The incidence of diabetes is escalating worldwide (Wild et al, 2004) and is associated with a number of complications including diabetic foot ulcers (DFUs; Boulton et al, 2005). Good medical management of DFUs should focus on the holistic care of the person with diabetes and specifically on pressure relief of the ulcerated area, wound-bed preparation (especially debridement) and the careful management of exudate levels, infection and pain (Frykberg, 2002).
Infected DFUs have been associated with increased risk of lower-limb amputation (Nather et al, 2008). DFU infection has also been associated with increased wound pain and increased sensitivity to pain, both of which have been implicated in delayed healing and reduced quality of life (White, 2009).
Modern dressings (e.g. soft silicones, hydrogels, hydrofibres, alginates), many combined with atraumatic adhesives, are less likely to cause pain during dressing changes than traditional dressings (White and Morris, 2009). Silver-containing dressings have been shown to be effective against a range of wound pathogens, including Staphylococcus aureus and beta-hemolytic streptococci, the most common pathogens associated with mild to moderate DFU infections (Ip et al, 2006; Bader, 2008).
Silver ions have been combined with some modern dressing types to simultaneously combat infection and minimise dressing-related pain (White, 2009). These dressings have been used with and without systemic antibiotics to treat infections in chronic wounds (Lipsky and Hoey, 2009; Ousey and McIntosh, 2009) – and specifically DFUs (Lansdown et al, 2003; Coutts and Sibbald, 2005; Rayman et al, 2005; Lipsky et al, 2006; Tong, 2009) – with success.
Here, the authors report the results of a case series designed to evaluate the effects of a silver-containing, soft silicone foam dressing on DFUs showing signs and symptoms of local infection.
Aims
The primary objective of this preliminary study was to evaluate the signs and symptoms of localised infection in DFUs during the course of treatment that comprised traditional wound care and the use of a silver-containing, soft silicone foam dressing (Mepilex® Ag; Mölnlycke Health Care, Gothenburg; Box 1). Secondary objectives were to evaluate and record: (i) the level of pain associated with dressing changes; (ii) change in wound area; (iii) investigator opinion of the test dressing’s performance; and (iv) adverse events.
Method
The investigation was designed as a single-centre, open, non-randomised case series. In- and outpatients attending a specialist podiatry clinic with active DFUs exhibiting signs of local infection that, in the opinion of the investigators and in line with the manufacturer’s instructions, were suitable for treatment with the test dressing were enrolled (inclusion and exclusion criteria listed in Table 1).
Each participant was treated according to local clinical practice and evaluated over a treatment period of 4 weeks (including weekly visits during which assessments for the purposes of this study were undertaken and results recorded) or until the ulcer healed, whichever occurred first. All participants received traditional wound care as part of their treatment (debridement and offloading appropriate for their foot and wound type). Systemic antibiotics were used concomitantly if judged necessary by the investigators. Dressing changes were undertaken according to local clinical practice (usually three times per week).
It was agreed by the local clinical governance committee that research ethics committee approval was not required for this study because it was an in-market evaluation of a CE-marked dressing in accordance with its instructions for use.
Baseline participant demographic data and the wound history were recorded at the first consultation. At the first consultation and subsequent dressing changes, the following variables were assessed by qualitative visual assessment by the investigators, unless stated otherwise:
- Signs and symptoms of localised infection (i.e. erythema, heat, oedema, exudate levels [Lipsky et al, 2006]); scored as: none, mild, moderate or severe.
- Pain severity reported by participants before, during and after dressing change using a validated visual analogue scale ranging from zero (no pain) to 100 (worst pain ever; Harms-Ringdahl et al, 1986).
- Ulcer size (length at the longest point, width at the widest point; measured in millimetres).
- Proportion of viable tissue in wound.
- Adverse events.
Photographs were taken during dressing removal and after cleansing and/or debridement. At the final dressing change, the investigators gave a rating (very good, good, poor, very poor) for each case for each of the following parameters: (i) overall experience with dressing; (ii) dressing conformability; (iii) dressing flexibility; (iv) fluid handling of dressing; (v) ease of application of dressing; (vi) ease of removal of dressing; (vii) dressing adherence (lack of) to wound bed.
Data generated from this study are presented in a descriptive manner. All efficacy endpoints are summarised by visit number (1–4 visits). No hypothesis testing was planned for this descriptive investigation.
Results
Fifteen participants (11 men, four women) met the inclusion criteria. All participants had type 2 diabetes. Mean participant age was 63.7 years (median 65 years; minimum 47 years; maximum 78 years; concurrent medical conditions listed in Appendix I). Data for each target ulcer at baseline are presented in Table 2. The majority (13/15, 86.6%) of target ulcers presented as Grade 1 or 2 in the University of Texas Diabetic Wound Classification System (Lavery et al, 1996).
Signs and symptoms of local infection
At baseline, erythema (13/15, 86.7%), oedema (11/15, 73.3%), heat (11/15, 73.3%) and exudate level (14/15, 93.3%) were mostly rated as mild or moderate, with a small percentage (2/15, 13.3%; 1/15, 6.7%; 2/15, 13.3; 1/15, 6.7%; 1/15, 6.7%, respectively) rated as severe. During the course of treatment, erythema, oedema and heat reduced and by the final visit these symptoms were rated as mild or none in all target ulcers (Figures 1b-d). Exudate levels followed a similar trend, with 93.3% (14/15) of target ulcers producing none or mild exudate by study end (Figure 1a). Visit-by-visit levels of local infection are detailed in Appendix II.
