Fibres and Surgical Dressings_Main Notes_PPT.pptx

Fibres and Surgical Dressings: Introduction, importance relevance, uses and classification of
various fibres (e.g. Vegetable, animal, synthetic and mineral etc tests to distinguish the various
types; Production of various fibres (raw cotton, absorbent cotton, chemical wood pulp; Viscose
rayon; Calcium alginate; silk; nylon; terylene, etc), their diagnostic characters, general
properties, standardization and evaluation of surgical dressings (composition and arrangements
of component material; qualitative, quantitative and functional standards) etc; Surgical products;
absorbents, dressings; surgical adhesive tapes; protectives and plasters etc; Classification of
dressings (dressings for general binding, for sprains, and fractures, plasters of Paris, absorbent
dressings, special dressings etc) surgical tapes; Surgical adhesive tapes; Textile tapes (woven and
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non woven); Plastic film tapes (water-proof, microporous, polythene, non porous etc; Non stitch
adhesive sutures, Linen-testers; Extraction Processes and Superlative Techniques

1. First Semester Lectures (7 Hours ) S. N. MATHIAS, Ph. D sylver_74ng@yahoo. com [phone] Department Of Pharmacognosy And Ethnopharmacy Usmanu Danfodiyo Univeristy Sokoto- N igeria

2. Fiber: are characteristic cells of plants or animals. In plant –they are elongated thick-walled cells with pointed ends. Cell wall from cellulose (lignin, hemicelluloses, pectin substances, resin, mineral substances, fats or waxes) may be present. Use in medicine as surgical dressings (natural and synthetic). Many Synthesized from petrochemicals.

3. Surgical dressing: materials used alone or in combination to cover and protect wound. Employed to: Reduce or prevent infections Offer protection to healing wound Offer mechanical support to the tissues. Bandage: material which holds the dressing in desired position. Role of fibres in surgical dressings and medical practices

4. Types of Surgical Dressings Surgical dressings are classified into various types, including adhesive, non-adhesive , and absorbent dressings. Each type serves a specific purpose in wound management, ensuring optimal healing conditions and protection against infection.

5. Classification of Fibres Used in Surgical Dressings

6. Classification of Fibers

7. Classification of Fibers

8. Classification of Fibers Synthetic fibres and their applications in medical dressing Role of Antimicrobial Agents

9. Chemical Tests for Identifying Various Fibres Vegetable and regenerated carbohydrate: composed of cellulose units, hence : Molisch reagent (α - naphthol and sulphuric acid ), they give violet colour Chlor – zinc iodine or mixture of iodine and sulphuric acid, they give blue colour Soluble in copper oxide in ammonia solution ( CuOXAM ) giving a blue colour .

10. Animal fibres and regenerated protein fibres are proteinous containing peptides linkage : Soluble in 5% aqueous potassium hydroxide solution. On heating with aqueous picric acid they are stained permanently yellow . They respond positively to Million’s reagent (nitric acid + mercury) → red stain . On ignition alone or boiling with soda lime they produce a disagreeable smell (smell of ammonia).

11. Synthetic and mineral fibres : do not respond to the above tests. Glass fibres on heating melt and form hard beads. Nylon and terelene form soft beads. No effect on asbestos fibres.

12. Overview of Common Plant and Animal Fibres

13. Synonyms : Purified cotton, surgical cotton, cotton wool. Biological source : epidermal hairs of seeds of Gossypium species e.g. G. herbaceum , G. hirsutum , G. barbadense , G. arboreum etc. Family Malvaceae . Freed from impurities, defatted, bleached and sterilized. Habitat : cultivated in Egypt, India, South America, USA some part of Africa and Pakistan.

14. Fig. 1: Cotton and cotton bole; fibres under the microscope

15. Collection and Preparation A shrub or small tree; capsule produces 3 – 5 cell. When ripe, it open on longitudinal sutures; white hair attached to brown seeds appear. Boles collected, dried and ginned. It is separated into short hair (linters for absorbent cotton) and long hair (staple for textiles). Impurities remove by carding and combing . It is treat with dilute sodium hydroxide and soda ash solution at 1 – 3 atm. for 10 – 15 hours. It is wash, bleach with sodium hypochlorite and treat with dilute hydrochloric acid. Wash again, dry and card into flat sheet, pack and sterilize by gamma radiations.

