Should one size fit all? An overview and critique of the VULCAN study on silver dressings

Nanocrystalline Silver Layer of Knitted Polyester Outperforms Other Silver-Containing Wound Dressings in an In Vitro Wound Model

Background Silver possesses cytotoxic properties against many microorganisms and is regularly used in wound care. Current evidence supporting the use of one type of silver-containing wound dressing (SCWD) is insufficient. Materials and methods To examine the ability of selected SCWDs to inhibit the growth of two strains of bacteria (Escherichia coli and Staphylococcus aureus) commonly found in wounds, an in vitro wound model was used. Bacteria were applied to the surface of nutrient agar, and a piece of each SCWD was applied to the bacteria. The plates were incubated at 37°C overnight. The zone of inhibition (ZI) around each SCWD was measured in cm2. Results The mean ZI for Acticoat Flex-3 on E. coli was 1.59 ± 0.15 cm2, which was significantly greater than that observed for Aquacel Ag (p<0.001), Mepilex Ag (p<0.0001), Mepitel Ag (p<0.001), Optifoam (p<0.0001), and Tegaderm Alginate Ag (p<0.01), but statistically indistinguishable from Maxorb II Ag. The mean ZI on S. aureus was 1.21 ± 0.16 cm2, which was greater than Aquacel Ag (p<0.05), Mepilex (p<0.0001), Optifoam (p<0.0001), and Tegaderm Alginate Ag (p<0.05), but statistically indistinguishable from Maxorb II Ag or Mepitel Ag. Conclusion Of the SCWDs tested, Acticoat Flex-3 demonstrated the most robust antimicrobial effect. Herein, we show that Acticoat Flex-3 may provide the most wound protection against bacterial infection. In conclusion, these data provide clinicians with additional independent evidence to inform their clinical practice on the use of specific wound dressings.

Effectiveness of testing hard-to-heal wounds for bacterial protease activity: a randomised clinical trial

OBJECTIVE

The study aimed to evaluate whether using a point-of-care test for bacterial protease activity (BPA) to target antimicrobial dressing use can improve outcomes for hard-to-heal wounds and reduce cost.

METHOD

Wounds asymptomatic for infection and testing positive for BPA were randomly assigned to two weeks' treatment with a silver antimicrobial dressing in addition to standard of care (SoC) (intervention group) or to SoC only (control group). The patient's outcomes were monitored for 12 weeks.

RESULTS

The study included 100 wounds. A reduction in annualised nursing resource of 29.0% (95% confidence interval (CI): 1.9-34.1) for hard-to-heal wounds was predicted for the intervention versus control group (44±25.10 intervention group nurse/clinic visits versus 62±31.23 control group nurse/clinic visits; p=0.034). The percentage of patients reporting problems reduced for all EQ5D-3L dimensions for the intervention group, with the largest reductions in 'pain/discomfort' (-36.2%) and 'anxiety/depression' (-19.1%). Prescription of antibiotics fell by 45% for wound-related infections in the intervention group compared with the control group. In the intervention group the number of patients who did not receive a prescription was 37/50 (74%), nine (18%) patients received one prescription and four (8%) patients received two or more prescriptions. In the control group 29/50 (58%) patients did not receive a prescription, 12 (24%) received one prescription and nine (18%) patients received two or more prescriptions; p=0.068.

CONCLUSION

The utility of the BPA test to reduce predicted annualised nursing time was demonstrated. The strong trend towards reduced antibiotic prescribing and improved quality of life for patients with wounds treated for BPA deserves further study.

Restoring balance: biofilms and wound dressings

Biofilms are responsible for stimulating and maintaining wound inflammation, increasing infection risk and delaying wound closure. Appropriate biofilm management is required to fight against local and systemic infection and to restore balance to the wound environment. The most effective way to remove biofilms involves the use of mechanical techniques, with the wound dressing representing an important component of this strategy. Wound dressing fibres, such as polyacrylate fibres, have been shown to be effective in affecting biofilm architecture by disrupting the biofilm matrix. This helps enhance the efficacy of antimicrobials, such as silver. Focusing an antibiofilm strategy on active agents alone does not constitute a sustainable approach to biofilm management. Furthermore, adding too many active chemicals into a wound can be highly detrimental to the wound bed, and potentially may have both short- and long-term biological concerns. Particular attention on the characteristics and key features of wound dressings is discussed in this paper. The aim of the paper is to review the ideal characteristics of wound dressings, in conjunction with antimicrobials, that are considered a fundamental part of an antibiofilm strategy and growing requirement for enhanced wound healing.

