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An assessment of the wound healing properties of Algisite* M dressings

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VOL: 99, ISSUE: 42, PAGE NO: 54

Gerhard Kammerlander, DGKP, is certified wound manager

Thomas Eberlein, MD, is dermatologist; both at the Wound Competence Centre, Linz, Austria

Haemostasis and fibrin formation contribute to the formation of a wound scab following skin damage. This process facilitates repair by providing a matrix within which cell migration and angiogenesis take place (van Hinsbergh, 2001; Phillips, 2000).

Haemostasis and fibrin formation contribute to the formation of a wound scab following skin damage. This process facilitates repair by providing a matrix within which cell migration and angiogenesis take place (van Hinsbergh, 2001; Phillips, 2000).

Following injury, macrophages, which are normally present in tissue, increase in number, attracted by chemical messages released by the activation of the inflammatory process. They release the protein chemical messages, growth factors and growth stimulants needed to orchestrate the healing process (Leibovich and Ross, 1975).

Macrophages have an essential role in the transition from wound inflammation to wound repair, the latter being characterised by the formation of granulation tissue (Clark, 1985).

The wound heading environment
A moist wound environment promotes accelerated wound healing, better quality of healing and results in less tissue necrosis compared with dry wound healing (Bolton et al, 2000; Brunner and Eberlein, 2000; Vogt et al, 1995). The use of moisture-retentive dressings also appears to be associated with fewer clinical infections, reduced scarring and greater patient comfort (Bolton et al, 2000).

Clinical studies involving alginate dressings, which support moist wound healing and absorb exudate (Timmons, 1999), have been shown to initiate and accelerate the healing process in chronic wounds, provided that the underlying pathology associated with the wound is also treated (Thomas et al, 2000).

Alginates are effective in a wide variety of acute and chronic wounds (Piacquadio and Nelson, 1992) and some alginate-based dressings are reported to have haemostatic properties (Segal et al, 1998); they may also trigger the activation of human macrophages (Thomas et al, 2000).

The study
A study was conducted to determine the performance of Algisite* M, an alginate dressing, in patients with granulating wounds that required a moist wound-healing environment and management of exudate. This was an open-label study, so that both the researcher and participants were aware of the product under evaluation.

Method
Patient selection - Male and female patients were recruited from centres in Austria, Germany and Switzerland. Patients aged 18 years and over were eligible to enter if the following requirements were met:

- They presented with granulating wounds, healing by secondary intention, that needed a moist wound-healing environment and management of exudate. Wounds that contained non-viable tissue (black necrotic, yellow slough, purulent discharge, debris) were included;

- Patients were willing and able to comply with the study requirements and gave informed consent.

Patient record forms were completed for one wound only. Where a patient presented with more than one wound, the largest was chosen for study. Patients who were known to have poor concordance with medical treatment were excluded.

Conduct of the study - The intention was to retain patients in the study until the following occurred:

- They had six weeks of treatment, or a total of 15 dressing changes;

- The wound was closed;

- They chose to withdraw.

However, if a patient had an extensive wound, the condition of the wound was monitored until it had healed. If treatment was interrupted for more than six days, either consecutively or in total, that person was withdrawn from the study.

The dressing - Wounds were cleaned with normal saline solution before being photographed. The photographs were taken at the initial assessment, and thereafter every two weeks, and at the final assessment. The date and a metric scale were included as part of the photo.

Wounds were then covered with the trial dressing, which was in turn covered with an appropriate secondary dressing chosen by the researcher (Martini et al, 1999; Kurring et al, 1994). The frequency of dressing changes was at the discretion of the clinician, and depended on the quantity and nature of exudate weeping from the wound. The recommendation was to change the dressing every one to three days.

Measuring the wound area - The total area of the wound was measured at week 0, at the time of withdrawal and at weeks 2, 4 and 6, if the wound had not healed. The area was calculated from tracings of the ulcer margins and from the digital photographs.

