Fibres are used for dressing purposes both in their normal forms and in woven or fabric forms. Dressings are compulsorily needed for proper management and subsequent healing of wounds caused by injuries, burns, microbial infections and surgical operations. Fibres and the surgical dressings made from them are of immense value in medical and pharmaceutical practices. They are used to provide ample protection to the exposed tissues against microbial infections as well as other natural hazards. Surgical dressings not only aid in healing process but also help to stop further tissue damage. The success of wound management largely depends on the type and quality of the dressings used. To be able to choose the right kind of the surgical dressings one must be aware of the types of available dressings, their qualities and usefulness. The quality of surgical dressing depends on the type of the fibre used to prepare the dressings . Pharmacist are responsible for handling and dispensing most medical aids including surgical dressings and thus should possess a good knowledge of suitable fibres and the surgical dressings made from them
FIBRES
Fibres that are used in wound management and healing include
Natural Fibres { plant or animal origin}
Artificial Fibres { Regenerated Fibre}
Synthetic Fibres
PLANT FIBRES
Plant fibres includes:
{a} epidermal trichomes e.g cotton
{b} phloem fibres e.g Jute
{c} pericycle fibres e.g flax and hemp
COTTON ( RAW COTTON, COTTON WOOL, ABSORBENT COTTON)
Biological source: cotton consist of the epidermal trichomes of the seeds of Gossypium Herbaceum Linn. and other species of Gossypium of the family Malvaccae. Gossypium species are cultivated for commercial production of cotton in the United States of America, West indies, Peru Brazil, India, China and Egypt, Cotton are also now cultivated in Nigeria.
PREPARATION OF RAW COTTON AND ABSORBENT COTTON WOOL: Bolls of cotton are collected from the ripe and dehisced fruits of Gossypium. The trichomes are separated from the seeds by a ginning process using a machine called a GIN, in which the trichomes are drawn through a narrow space. The masses of these separated trichomes are drawn through a narrow space. The masses of these separated trichomes constitute Raw Cotton. Raw cotton thus prepared contains impurities, chiefly colouring matter, and about 0.6 percent of wax and oil, which form a thin film around the fibres and render them non-absorbent. Raw cotton is then variously treated, combed and spinned to convert it to yarn or thread, which are woven to make fabrics and cloths.
ABSORBENT COTTON WOOL is prepared from the various cotton wastes obtained during the processing of raw cotton for making yarns. The wastes are loosened and then boiled for 10 to 15 hours under a pressure of about 30Lbs in a dilute solution of caustic soda and ash. This treatment removes the fatty cuticle and renders the trichomes absorbent. The boiled material is then washed thoroughly with water, bleached with water, bleached with dilute sodium hypochlorite solution and treated with very dilute hydrochloric acid. The bleached mass of fibres is then dried, loosened, scutched and carded by using appropraite machines. The resultant product is a thin continuous film of absorbent cotton wool. Several such films are superimposed on one another and rolled.
MACROSCOPICAL AND MICROSCOPICAL CHARACTERS: Cotton wool is a loose mass of thin filaments, soft to touch and white in colour. Absorbent cotton wool is more white than the raw cotton, which has a brownish tint. When pulled apart, a wad of cotton wool separates with resistance and in a dragging fashion forming a thin film of fibres before being finally separated. When placed on the surface of water, raw cotton floats while absorbent cotton rapidly sinks. The cotton trichomes are tubular, flattened and twisted with large lumen. The apex is rounded. The cellulose wall of the raw cotton fibre is covered wih a waxy cuticle. When treated with ammonical sulphide solution (cuoxam) raw cotton fibres dissolve with ballooning , while those of absorbent cotton dissolves with uniform swelling. Cotton dissolves in 80 percent cold sulphuric acid.
Different commercial varieties of cotton can be distinguished by the length or staple of the trichomes. The staples of the important varieties of cotton are as follows: Sea island, upto 54.5mm; Egyptian, 31 to 38mm; Peruvian and Brazilian, 29 to 30mm, and India, 21.4 to 29.2mm
Constituents: Raw cotton contains about 90 per cent of cellulose and small amounts of wax, fat, remains of protoplasm and ash. Absorbent cotton is almost pure cellulose.
Uses of Cotton
Cotton is used as the chief material for many surgical dressings.
