Medical textilesIntroduction

Combination of textile technology and medical sciences has resulted into a new field called medical textiles. New areas of application for medical textiles have been identified with the development of new fibers and manufacturing technologies for yarns and fabrics. Development in the field of textiles, either natural or manmade textiles, normally aimed at how they enhance the comfort to the users. Development of medical textiles can be considered as one such development, which is really meant for converting the painful days of patients into the comfortable days.

A general term which describes a textile structure which has growing part of the textile industry is medical, hygiene and health sector. The extent of growth is due to the development and improvement of knowledge in both textile as well as medical sector.  The engineering approach to develop textile products that will be suitable for medical and surgical application should possess a combination of the following properties e.g. strength, flexibility been designed and produced for use in any of a variety of medical applications, including implantable applications. Materials include natural fibre, monofilament as well as multifilament yarns.

Fibres used 

Fibres used in medical application may be classified as follows;1. According to source of origin

Natural- Cotton and silk most widely usedSynthetic- Viscose, polyester, polyamide, polytetrafluoroethylene (PTFE), polypropylene, carbon, glass, and so on. 2. According to biological resistance Biodegradable- Fibres which are absorbed by the body within 2-3 months time after implantation and include Cotton, Viscose rayon, polyamide, polyurathene, collagen, and alginate, polycaprolactone, polypropiolactone.Non biodegradable-Fibres that are absorbed by the body slowly and take more than six months time to degrade are considered as non biodegradable. Non-biodegradable fibres and include polyester (e.g. Dacron), polypropylene, PTFE and carbon.

Fibre used:

Traditionally cotton, silk and viscose have long been used for medical and surgical purposes. One such area of application is wound care, where moisture and liquid exude from the wound is absorbed by the fibrous structure to promote healing in relatively dry

conditions.  However upon healing small fibrous elements protruding from the wound dressing are

usually trapped in the pores of the newly formed tissues which make their removal distressing to the patients.

Research show that wound under moist condition would in fact heal better and faster, which would also remove the problem of fibres being trapped in the healing wound.

The concept of moist healing has since been responsible for the development of many fibres which have vastly improved wound management techniques and patient care.

A variety of polymers such as collagen, alginate, chitin, chitosan have been used to be essential materials for modern wound dressings.

Collagen which has been obtained from bovine skin is used to produce biodegradable fibres used as suture which is as strong as silk.

The fibre can also be converted to transparent gel like film structure which has very good oxygen permeability.

Alginate (obtained from sea weeds) and chitin (obtained from shrimp shells) are widely used for treatment of wound healing. Chitin nonwoven fabric is used as artificial skin.

Constituent element of Medical Textile products

Characteristics of materials for medical use

The major requirements for biomedical polymers

must be non-allergenicmust be non-carcinogenicmust be able to be sterilized without impairing any change in their physical or chemical characteristics.where necessary biodegradablewhere necessary non biodegradable

.

Fibres used for medical and healthcare application

Textiles materials that are used in medical applications include fibres, yarns, fabrics and composites. Depending upon the application, the major requirements of medical textiles are absorbency, tenacity, flexibility, softness and at times biostability or biodegradability.Fibres used in medical field may vary from natural fibre such as cotton, silk, regenerated wood fluff (absorbent layer), to manmade fibres like polyester, polyamide, polyethylene, glass etc

A number of crucial issues regarding medical products in general and healthcare and hygiene products in particular have been identified and debated amongst clinicians, environmentalist, drug companies etc. for a long time. The issues such as:

Natural against chemical or manufactured fibres

Disposable against reusable or durable fabrics

Antibacterial or antimicrobial fibres against finishes or coatings for infection control

Methods of disposal of clinical waste i.e. landfills against incineration and other forms of medical and clinical waste disposal

There is general move towards an increased use of natural polymers that are biocompatible, biodegradable and nontoxic

Classification of Medical Textiles

These are the textile products for medical applications that include materials as fibres, yarns, woven, knitted, nonwoven, PTFE felts and mesh etc. Depending upon the usage, they are classified asa.       Healthcare and Hygiene productsb.       Extracorporeal devicesc.       Implantable materialsd.       Non-implantable materials

Medical textiles can be classified as follows:

Some areas of usage are: Healthcare/ hygiene products- Include bedding, clothing, surgical clothes, products for feminine hygiene like sanitary napkins, baby

and adult diapers ,surgical gown clothes, filters, bandages, support and protective material, surgical sutures etc.

