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| Issue date:01/02/2006 |
| ATA Journal for Asia on Textile & Apparel - Feb 2006 Issue |
| Source:Journal for Asia on Textile & Apparel |
| by Geoff Fisher |
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| Use of a compression bandage |
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The global medical textiles market has an estimated value in excess of US$4 billion (excluding disposable hygiene products) with a production volume of around 1.65 million tonnes, which represents almost 12% of the total technical textiles market. Recent developments in the more traditional areas of bandages, wound care and operating gowns highlight the close co-operation between textile technology and medical science.
Major global markets continue to increase due to the growth in healthcare expenditure. For example, the orthopaedics sector, through the introduction of less invasive and longer-lasting surgical techniques and implants, is expanding while technological advances in treating hard-to-heal wounds are driving growth in the active-healing sector of the advanced wound management market.
The past 10 years have witnessed major developments in medical products, the materials they are made of and the technology used to produce them. Medical textiles are essentially fiber-based products and include dressings, orthopaedic bandages, compression devices, surgical textiles (gowns, drapes, sterilisation wraps, etc.), sutures, prostheses (e.g. vascular grafts) and filters for blood.
Depending upon their usage, medical textiles can be subdivided into:
non-implantable materials, such as wound dressings, bandages and disposable hygienic products;
implantable materials, such as sutures, vascular prostheses, artificial joints and scaffolds;
other healthcare/hygiene products, such as hospital bedding and clothing, operating room garments and drapes, curtains and wipes.
Wound care
Traditional wound dressings made from cotton gauze are being replaced by more sophisticated products and management techniques that alleviate the need for frequent replacement and attention by healthcare professionals. New wound management techniques concentrate on moist wound healing.
Bandages are one of the most important medical textiles and have a range of uses, including retention of dressings, providing support to joints, preventing the development of oedema, exerting pressure on a limb, treating skin diseases and providing protection against physical damage.
The fibers and fabrics used for bandage applications are dependent upon their intended functions. Warp-knitted spacer fabrics, elasticated woven fabrics, tubular knitted hose with elastane fiber, and nonwovens, for example, are widely used.
Biologically active textiles produced by chemical modification of fiber-forming polymers (mainly cellulose) with medicinal preparations have been developed to treat necrotic wounds, burns and frostbite, for example. Fibrin bandages have been manufactured by saturating a biodegradable cloth with blood-clotting chemicals and an enzyme purified from human blood, which prevents excessive blood loss in severe injuries.
Wound dressings based on chitin (a biopolymer found in the exoskeleton of insects and marine invertebrates) and its derivative chitosan can be absorbed by the body and are able to promote the healing of tissues. Chitin is biodegradable in the presence of human enzymes and is non-toxic and beneficial to the human body. However, due to its hydrogen bonding and highly crystalline structure, chitin is insoluble in common organic solvents; therefore, direct industrial applications of this polysaccharide are difficult. Poor textile processing properties of resulting fibers has also been a major problem.
Among the various fibrous and hydrogel products, alginate-based products are currently the most popular for use in wound management as they offer many advantages over traditional cotton and viscose gauzes. In particular, they are biocompatible and form a gel on absorption of wound exudates. Such gelation prevents the wound surface from drying out. This is beneficial as a moist wound environment promotes healing and eliminates fiber entrapment in the wound, which is a major cause of patient discomfort during dressing of the wound.
Implantable materials
The use of textiles in the construction of prostheses has greatly expanded, with such application as arteries, hernia repairs, tendons and artificial skin. The materials used include biodegradable and non-biodegradable polymers, such as polylactide and polyester; new biodegradable polymers under development are likely to replace some of the non-biodegradable polymers.
A vascular graft placed inside an aortic abdominal aneurysm |
Vascular prostheses (grafts) are used as artery substitutes that can be implanted into the human body, and can be made from synthetic or natural materials. At present, about 50% of the vascular grafts produced worldwide are obtained by weaving. This combines the advantages of knitted grafts with those of extruded grafts, such as reduced porosity, reduced unravelling when cut, dimensional stability, increased burst resistance, elasticity and flexibility, softness and pliability, and reduced mass.
Multilayered vascular prostheses can be made from two porous layers and one nonporous layer. The graft can be tubular with the porous layers positioned inside and outside of the prosthesis.
Another type of implantable material, tissue engineered scaffolds are three-dimensional structures that provide a site for cells to attach, proliferate, differentiate and secrete extracellular matrix, which eventually leads to tissue formation. These scaffolds can be either permanent or temporary, depending on the application and the function of the neo-tissue. Temporary scaffolds are made from biodegradable polymers, such as polyglycolic acid (PGA), which degrade within the body to leave a purely biological neo-tissue. Permanent scaffolds remain within the body, working with ingrown tissue to form a polymeric/biological composite.
Sutures are the largest group of devices implanted into humans and are manufactured from a wide range of materials. Standards and guidelines for suture manufacture are set by the United States Pharmacopoeia, European Pharmacopoeia and British Pharmacopoeia.
Sutures are classified into two broad categories: absorbable and non-absorbable. The absorbable surgical suture, which loses its entire tensile strength within two to three months of implantation, is a sterile, flexible strand prepared from collagen derived from healthy mammals, or from a synthetic polymer.