Antimicrobial Silver Nanoparticles for Wound Healing Application: Progress and Future Trends

Recent data have reported that the burden of infections related to antibiotic-resistant bacteria in the European Union and European Economic Area (EEA) can be estimated as the cumulative burden of tuberculosis, influenza, and human immunodeficiency virus (HIV). In wound management, the control of infections represents a crucial issue and a multi-billion dollar industry worldwide. For diabetic wounds ulcers, in particular, infections are related to the majority of amputations in diabetic patients, which today represent an increasing number of the elderly. The greatest barrier to healing is represented by the biofilm, an organized consortium of bacteria encapsulated in a self-produced extracellular polymeric substance with high resistance to conventional antimicrobial therapies. There is an urgent need for novel anti-biofilm strategies and novel antimicrobial agents and, in this scenario, silver nanotechnology has received tremendous attention in recent years in therapeutically enhanced healthcare. Due to its intrinsic therapeutic properties and the broad-spectrum antimicrobial efficacy, silver nanoparticles have opened new horizons towards novel approaches in the control of infections in wound healing. This review aims at providing the reader with an overview of the most recent progress in silver nanotechnology, with a special focus on the role of silver in the wound healing process.

Clinical evaluation of a dressing with poly absorbent fibres and a silver matrix for managing chronic wounds at risk of infection: a non comparative trial

OBJECTIVE

To assess the efficacy, safety and acceptability of a new silver poly absorbent dressing (UrgoCleanAg) in the local management of exudative chronic wounds at risk of infection, with inflammatory signs suggesting heavy bacterial load.

METHOD

This prospective, multicentre, non-comparative clinical trial was conducted in French hospital wards (dermatology and vascular medicine) or specialised private-practice physicians. Patients were considered at high-risk of infection when presenting with at least three of five selected inflammatory clinical signs, suggesting a heavy bacterial load (pain between two dressing changes, erythema, oedema, malodorous wound and presence of a heavy exudate). They were treated for a maximum period of four weeks, and followed by the physician on a weekly basis, including a clinical examination, area tracings and photographs. The primary efficacy criterion of the trial was the relative wound surface area reduction at the end of the four weeks of treatment. Acceptability was documented by the nursing staff at each dressing change between the weekly evaluations.

RESULTS

We recruited 37 patients with chronic wounds. Wound surface area, mostly covered by sloughy tissue, was reduced by 32.5% at the end of the treatment (median value), while the clinical score (maximum value of 5, based on inflammatory clinical signs) decreased from 4.0 to 2.0. Effective debridement properties were documented (62.5% relative reduction of sloughy tissue at week 4; 58.8% of debrided wounds at week 4) and improvement of the periwound skin status was noted (healthy for 28.6% of the patients at week 4 versus 2.7% at baseline). In addition, the tested wound dressing presented a good safety profile associated to a high level of acceptability, noted by both patients and nursing staff.

CONCLUSION

These clinical data support that the tested dressing is a credible therapeutic alternative for the management of chronic wounds at risk of infection with inflammatory signs suggesting heavy bacterial load.

Wounds research for patient benefit: a 5-year programme of research

Background

Complex wounds are those that heal by secondary intention and include lower-limb ulcers, pressure ulcers and some surgical wounds. The care of people with complex wounds is costly, with care mainly being delivered by community nurses. There is a lack of current, high-quality data regarding the numbers and types of people affected, care received and outcomes achieved.

Objectives

To (1) assess how high-quality data about complex wounds can be captured effectively for use in both service planning and research while ensuring integration with current clinical data collection systems and minimal impact on staff time; (2) investigate whether or not a clinical register of people with complex wounds could give valid estimates of treatment effects, thus reducing dependence on large-scale randomised controlled trials (RCTs); (3) identify the most important research questions and outcomes for people with complex wounds from the perspectives of patients, carers and health-care professionals; (4) evaluate the potential contributions to decision-making of individual patient data meta-analysis and mixed treatment comparison meta-analysis; and (5) complete and update systematic reviews in topic areas of high priority.

Methods

To meet objectives 1 and 2 we conducted a prevalence survey and developed and piloted a longitudinal disease register. A consultative, deliberative method and in-depth interviews were undertaken to address objective 3. To address objectives 4 and 5 we conducted systematic reviews including mixed treatment comparison meta-analysis.