It is also used as a filtering medium as well as an insulating material
JUTE ( GUNNY)
Biological source: Strands of phloem fibres of the stem bark of Corchorus olitorious Linn. and C. capsularis Linn. (Family Tiliaceae) constitute Jute. Jute is extensively cultivated as a cash crop in Bangladesh, which supplies more than 95 per cent of the world’s requirement of this important fibre. It is also cultivated in small quantities in some parts of India.
PREPARATION OF JUTE FIBRE: Jute plants are normally straight and unbranched. They are cut from the base when the plants are in flower, tied into small bundles, stacked and soaked in stagnant water for about three weeks for retting. The stack are covered with straw or water hyacinths to keep them wet and to protect from direct sunlight. When the stem bark is well macerated by the retting process, the strands of the phloem fibres are separated manually from the wood and washed free from the surrounding softer tissues and other dirts thoroughly in clean water. The fibres are then dried in direct sunlight and made into small bundles. Jute fibre is exported in bales made by hydraulic pressure.
MACROSCOPICAL AND MICROSCOPICAL CHARACTERS: the strands of jute are pale buff or silvery grey in colour, 1 to 3 m long and about 30 to 140um in diameter, somewhat coarse in texture. They have great tensile strength. The individual fibre varies from 0.8 to 5.0 mm in length and 10 to 25um in diameter, with a quite smooth surface. The lumen is not uniform throughout the length of the fibre owing to variation in the thickness of the walls. The ends of the fibres are rounded and blunt. In transverse sections the cells appear polygonal in outline with a rounded lumen which varies considerably in size.
Jute fibres do not swell in euoxam. They are insoluble in 80 per cent sulphuric acid and stain red with phloroglucinol and hydrochloric acid.
Constituents: Jute fibres are composed of 53 per cent cellulose and 22 per cent hemicellulose and contain 11 per cent of lignin, 1 per cent of fats and waxes and 1 per cent of ash.
Uses
Pharmaceutical uses: Jute is used for the manufacture of medicated tows, for padding splints, as a filtering or straining medium and for soaking fluids
Industrial Uses: jute is used in the manufacture of ropes, gunny bags, carpet backings and yarns for some fabrics.
FLAX
BIOLOGICAL SOURCE: flax consists of the strands of pericycle fibres of the stem of Linum utatissimum Linn., a cultivated plant of the family Linaceae. Flax is prepared commercially in Russia, Northern Ireland, U.S.A and Argentina.
Preparation Of Flax: The plants are uprooted by hand just about the time of ripening of the fruits, tied in sheaves and left to dry in the field. The dried plants then undergo a “rippling” process to remove the capsules, after which the stems are tied in bundles and subjected to a “retting” process similar to that of jute. When retting is complete, the stalks are dried in the sun, broken into pieces in a mill and the pieces of the xylem tissues removed by the teeth of a ‘scutcher’. The residual bark from the stem is then mechanically combed to make the fibres parallel.
Macroscopical and Microscopical characters: the strands of Flax fibres have more tensible strength than cotton. They are about 50 cm in length. The individual fibres vary in length from12 to 30m; have very thick walls, uniform narrow lumen and finely pointed ends. Fine obliquely transverse markings are present on the fibres. They are also finely striated longitudinally.
CONSTITUENTS: flax is made up of pecto-cellulose.
Uses: flax is used as a filtering medium for some preparations. It is rarely used in the manufacture of lints
ANIMAL FIBRES
SILK
BIOLOGICAL SOURCE: Silk consists of fibre prepared from the filaments of the cocoons spun by the larvae of Bombyx mori Linn. (Family Bombycidae), the mulberry silkworm, and those of other species of Antheraea (Family Saturnidae). Silk is cultivated in Japan, China, France and Italy. It is also cultivated in small quantities in Bangladesh and india.
Macroscopical and Microscopical characters: Silk consists of very fine, soft, smooth and solid threads, usually yellow in colour. The threads possess considerable tensile strength . under the microscope, silk appears as cylindrical or slightly flattened, strutureless solid threads, 5 to 25nm in diameter. It is easily soluble in cuoxam, 66 per cent cold sulphuric acid and concentrated hydrochloric acid.
Constituents: The mass of the silk fibre is made up of the protein fibroin, coated externally by another protein sericin or silk gum, which cements the fibres together. The protein of silk do not contain sulphur.
USES: The Pharmaceutical uses of silk include the manufacture of ligatures, oiled silk and some sieves.