Sutures are the largest group of devices implanted into humans and are manufactured from a wide range of materials |
Silk is a traditional fiber used as sutures in medical applications. Although biodegradable, its major disadvantage is its lower tensile strength and reaction with tissues. Polyester, nylon and polypropylene filaments offer excellent strength and can be used as non-absorbable sutures due to their non-biodegradability.
Bio-absorbable and biodegradable natural materials, such as collagen and catgut fiber, can be used for implantable sutures in internal surgery. However, the commercial availability of medical-grade material is scarce and they suffer strength loss during use due to their reaction with body tissues.
Newer suture materials from synthetic aliphatic polyester fiber, made from glycolide homopolymer, are biodegradable and strong enough to find applications in vascular and microsurgery of internal organs.
The problem of strength retention in the case of bio-absorbable commercial sutures is being tackled by different surface modification techniques. Polypropylene and polyester filament coated with Teflon, for example, are employed for vascular surgery. Carbon fiber-based sutures have been produced by the modification of cellulose filament.
Surgical gowns and drapes
Concerns over infection in the operating room have stimulated research into improved surgical gowns and drapes. There continues to be a growing demand from operating theatre staff for improved security and protection against blood- and liquid-borne pathogens, especially viruses such as hepatitis B and acquired immune deficiency syndrome (AIDS). The protection of patients against new variant Creutzfeldt-Jakob disease (CJD) for certain surgical procedures has also heightened awareness of potential infections.
Concerns over infection in the operating room have stimulated research into improved surgical gowns and drapes |
Although the industrial laundering of reusable surgical gowns and drapes has been shown to have a lower impact on the environment, disposable products appear to be gaining the upper hand in the market. Single-use nonwoven products are now used in at least 45% of all surgical interventions undertaken in Europe, for example, and this proportion is growing.
Several studies have confirmed the superiority of single-use surgical products in terms of resistance to bacterial and liquid penetration. Recent European research suggests that some reusables fail quality standards and could endanger patients. Further improvements can be expected for single-use surgical textiles with new nonwovens and films that improve barrier performance and comfort properties for gowns.
In the reusable segment, development has been concerned with the production of laminates, particularly spunbond-meltblown-spunbond (SMS) nonwoven structures. Operating room gowns made from such fabrics now have the same level of comfort and protection as garments made from microfibers. The commercial development of bactericidal uniforms for hospital and medical workers as well as for hospital bedding is also imminent.
Fibers in medical textiles
Fibers from natural origins, such as cotton, silk, and regenerated cellulose, are mainly used in non-implantable materials. Synthetic fibers, such as polyester, polyamide polytetrafluoroethylene (PTFE), polypropylene, carbon and glass, are used for implantable as well as high-performance products.
Speciality fibers from a variety of polymeric fibrous materials have been derived from natural polymers (e.g. alginate, collagen, chitin, chitosan, polylactic acid, polypropiolactone, polycaprolactone and PGA), and are finding innovative medical applications due to their biodegradability and biocompatibility.
Fibers manufactured from polyvinyl alcohol (PVA) resin are soluble in water at temperatures above 93¡C. Fabrics produced from PVA are useful in certain medical applications such as towels, sponges and gauzes.
Bioactive fibers are modified man-made fibers manufactured to resist and control the growth of potentially harmful micro-organisms. They are produced by introducing an antibacterial additive during the spinning stage.
Naturally derived, biodegradable polymers have received much attention recently, not only because they have advantages in terms of waste disposal and environmental friendliness, but also because of their use in the medical field due to their biocompatibility, bio-safety and bio-absorbable properties, which offers potential as a material or in technologies in drug delivery systems.
Advanced medical textiles
Biofunctional materials are opening up new possibilities for the medical textiles sector. Here, active substances are incorporated into the fiber by chemical modification or applied onto the fiber surface during the spinning process. These additives are transferred to the skin by body moisture and body heat with improved bioclimatic and hygienic properties including:
protection to the skin from liquids, particles and bacteria;
providing an effective barrier against germs, fungi and risk of infection;
thermoregularity characteristics;
moisture and liquid absorption;
ease of laundering, sterilization and antistatic behavior;
low level of textile chemicals and dyes with high mechanical stability.
Functional, three-dimensional spacer fabrics can provide such attributes and are often superior to conventional textile materials for medical applications, such as bedding for preventing bed sores, orthopaedic casts and bandages.
New fabrics are being developed to resist bacteria, mildew, stain and odor for healthcare applications. For example, anti-allergen finishing agents are used on fabrics to provide relief to patients suffering from asthma and allergies caused by dust mites.
Active substances can also be made available to the skin as an aqueous solution by micro-encapsulation or by their insertion into water-adsorbing network polymers, which are affixed to the fiber. Advanced processes also offer the potential for the development of bioactive, drug-delivering textiles and the controlled treatment of diseases.
Wound dressings that change color depending on the type of infection present in a wound and ultimately bandages that release antibiotics when the wound has become infected are nearing commercialization. Bacteria impregnated into the fibers of medical fabrics and made into drug-producing or antiseptic bandages are also at the early stages of development.
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| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
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| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
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