Non-implantable materials- For wound care that includes absorbent pad (wound contact layer, base material viscose,

plastic film) and bandages (simple inelastic/elastic, orthopaedic, plasters, gauzes, lint, padding)

Textiles in Extracorporeal devices- Like artificial kidney, liver and lungs.

Implantable materials- Like sutures (biodegradable and non-biodegradable), soft tissue implants, artificial tendon (meshes),

artificial ligament, artificial cartilage, orthopedic implants artificial joint, cardiovascular implants vascular grafts, heart valves.

Healthcare & hygienic products

An important area of textile is the healthcare and hygiene sector among other medical applications. The range of products available for healthcare and hygiene is vast, but they are typically used either in the operating theatre or in the hospital wards for hygiene, care and safety of the staff and patients. They could be washable or disposable.

Healthcare and hygiene products Product application Fibre type Fabric type

Surgical clothing gowns Cotton, Polyester, Viscose rayon, Polypropylene

Nonwoven, Woven

Caps & masks Viscose rayon, Polyester, Viscose, Glass

NonwovenNonwoven

Surgical covers Drapes cloth

Polyester, Polyethylene Polyester, Polyethylene

Nonwoven or Woven Nonwoven or Woven

Beddings, Blankets Sheets

Pillow covers

Cotton, Polyester Cotton Cotton

Woven, KnittedWovenWoven

Clothing uniforms Protective clothing

Cotton, Polyester Polyester, Polypropylene

Woven Nonwoven

Cloths/ Wipes Viscose rayon Nonwoven

Healthcare and hygiene products

Product application Fibre type Fabric type

Incontinence Diaper sheet Polyester, Polypropylene Nonwoven

Coverstock Wood fluff Nonwoven

Absorbent layer Superabsorbents Nonwoven

Outer layer Polyethylene fibre Nonwoven

Operating theatre This includes surgeons gown, caps and mask, patient

drapes and cover cloth of various sizes.

Surgical gown: It is essential that environment of operating theatre is clean and strict control of infection is maintained. A possible source of infection to the patient is the pollutant particle shed by the nursing staff, which carries bacteria. Surgical gowns should act as barrier to prevent release of pollutant particles into air. Traditional surgical gowns are woven cotton goods that not only allow the release of particles from the surgeons but also a source of contamination generating high levels of dust (lint). Disposable non woven surgical gowns have adopted to prevent these sources of contamination to patients and are often composite materials of nonwoven and polyethylene films.

Surgical masks: They should have higher filter capacity, high level of air permeability, lightweight and nonallergic.

Surgical caps: These are made from nonwoven materials based on cellulose.

Surgical drapes and cover cloths: These are used to cover patients or to cover working areas around patients. It should be completely impermeable to bacterial and also absorbent to body perspiration and secretion from wound.

Hospital wardThis includes beddings, clothing, mattresses covers, incontinence products, clothes and wipes. In hospital cross infection should be prevented and hence traditional woolen blankets replaced by cotton leno woven blankets.

Incontinence products for patients are available in both diaper and flat sheet forms with latter used for bedding. Cloths and wipes are made from tissue paper or nonwoven bonded fabrics, which may be soaked with an antiseptic finish.

Super absorbent fibers for healthcare and hygiene products

They absorb up to 50 times their mass of water, whereas the conventional wood pulp and cotton linter absorbents absorb approximately 6 times their mass of water. The superabsorbent fibres offer advantage as compared to superabsorbent powders due to their physical form, or dimensions, rather than their chemical structure. Whilst they do absorb fluids to a similar level as powder, they do, however, do it faster. This is due to the small diameter of the fibres, which gives a very high surface area for contact with the fluid. Typically fibre will absorb 95% of its ultimate capacity in 15 seconds.

