Editor—Harding et al's review article on healing chronic wounds1 fails to mention treatment with topical negative pressure, which has an emerging role in the management of chronic wounds.2,3
The simple technique entails applying an open-pore foam dressing (polyurethane ether) to the wound. This dressing is sealed with transparent adhesive drape. A negative pressure or suction force is then applied across the wound via a drainage tube embedded in the foam.4 There are various regimens, describing the amount of negative pressure, continuous or intermittent pressure cycle, and frequency of dressing changes.
Delivery of topical negative pressure is critical to the healing of wounds and can be done with a commercially available device (VAC pump, KCI), wall suction, or surgical drainage bottles. Commercially available devices tend to be most reliable, providing controlled pressure delivery, and have built in safety devices.
The exact mechanism of action of treatment with topical negative pressure is still not clear.2 Proposed mechanisms of action include:
Change in microvascular blood flow dynamics, with an improved local blood supply
Removal of fluid exudate
Stimulation of the formation of granulation tissue
Reduction in bacterial colonisation
Mechanical closure of wounds by reverse tissue expansion
Maintenance of a moist wound environment with better wound healing
Treatment with topical negative pressure can be used in both hospitals and community settings. Cost implications are important, and currently the commercially available suction pumps are more expensive than conventional dressings. However, such treatment is associated with accelerated healing rates, reduced nursing time, simpler operations, and decreased bed occupancy. All of these mitigate the initial cost of treatment.
Treatment with topical negative pressure is presently undergoing worldwide evaluation and is being used for acute, subacute, and chronic wounds with good results.2 A recent Cochrane review suggests weak evidence with regard to chronic wound healing.5 This possibly relates to the paucity of large randomised controlled trials of the treatment. In our experience it has an emerging role in chronic wound healing, and a large controlled trial would scientifically address the issue.
References
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