Two participants received adjunctive antibiotic therapy to manage DFU infection during the study period. One participant (participant 104) exhibited increased clinical signs of infection in the target ulcer after 7 days of treatment with the test dressing; one participant (participant 105) was receiving systemic antibiotic therapy (amoxicillin) prior to enrolment, which was continued into and beyond the study period. Participant 104 was also receiving trimethoprim for the treatment of a urinary tract infection at enrolment, which resolved and the trimethoprim was discontinued between visits 1 and 2.
Pain
At baseline, mean pain severity scores reported by participants prior to, during and after dressing removal/application were 19.9, 16.7 and 9.7, respectively. At subsequent visits, the pain severity scores were lower than that recorded at baseline (Figure 2).
Wound size reduction
During the study period, a trend toward reduction in wound area was seen (Figure 3). Visit-by-visit wound size are detailed in Appendix II.
Investigator ratings
The overall experience of using the dressing was rated by investigators as good (20.0%) or very good (80.0%). Conformability was rated as good (6.7%) or very good (93.3%) and the ease of application/removal, lack of adherence to the wound bed, fluid handling and flexibility of the dressing were all rated as very good (Table 3).
Adverse events
One adverse event occurred during the study; a target ulcer exhibited increased clinical signs of infection after 7 days of treatment with the test dressing. The participant concerned was treated with systemic antibiotics (doxycycline) and the infection resolved 2 days later. It is generally accepted clinical practice to use topical antimicrobial agents as an adjunct to antibiotics (European Wound Management Association, 2006), hence it was deemed appropriate by the investigators that this participant continue in the study.
Discussion
The findings of the present study suggest that the signs and symptoms of local infection in DFUs can be efficiently resolved by use of a silver-containing, soft-silicone foam dressing regimen in conjunction with good traditional wound care and, where necessary, systemic antibiotics. While case series alone cannot demonstrate the efficacy of an intervention, they do provide insight into how the intervention may be used to overcome clinical challenges. However, a randomised controlled trial is required to definitively assess the efficacy of this intervention.
Coutts and Sibbald (2005), Rayman et al (2005), Jude et al (2007) and Tong (2009) report results similar to those presented here for resolution of local infection associated with the use of silver-containing dressings in the treatment of DFUs. A 2006 Cochrane Database Systematic Review (Bergin and Wraight) on silver-containing dressings and topical agents for the treatment of infected DFUs highlighted that, to date, no randomised or controlled clinical trials have evaluated the effectiveness of these agents. Yet, it should be recognised – especially in the area of wound care – that data obtained from lower down the hierarchy of clinical evidence (e.g. case studies) may be more representative of clinical practice and should be taken into account when reviewing treatment options for suitable patient groups (Gottrup, 2008).
Pain in people with diabetes is complex: loss of protective sensation is often a key factor in the development of DFUs, however recent research has highlighted that pain can be associated with both neuropathic and neuroischaemic ulceration (Bengtsson et al, 2008). It has also been suggested that nerves play a central role in tissue homeostasis and may orchestrate complex reparative processes (Schaper et al, 2008). Interestingly, a genetic link has been identified that may predict which people will suffer DFU-related pain (Cheng et al, 2009).
In a randomised controlled trial to determine the comparative effectiveness and cost-effectiveness of three dressing products for DFUs, between 13% and 22% of participants reported pain in the region of the wound at all visits, with least pain reported by those receiving non-adherent dressings (P=0.012; Jeffcoate et al, 2009). In the present study, all participants reported experiencing dressing change-related pain at baseline. The pain severity scores relating to subsequent visits were all lower than that recorded at baseline. Importantly, the greatest reduction in pain scores occurred between baseline and the first visit, suggesting a dressing effect rather than simply a reduction in the pain associated with resolution of infection or healing of the wound – a finding in line with that of Jeffcoate et al (2009).
Clinicians should consider dressing-related pain when managing DFUs and when possible select dressings that lessen this pain. Adhesive dressings may damage fragile diabetic skin (Holewski et al, 1989; Tantisiriwat and Janchai, 2008; Lawton and Langoen, 2009). The belief that people with diabetic peripheral neuropathy do not suffer wound and/or dressing-related pain should be set aside and treatments that reduce these burdens embraced.
During the study period, a trend toward reduction of wound area was seen. The rate of healing was consistent with that reported by other authors working in DFU populations (Coutts and Sibbald, 2005; Rayman et al, 2005; Jude et al, 2007; Tong, 2009), although direct comparison with these studies would not be appropriate due to differences in study protocols and populations.
Conclusion
Infection is a significant problem in DFU management; it delays healing and increases wound-related pain and risk of amputation, and is a burden on the healthcare economy. The use of a silver-containing, soft-silicone foam dressing in the cases reported here resulted, in the majority, in the rapid resolution of the signs and symptoms of local infection, and reduced the levels of pain associated with dressing change. These results suggest that the dressing – when used as one component of a regimen that includes holistic patient care, good traditional wound care and systemic infection control when necessary – is a useful therapeutic modality.
Acknowledgement
The authors would like to thank Mölnlycke Health Care for providing dressings and financial support for this study.
