October, 2005

Dear Readers,

In this month’s Evidence Corner, Dr. Laura Bolton critiques the published information on radiant heat therapy (RHT) used for treating chronic wounds. Some studies have suggested RHT accelerates healing rates compared to standard dressings alone. Two articles are reviewed in this column—“A randomized controlled clinical trial to evaluate the effects of noncontact normothermic wound therapy on chronic full-thickness pressure ulcers” (Kloth et al.) and “A controlled, randomized, comparative study of a radiant heat bandage on the healing of stage 3–4 pressure ulcers: a pilot study” (Thomas DR et al.). In the first study, the researchers concluded that RHT exerted a positive effect on ulcer healing compared to standard dressings, including saline-impregnated gauze, alginates, hydrogels, and hydrocolloids. The authors of the second study found no statistically significant differences between RHT and a standardized moisture-retentive dressing control. In her commentary, Bolton provides a general discussion on the importance of considering the effects of a control dressing in any comparative study. In reconciling the different conclusions of the 2 articles reviewed, she points out that moisture-retentive dressings (eg, films or hydrocolloids) have been shown to accelerate some aspects of healing and also to maintain higher wound temperatures, presumably by preventing evaporative cooling. While there is general agreement that maintenance of a physiologic temperature is important in healing, it would appear that additional studies are needed to confirm the effectiveness of RHT.

Ascherman et al. (The histologic effects of retention sutures on wound healing in the rat) present microscopic findings on excisions in rats closed with evenly spaced simple 3-0 sutures compared to excisions closed with 2-0 retention sutures as well as evenly spaced 3-0 sutures. They found that the use of retention sutures was associated with an increase in inflammation, increased evidence of infection, and disorderly collagen formation. Although controversial, retention sutures are commonly used in an effort to prevent dehiscence. The results of this experimental study do not support the use of retention sutures; however, the authors suggest that conclusive evidence will depend upon further studies in higher mammals.

Dr. Steven Miller (Compression therapy for foot wounds: overview and case reports) reports his experience in the use of reduced compression therapy (3-layer bandage) applied distal to a lower-extremity bypass in treating 2 difficult cases of foot wounds. The lower compression was judged to be safe and apparently effective in healing these specific wounds. The author recognizes the difficulty of drawing hard conclusions from the 2 case studies presented and suggests “…additional research in aggressive edema reduction in pedal wounds…particularly with patients with arterial insufficiency.”

Carson et al. (Healing chronic infected foot wounds with human fibroblast-derived dermal substitute and silver dressings) report on a series of 30 patients with diabetes and poorly healing to nonhealing chronic foot wounds despite good wound care approaches. These recalcitrant wounds were selected to receive maintenance sharp debridement and moist silver dressings. A dermal substitute was applied every 15 days until healing or grafting. Of the 30 patients, 17 healed their wounds, 8 required grafting, and 5 did not heal and required amputations. The authors discuss how the use of dermal substitutes and silver dressings may have effected the positive results seen in this series of difficult-to-heal wounds.

Dr. Michael S. Miller (Commentary: new microvascular blood flow research challenges practice protocols in negative pressure wound therapy) reviews the literature on negative pressure wound therapy (NPWT) with special emphasis on conventional pressure settings and treatment protocols of 3 NPWT systems. He concludes that NPWT is beneficial in wound healing; however, he believes that further research to define pressure intensity, duration of treatment, and interval between treatments is required to optimize its effects.