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OBJECTIVE

To compare the effect on the microcirculation in venous leg ulcers (VLUs) of two treatment regimens that promote a moist wound environment versus paraffin gauze. The hypothesis is that moist wound dressings are more likely to stimulate the microcirculation and therefore angiogenesis.

METHOD

Patients with non-healing VLUs were randomised to receive either a foam dressing (Suprasorb P), a collagen dressing (Suprasorb C) plus the foam dressing, or paraffin gauze (control). All patients wore short-stretch high compression bandages. Parameters used to measure the effects of the treatments on the microcirculation were: TcPO2 measurements, video laser Doppler measurements and the number of capillaries in the wound bed. The progression towards healing was measured by the reduction in ulcer area and formation of granulation tissue. The treatment period was four weeks.

RESULTS

Significant increases in TcPO2 values were reported between baseline and week 4 for patients receiving the foam dressing only or the collagen plus foam dressing combination (p<0.008 versus p<0.003 respectively). There was also a significant increase in the number of capillaries for the collagen plus foam treatment only (p<0.002).

CONCLUSION

This pilot study suggests that a moist wound environment stimulates perfusion of blood and oxygen to the wound tissue, thereby promoting angiogenesis. The collagen and foam dressing combination demonstrated superior results to the control and the foam dressing only. Monitoring the microcirculation may help to assess the effect of dressings on VLU healing, although more research is needed.

DECLARATION OF INTEREST

This pilot study was supported by a limited grant from Lohmann & Rauscher GmbH, Germany.

In the treatment of chronic wounds, it is necessary to establish a physiological wound milieu to improve healing. Application of collagen as wound dressing has been described as beneficial as it possesses the ability to reduce elevated levels of proteases, cytokines, and free radicals. Consequently, a wide range of wound dressings based on collagen have been developed. Native collagen is susceptible to alterations because of influences during the production process; to minimize effects on the molecule itself collagen wound dressings are usually aseptically produced. Common sterilization methods (autoclaving, irradiation, and ethylene oxide (EtO) treatment) can induce changes in the protein chemistry and physical properties, potentially affecting the absorption rate, mechanical strength, or performance. In this study, we have evaluated the influence of gamma- and beta-irradiation as well as EtO sterilization on the binding capacity of collagen type I for selected proteases and cytokines associated with nonhealing wounds. Although a pronounced effect on the physical properties of the collagen was found, there was no significant loss in the binding affinity for polymorphonuclear elastase, matrix metalloproteinase-2, and interleukin-1beta, or in the antioxidant capacity.