Extracorporeal devices

These are extracorporeally mounted devices used to support the function of vital organs, such as kidney, liver, lung, heart pacer etc. The extracorporeal devices are mechanical organs that are used for blood purification and include the artificial kidney (dialyser), the artificial liver, and the mechanical lung. The function and performance of these devices benefit from fibre and textile technology.

Extracorporeal devices-

1 Artificial kidney The function of artificial kidney is achieved by circulating the blood through a membrane, which may be either a flat sheet or a bundle of hollow regenerated cellulose fibres in the form of cellophane that retain the unwanted waste materials. Multilayred filters composed of numerous layers of needle punched fabrics with varying densities may also be used and are designed to remove the waste materials rapidly and efficiently.

Tiny instrument, about the size of a two-cell flashlight.Made with hollow hair sized cellulose fibres or hollow polyester fibres slightly larger than capillary vessels.Fabric, which is used to remove waste products from patients blood. 2 Artificial heartAn 8-ource plastic pump lined with velour to reduce damage to blood and is a chambered apparatus about the size of human heartSilastic backing makes the fabric impervious to emerging gas that is not desirable in the blood.

.  

3 Artificial liverMade of hollow viscose to separate and dispose patients plasmas and supply fresh plasmaThe artificial liver utilizes hollow fibres or membranes similar to those used in artificial kidney to perform high permeability to gases but low permeability to liquids and function in the same manner as in the natural lung allowing oxygen to come into contact with the patient’s blood.

4 Mechanical lungMade with a hollow polypropylene fibre or a hollow silicone membrane.Used to remove carbon dioxide from patients blood and supply fresh oxygen.

Implantable materialsTextile fibres, yarns, fabrics, composites and 3-D shaped fabrics from woven, knitted, nonwoven, braided and embroidery play a vital role in the manufacture of various implants, including the replacement of diseased or non-functioning blood vessels and segments of aorta or other big arteries. It is even feasible to produce vascular prosthesis as fine as 2-3 mm in diameter.

These materials are used in effecting repair to the body whether it is wound closure (sutures) or replacement surgery (vascular grafts, artificial ligaments etc)

Implantable materials-

Biocompatibility is of prime importance if the textile materials are to be accepted by the body and four key factors will determine how the body reacts to the implant, these are as follows:

•The most important factor is porosity which determines the rate at which human tissue will grow and encapsulate the implant.•Small circular fibres are better encapsulated with human tissue than larger fibres with irregular cross section.•Toxic substances must not be released by the fibre polymer and the fibres should be free from surface contaminations such as lubricants and sizing agents.•The properties of the polymer will influence the success of the implantation in terms of its biodegradability. Polyamide is the most reactive material losing its overall strength after only two years as a result of biodegradation. PTFE is the least reactive with polypropylene and polyester is in between.

Why textile implants?

Biocompatible materials Material combinations 2D- and 3D-structures

Mechanical characteristic adapted to the environment

Adjustable macroscopic structure

Specific surface design

Non-implantable materials

These materials used for external applications on the body and may or may not make contact with skin.

This includes wound care, bandages, plasters, pressure garments, orthopaedic belts etc.

Surgical dressing:- These are employed as coverings, adsorbent, protective and supports for injured or diseased part. They are of different types  Primary wound dressing  Absorbent  Bandages  Protective Adhesive tapes

Primary wound dressing

Placed next to the wound surface Nonwovens with a binder content of 60% and made of cellulose fabrics are being used.

Wound care products– The purpose of these products are to provide protection against infection, absorb blood and exudates, promote healing and in some instances apply medication into the wound.Common wound dressings are composite materials consisting of an absorbent layer held between a wound contact layer and a flexible base material. The absorbent pad absorbs blood or liquids and provides cushioning effect to protect the wound. The wound contact layer should prevent adherence of the dressing to the wound and be easily removed without disturbing new tissue growth. The base materials are normally coated with acrylic adhesive to provide the means by which the dressing is applied to the wound. The use of collagen, alginate, and chitin fibres contribute significantly to the healing process.When alginate fiber is used as wound contact layer the interaction between the alginate and the exuding wound creates a sodium alginate gel which is hydrophilic and permeable to oxygen and impermeable to the bacteria and contribute to the formation of new tissue.

