Foam Dressings: Are We There Yet?

Foam Dressings on Chronic or Acute Wounds

  Reference: Chaby G, Senet P, Vaneau M, et al. Dressings for acute and chronic wounds: a systematic review. Arch Dermatol. 2007;143(10):1297–1304.
  Rationale: In the United States more than 1.25 million individuals are treated for burns and more than 6.5 million are treated for chronic pressure, venous, or diabetic ulcers. Professionals involved in the wound care medical arena have known for half a century that moisture-retentive dressings promote wound healing and reduce pain and healing time, yet the ideal dressing choice has remained controversial.
  Objective: Critically review literature on healing efficacy of modern dressings in chronic and acute wounds that heal by secondary intention.
  Methods: MEDLINE, EMBASE, and Cochrane reference databases were searched from January 1990 through June 2007 for English or French reviews, practice guidelines, meta-analyses, or randomized controlled trials (RCTs) measuring complete healing of acute or chronic wounds dressed with hydrocolloid, foam, alginate, hydrogel, Hydrofiber®, bead, protease-modulating, silver, activated charcoal, hyaluronic acid, other nongauze dressings, and all types of gauze dressings. Included studies were reviewed by 2 of 19 independent reviewers and were rated as Level A if the studies were well-conducted, large, randomized, double-blind, controlled RCTs, or meta-analyses (MA) of such RCTs that had low a and b errors. Small, well conducted RCTs or MA including same or including Level C RCT were rated as Level B. RCTs with one or more methodological shortcoming were rated Level C.
  Results: No Level A, large, RCT was found among the 89 RCTs and 3 MA selected for analysis. The most evidence was found for hydrocolloid (34 RCTs, 3 MA), foam (22 RCTs, 2 MA), and alginate dressings (21 RCTs).  Five RCTs and one MA on chronic wounds provided Level B evidence supporting the following conclusions: 1) improved complete healing rates of hydrocolloid-dressed (HCD) leg and pressure ulcers as compared to paraffin impregnated or wet-to-dry gauze; 2) No consistent difference in complete healing between HCD and foam-dressed wounds; 3) Alginate dressings reduced pain during dressing changes compared to HCD or paraffin-gauze-dressed wounds; and 4) debrided more fibrous tissue from pressure ulcers than dextranomer beads; 5) A nonadherent dressing evoked less dressing change pain than HCD in one study that did not measure complete healing.  For acute wounds, 4 RCTs provided Level B evidence that: 1) Split-thickness skin graft donor site (SSDS) healing efficacy did not differ between foam, paraffin gauze, or film dressings; 2) SSDS healed faster when dressed with a foam as compared to a silver-coated dressing; and 3) healed faster with less pain during dressing changes when dressed with a Hydrofiber® as compared to paraffin gauze dressing; or 4) when dressed with a glycerin-impregnated dressing as compared to a hyaluronic acid dressing. No consistent effects on healing or dressing change pain were observed in the remaining two RCTs both on surgical wounds.
  Authors’ Conclusions: Reviews provide a weak level of evidence on clinical efficacy of different dressing types on wounds. Hydrocolloids and foam dressings have the best evidence for optimizing complete healing of chronic wounds. Alginate dressings have the best evidence for chronic wound necrotic tissue debridement. Hydrofiber® dressings have the best evidence for speeding healing of acute wounds. More large, A-Level, RCTs are needed to support wound care dressing decisions.

Comparing Two Foam Dressings

  Reference: Franks PJ, Moody M, Moffatt CJ, et al. Randomized trial of two foam dressings in the management of chronic venous ulceration. Wound Repair Regen. 2007;15(2):197-202.
  Rationale: Venous ulcers (VU) affect more than 100,000 patients in the United Kingdom and 400,000 in the United States at any time, with 3 to 4 times that number having a healed VU at risk of recurrence. Randomized, controlled trial evidence supports VU healing, quality of life and cost effectiveness of compression sufficient to improve venous return, but there is little evidence supporting the relative merits of VU dressings.
  Objective: A prospective RCT compared two foam dressings and their effects on healing and pain of patients with chronic VU.
  Methods: A European 12-center prospective stratified, parallel-group, open-evaluated, factorial RCT compared healing and pain in VU patients dressed with Allevyn® Hydrocellular, (Smith & Nephew; n = 81) or Mepilex® (Mölnlycke Health Care AB; n = 75) primary foam dressings. Patients were stratified so that similar numbers of VU larger or smaller than 10 cm² in area on enrollment were randomized 1:1 to either dressing and randomized within dressing groups 1:1 to receive either a 4-layer (4LB; n = 74) or short-stretch (SS; n = 82) compression bandage. Treatments at least once weekly continued for 24 weeks with an additional 24-week follow-up during which subjects were provided compression. Photoplethysmography confirmed VU etiology. Patients who were included had a moist 2- to 52-week duration VU without active cellulitis and were not taking antibiotics. The primary outcome was complete epithelization of all VU on the study leg compared using Cox proportional hazard regression analysis of Kaplan-Meier healing curves with and without adjusting for baseline ulcer area and compression bandage. Wilcoxon rank-sum tests compared VU pain assessed using the McGill pain questionnaire at baseline and 4 weeks. Pain intensity was measured using a 10-point visual analog scale (VAS) before dressing removal and after both dressing and compression bandage were in place.
  Results: After 12 weeks, 47.5% of Allevyn-dressed and 50.7% of Mepilex-dressed VU healed (P = 0.16) and 61.7% and 66.6%, respectively, healed after 24 weeks. Both groups experienced similar withdrawal and adverse event patterns. Pain intensity declined by 4 weeks (P   Authors’ Conclusions: Healing rates, patient-reported pain, and study withdrawal rates were similar for the two foam dressings. Patients’ perceived pain improved during VU treatment progressively over time, and compared with pre-dressing change levels at baseline and 4 weeks.

Clinical Perspective

   We have taken early steps toward evidence-based use of foam dressings. Comparisons to gauze dressings support their reduction of pain and nursing time in open surgical wounds² and healing time for chronic wounds, but the evidence is not yet compelling.
   Chaby et al cite the need for large, good quality RCTs that support efficacy of wound dressings. Though their evidence levels are more stringent than those usually³ proposed for evidence-based practice, this review is a grim reminder that wound care lags behind other medical fields in support of evidence-based practice. One limitation of this review is omission of pre-1990 trials despite ample qualifying RCTs.⁴ Wise clinicians heed pearls from the past. Also, I could not find what was meant by “large RCT.” This would typically mean of sample size sufficient for less than 5% likelihood of a Type 1 error (a 80%). In a dressing efficacy RCT, a is the probability that the statistically significant difference between dressings observed in the RCT occurred due to chance alone; while b (or Type 2 error) is the probability that one incorrectly concluded no significant difference in dressing efficacy.
   In reviewing the Franks et al RCT, it was difficult to understand how the VU remained sufficiently “moist” for foam dressing use during the entire study. Would a more clinically relevant protocol have included sequential use of a more moisture-retentive dressing as wound fluid diminished? The authors noted as a limitation that pain measurement was done only before dressing removal and after both dressing and compression bandage were in place; no pain measurement occurred during dressing removal.
   The comparative effects of these two dressings on this clinically important aspect of wound care remain to be tested. These two studies highlight opportunities to unify wound dressing research by using standardized, validated measures for wound outcomes, such as healing and wound pain, to improve the evidence supporting wound care decisions.