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A medical fabric with a silky, smooth texture developed by DuPont exceeds the requirements of EN 13795.

Medical textiles are used in a range of applications from wound-care products and surgical drapes and gowns to tissue-engineering scaffolding. They are also a burgeoning sector within the technical textiles industry. Medical technology represented approximately 9% of global consumption of technical textiles in 1990, according to a study conducted by David Rigby Associates, a consultancy based in Manchester, UK. And the future looks bright. Experts predict annual growth in volume of 4.5% through 2010, writes Robert Czajka of the Faculty of Textile Engineering and Marketing at the Technical University of Lodz in Poland. Nonwovens will account for a high percentage of the sector’s overall growth in terms of tons of fibres used, he notes in a paper published in the January/ February 2005 issue of Fibres & Textiles in Eastern Europe.

“Another feature of the medical textile market will be the growing proportion of composite materials used in wound-management products,” explains Czajka. “The increased use of textiles in composite applications will provide major growth [in the volume] of fibre consumption.”

Regarding wound-care products, one recent innovation that has received a great deal of attention is the use of chitosan in fibres to promote healing. Mohsen Miraftab, PhD, a senior lecturer and researcher in medical and technical textiles at the University of Bolton (Bolton, Lancs, UK), has studied the use of chitosan in wound care.

Thinking Outside the Shell

“A derivative of chitin, chitosan is extracted from crab and lobster shells,” explains Miraftab. “It is widely used as a dietary supplement, but what interests polymer scientists and the biomaterial community is its haemostatic, antimicrobial, and healing ability.”

Chitosan is made from chitin by removing acetyl groups from the chitin polymer chain with dilute acid. By controlling the number of acetyl groups along the chain, or by adding new groups, chemists can fine-tune the properties of chitosan.

“Lysozyme, an enzyme present in body fluids, breaks down the chitosan to N-acetyl-glucosamine,” says Miraftab. “This initiates fibroplast proliferation and, thus, the healing process.” Elevated processing costs and the brittle nature of the material have hampered its use in wound-care products, but researchers at Bolton have developed a technique that may skirt these obstacles.

“We have developed and patented a new fibre based on bicomponent technology,” Miraftab explains. “Alginate is used as the core material and chitosan serves as the sheath. This fibre can be processed more easily, and the alginate component enhances the absorbency of the fibre as well as making it more durable.” The use of chitosan in advanced wound care is already proving its mettle in the battlefields of Iraq.

Hem-Con Inc. (Portland, OR, USA) is using a modified form of chitosan in a field dressing that has been adopted by the US military. In fact, the US Army has been sufficiently impressed by its performance to order tens of thousands of the bandages and award US$6 million to the manufacturer to expand production capabilities.

Advanced wound-care applications are also on the minds of researchers at DuPont (Luxembourg) and a partner company. “We are in the process of developing a semifinished product designed for hard-to-heal wounds,” explains Christoph Koslowski, account manager, medical specialties Europe. “Our aim is to provide natural fibres with antimicrobial components as an alternative to silver-based materials. The product will not release anything into the wound; rather, it is engineered to attract microbes and kill them once they have been captured,” he explains.

Research is in the very early stages, but the technology shows great promise, says Koslowski. “Initial studies have shown that the material can reduce the healing process of severe wounds from several months to a couple of weeks.” For now, Koslowski is tight lipped, but he expects to be able to divulge further details during the first half of 2006.

Biomedical Textile Research in Scotland

The Biomedical Textiles Research Centre (BTRC) at Heriot-Watt University (Netherdale, Galashiels, UK) is a bit of a newcomer to the field, but it has a prestigious pedigree. “Most people around the world will recognize us as the Scottish College of Textiles in Galashiels,” explains BTRC director Alex Fotheringham, PhD. “We merged with the university in 1998, which is roughly when our medical specialization began.”

The overarching goal of the centre’s researchers is to engineer products with desirable mechanical and biological properties at an early stage of development. “Unlike products that you buy off the shelf and then try to make biocompatible, we strive to engineer materials that are fit for the purpose by building in the necessary biological properties,” says Fotheringham.

The centre’s current textile-based projects include the development of an artificial spinal disk and a dental insert that slowly releases fluoride to prevent caries among at-risk children. The BTRC is also conducting extensive research into the medical applications of gas-discharge plasma treatment technology.

“This process can be used to make a foam or fibre surface either hydrophilic or hydrophobic,” explains Fotheringham. “It’s a change you can’t see or feel…that is difficult to detect…but it’s there. We can make a plastic sticky in chemical terms and attach ligands and enzymes, for example, or coat implants,” Fotheringham adds. The centre is also actively involved in the development of textile-based scaffolding for use in tissue-engineering applications.