Results

From the prevalence survey we estimated the point prevalence of all complex wounds to be 1.47 per 1000 people (95% confidence interval 1.38 to 1.56 per 1000 people). Pressure ulcers and venous leg ulcers were the most common type of complex wound. A total of 195 people with a complex wound were recruited to a complex wounds register pilot. We established the feasibility of correctly identifying, extracting and transferring routine NHS data into the register; however, participant recruitment, data collection and tracking individual wounds in people with multiple wounds were challenging. Most patients and health professionals regarded healing of the wound as the primary treatment goal. Patients were greatly troubled by the social consequences of having a complex wound. Complex wounds are frequently a consequence of, and are themselves, a long-term condition but treatment is usually focused on healing the wound. Consultative, deliberative research agenda setting on pressure ulcer prevention and treatment with patients, carers and clinicians yielded 960 treatment uncertainties and a top 12 list of research priorities. Of 167 RCTs of complex wound treatments in a systematic review of study quality, 41% did not specify a primary outcome and the overall quality of the conduct and reporting of the research was poor. Mixed-treatment comparison meta-analysis in areas of high priority identified that matrix hydrocolloid dressings had the highest probability (70%) of being the most effective dressing for diabetic foot ulcers, whereas a hyaluronan fleece dressing had the highest probability (35%) of being the most effective dressing for venous ulcers; however, the quality of this evidence was low and uncertainty is high.

Conclusions

Complex wounds are common and costly with a poor evidence base for many frequent clinical decisions. There is little routine clinical data collection in community nursing. A prospective complex wounds register has the potential to both assist clinical decision-making and provide important research evidence but would be challenging to implement without investment in information technology in NHS community services. Future work should focus on developing insights into typical wound healing trajectories, identifying factors that are prognostic for healing and assessing the cost-effectiveness of selected wound treatments.

Funding

The National Institute for Health Research Programme Grants for Applied Research programme.

Cost-effective use of silver dressings for the treatment of hard-to-heal chronic venous leg ulcers

AIM

To estimate the cost-effectiveness of silver dressings using a health economic model based on time-to-wound-healing in hard-to-heal chronic venous leg ulcers (VLUs).

BACKGROUND

Chronic venous ulceration affects 1-3% of the adult population and typically has a protracted course of healing, resulting in considerable costs to the healthcare system. The pathogenesis of VLUs includes excessive and prolonged inflammation which is often related to critical colonisation and early infection. The use of silver dressings to control this bioburden and improve wound healing rates remains controversial.

METHODS

A decision tree was constructed to evaluate the cost-effectiveness of treatment with silver compared with non-silver dressings for four weeks in a primary care setting. The outcomes: 'Healed ulcer', 'Healing ulcer' or 'No improvement' were developed, reflecting the relative reduction in ulcer area from baseline to four weeks of treatment. A data set from a recent meta-analysis, based on four RCTs, was applied to the model.

RESULTS

Treatment with silver dressings for an initial four weeks was found to give a total cost saving (£141.57) compared with treatment with non-silver dressings. In addition, patients treated with silver dressings had a faster wound closure compared with those who had been treated with non-silver dressings.

CONCLUSION

The use of silver dressings improves healing time and can lead to overall cost savings. These results can be used to guide healthcare decision makers in evaluating the economic aspects of treatment with silver dressings in hard-to-heal chronic VLUs.

The use of biatain Ag in hard-to-heal venous leg ulcers: meta-analysis of randomised controlled trials

Background

Venous leg ulcers are common, troublesome, and their failure to heal is often related to a heavy bio-burden. Ionized silver has both anti-inflammatory and antimicrobial properties. The ulcer healing properties of the silver releasing foam dressing Biatain Ag has been examined in 4 randomized controlled trials (RCTs).

Aim

To evaluate ulcer healing through a meta-analytic approach after treatment with either Biatain Ag or a non-active dressing.

Patients and Methods

685 subjects with pure or mixed hard-to-heal venous leg ulcers were included in the meta-analysis.

Results

Biatain Ag showed a significant treatment effect (p<0.0001), responder rate (p<0.001), and healing rate (p = 0.002).

Conclusion

The meta-analysis of the 4 RCTs provided statistical significant evidence to support the use of Biatain Ag dressing in treatment of hard-to-heal venous leg ulcers.

Clinical efficacy of a silver-releasing foam dressing in venous leg ulcer healing: a randomised controlled trial

Biatain and Biatain-Ag are two identical wound dressings except the fact that Biatain-Ag releases silver. In the present multinational double-blinded randomised controlled trial the effect of the two dressings were compared for treatment of venous leg ulcers. A total of 181 patients were treated for 6 weeks with either Biatain or Biatain-Ag followed by 4 weeks treatment with Biatain. Biatain-Ag showed superior performance in relative wound area reduction after 6 weeks treatment and the estimated treatment difference increased after 10 weeks indicating that the effect of silver continues at least for 4 weeks after treatment. A subgroup of the patients differed significantly from the others with respect to parameters associated with a poor healing prognosis; patients were older, had significant history of venous thrombosis, larger ulcers with longer duration and more often recurrent. For this subgroup of patients Biatain-Ag showed significant (P < 0·05) better performance in terms of relative ulcer area reduction and healing rate. In conclusion, this study suggests the superior performance of Biatain-Ag compared with the non silver-releasing dressing Biatain in particular for patients having ulcers associated with a poor healing prognosis.