16. Characters : Occurs as white, soft and fine hairy filament. Under microscope, each filament is a unicellular hair (appearing like an empty-twisted hose). 2.5 – 5.0 cm length and 9 – 24 µm diameter. Number of twists varies – 75 to 150 cm -1 . Hairs are cylindrical when young but become flattened and twisted on maturing. Odorless and tasteless.

17. Chemical Nature : Purified cotton is pure cellulose – glucose units linked by β –1, 4–linear glycoside bonds . Cellobiose unit: β – 1, 4 – glucoside

18. Chemical Test : Positive to all vegetable fibres tests. In addition it dissolve in cold 80% sulphuric acid. Raw cotton dissolve in CuOXAM with characteristic ballooning leaving fragments of cuticle. Storage: Cotton wool is stored in a cool place away from dust and microbial contamination. Heat and long storage makes it non absorbent.

19. Uses: It is used for surgical dressings. Serves as a mechanical support and also absorb blood, mucus, pus etc. It also protect wound from bacteria. Also used in textile industry, for manufacture of explosives, cellulose acetate and other cellulose derivatives.

20. JUTE Synonyms : Gunny Source : Phloem fibres from Corchorus species e.g. C. capsularis , C. olitoritus etc. ( Tiliaceae ) Habitat : Cultivated in India, Bangladesh and in most tropical countries. Fig.2. Jute fibre plant

21. Collection and Preparation Annual plant; grows to about 3 – 4 m in height. Straight stems are cut in July (flowering stage). Leaves removed; stems submerged in water tanks (covered with straw) in bundles for retting. After 3 weeks; edges are beaten to separate wood from fibres. Fibres are clean, suns dried, bleach and spun into yarn and ropes. Short fibres left, constitute ‘tow’ in Pharmacy.

22. Characters : Colour : Yellowish brown. 1 – 3 m long and 30 – 40 µm in diameter; individual fibres (0.8 – 5.0 mm long and 10 – 25 µm in diameter). Bluntly pointed apex, a rounded wall with no markings and variable lumen. Fig. 3: Jute rope and herbarium specimen

23. It gives: Deep red colour with phloroglucinol/HCl (due to lignin). Yellow with iodine/H 2 SO 4 and also chlor – zinc – iodine. Chemical Nature: Main constituent lignocelluloses . Lignin forms the middle lamella, can be destroyed by an oxidizing agent e.g. mixture of HNO 3 and KClO 3 . Uses: Preparation of medicated tows, padding splint, gunny bags, yarn and ropes. Also as a filtering and straining medium.

24. FLAX Synonyms : linen, Source : Flax is the pericyclic fibres of the stem of Linum usitatissimum family: Linaceae . Geographically, it is cultivated in countries like Argentina, Russia, Canada, India, Holland and USA . Collection and Preparation: Flax fibres are prepared by the process of retting similar to that of Jute.

25. Characters : Flax has a sharply pointed apex, an average length of 25 – 30 mm and diameter of 12 – 25 µm with a narrow lumen. The walls are thick with fine cross lines some intersecting. It gives colourless or slight pink colour with phloroglucinol / HCl (absent of lignin), blue or violet colour with I 2 /H 2 SO 4 and purple – yellow with chlor – zinc – iodine . Chemical Nature : Flax is mainly pecto -cellulose; the fibres therefore have good luster and more tensile strength than cotton. However, if the stem is allowed to grow old before retting the fibre become coarse and harsh to touch . Uses of Flax : They were earlier used in the production of lint but cotton has now replaced them. It is now used as a filtering medium, in the preparation of rugs, lace and lawn .

26. HEMP Source : Pericyclic fibres of Cannabis sativa family: Cannabinaceae – cultivated for the fibre in Russia, Italy, France and America. Preparation : Retting as in Jute. Fig. 4: Hemp plant and fibre

27. Characters : Apex bluntly rounded or forked. Measured about 35 – 40 mm in length and 16 – 50 µm in diameter. Walls thick with fine cross lines. Lumen is large and uniform. It give slight red colour with phloroglocinol /HCl; Inner wall blue and middle lamella yellow with I 2 /H 2 SO 4 Purple to yellow with chlor – zinc iodine.

