Effectiveness of a Biocellulose Wound Dressing for the Treatment of Chronic Venous Leg Ulcers: Results of a Single Center Randomized Study Involving 24 Patients

Oscar M. Alvarez, PhD; Mayank Patel, MD; Juanita Booker, RN, BSN; Lee Markowitz, DPM


Wounds. 2004;16(7) 

In This Article

Materials and Methods

Biocellulose wound dressing (BWD; XCell®, Xylos Corporation, Langhorne, Pennsylvania) is a biosynthetic matrix that is hydrophilic and has excellent tensile strength. BWD is unique in that it has the ability to either donate or remove (absorb) moisture (Figure 1). It is synthesized by Acetobacter xylinum and processed into a matrix material that is biocompatible, pyrogen free, and nontoxic. The dressing is provided sterile in sealed foil pouches and available in four sizes (3x3, 5.5x8, 6x7, 8.5x0.75 inches). Application and appearance of BWD in venous ulcer treatment are shown in Figure 2. BWD was provided by the study sponsor, Xylos Corporation, Langhorne, Pennsylvania (lot number NB031902) for the purpose of clinical evaluation.

Absorption donation profiles of several wound dressings.

A) Photograph of BWD prior to application; B) within one week, BWD forms a blister roof-like seal over the ulcer; C) venous ulcer immediately after the removal of BWD. Note the exposed edges and the migrating epithelium along the wound margins.

A) Photograph of BWD prior to application; B) within one week, BWD forms a blister roof-like seal over the ulcer; C) venous ulcer immediately after the removal of BWD. Note the exposed edges and the migrating epithelium along the wound margins.

A) Photograph of BWD prior to application; B) within one week, BWD forms a blister roof-like seal over the ulcer; C) venous ulcer immediately after the removal of BWD. Note the exposed edges and the migrating epithelium along the wound margins.

The primary dressing used as the control was a nonadherent petrolatum emulsion impregnated cellulose acetate gauze (Adaptic®, Johnson & Johnson, Inc., Fort Worth, Texas). It is sterile and packaged in a plastic pouch.

A modified Unna's boot was used to treat the venous insufficiency in all of the patients. The modified Unna's boot consists of inelastic and elastic compression. The inelastic component of the compression bandage is the Unna's paste boot (Viscopaste® Boot, Smith & Nephew Inc., Largo, Florida) and the elastic component is a cohesive elastic bandage (Coban®, 3M Inc., Minneapolis, Minnesota). The modified Unna's boot provides between 20 and 35mmHg compression above the ankle depending on leg circumference. The modified Unna's boot is accepted as standard care in the treatment of lower leg ulcers secondary to chronic venous insufficiency.[20]

All study supplies were purchased by the sponsor from Suburban Ostomy/Invacare, Holliston, Massachusetts.

The study was a prospective, parallel-group, comparative, open trial. Eligible patients between the ages of 18 and 90 were randomly assigned to receive either BWD plus a modified Unna's boot or standard care consisting of a nonadherent wound dressing plus a modified Unna's boot (Control). The patients were followed for 12 weeks or until healing for analysis of efficacy endpoints prospectively set at one-week intervals. Healing was defined as a wound that had fully (100%) re-epithelialized with the absence of drainage and not needing a dressing.

To enroll the patient, the target ulcer had to be secondary to chronic venous insufficiency (having the signs of venous disease). Minimum ulcer duration was set at two months with no upper limit. The wound, in the opinion of the investigator, had to require debridement (more than 50% of the surface area covered with nonviable tissue fibrin). Appropriate vascular studies (ankle to brachial index [ABI] of >0.75 or a normal pulse volume recording [PVR]) were obtained in order to exclude peripheral arterial occlusive disease. Exclusion criteria were as follows: clinical signs of infection, cellulitis, osteomyelitis, inadequate nutrition, uncontrolled diabetes, and other clinically significant conditions that would impair wound healing inclusive of renal, hepatic, hematologic, neurologic, or immunological disease. Patients receiving corticosteroids, immunosuppressive agents, radiation, or chemotherapy within one month prior to entry into the study were also excluded. If the patient had more than one venous ulcer that satisfied the criteria for enrollment, the ulcer of longest duration was designated the target ulcer. If two or more ulcers were present for the same period of time, the ulcer with the largest surface area became the target ulcer. Patients were entered into the study after an institutional review-board informed consent was obtained. Patients were assigned treatment according to a computer-generated randomization schedule.

This report summarizes the data obtained from one clinical center as part of an ongoing multi-center trial.

Twenty-four patients were randomized and received treatment. Patient demographics and wound characteristics of the two treatment groups are presented in Table 1 . There were 12 evaluable patients in each treatment group. Ten out of the 12 patients (83.3%) assigned to BWD completed the study without protocol violations. Two patients missed two or more clinic visits for evaluation but completed the 12-week period. In the Control group, all patients completed the study, but there were five patients with protocol violations (missed visits [3], infection [1], stasis dermatitis [1]).

Wound cleansing was performed with normal saline without the use of forceful irrigation. Surgical, mechanical, enzymatic, or chemical debridement was not allowed at any point throughout the study, and topical wound treatments were not allowed. Manufacturer suggestions for dressing application were followed in accordance to the package inserts whenever possible. Treatment with the test agents was performed at the initial (baseline) visit and once weekly until healing or 12 weeks. If the patient was unable to come to the clinic every week, a visiting nurse was provided to change the dressing and apply the compression bandages at home.

All evaluations were performed at the same outpatient clinical center by the same investigator or study coordinator. Patients were evaluated prior to the initial treatment (baseline visit, day 0) and once weekly thereafter immediately after wound cleansing. At each evaluation, the nonviable tissue type was described as follows: fibrin slough, eschar (solid crust covering the ulcer), or a combination of fibrin and eschar. Nonviable tissue amount covering the ulcer was clinically estimated using the following scale: 5=none, 4=<25 percent, 3=25-49 percent, 2=50-74 percent, and 1=75-100 percent. The amount of granulation tissue was also graded clinically using a five-point scoring scale (5=100% complete granulation, 4=>75%, 3=50-74%, 2=25-49%, and 1=<25%). Local wound pain was evaluated using a clinically validated visual graded categorical analog scale from 0 (no pain) to 10 (extreme pain). Wound size was determined by measurement (maximal length and width) as well as by computerized planimetry of wound tracings. Other clinical assessments included wound exudates, wound odor, signs of infection, interstitial (lower leg) edema, and adverse events.

Data analysis was performed using Statistical Analysis System software (SAS Institute Inc., Cary, North Carolina). Fisher's exact test was computed to compare autolytic debridement, exudate amount, and wound pain between treatment groups. A survival analysis was performed to compare the amount of nonviable tissue, time to granulation, and time to 50 percent re-epithelization between treatments using the Kaplan Meier method and the log rank chi-square test. Due to heavy censoring (missing data points), it was not possible to compare survival curves when the outcome of interest was 100-percent (complete) granulation or healing. Therefore, time to 75-percent granulation and time to 50-percent re-epithelization were compared between treatment groups. The Mann-Whitney U test was employed to compare nonparametric data, such as wound measurements and other clinical assessment parameters.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.