Extending the TIME concept: what have we learned in the past 10 years?(*)

The TIME acronym (tissue, infection/inflammation, moisture balance and edge of wound) was first developed more than 10 years ago, by an international group of wound healing experts, to provide a framework for a structured approach to wound bed preparation; a basis for optimising the management of open chronic wounds healing by secondary intention. However, it should be recognised that the TIME principles are only a part of the systematic and holistic evaluation of each patient at every wound assessment. This review, prepared by the International Wound Infection Institute, examines how new data and evidence generated in the intervening decade affects the original concepts of TIME, and how it is translated into current best practice. Four developments stand out: recognition of the importance of biofilms (and the need for a simple diagnostic), use of negative pressure wound therapy (NPWT), evolution of topical antiseptic therapy as dressings and for wound lavage (notably, silver and polyhexamethylene biguanide) and expanded insight of the role of molecular biological processes in chronic wounds (with emerging diagnostics and theranostics). Tissue: a major advance has been the recognition of the value of repetitive and maintenance debridement and wound cleansing, both in time-honoured and novel methods (notably using NPWT and hydrosurgery). Infection/inflammation: clinical recognition of infection (and non infective causes of persisting inflammation) is critical. The concept of a bacterial continuum through contamination, colonisation and infection is now widely accepted, together with the understanding of biofilm presence. There has been a return to topical antiseptics to control bioburden in wounds, emphasised by the awareness of increasing antibiotic resistance. Moisture: the relevance of excessive or insufficient wound exudate and its molecular components has led to the development and use of a wide range of dressings to regulate moisture balance, and to protect peri-wound skin, and optimise healing. Edge of wound: several treatment modalities are being investigated and introduced to improve epithelial advancement, which can be regarded as the clearest sign of wound healing. The TIME principle remains relevant 10 years on, with continuing important developments that incorporate new evidence for wound care.

Comparative evaluation of silver-containing antimicrobial dressings on in vitro and in vivo processes of wound healing

OBJECTIVES

To compare the in vitro and in vivo effects of silver products on wound healing.

METHODS

Eight silver products were compared to determine: fibroblast function using fibroblast-populated collagen lattices (FPCLs), fibroblast viability using the Trypan Blue exclusion test, and fibroblast mitochondrial activity using the MTT [yellow tetrazolium salt; 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. In vivo effects of 9 silver products were evaluated utilizing a rat model of contaminated wounds. Serial quantitative bacteriology was performed on tissue biopsies over a 10-day period and serial wound areas were obtained over 12 days.

RESULTS

Fibroblast cytotoxicity occurred for all of the silver products evaluated. Remaining viable fibroblasts were insufficient to allow FPCL contraction. Mitochondrial activity of the fibroblasts allowed a separation of the various silver compounds. Actisorb Silver and Silvercel had the greatest viable fibroblast activity, but less than the control. Despite in vitro cytotoxicity, all of the silver products except Contreet Foam and Acticoat Moisture Control accelerated wound healing.

CONCLUSIONS

Silver-containing dressings appeared to benefit healing of the wounds. Just as in vitro bacterial analyses do not fully predict the effect of an antimicrobial in the in vivo setting, in vitro cytotoxicity tests do not fully predict the effect of an agent on wound healing trajectories. Because of the varied antimicrobial and wound healing responses among products, a careful consideration of the particular effects of individual silver-containing dressings or drugs is warranted.

An overview of the evidence on the efficacy of silver dressings

While there is a plethora of clinical and anecdotal evidence on the efficacy of silver dressings, there is no rigorous RCT data to support this. This has led procurement managers to defer the inclusion of silver dressings on wound formularies, despite its clinical popularity. This article gives an overview of the evidence on topical antimicrobials, in order to determine whether there is a case for such a stance.

An approach to assessing evidence that can inform clinical decision-making

Following the Cochrane meta-analyses findings, doubts are being expressed about efficacy of silver dressings. However, the need for topical antimicrobials has not diminished, and the evidence for non-silver agents is no better than that for silver. This article describes an alternative system to Cochrane for analysing the evidence base, and suggests a practical approach to making a case for silver to procurement managers.