We have all heard about the concept of moist wound healing. We know that the right moisture balance is critical to the healing of chronic wounds because it promotes a healthy wound environment. We have modalities such as hydrogels and hydrocolloids, as well as normal saline and gauze. The latter is becoming antiquated but nonetheless continues to support the theory of moist wound healing principles.
The new modality to emerge in wound care is the XCell® Cellulose Wound Dressing (Xylos Corporation). This product reportedly provides both hydration and absorption to achieve the moisture balance that wounds require for optimal healing.
XCell is derived from a new technological process. The product is comprised of biosynthesized cellulose which is produced in a liquid media during a static fermentation process. Cellulose is one of the most abundant natural biopolymers and is synthesized by many organisms, including multicellular plants, unicellular plants and bacteria.
The organism in this fermentation process is the Acetobacter species, which takes in sugar molecules and polymerizes them into distinct microfibrils excreted through the organism’s cell wall. This same bacteria is also used in the manufacturing of natural vinegar. The cellulose film is generated on the liquid surface during fermentation, and the length of the fermentation process determines the thickness and amount of the material formed. These sheets of cellulose are called a pellicle. The cellulose pellicle contains 99 percent fluid and 1 percent solid. The bacteria cells that produce the cellulose are removed by a series of chemical washes without disrupting the existing cellulose matrix.
This biosynthesized cellulose is about 200 times smaller than the cellulose from multicellular plants (trees and cotton), giving it a natural high fluid holding capacity and tensile strength. It also has shape retention superior to many synthetic fibers so you can form or cut the material into virtually any size or shape.
Assessing The Indications And Possible Impact Of The Dressing
The XCell Wound Dressing is available in 3.5-inch and 5.5-inch square pads, a larger 6- by 7-inch sacral pad and in a rope form. It comes individually in a single use sterile pouch. The indications for this product include autolytic debridement, exudate absorption and tissue hydration. You can leave it in place for up to seven days. The non-adherent nature of the dressing allows for painless dressing changes with little to no disruption of new granulation tissue within the wound bed. The features of this dressing may simplify the complex process of dealing with chronic wounds at the clinic level.
This dressing may facilitate an easier dressing change and possibly less of them. If we can reduce the amount of materials needed, reduce the frequency of dressing changes and make it easier for patients to make the dressing change themselves, it can certainly reduce the cost of caring for these chronic wounds. Using the dressing may also reduce or eliminate the cost of home care nursing.
However, keep in mind that when you use XCell, you do need to use a secondary dressing whether it’s a thin film or gauze and Kling. XCell is also now available with antimicrobial properties.
What Clinical Testing Has Revealed About Cellulose Products
There have been several publications about the use of biosynthesized cellulose products as a temporary skin substitute. One of the latest articles on biosynthesized cellulose illustrates its use as a permanent implantable patch for neurosurgical applications for repairing dura mater.
The preclinical animal testing and biocompatibility testing have shown no evidence of delayed dermal contact sensitization in the guinea pigs, and there was no evidence of significant irritation or toxicity when it was injected subcutaneously into rabbits. The cytotoxicity of the dressing with mammalian cells showed no cytotoxicity and did not inhibit cell growth. The cellulose wound dressing successfully passed all of these tests, ensuring that the product is biocompatible, safe and will not inhibit wound healing.
During human clinical trials, the cellulose wound dressing exhibited strength in removing slough necrosis in deep pressure ulcers. It also reduced the hypergranulation tissue down to the level of the surrounding epithelium. Researchers found the dressing also helped promote autolytic debridement and provided a moist wound environment to maintain a healthy granulation tissue base. The wound dressing also aids in cleansing wound margins to help epidermal migration, which leads to wound size reduction and the healing of various chronic wounds.
Case Study: How XCell Can Aid Ulcer Healing
A 66-year-old Hispanic female presents to our office with a non-healing ulcer to the plantar aspect of the left hallux. She has been treated by a general surgeon since 1996 for this condition. The patient has undergone several debridements and hospitalizations with IV antibiotic therapy. She has also used orthotics to reduce pressure to this area. A biopsy of the ulceration showed squamous epithelial hyperplasia, parakeratosis and marked inflammation.
