, and FLAIR). Deflection and torsion were not detected in control or silver-based dressings. For all combinations of dressings and MRI scans, average heating was between 0-0.2°C. Additionally, dressings, in dry and hydrated forms, caused no image distortion in any MRI scan performed. Evaluation of MRI safety and compatibility revealed no concerns for safety or image distortion in any of the silver-containing wound dressings tested thus it would be acceptable to leave these dressings intact during MRI. The ability to leave dressings in place during imaging will provide a significant benefit to patient care by reducing pain associated with dressing removal.