WOOL [ANIMAL WOOL, SHEEP’S WOOL}
BIOLOGICAL SOURCE: wool consists of the hairs of the fleece of the sheep, Ovis aries Linn., family Bovidae. Wool is produced and exported by the U.S.A, Australia, Argentina, Russia and the British isles.
Macroscopical and Microscopical characters: Wool occurs as a loose, soft mass of elastic, lustrous curly hairs. When pulled, a wad of wool separates out with considerable resistance due to the clinging nature of the hairs. The individual hairs are sub-cylindrical, more or less curved, 2 to 50cm in length, 5 to 100um in diameter. They are covered with imbricated flattened epithelial scales. A darker coloured narrow band is present along the central axis of the hairs. When treated with cuoxam the fibres do not produce swellings, but stain blue. They are insoluble in 80 per cent sulphuric acid.
Constituents: Wool fibre are composed almost entirely of the protein Keratin, which contains C,H,O,N and S
Uses: Wool is used in the manufacture of dressings like fiannel, domette and crepe bandages. Wool fibres and their yarns are of immense commercial value for their use in the textile industries for manufacturing warm fabrics.
REGENERATED FIBRES
CELLULOSE WADDING { WOOL CELLULOSE, CHEMICAL WOOD PULP}
Biological source: Cellulose wadding is prepared from bleached sulphite wood pulp obtained from the wood of various conifers belonging to the family Pinaceae. Supplies of cellulose wadding come chiefly from the U.S.A, Canada and Germany.
Macroscopical and microscopical characters: The ‘beaten’ wood pulp is strained through the ‘wire’ of a machine and thus a fine web of fibres is left on top of the ‘wire’. This web after being dried and creped gives a thin, soft, absorbent sheet. About 30 of these sheets laid together make a cellulose wadding. Thus it occurs as a felted sheet, about 1cm thick, 100 square centimeter of which weighs about 4.7 g. it is almost white in colour as cotton, but harsher in texture. It breaks quickly when pulled (distinction from cotton wool). It is very absorbent and sinks in water more rapidly than cotton wool.
Characteristics wood elements are present in the fibres of Cellulose wadding. These elements are mainly tracheids with bordered pits and characteristic medullary ray cells. Cellulose wadding is soluble in 60 per cent cold sulphuric acid and cuoxam.
Constituents: Cellulose wadding consists almost entirely of pure cellulose.
Uses: uses of cellulose wadding are similar to those of absorbent cotton wool. For certain purposes it is preferred to absorbent cotton wool because of its superior absorbent property and the readiness with which it disintegrates.
RAYON {Regenerated Cellulose, Artificial Silk}
Biological source: Rayons are prepared from the polysaccharide cellulose molecules derived from wood pulps by maceration and treatment with various chemical substances. Depending on the means used to bring the cellulose into solution to prepare the rayon fibres, Rayons are variously named such as acetate rayon, viscose rayon, cuprammonium rayon, nitrate rayon, etc. Out of these Viscose rayon is mainly used for surgical dressing purposes.
Macroscopical and Microscopical characters: Viscose rayon occurs in fibres which are white and highly lustrous. Its tensile strength is much less than that of Cotton. The fibres are solid and transparent, and have a diameter ranging from 15 to 25um. Their surface is finely grooved by longitudinal lines. In transverse sections they show an irregularly crenate margin.
Viscose rayon gives cellulose test with N/50 iodine solution and 80 per cent sulphuric acid (blue colour). It is soluble in cuoxam and 60 per cent cold sulphuric acid, but insoluble in 5 per cent boiling potassium hydroxide solution.
Constituents: Like Cellulose Wadding, viscose rayon rayon is also composed almost entirely of cellulose. It also contains about 0.03 per cent of sulphur and yields about 0.2 to 0.3 per cent of ash.
Uses: Lint, guaze, net and other surgical dressings are made from Viscose rayon.
ALGINATE FIBRES { Calcium Alginate fibres}
Source and preparation: Alginate fibres of surgical dressings are represented by the calcium alginate fibres, which are prepared from solutions of sodium alginate and calcium chloride. A spinning process similar to that for viscose rayon is used for the preparation of these fibres. Calcium alginate fibres are also reduced to a staple for processing them to a wool or fabric like viscose rayon or cotton.