Grading the wounds - Wounds were graded using a modified diabetic wound classification system (DWCS) (Kammerlander, 2001). This is based on the visible characteristics of wounds (Table 1), such as colour and tissue type, as follows:

- Black wounds: necrotic tissue (black to yellow, black-yellow-red);

- Yellow wounds: sloughy tissue (yellow to red);

- Red wounds: granulating tissue (red to pink);

- Pink wounds - epithelium (wound healed).

Efficacy The following were calculated to determine the effectiveness of the dressing:

- Percentage of patients with healed wounds;

- Percentage reduction in wound area;

- Percentage improvement in wounds;

- Percentage change in the stage of the wound;

- Time between dressing changes.

All adverse events reported by the patient and those observed by the clinician were recorded.

The results
A total of 77 patients entered the trial, of whom 47 (61 per cent) were male and 30 (39 per cent) female. The average age was 70.5 years (range 30-94): for males, it was 66.4 years (range 30-89) and for 76.9 years (range 45-94). The average baseline wound area was 5.1cm2 and the median baseline wound area was 3.0cm2 (range 1.0-27.0cm2). The type of wounds at study entry are illustrated in Fig 1 (see p56).

The average duration of treatment per wound was 29.2 days, with an average of 13.7 dressing changes per wound. Dressings were left in place for an average of 2.3 days.

Algisite* M did not disintegrate in the wound and had sufficient absorbent capacity to manage exudate effectively. Its cleansing effect was observed to be good and it was effective in stimulating granulation tissue.

The classification of wounds at the start and the end of treatment is shown in Table 2. Complete healing occurred in 23 of the 77 (30 per cent) wounds, 15 (19 per cent) had almost healed, and a further 23 (30 per cent) showed signs of granulation.

The average wound area at the start and end of treatment is shown in Table 3. The average percentage reduction in wound area was 54.9 per cent and the median percentage reduction was 66.7 per cent. Overall, improvement in wound condition was observed for 82 per cent of patients, it was unchanged in 13 per cent and had worsened in 5 per cent of patients.

The clinician's subjective opinion of the effects of Algisite* M was also recorded. The researcher felt that it achieved a very positive outcome for 47 (61 per cent) patients; a positive outcome for 27 (35 per cent); and an acceptable outcome for three (four per cent).

Discussion
The trial was conducted to assess the performance of Algisite* M in managing chronic wounds. Large quantities of alginate dressings are used each year to treat exuding wounds such as leg ulcers, pressure sores and infected surgical wounds. There is evidence to suggest that alginates may affect wound healing in a number of ways, although these are not yet fully understood (Thomas, 2000).

In this study Algisite* M was found to be an effective dressing for managing a range of wounds, including diabetic and pressure ulcers. The majority of wounds fell into two categories: venous ulcers (24 per cent) and diabetic ulcers (17 per cent). The percentage of patients with completely healed wounds was 30 per cent and 19 per cent had wounds that had nearly healed. Overall, improvement in wound condition was 82 per cent.

Higher rates of complete healing could be expected in the case of acute and less serious wounds (Thomas, 2000). A previous study of a calcium alginate dressing on split skin graft donor sites reported that 67 per cent of patients had completely healed wounds after 10 days of treatment (O'Donoghue et al, 1997).

The mean dressing wear time was 2.3 days. The time between dressing changes is influenced by factors such as the amount of exudate produced by wounds and the secondary dressing used, making it difficult to compare the outcome with the results of other trials.

Conclusion
Used in conjunction with a secondary dressing, Algisite* M was found to be effective in managing wounds that produce moderate to high amounts of exudate and was well accepted by clinicians. The alginate was also effective in stimulating granulation and cleansing the wound bed.

In the clinical setting, it was found to be effective in treating wounds at various stages of healing. Clinicians and patients found the dressing to be well tolerated and cosmetically acceptable. Further clinical studies are needed to confirm these findings.

- This study was supported by Smith and Nephew, Germany.

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