Her past medical history includes IDDM for 16 years, HTN, hyperlipidemia and depression. The patient underwent a left breast mastectomy and is currently undergoing chemotherapy. She also experienced renal failure and is undergoing renal dialysis with the fistula in the left upper arm. Her current medications include insulin and a HTN medication. The patient does not know the name of the HTN medication. She denies using tobacco and alcohol. The patient was scheduled for X-rays, lab work with CBC w/diff, A1c and noninvasive vascular studies. She reports a random blood sugar of 120 to 140.
The physical exam reveals a frail woman, who is cooperative and oriented. She is concerned that her toe will need to be amputated, which is adding to her stress and depression. The exam of the lower extremity shows nonpalpable pulses. Her skin temperature is warm proximal to distal with equal and adequate hair distribution to bilateral limbs and toes. There are no foot deformities other than the ulceration to the left plantar hallux and edema to the entire left hallux. There is no cellulitis. We did note mild erythema distal to the first metatarsophalangeal joint.
The wound itself is 3 cm in diameter with a thick callus rim and 2 mm deep. The base of the wound appears macerated with white and yellow fibrotic tissue with bleeding within the hyperkeratosis layer. The wound did not bleed with debridement. There was a foul odor during the debridement but no drainage.
Proceeding With Treatment
We emphasized an initial home care regimen, having the patient apply enzymatic debridement ointment daily with saline moistened gauze and Kling wrap. We ordered a wheelchair for the patient to faciliate offloading.
The X-ray findings do not show evidence of acute or chronic osteomyelitis. They did reveal diffuse osteopenia. Her labs were normal and, as expected, the noninvasive vascular study is abnormal with moderately severe occlusive disease, femoral-popliteal disease. The left ABI is 0.41 mmHg.
The patient lives one hour from the clinic and has missed several appointments, but I maintained phone contact weekly to stress to the patient the need for follow-up and to remind her of the signs of worsening of the condition.
Two months later, the wound was unchanged. I obtained a wound biopsy and requested quantitative analysis. At this point, I initiated the antimicrobial XCell wound dressing along with continued sharp debridement. The patient began performing dressing changes herself with the XCell dressing, followed by normal saline moistened gauze and Kling every other day.
Results of quantitative analysis was 2.2 x 10^6 bacteria, gram positive cocci. I did not initiate an oral antibiotic based on the clinical exam and my clinical experience.
A month later, the exam showed resolution of the ulceration so I discontinued the wound care regimen and fit the patient for multi-density insoles and extra depth shoes. I encouraged the patient to continue nonweightbearing to prevent reoccurrence until she receives her new insoles and shoes.
This biosynthesized cellulose wound dressing, which has a dual moisture handling capability to donate moisture to dry surfaces and absorb fluid from a highly hydrated environment, shows promise in caring for diverse wounds. The ease of application and the ability to leave the dressing in place for up to seven days allows the private practice clinician to offer wound care services within his or her own practice, and schedule follow up care that is more manageable on a weekly basis.
Does this mean we only need to have one type of wound care dressing available in our clinics? That remains to be seen. However, the concepts that originated this material are founded in sound science and as I have used the wound dressing in a wide variety of cases, I have found it useful in almost every case. As always, we cannot forget the need for sharp debridement, when appropriate, as well as a complete and comprehensive history, physical exam, and clinical assessment of the patient and the wound to determine why the wound has gone from an acute wound to a chronic wound.
All wounds need some sort of dressing and XCell may be able to play a more significant role as the first choice, regardless of the wound type, due to its pure nature to hydrate dry necrotic areas, cleanse wound margins and to absorb excess exudate when present.
Dr. Aung is in private practice in Tuscon, Ariz. She currently serves on the Diabetes Advisory Committee of the American Podiatric Medical Association and is a PPOD (podiatry, pharmacy, optometry, dental) Workgroup Member for the CDC-NIH National Diabetes Education Program.
Editor’s Note: For a related article, see “Achieving Adjunctive Success With Wound Dressings” in the July 2003 issue of Podiatry Today or check out the archives at www.podiatrytoday.com.