28. ANIMAL WOOL Synonyms : wool, sheep’s wool. Sources: fleece of the sheep Ovis arries Family: Bovidae ; Order: Ungulata . Major producers: Australia, USA, Argentina, Russia and India. Fig. 5: Ovis arries source of animal wool

29. Preparation : Hairs are remove (at shearing time). Cleaned from dirt. Grease remove with soap and Na 2 CO 3 . Wash in hot water, dry and bleach with SO 2 or H 2 S. Card and spin into thread or yarn. Fig. 6: Animal wool and Ovis arries

30. Microscopy : consist of three layers A central narrow core of rounded or polyhedral cells; Surrounded by a wide cortex of nucleated spindle-shaped fibres; Enclosed within a cuticle of flat overlapping scales pointing towards the apex. Number of scales per length is constant (9.7 – 12.1 per 100µm) - used to check substitutes. Fig. 7: Animal wool under the microscope

31. Characters : It is smooth , elastic , lustrous , curly , hygroscopic and slippery to touch. It measured 2 – 50 cm by 5 – 100 µm. Chemical Nature : (approximate) consist of fibre 31%, sweat or suint (mainly potassium salt of fatty acid) 32%, dirt and dust 25% and wool grease. Fibre compose of keratin (rich in cystine ). Test : in addition to general tests It gives black ppt. PbS 2 with lead acetate. In warm HCl or cold conc. H 2 SO 4 – insoluble.

32. Uses: for preparation of crepe, demotte and flannel bandages. As filtering and straining medium. Storage: Long storage, exposure to sunlight and larval attack destroy wool. It has good resistance to dry cleaning solvent.

33. SILK Source : cocoons of Bombyx mori (Silkworm or Mulberry silkworm), other species of Bombyx and Antheraeae like A. mylitta , A. assama , A. pernyi and A. yama-mai . Family: Bombycidae Order: Lepidoptera. Produced in Japan, China, France, Italy and India. Fig. 8: Silk larvae and cocoons

34. Preparation : Larvae produce fibroin from the gland in its mouth. Siricin – a gum-like secretion cement fiber together. Semi-liquid secretion coagulates and hardens on contact with air and is spin into the cocoon. Cocoons are collected, heated at 60 – 80 o C for a few hours or exposed to steam for a short time to kill the insect. It is then put in water to dissolve the gum and separate the fibers. A reel takes 2 to 15 loose end of the fibers twists them into a single thread.

35. Characters : Threads are structure less, cylindrical or slightly flattened, fine and smooth. Measure 5 – 25 µm in diameter, and up to 1200 m in length. Yellow in colour with remarkable tensile strength. Silk is soluble in CuOXAM , concentrated alkalis and conc. HCl . Fig. 9: Silk under microscope and silk thread

36. Chemical Nature : Consist chiefly of the protein – fibroin On hydrolysis yield glycine (44%), alanine 27%, serine 11%, tyrosine 5% and other amino acids. It contains little or no sulphur (no precipitate with lead acetate). Uses of Silk : In making ligatures, sutures, and sieves. It is also used for making dental floss.

37. MINERAL FIBRES Mineral substances are other sources of natural fibres that may find use in the medical profession. Some examples are given below . Synonyms: Glass fiber, fiber glass. Source: fibers are made from sand mixed with oxide of some metals. Preparation : Glass is made by heating sand or silica with oxides of Ca , Mg, Al and B. GW is produce by melting some selected glass and forcing the melted glass through small nozzles. Diameter is determined by nozzles size, temperature, viscosity and speed of drawing the fiber. 1. Glass Wool

38. Characters : Fibers are transparent, lustrous, hard and brittle. When heated in porcelain it melt and form beads. Uses : For filtration of corrosive liquids, in electrical, heat and sound insulation. Fig. 10: Glass fibres

