BB&T Contributing Editor
SAN ANTONIO – The 19th annual Symposium on Advanced Wound Care was held recently at the Henry B. Gonzalez Convention Center, with 133 exhibitors and more than 2,000 nurses, physicians and researchers attending. The sympoisum was sponsored by HMP Communications (Malvern, Pennsylvania) and the University of Miami (Coral Gables, Florida).
Wound care is a new and emerging market, rapidly expanding beyond the “gauze and antiseptic” stage as new technologies come online and a variety of competitors grapple for a piece of an expanding pie. That expansion is the result of the both demographics and disease: the growing number of elderly, along with the growing perception that end-of-life care is placing increasing burdens on the healthcare budget; and the increase in wound-producing disease, primarily diabetes.
Wounds of all types
Additionally, there is the growing perception that a “one-dressing-fits-all wounds” approach hardly meets the variety of particular wound types. The result has been a proliferation of wound dressings, varying in design, materials and construction.
The diversity of wound dressings is due to the varying needs and characteristics of the wounds being treated. There are acute and chronic wounds, infected and necrotic wounds, dehiscent and oozing wounds, surgical wounds (incisions, donor sites, laser skin rejuvenation) and traumatic wounds (abrasions, lacerations, second degree burns), and so on. Additionally, not every clinician agrees on the best strategies to be used for each type of wound and the method of treatment. These differences may be so simple and basic as competing views on whether a wound bed should be kept moist or dry.
The principal features of wound dressings are strategies for “wicking” of fluids away from the wound site, non-adherence of the dressing to the wound and absorbency. Examples of absorbent materials used in wound dressings are gauze, wood pulp, non-woven fabric, foam and hydrogel. Non-adhering porous and mesh facing materials are employed, these providing surfaces that may be treated with silicone or petrolatum to prevent sticking of the dressing to the wound site. Polymeric backing materials are used to contain fluids within the dressing and prevent leakage.
In general, any new type of dressing from a major marketer has been met with competing products, such as has occurred with semi-occlusive dressings (using semipermeable films), hydrocolloids (hydrogels) and calcium alginate dressings. In recent years, dressings have been introduced which contain an antimicrobial agent to prevent infection, the most common being silver-treated wound dressings.
Wound care products are also available in the form of gels, ointments, absorbent beads and fibers, paint-on liquid film-formers and glues (fibrin and albumin-based). Surgical incisions on the skin surface can be closed with sutures, staples, zippers, high-tension tape or surgical glues over which a dressing may, or may not, be applied. Internal organ incisions can be closed with sutures, staples, ligating clips and sealants (paint-on and photoactivated). Sutures and staples are available in permanent (removed by health practitioner) and absorbable forms.
Consensus via Delphi
Criteria to identify infection in different wound types have been developed through the process of collating and refining opinions using the Delphi approach. This entails convening a panel of experts who respond to statements or questions. The responses are collated and returned for rating. This process continues until a consensus is reached. The Delphi approach differs from other consensus groups by relying on the fact that panel members are not aware of the identities of their co-members. Using this method, six categories of infected wound types has been compiled: diabetic foot ulcers, pressure ulcers, venous leg ulcers, arterial leg ulcers, acute and surgical wounds, and full thickness burns.
Chronic wounds have attracted a great deal of attention from marketers of wound dressings because the market is large and the need long-term. This category includes ulcerated wounds such as pressure sores (also called decubitus ulcers or bed sores), diabetic food ulcers, venous stasis ulcers and vascular ulcers.
Another sector is the burn wound market, which has attracted companies that have developed artificial skin substitutes. Although the need for these products by the burn victim is great, the overall market is small, and several of these companies have gone out of existence. Here, a key barrier is the very complex nature of the skin, that complexity baffling attempts to produce either a synthetic or biologically active substitute.
A particularly interesting session at the symposium was dedicated to the negative impact of biofilms in wound infections and infections related to implanted devices. A biofilm is a complex community of bacteria that frequently colonizes and infects and leads to the development of systemic infections and is also a cause in the failure of implantable devices. Additionally, biofilm-associated microorganisms exhibit markedly reduced susceptibility to antimicrobial agents and host immune defenses.
Symposium participants agreed that current strategies do not adequately prevent the formation of pathogenic biofilm. This is a concern for patients with ulcerated wounds, for critically ill patients in whom medical devices are needed for delivery of care and for patients who require long-term insertion or placement of an implantable medical device, given that the risk of infection dramatically increases with time. It was reported that diabetic patients have a 3.5 times higher infection rate than non-diabetic patients.
Centegen (Baltimore) is a newly formed company exploring the use of RNA-III inhibitor peptide as an agent to prevent and treat biofilm formation and toxin production by Staphylococcus aureus and Staphylococcus epidermidis, the most common causative agents of infections. The company is currently conducting IND-enabling clinical studies.
Hydrofera (Willimantic, Connecticut) markets Hydrofera Blue, a bacteriostatic, compressed polyvinylalcohol foam sponge that contains both Gentian violet and methylene blue for use against gram positive and gram negative organisms, respectively. The sponge becomes soft and compliant when wetted with any fluid and is suitable for all wound types except burns.