Gauze- It is an open weave absorbent fabric, when coated with paraffin wax is used for the treatment of burns and scalds. In surgical application gauze serves as an absorbent material.  Lint- It is a plain weave cotton fabric that is used as protective dressing for first aid and mild burn application. Wadding-It is a highly absorbent material that is covered with a nonwoven fabric to prevent wound adhesion or fibre loss.

Bandages- Bandages are designed to perform a whole variety of specific functions depending upon the final medical requirements. They can be -woven, -knitted, -or nonwoven and are -either elastic or nonelastic.

A dressing should possess the following properties:

Healing properties, regulated mainly with the substances which are applied to or added to the dressing. Causing no mechanical injury of a granulating wound. Decreased adherence surface. Eliminating a possibility of loose fibers getting caught in the wound.Stable and spatial structureEasy penetration of wound secretion to the absorbing dressing.Non- interrupted process of wound healing - as only the outer gauze compress is changed.Painless changing of the dressing.

Absorbent

Similar to wound pads used in surgery. Manufactured from well bleached, carded and cleaned cotton fabrics. Absorbent lint is cotton of plain weave, warp raised on one side, by a process known as linting EPI 36, PPI 32, used as an external absorbent and protective dressing and for the applications of ointments and lotions, as antiseptic adsorbent and protective dressing in first aid treatment.

Surgical and other gauze provide absorbent materials of sufficient tensile strength for surgical dressing. They are made of cotton gauze loosely woven. Now-a days nonwovens are used

BandagesThese are narrow cotton or linen, plain weave cloth of low texture, either woven or knitted. There are different types:Cotton and rubber elastic bandages- for sprains and strainsCotton rubber elastic net bandages- net fabric of lace construction.Plaster of Paris bandages- cotton cloth is impregnated with a mixture of calcium sulphateOrthopedic cushion bandages.Crepe bandage- elastic in nature due to special weave allows it to stretch twice its length

Various types of bandages along with their function are mentioned below:

1. Simple Bandage hold dressings in place.2. Elasticized Bandage: Impart support and conforming.3. Light support Bandage: management of sprains or strains.4. Compression Bandage: Treatment and prevention of deep vein thrombosis, leg ulceration.5. Orthopedic Bandage: Used under plaster casts, provide padding and prevent discomfort.6. Gauze: Serves as absorbent material.7. Lint: Used as protective dressing for use in mild burn applications. 8. Wadding: prevent wound adhesion.

Protective eye padScientifically shaped to lit over

the eye used in outpatient clinic and industrial department.

Adhesive tapesIt is narrow, plain weave fabric having a coating of adhesive

paste. It is used with other pads to conform them on the injury.

Due to astounding technological developments, techincal textiles are extensively used in the healthcare industry today. In the field of medical application, technical textiles are not just used in contact with the skin, but also fulfill important functions within the body (intra-corporal applications like implants). Technical textiles offer medical and hygiene industry with unparalleled protection, comfort and cost saving.

These highly specialized and bio- compatible technical textiles, used for medical and hygiene applications are called “MEDTECH.” The characteristics required of MEDTECH vary depending on the task for which they are to be used. Some applications demand a protective function, others a high absorptive capacity and some other others impermeability. Special antimicrobial finishes are an important characteristic of these textiles

Depending on the nature of application, most of the medical products are disposable in nature and are made of nonwoven fabrics. In global markets disposables are fast replacing non-disposable health care textiles.

Absorbents, Bandages: Plaster of Paris Bandage, orthopedics bandage, crepe Bandage, etc. Protective eye pads, Adhesive tapes, Wipes, Surgical gowns,

Artificial kidney, Artificial liver, Artificial heart, Mechanical lung

12/02/2022 37Compiled by: Dewan Murshed Ahmed (DMA)