What are AQUACEL® Ag+ dressings?

AQUACEL® Ag+ dressings, combining Hydrofiber® technology with MORE THAN SILVERTM technology have been specifically designed and proven to effectively disrupt and destroy biofilm, resulting in wound progression in the management of hard-to-heal wounds.
 

Why is wound biofilm an issue?

The term ‘hard-to-heal’ intends to challenge the usual descriptor of a wound that is non-healing as ‘chronic’, since the latter can be perceived as being an acceptable state, when in reality, most chronic wounds can be healed with correct care (Murphy et al, 2020). When a wound is considered hard-to-heal, the presence of biofilm may be a contributing factor (Murphy et al, 2020). It is now acknowledged that at least 78% of non-healing wounds contain biofilm (Hurlow et al, 2015; Bjarnsholt et al, 2017; Malone et al, 2017). Biofilm is also recognised as the precursor to, and primary cause of, chronic wound infection (Holby, 2015; Wolcott et al, 2016).
Biofilm is clinically challenging as it forms quickly within the wound, and following disruption, it can reform within 24 hours (Wolcott, 2010). Once established, biofilm has the ability to block the action of the body’s natural immune response, systemic antibiotics, and topical antiseptic treatments making it difficult to eradicate (Percival and Bowler, 2004; Bowler, 2018). This is because the microbial cells within a biofilm produce a protective matrix of extra-cellular polymeric substances (EPS) that protect them from immune cells and anti-microbial interventions.

Unfortunately, the presence of biofilm within a wound causes a sustained, non-beneficial inflammatory response, and impaired granulation and epithelialisation (Gurjala et al, 2011), resulting in delayed healing (Metcalf and Bowler, 2013; Hurlow et al, 2015).

AQUACEL® Ag+ dressings can disrupt and destroy wound biofilm (Metcalf et al, 2017), which may help hard-to-heal wounds to progress.
 

Mode of action: how does AQUACEL®Ag+ disrupt and destroy biofilm?

AQUACEL® Ag+ dressings use Hydrofiber® technology to create a moist wound healing interface, in conjunction with MORE THAN SILVERTM technology that combines three components – a surfactant, a metal chelating agent and ionic silver. These components are specifically formulated to act synergistically to disrupt and destroy biofilm and prevent its reformation. This combination has been shown to be more effective when compared to ionic silver alone (Bowler and Parsons, 2016).

1. Surfactant: BEC
Surfactant reduces surface tension, aiding the removal of contaminants from surfaces. BEC, the surfactant component of AQUACEL® Ag+ dressings, reduces biofilm surface tension, making it more susceptible to the actions of the metal chelating agent EDTA, and ionic silver (Chen and Stewart, 2000; Banin et al, 2006; Said et al, 2014; Seth et al, 2014).

2. Metal chelating agent: EDTA
Metal chelating agents such as EDTA strongly bind and attract metal ions, boosting the action of surfactants. EDTA helps to remove the metal ions that hold the biofilm’s protective matrix together, exposing the micro-organisms within the biofilm to the anti-microbial effects of ionic silver (Chen and Stewart, 2000; Banin et al, 2006; Said et al, 2014).
3. Ionic silver 
Ionic silver is a broad-spectrum anti-microbial, making it effective against the differing species of bacteria commonly found in wound biofilm. It accumulates on the bacterial cell wall, then enters the cell resulting in cell death (Hobot et al, 2008; Beveridge and Fyfe, 1985).

Through the actions of the three components of MORE THAN SILVERTM technology, the protective EPS covering of the biofilm is disrupted and the micro-organisms within are killed, and are then absorbed and removed from the wound bed by the Hydrofiber® technology of the dressing (Hurlow et al, 2012; Parsons et al, 2016).

The likelihood of biofilm development is increased if exudate is poorly managed (Hurlow and Bowler, 2012), so the Hydrofiber® technology used in AQUACEL® Ag+ dressings is also beneficial in preventing biofilm formation by managing moisture and supporting healing (Parsons et al, 2016).

What is the evidence for using the AQUACEL® Ag+ dressings range?

MORE THAN SILVERTM technology was developed following years of research in which more than 60,000 potential agents were combined and tested, before the combination of surfactant, metal chelating agent and ionic silver were discovered. A body of evidence with 25 publications exists that demonstrate the efficacy of AQUACEL® Ag+ dressings and biofilm, in vitro, in vivo and in clinical practice.

An in vitro study (Bowler and Parsons, 2016) found that MORE THAN SILVERTM technology was able to effectively disrupt biofilm and kill bacteria, presenting a new therapeutic option for the management of hard-to-heal wounds.

The ability of AQUACEL® Ag+ dressings to promote healing in chronic wounds that were stalled or deteriorating at baseline was evaluated in a study of 111 patients from 60 centres across the UK and Ireland (Metcalf et al, 2017). Results indicated that 78% of wounds progressed following treatment with AQUACEL® Ag+, while 13% healed during the average evaluation period of 3.9 weeks.
Before & after chart
Product image
Figure 2 – AQUACEL® Ag+ flat and ribbon dressings.

How do I use AQUACEL® Ag+ dressings?

The AQUACEL® Ag+ dressing range comprises of AQUACEL® Ag+ Extra, flat primary dressings and AQUACEL® Ag+ Ribbon, primary ribbon dressings for cavity wounds (Figure 2). They can be used on a variety of acute and chronic wounds including those that are infected, or at risk of infection. They both require a secondary dressing, such as AQUACEL® Foam.

Wound HygieneTM and AQUACEL® Ag+ dressings: an early intervention against biofilm

Wound HygieneTM is a simple, early intervention strategy that was developed to address the problem of biofilm in hard-to-heal wounds. Like all hygiene practices, e.g. hand hygiene, the fundamental principle is based on repetition. Wound HygieneTM uses a four-step approach that comprises cleansing of the wound and peri-wound, wound debridement, refashioning of the wound edges and the selection of an appropriate antimicrobial dressing (Murphy et al, 2020).

Antimicrobial dressings alone are not sufficient to disrupt and remove biofilm. They should be used as an adjunct to address residual biofilm and prevent its re-formation. This can only be achieved if effective wound hygiene is routinely carried out.

Wound HygieneTM clears the barriers to wound healing, helping antimicrobial dressings to achieve maximum efficacy (Percival et al, 2019). When selecting an antimicrobial dressing, it is important to consider whether it has any anti-biofilm properties as well as its suitability for the individual and their wound, such as its exudate management capabilities.

While Wound HygieneTM addresses local biofilm issues in the wound, however, underlying conditions and other factors contributing to delayed healing should be addressed where possible to optimise healing outcomes (Murphy et al, 2020).
 


For more information

Website: www.convatec.co.uk
Facebook: ConvaTecWoundUK
Twitter: ConvaTecWoundUK
Wound Helpline: Wound.Webcare@convatec.com
0800 289 738 (UK)
1800 946 938 (ROI)
www.woundhygiene.com
Wound HygieneTM is a medical education initiative supported by ConvaTec. Wound Hygiene is a trademark of ConvaTec Inc.
®/TM indicates a trademark of ConvaTec Inc. © ConvaTec Inc. 2020

References

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Bjarnsholt T, Eberlein T, Malone M (2017) Management of wound biofilm made easy. Wounds International, London. Available at www.woundsinternational.com

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Wolcott R, Sanford N, Gabrilska R et al (2016) Microbiota is a primary cause of pathogenesis of chronic wounds. J Wound Care WUWHS Suppl 25(10): S33–43
 

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