Summary of Scientific Paper - The Ideal Split-Thickness Skin Graft Donor-Site Dressing: A Clinical Comparative Trial of a Modified Polyurethane Dressing and Aquacel - Arjun Mehta

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The Ideal Split-Thickness Skin Graft Donor-Site Dressing: A Clinical Comparative Trial of a Modified Polyurethane Dressing and Aquacel

Summary of Scientific Articleby Arjun Mehta, UCLA Bioengineering Undergraduate

November 15, 2011

Authors: Ulf Dornseifer, M.D., Daniel Lonic, M.D., Tristan Ivo Gerstung, M.D., Frank Herter, M.D., AndreasMax Fichter, M.D., Charlotte Holm, M.D., Ph.D., Tibor Schuster, Ph.D., Milomir Ninkovic, M.D.,Ph.D.

Published: Plastic and Reconstructive Surgery. 2011.

Introduction

Skin grafting still remains the most common form of tissue repair for severe tissue damage arisingfrom burns, chronic wounds, and ulcers. Often, a patient can be treated via a split-thickness graft

taken from another part of the body, such as the thigh. While the skin removed at the donor-sitecan still be regenerated, it must be treated with care in order to prevent infection and promotereepithelialization.

As a result, many wound care dressings have emerged, such as BioBrane, Tegaderm, andAquacel. The optimal dressing should have the following characteristics: protect the wound fromdesiccation, permit gas exchange to accelerate reepithelialization, be impermeable to exogenousmicroorganisms, be comfortable for the patient and ward staff, require minimal labor, be flexibleand pliable, have a good tensile, and be resistant to linear and shear stress. Additionally, it shouldpossess these characteristics while being low in cost. Existing dressings fulfill some of thesecriteria, but not all of them. Thus, there is still a need to create a better dressing

Theoretically, a polyurethane film would be a superior dressing to existing products were it not for

its uncontrollable leakage of exudate at the wound surface. The authors of this study sought totest a modified polyurethane dressing that expels controlled leakage into a second absorbentlayer.

In a randomized, comparative, double-blind study, the authors tested the efficacy of their modifiedpolyurethane dressing against Aquacel. The primary outcome measurement wasreepithelialization, and the secondary variables were pain, cost, and scarring.

Methods

Patient Profile This double-blind study was performed on 50 patients between June 2008 and June 2009.Patients required skin grafting either as a single procedure or in combination with other

reconstructive surgery. 23 were men and 27 women, ranging from age 18 to 95 (mean age of62.65 years). The donor-site dimension ranged from 90 to 732 cm2, with a mean of 233 cm

2.

Skin Grafting Procedure All skin grafts had the same thickness of 0.012 inches and were taken from the same donor site:the anterolateral thigh of the patient. An air-driven Dermatome (Zimmer, Freiburg, Germany) wasused to obtain the graft, and the donor site was immediately covered with a moist pack until therest of the surgery was completed.



Application of the Dressing On each patient, the modified polyurethane dressing was adapted to fit over half the donor-site,and the Aquacel dressing was adapted to fit over the other half (Figure 1). Two layers of cottongauze pads were placed over both the dressings to allow double-blind evaluation. The dressingswere then left in place for 10 days, the maximum time expected for complete reepithelialization byAquacel. The dressings were only removed if an infection was suspected, in which case thepatient was additionally treated with an antimicrobial dressing and removed from the experiment.

Evaluation of Reepithelialization and Local Pain After 10 days, reepithelialization was evaluated on each half of the donor sites in a blindedmanner (Figure 2, Figure 3). Wounds were considered to have completely reepithelialized if therewas no body exudate, and exposure to an antiseptic solution and air did not cause pain.Investigators had to mark whether each half of the donor site was completely reepithelialized ornot, and compare which half was more complete. In addition, local pain was measured eachpostoperative day and during dressing removal using a pain scale of 0 (no pain) to 5 (maximalsevere pain). Patients were asked to rate the pain at each half of the donor site, and comparewhich site inflicted more pain.

Evaluation of Scarring 60 days after the surgery, scarring at the donor site was analyzed in a blinded fashion using the

Vancouver Scar Scale.

Results

1. Polyurethane dressing exhibited higher rate of complete reepithelialization : 86.4% ofthe donor sites treated with the polyurethane completely reepithelialized, compared to 54.5%of the Aquacel-treated sites (p < 0.001).

2. Local pain was consistently low during healing : 90% of the values on the pain scale wereless than or equal to 1. However, when asked to compare the two halves on the donor site, asignificantly higher percentage rated the polyurethane dressing site to be less painful thanthe Aquacel site. This percentage increased over time (Figure 4), meaning that Aquacel wasconsistently rated more painful as day 10 approached.

3. Local pain was lower in polyurethane during removal : 59% of the patients rated theAquacel site more painful than polyurethane during removal, whereas 6.8% rated thepolyurethane removal more painful (p < 0.001).

4. Aquacel is 4 times more expensive than the polyurethane dressing: When compared to a donor site of 8 x 20 cm

2 , Aquacel dressing cost approximately four times more.

5. Limited scarring from both dressings: Both sites exhibited inconspicuous scarring, and no significant differences could be measured between dressings.

