Dextranomer: A Review of its General Properties and Therapeutic Efficacy

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Synopsis: Dextranomer1is a hydrophilic dextran polymer advocated as a ‘cleansing agent’ for various types of exudating wounds or ulcers, including stasis (venous) ulcers and decubitus ulcers. It appears to exert its effect by a capillary action which absorbs wound exudate, as well as wound debris and micro-organisms, into the dextranomer beads or into the spaces between the beads, thus removing such products from the wound surface. Dextranomer is an aid to wound or ulcer management, and does not directly affect tissue repair in such ulcers, but as with other ‘cleansing’ agents or techniques, removal of debris (and possibly micro-organisms) from the wound could be expected to promote natural healing. Reports of its effectiveness in open studies, often in patients with seemingly resistant lesions, have been encouraging. Similarly, in comparative trials results have usually favoured dextranomer, but a clear indication of the relative efficacy and benefits as compared with other treatments used for exudating lesions has not yet emerged. Further well designed comparative studies are needed to provide such information.

General Properties: When applied to an exudating wound, dextranomer produces a ‘chromatographic like’ separation of constituents of the wound exudate and of other particles (e.g. bacteria, cellular debris) which may be found at the wound surface. Prostaglandins, hormones and other relatively small molecules freely enter the beads and are removed along with the beads at dressing changes: Larger particles such as micro-organisms and wound debris remain in the spaces between the beads and appear to be drawn by capillary flow toward the surface of the dextranomer layer, and thus away from the wound surface. It would seem that such a ‘cleansing’ effect is likely to generally promote healing, but the clinical significance of the removal from the wound surface of prostaglandins and other possible mediators of the inflammatory response, and of fibrinolytic substances, is unclear.

Therapeutic Trials: Dextranomer clearly aids in ‘cleansing’ exudate and wound debris from moist wound lesions. Indeed, its ability to remove accumulated exudate has resulted in some reports of transient initial apparent increases in wound size, due to removal of debris. Results reported in open studies with dextranomer, often in patients with chronic, seemingly nonresponsive ulcers or wounds, have seemed impressive, although such studies were often anecdotal in nature and must be interpreted with caution. Comparative studies in patients with decubitus or stasis ulcers or other wounds are made more difficult by the lack of an accepted standard treatment to use for comparison, and by the difficulty in objectively evaluating improvement in such lesions. Indeed, most of the ‘traditional’ treatments used have not been well studied. Nevertheless, well designed controlled studies are needed to clearly establish the efficacy of any agent used in wound treatment. A few controlled studies have been reported with dextranomer, and in those studies which made the best attempts to overcome design difficulties, dextranomer was usually more effective in many of the various evaluation parameters used (e.g. effect on pus and debris, pain, oedema, erythema, granulation, epithelialisation and in some studies wound healing) than treatment such as normal saline dressings, ‘conservative’ debridement with repeated gauze dressing changes, collagenase ointment or povidone iodine. However, a more clear picture of dextranomer's relative efficacy as compared with these and other treatments used for exudating wounds or ulcers, such as Unna's boot treatment, benzoyl peroxide, pressure bandaging with adequate exercising, etc., must await further well designed comparative studies.

Adverse Effects: Dextranomer is well tolerated. With the exception of isolated reports of erythema or slightly blistered skin, or other isolated occurrences for which a causative association with dextranomer was not clearly established, the only adverse effect seems to be pain on removal of the saturated beads from some wounds. This would probably also occur with other treatments during cleansing and dressing changes.

Method of Use: Dextranomer is poured on to a wound, which has been previously cleaned with normal saline, to a thickness of a least 3mm. Alternatively, if the wound is shallow or in an awkward place, a paste of dextranomer and glycerol (4:1) may be prepared just prior to use and applied in the same thickness. The wound is then bandaged, but room for expansion of the beads as they absorb fluid must be allowed. The dextranomer should be replaced on an individualised schedule, depending on the extent of exudation. When it assumes a grey to yellow colour it is saturated and no longer exerting a capillary effect. Normal saline solution should be used to remove the saturated gel and to wash the wound before adding fresh dextranomer. Most wounds require twice daily changes.

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