Using fibres to create 3-D knitted or nonwoven structures affords researchers considerable freedom in terms of designing pore sizes, says Fotheringham. “The fabric can be structured as loosely or as tightly as the application requires,” he says. “We can produce the porosity that is needed to [promote optimal] cell growth.” The versatility of the scaffolding, which can be knitted, woven, nonwoven, braided, embroidered, or made using a combination of these techniques, and the choice of materials available make textiles ideally suited for encouraging cells to recreate the natural tissue geometry, according to Fotheringham.

DuPont Launches Nonwoven Material in Europe

As an internationally recognized company, DuPont needs no introduction. But its new Suprel medical nonwoven material does.

“DuPont created Sontara in 1973,” explains Jean-Francois Teneul, who is in charge of medical fabrics used in surgical drapes and gowns for Europe. “It was important for us to bring something new to the market.” Following intensive discussions with users of its materials in hospitals, DuPont determined that there was a need for a product that would provide advanced barrier properties and a high level of comfort. Suprel, a fabric based on DuPont Nonwovens’ Advanced Composite Technology, was designed to respond to this demand.

“What is unique about this material,” says Paul Dewingaerden, business manager, medical fabrics, “is its bicomponent structure. It combines polyester for strength with polyethylene for softness. Suprel offers a high level of protection without compromising comfort,” he explains. One can’t underestimate the latter property when it comes to surgical gowns, adds Teneul. “It’s important for the OR staff to focus on the intervention, not the clothing, in the operating room.”

The new product range, which has been available in North America for two years and is now being introduced to the European market, is described as a real alternative to existing medical fabrics for the single-use and multipatient markets. “This bicomponent formulation is a unique new technology that is protected by 29 patents,” stresses Dewingaerden.

Suprel features a silky texture that makes it easy to wear without catching or grabbing, according to the firm. It is described as being more durable than competing OR gown and drape fabrics, eliminating the need to worry about tearing. Suprel surpasses all of the EN 13795 requirements in terms of resistance to liquid and microbial penetration, bursting and tensile strength, and linting.

For DuPont, the introduction of Suprel in Europe is more than a product launch: it represents diversification for the company and a greater choice in materials for the marketplace. “Instead of presenting a specific fabric to our customers that they can have in any colour as long as it’s blue, and in any basis weight as long as it’s 67.2 g/m2, we now can offer them a range of materials suited to their product needs and target markets,” says Dewingaerden. Applications such as cardiology, neurology, and orthopaedics, are especially promising for the material, he adds.

The Impact of EN 13795

DuPont has been an active participant in the drafting of EN 13795, a new European standard for surgical gowns, drapes, and clean-air suits. The standard defines the minimal requirements and test methods for single-use and reusable surgical coverings used as medical devices in healthcare facilities for patients, clinical staff, and equipment. Part I, which compiles general requirements for manufacturers, processors, and products, and Part II, which establishes test methods, have been published. Part III, which defines performance requirements and levels based on the characteristics outlined in Part I, is expected to be published in 2006.

The standard obliges manufacturers and processors alike to demonstrate that the requirements, as stated in EN 13795, have been met, and that fitness for purpose has been established for each use, both for single-use and reusable medical devices. Taken at face value, these requirements would seem to favour single-use fabrics. Dewingaerden offers a more nuanced opinion.

“It is important to note that this new European standard applies both to single-use and reusable or multipatient products,” says Dewingaerden. Consequently, all products will have to pass quality control tests that will ensure consistent product quality and be certified as fit for use after being laundered and reintroduced in the OR. “If a fabric can be washed 50 times, for example, and still perform to the standard at the time of its use in the OR, fair enough,” says Dewingaerden. The reality, though, is that tracking usage may be challenging, given the evolution of healthcare practices in Europe.

“The laundries that used to be operated by hospitals are disappearing,” explains Dewingaerden. The personnel costs were simply too high, he adds. As a result, laundering is being outsourced, and everything that enters or reenters the hospital needs to be shown to be fit for use.

Currently, nonwovens represent approximately a 50% market share in Europe. “Penetration is a bit higher for drapes than it is for gowns,” says Dewingaerden, “but the overall trend is definitely moving in the direction of nonwovens.” In the United States, he adds, the penetration of single-use fabrics is closer to 90%.

The role of the nonwovens industry in providing advanced infection prevention and the implications of EN 13795 will be among the topics of a global conference in Prague scheduled for 20 and 21 March. Sixteen papers from healthcare professionals and members of industry will explore these and related themes at the event organized by the European Disposables and Nonwovens Association. For more information on the conference, see the sidebar to this article.