39. 2 . Asbestos Synonyms : Amianthus Source : Fibrous mineral silicates found in the earth’s crust. It occurs in two main forms as: the fibrous serpentine Mg 6 (S 14 O 10 ) (OH) 8 and the amphibole which in addition to the magnesium silicate contains iron or calcium silicate in it structure. It is found in Canada, Italy, Australian and Zimbabwe. It is mined in open quarries . Description : asbestos is a white to slightly greenish mineral, odorless and easily broken into long, fine and flexible fibres. It can be spun and woven to form a coarse cloth. It is resistant to heat and alkalis. Serpentine is attacked by acid while amphibole is acid resistant.

40. Chemical Nature : It is a double silicate of Ca – Mg with little amount of Fe which gives colour to asbestos. Uses : as filtering medium for caustic alkalis for bacterial filters, heat resistant insulators, fire-proof gloves, and fire-proof clothing. Caution : exposure to asbestos is carcinogenic .

41. 1.Viscose Rayon A viscous orange-red aqueous solution of sodium cellulose xanthogenate . Synonym s: Regenerated cellulose, Rayon, Viscose BP Preparation : Cellulose from coniferous wood or cotton linters is delignified to white pulp (80 – 90% cellulose and some hemicellulose ). It is dissolved in NaOH (to remove hemicellulose ); product (sodium cellulosate ) is dissolved in CS 2 and NaOH to give solution of rayon. REGENERATED FIBRES Regenerated fibres are produced by chemical modification of the naturally occurring long chain molecules of the natural fibers to obtain a suitable fibres form.

42. It is allowed to ‘ripe’, filter and then force through a spinneret into an acid bath to form solid filament. It is combine, twist, de- sulphurize , bleach, wash, dry and conditioned to a moisture content of 10%. It is cut to a length of 1 – 8 inches or left as loose fiber as absorbent wool. Fig. 12: Viscose rayon thread and under the microscope

43. Characters: White, highly lustrous, solid and transparent. Measured 15 – 20 µm in diameter. Slightly twisted and contain grooves. De- lustred by addition of TiO 2 . Chemical Nature : Purely cellulose (450 glucose residue units). It gives general test for vegetable fibers Distinguished from cotton by its solubility in 60% cold sulphuric acid.

44. Uses of Rayon : For making lint, gauze, net and other surgical dressing. Have similar absorbent property of cotton, but no loss of absorbency on storage.

45. a) Cellophane paper : viscose solution is passed through a narrow slit. Moisture-proof, transparent, non-adhering packing material used for wrapping. Also used as a dialyzing membrane, as a protective dressing and as a substitute of oiled silk . b) Cuprammonium rayon : cellulose is dissolved in ammoniacal copper hydroxide. Resultant solution is forced through the spinnerets into water; Treatment with dilute sulphuric acid yield filament. 2 . Rayon Product

46. c) Cellulose acetate : Obtain by dissolving cellulose in acetic anhydride, acetic acid and H 2 SO 4 to produce acetone insoluble (primary) acetate. Primary acetate group is hydrolyzed to secondary acetone soluble acetate. Solution is forced through spinnerets into warm air chamber and solid filaments are produced.

47. Derivative Fibres (from nature) 1. Methyl Cellulose Synonyms : Cellulose methyl ether, Tylose , Cologel , Nicel , Hydrolose . Preparation : By the action of methyl chloride under pressure on an alkali cellulose. Quality grade is where 2 of 3 hydroxyl groups of glucose are converted. Characters : White, fibrous powder, swells in water to form clear to opalescent viscous colloidal solution in cold water. Insoluble in hot water, alcohol and ether.

48. Uses of Nicel : In Pharmacy to increase viscosity, to stabilize lotions, suspensions, pastes, ophthalmic preparation and some ointments. In Medicine, as a hydrophilic colloid, laxative in chronic constipation and to curb appetite in obese people. Also use in food and cosmetics industries.