Among the most innovative device-based approaches to fighting bacteria comes from Celleration (Eden Prairie, Minnesota), which featured its MIST therapy ultrasound system. The system promotes wound healing through cell stimulation while removing bacteria from a wound. It consists of a portable ultrasound power generator, a hand transducer and a single-use applicator that holds a bottle of saline solution. The non-contact MIST technology has been cleared by the FDA and can be used on acute, chronic, traumatic and dehisced wounds. The company completed a randomized and controlled multicenter clinical trial on diabetic foot ulcers.
MIST technology is believed to work via the following steps: debridement of the wound, increase in circulation thereby creating an angiogenic effect, destruction of bacterial cell walls, stimulation that releases growth factors and the laying down of proteins and collagen.
Celleration’s approach is so unique that it took a rather unusual path to achieve FDA clearance (see sidebar, p. 13).
Another unique approach is that of Dynatronics (Salt Lake City) which is seeking to enter the wound healing market with its D702 infrared light therapy equipment that increases cellular metabolism and attempts to accelerate healing with an added blue light to kill bacteria.
Healing with silver
Silver is the most commonly used antimicrobial agent incorporated in wound dressings. Silver is also used commercially as a surface treatment on other medical products such as catheters and related devices. Both ionic and molecular (metallic) silver are used although the ionic form is believed to provide the antimicrobial protection.
Various methods for depositing silver in wound dressings are used, and the antimicrobial activity of the silver varies with the type of process used. Silver sulfadiazine is widely used in creams and ointments for treating burns.
Dr. Gary Sibbald, of the University of Toronto, a leading researcher on wound care, presented an assessment of wound care technologies and devoted much attention to the widespread use of silver-containing dressings, referring to it as “silverization of the world.” He cautioned that the antimicrobial and antifungal properties of ionized silver may be compromised by the body developing a resistance from repeated use. He called for more selective use of silver-containing products and for research into other methods for controlling bacteria.
Numerous silver-treated dressings were on display. They included Argentum Medical’s (Willowbrook, Illinois) Silverlon CA, a calcium alginate dressing, and Silverlon NPD, a negative pressure dressing, designed for use with negative pressure wound therapy that can last for five to seven days between changes; Medline Industries’ (Mundelein, Illinois) SilvaSorbSite percutaneous site dressing and Maxorb Extra Ag highly absorbent dressing; MPM Medical’s (Irving, Texas) SilverMed hydrogel; and DeRoyal’s (Powell, Tennessee) Algidex Ag alginate wound dressing.
Nobel Fiber Technologies (Summit, Pennsylvania) produces the X-Static brand silver fiber for use in medical, consumer industrial and military markets. Its X-Static silver fibers are used in its stockinette that is placed under an orthopedic cast to kill bacteria and prevent malodor, its Silver Seal hydrogel wound dressing, in compression hosiery sold by Juzo (Paris), and in Silvercel antimicrobial alginate dressing sold by Johnson & Johnson Wound Management, a unit of Johnson & Johnson’s Ethicon (Somerville, New Jersey) subsidiary.
Copper and oxygen
Cupron (Greensboro, North Carolina) is developing surgical dressings and consumer products that contain copper oxide as an antibacterial and antifungal agent and is conducting a clinical trial on gauze containing copper oxide. More than 100 patients with chronic wounds (diabetic foot ulcers and decubitis ulcers) that have failed previous treatment have been treated with the copper oxide-containing gauze dressing and have shown significant improvement within one to three weeks.
The copper oxide is believed to stimulate healing as well as kill bacteria. A commercial application of fibers impregnated with copper oxide is in socks produced by Renfro (Mount Airy, North Carolina), for use in preventing athlete’s foot and malodor.
Ogenix (Beachwood, Ohio) markets its EpiFLO transdermal sustained oxygen therapy device. It is a hand-held and disposable device that continuously delivers 3 mm per hour of pure oxygen through a 5 fr cannula directly to the wound bed under an occlusive dressing.
KCI (San Antonio) had a high profile at the conference and was showing its newest product, a silver-impregnated foam for treating infected wounds which can be cut to shape. The company’s flagship product, however, is its V.A.C. (vacuum-assisted closure) therapy system and ancillary products which have established a leading position in the wound care market. It promotes wound healing by applying localized negative pressure to the wound, removing interstitial fluid and infectious materials. This system can be used to treat chronic wounds, non-healing acute and traumatic wounds and dehisced wounds.
Oxygen is key to all phases of wound healing. It is metabolized at the cellular level and assists in epithelialization by stimulating the production of growth factors and the formation of granulation tissue. Researchers from the VA Medical Center (Cleveland) presented a poster that reported using the EpiFLO device to heal chronic diabetic ulcers after other therapies failed.