MACROSCOPICAL and MICROSCOPICAL Characters: Calcium alginate fibres are cream-coloured lustrous fibres. Under the microscope they appear as longitudinally finely grooved solid rods similar to those of viscose rayon. They are harsh in texture, colourless and tasteless. Calcium alginate fibres swell and dissolve in ammoniacal copper nitrate, but are insoluble in 60 per cent cold sulphuric acid, 5 per cent boiling potassium hydroxide solution and warm hydrochloric acid.
Uses: calcium alginate fibres are used to prepare guazes for absorbable haemostatic dressings and bacteriological swabs.
SURGICAL DRESSINGS
Surgical dressings is a general term applied to various fibrous materials used for scientific and hygienic management of wounds and for providing sufficient protection to the exposed tissues. They include both loose masses of fibres and fabrics, guazes, lints, plsters, etc. made from them. Surgical dressings may be divided into various smaller groups according to their state of occurrence, composition , method of preparation and uses.
The group of various types of surgical dressings may be summarized as
Guazes
Bandages
Lints
Plasters
Standard Dressings
Cotton fabrics form the basic materials for the preparation of most of the above surgical dressings, although wool constitute the main material of some special bandages. Cotton fabrics are woven materials prepared from cotton yarns. The thickness of the yarn and the type of the weave of the fabric vary with the type of the surgical dressings made. The number of threads per inch of the wrap (threads running lengthwise) and weft (threads crossing the warp at right angles) of the fabric also varies from dressing to dressing.
Gauzes
Gauzes are usually absorbent dressings principally made from cotton fabrics. They can be either medicated or unmedicated. Medicated gauzes and also other medicated dressings are prepared by immersing the fabric in a solution of the medicament and drying off the solvent. Medicated guazes include the following;
Boric acid guaze, Euflavine guaze, Double Cyanide guaze, Iodoform guaze, Trinotrophenol gulyaze, Capsicum guaze.
Unmedicated guaze include: absorbent guaze, absorbent ribbon guaze, absorbent guaze tissue and cellulose tissue.
BANDAGES
Bandage are continuous length of fabrics and contain on joints. Their edges are evenly cut, parallel with the warp threads. They are reasonably free from loose thread. Bandages are chiefly made from plain or treated cotton cloths but some of them are made from wool . in addition to these there are some bandages which are made from fabrics containing a texture of both cotton and wool. Bandages may therefore be grouped into four categories according to the type of fabrics they are made from as follows;
Plain cotton bandages examples include open wove bandage, bleached calico bandage, unbleached calico bandage and muslin bandage
Treated cotton cloth bandage examples include battiste, jaconet, oiled cambric and zinc paste bandage
Wool-containing bandage e.g Flannel bandage, Domette bandage, Crepe bandage
Silk Bandage e.g Oiled silk bandage
LINTS
Lints are medicated or unmedicated absorbent surgical dressings. They are made of plain-wove absorbent cotton fabrics. The threads in the warp of the lint-fabrics are raised to form a nap. They contain not less than 39 thread per inch in the warp and 24 in the weft. 230 to 250sq inch superficial area of the lints should weigh about 28.35g. medicated lints available include; Boric acid lint and Euflavine Lint
PLASTERS
Plasters are a kind of adhesive bandage made from bleached cotton fabric . An adhesive compound is spread on one side of the bandage to make it stick to the skin . Plaster s may be either medicated or unmedicated. Some common plasters include the following: Rubber Adhesive Plaster, Zinc Oxide plaster, Elastic Adhesive Plaster, Plaster of Paris Bandage.
STANDARD DRESSINGS
This group of surgical dressings includes some standardized compound dressings described in British Pharmaceutical Codex and other official publications. These dressings are prepared ready for use and consist of a pad of medicated cotton wool, guaze or lint stitched to an open-wove bandage at certain distance from one end. The longer end of the bandage is rolled and placed inside the pad and the other end is wound round the rolled pad. The complete dressing is wrapped in impermeable paper and sterilized. However, in case of standard elastic adhesive dressings, the pad is fixed to a base of elastic adhensive cotton fabric, and no bandage is required. This type of standard dressings are not sterilized.
The Standard dressings of B.P.C. are numbered 1 to 15 and variously named as follows:
Double cyanide dressing ( standard dressing no 1)
Fomentation dressing ( standard dressing no 2)
Adhesive wound dressings ( standard dressing no 3, 4, 5 and 6)
Medicated wound dressings ( standard dressing no 7, 8 and 9)
Burn dressings (standard dressing no 10, 11, 12)
Plain wound dressings ( standard dressing no 13, 14 and 15)
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