Discussion

This paper uses double-blind study to demonstrate that a modified polyurethane film is superior toa leading dressing (Aquacel) in that it better promotes complete reepithelialization, provides morepatient comfort, and is less expensive. One thing the authors point out is that they did not use thesame method for applying Aquacel as the method in another study that achieved completereepithelialization in 7-10 days. While the other study used more than one layer of Aquacel andreplaced the dressing as needed, this study used only one layer of Aquacel. This could accountfor both the poorer reepithelialization and increase in local pain, since Aquacel exhibitsdegradation over time. The authors argue that the replacement of a wound dressing exposes the



patient to potential infection, and when weighted against additional factors such as cost andlabor, Aquacel is an inferior dressing. Nevertheless, this paper successfully demonstrates that amodified polyurethane film used with an absorbent layer is an effective wound dressing, and mayvery well be the next gold standard.

Figures & Controls

Controls:Aquacel dressing

None

Suggested:

wound withoutdressingdouble-layeredAquacel from

Barnea et al.protocoladditional dressingproducts (e.g.BioBrane,

Tegaderm, etc.)

Controls: Aquacel dressing

None

Suggested:

wound withoutdressingdouble-layeredAquacel fromBarnea et al.protocoladditionaldressing products

(e.g. BioBrane,

Tegaderm, etc.)

Figure 1: Arrangement of dressings on donor sites

Figure 2: Evaluation of Reepithelialization



Controls:Aquacel dressing

None

Suggested:

wound withoutdressing double-layeredAquacel fromBarnea et al.protocoladditionaldressing products

(e.g. BioBrane,Tegaderm, etc.)

Controls:None

None

Suggested:To ensure results areindependent of thelocation of the site,polyurethane site andAquacel site shouldbe randomized (left orright side of the donorsite)

To ensure that resultsare independent of theorder in which site the

patient is asked about,investigators shouldrandomize the order inwhich they referenceeach half on the donorsite.

Figure 3: Evaluation of Reepithelialization

Figure 4: Local Pain Comparison



Controls:None

None

Suggested:

Reference values:

Tap on the armFlick on the armPinch on the arm

Controls:None

None

Suggested:

Reference values:

Image of noscarringImage depictingvisible scarring

Figure 5: Pain evaluation during dressing removal

Figure 6: Evaluation of scarring after 60 days



Critique

While most of the data is sound, some of the methods and results could have been elaborated.For example, the authors should also have tested the Barnea et al. protocol, in which Aquacelcaused complete reepithelialized in 7-10 days. In the protocol, Aquacel was double-layered andreplaced when soaked. This would have provided more insight into the efficacy of the modified

polyurethane dressing compared to Aquacel in optimal conditions. It would also be ideal to testone dressing exclusively on each patient instead of both on the same donor site. This wouldensure each dressing is acting alone without beneficial or diminutive effects of the other dressingcrossing over.

The pain evaluation system was not without flaws, either. The dressings should be randomlyplaced on either half of the donor site, and the order of scaffold removal should also be random.This will ensure that the location of the dressing or order in which it was removed does not biasthe patient. In addition, investigators should randomize the order in which they address the painfrom each dressing in order to remove the chance that patients are more likely to select onebased on the order in which it was mentioned.

The authors claimed that Aquacel was approximately 4 times more expensive than thepolyurethane film, but did not support their conclusion with any data. They also did not mentionwhether they estimated the cost for each patient and came up with an average, or calculated thecost for only one case.

A proper measurement for scarring was not detailed in the report. It would have been helpful todisplay a chart of Vancouver Scar Scale with examples of different values. Without this chart,there is no way to understand how little or how much scarring actually occurred.

Lastly, the authors claim that the polyurethane film is suitable for use in donor sites up to 1050cm

2, yet the largest donor site in the experiment was 732 cm

2.

Suggested Experiments

1.) Test multiple dressings, each isolated and randomly placed on a separate donor site.In addition to Aquacel, the polyurethane film should be compared to a negative control of justgauze, as well as other dressings such as BioBrane and TegaDerm. Each dressing should betested using optimal methods, and evaluated after 10 days.

Controls:GauzeAquacelTegaDerm

Each donor site will be separate from one another. Dressings will be randomly placed on one of the 4 donor sites.



2.) Set standards for daily pain evaluation.Before obtaining a pain score from 0 to 5 for the donor sites, obtain a score for the following:

Tap on the arm

Flick on the arm

Pinch on the arm

Additionally, collect data to determine whether a particular donor site consistently yielded a higherpain score.

3.) Test the limits of the polyurethane film.Test larger donor-site size to prove viability for donor sites up to 1050cm

2or larger. Measure

complete reepithelialization after 10 days.

Controls:Dressing known to work at1050 cm

2

4.) Compare total cost of each dressing.For each patient, calculate the total surgical and post-operative costs within 60 days of treatmentfor each dressing. Determine the average cost per area of donor site.

Controls:AquacelTegaDerm

ReferencesOriginal Article: http://www.ncbi.nlm.nih.gov/pubmed/21681125

Dressing known to cause complete reepithelialization at 1050 cm2

Polyurethane Film Dressing

732 cm2

900 cm2

1050 cm2

732 cm2

900 cm

2

1050 cm2

http://www.ncbi.nlm.nih.gov/pubmed/21681125




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Summary of Scientific Paper - The Ideal Split-Thickness Skin Graft Donor-Site Dressing: A Clinical Comparative Trial of a Modified Polyurethane Dressing and Aquacel - Arjun Mehta