Another use of oxygen comes from IYIA (San Marcos, California). IYIA has developed a proprietary device, O2 Misly, that delivers topical oxygen therapy at a slightly positive pressure to slowly healing wounds. This treatment irrigates the wound with a humid mist and offers the ability to add an antibiotic or antimicrobial agent to the mist. The company has received FDA 510(k) clearance and is conducting a postmarketing surveillance study. Its initial target market is podiatrists who treat 39% of diabetic foot ulcers. TherOx (Irvine, California) is also investigating the use of its aqueous oxygen therapy for wound healing applications.
Additional players, some large
BlueSky Medical (Carlsbad, California) markets the Versatile 1 wound vacuum system, a technology that has attracted a patent infringement suit from KCI. BlueSky differentiates its device from KCI’s V.A.C. system in that it uses one-half the negative pressure and that it is sold at one-half the cost. It also uses a different drain, the Miller DermiVex wound drain. Versatile 1 is used along with AMD gauze supplied by Kendall, a division of Tyco Healthcare (both Mansfield, Massachusetts) which utilizes polyhexamethylene biguanide as the antimicrobial agent.
Molnlycke Health Care (Norcross, Georgia/Gothenberg, Sweden), a major European supplier of surgical dressings, launched Mediplex Heel, an hourglass-shaped foam dressing that conforms to the heel and utilizes the company’s Safetac soft silicone technology for reducing the risk of maceration and to minimize the trauma and pain of dressing changes.
Kendall (Mansfield, Massachusetts) featured its recently introduced COPA ultra-soft foam wound dressings and its AMD packing strips.
Coloplast (Marietta, Georgia/Humlebaek, Denmark), a leading European supplier of ostomy and wound care products, introduced at the gathering its Citric-Aid Clear barrier ointment for use with light or heavy incontinent patients and Citric-Aid Clear containing 2% miconazole for treating perineal skin irritation due to fungal infection.
Smith & Nephew Wound Management (Largo, Florida), a subsidiary of Smith & Nephew (Hull, UK), featured its new Acticoat moisture control and antimicrobial barrier dressing made from hydrocellular foam with a non-adhesive wound facing and Silcryst silver nanocrystals contained in the backing material. It is claimed to work up to five times faster than other antimicrobial dressings.
The company recently reacquired marketing rights from Healthpoint (Fort Worth, Texas), a subsidiary of DPT (San Antonio), for the Iodosorb antimicrobial dressing that contains 0.9% iodine suspended in a cadexomer starch polymer. It is use to remove slough for the debridement of wounds having a high bacterial load and offers up to three days antimicrobial activity.
3M Health Care (St. Paul, Minnesota) introduced its new Tegaderm mesh silver dressing that can be used either as a primary dressing or with absorbent wound fillers and can be cut to size. It includes the Coban 2-layer compression system provided as a soft roll of foam and provides sustained compression from its cohesive outer layer.
ConvaTec (Skillman, New Jersey), a subsidiary of Bristol-Myers Squibb (New York), introduced its new line of pediatric ostomy pouches for patients weighing under 10 pounds and its FlexiSeal fecal incontinence balloon, tube and pouch designed to reduce skin breakdown and infection.
Collagen and cellular approaches
TEI Biosciences (Boston) markets the PriMatrix acellular dermal tissue matrix that is comprised of type 1 and type 3 collagen and is derived from fetal bovine dermis. It is sold for soft tissue repair in neurosurgery by Medtronic (St. Paul, Minnesota), by Boston Scientific (Natick, Massachusetts) for urological applications and by Stryker (Kalamazoo, Michigan) for orthopedic use. PriMatrix also is used as a wound dressing and competes against the Oasis acellular wound dressing that is derived from porcine small intestinal mucosa. It also is sold by Healthpoint (Fort Worth, Texas) under license from Cook Surgical (Bloomington, Indiana).
Celgene Cellular Therapeutics (Cedar Knolls, New Jersey), a subsidiary of Celgene (Warren, New Jersey), exhibited its Biovance collagen-based wound dressing that is derived from the placenta after a full-term pregnancy Wound Care Innovations (Fort Lauderdale, Florida) displayed its CellerateRX activated collagen powder and gel, a type 1 hydrolyzed bovine collagen, for use as a wound bed filler. Competing products are Medifil from BioCore Medical Technologies (Elkridge, Maryland) and Fibracol from Johnson and Johnson Wound Management.
Cytomedix (Rockville, Maryland) has developed the AutoGel system for the preparation of an autologous cellular therapy to stimulate new tissue growth at the wound site. It is being used in extended care and government facilities. Clinical data is being reviewed by the FDA under a 510(k) submission, and the company will seek reimbursement for using this therapy on diabetic and pressure ulcers.
The company is defending its patents for the preparation of an autologous platelet rich plasma gel and has licensed its technology to Medtronic (Minneapolis); DePuy Acromed (Raynham, Massachusetts), a subsidiary of Johnson & Johnson (New Brunswick, New Jersey); SafeBlood Technologies (Little Rock, Aransas); Perfusion Partners and Associates (Ft. Myers, Florida); Harvest Technologies (Plymouth, Massachusetts); COBE Cardiovascular (Arvada, Colorado); and Italy’s Sorin Group.