49. 2. Oxidized Cellulose Synonyms : Absorbable cellulose, cellulosic acid, oxycel , Hemo-pak . Preparation : By oxidizing cotton wool or gauze with nitrogen dioxide (16 – 22% of hydroxyl to carboxylic acid). Alcoholic groups are now replaced with glucuronic acid. Characters : Identical appearance with cotton (except dull colour , a harsher texture, charred odour and sour taste). It disintegrate on handling, does not turn into a paste on chewing.

50. Soluble in dilute alkaline, insoluble in water and acidic solution. Uses of Absorbable Cellulose : As absorbable haemostatic dressing in surgeries but incompatible with penicillin, delays bone repair and cannot be sterilized by heat. Now use in chromatography.

51. Marine Fibres Alginate Fibers Synonyms : Calcium Alginate Biological Sources : purified carbohydrate extracted from brown seaweed: Macrocystis pyrifera , Laminaria hyperborean , L . digitata and Ascohyllum nodosum ; family Phaeophyceae . Habitat : Atlantic and Pacific oceans; Coastal lines of Japan, USA, Canada, Australia and Scotland. Major producers are US and UK.

52. Fig. 13: Pictures of seaweeds - Macrocystis pyrifera and others Preparation : Aqueous solution of sodium alginate is pumped through a spinneret in a bath of CaCl 2 , water insoluble filaments of calcium alginate is precipitated.

53. Filaments are collected, washed and dried, cut up to staple form of length 1 – 8 inches. Mould and bacteria inhibitors are added in the aqueous solution before spinning. Characters : Fairly lustrous and pale cream coloured . Under microscope similar to viscose rayon. Tasteless, odorless and harsh to touch. Give general test for vegetable fibers; In addition they are soluble in ammoniacal copper nitrate and 5% sodium citrate solution.

54. Uses of Calcium alginate : Non-toxic, non-irritant and compatible with antibiotics. Used as absorbable haemostatic dressings in neuro - and dental surgery. Internally, use to arrest bleeding, as protective dressing for burns or skin grafts sites. Also as a swab for pathological or bacterial studies. Sodium alginate is used as an  impression -making material in  dentistry ,  prosthetics ,  life-casting etc.

55. Chemical Nature : Alginic acid is a linear  copolymer with homo-polymeric blocks of (1→4)-linked β-D- mannuronate  (M) and α-L- guluronate  (G) residues, covalently  linked together in different sequences or blocks. The  monomers  may appear in homo-polymeric blocks of consecutive  G-residues  (G-blocks), consecutive  M-residues  (M-blocks) or alternating M and G-residues (MG-blocks). NB α-L-guluronate is the C-5  epimer  of β-D- mannuronate .

56. Guluronic acid (G block) and mannuronic acid  (M block) units

57. Synthetic fibres are produced by the poly-condensation of organic molecules mostly obtained from petrochemicals, giving fibres that are stronger than the natural ones. SYNTHETIC FIBRES

58. 1.Nylon Synonyms : Caprolan , Perlon , Amilon , Mirlon , Kabron . Preparation : By condensing adipic acid with hexamethylene diamine – polyamide. Molten polymer is pumped through a spinneret to produce filaments.

59. Fig. 14: Nylon fibres – rope, threads and under the microscope. Characters : Smooth solid cylinders, soften at 210 o C. Highly lustrous to dull and may be white or coloured . Available as monofilament in varying sizes or as multifilament braided into strands. Immune to microbial attack, resistant to most organic chemical but dissolves in phenol, cresol and strong acids.

60. Uses of Nylon: For preparation of filter cloth, sieves, non-absorbable sutures, nylon syringes, films, textiles fibers, fishing lines etc.

61. 2. Dacron Synonyms : Terylene Preparation : By the condensation of ethylene glycol and terephthalic acid. Product (a polyester) has similar properties and application to nylon.

62. Fig. 15: Terylene fibres – threads and under the microscope. Differentiated by boiling in 90% phosphoric acid for 1 min. Nylon dissolve but Dacron is insoluble.

63. SURGICAL DRESSINGS A sterile pad or compress applied to a wound to promote healing and/or prevent further harm. Functions to injured site : Stem bleeding – to help to seal the wound to expedite the clotting process; Absorb exudates – to soak up blood, plasma, and other fluids exuded from the wound; Ease pain – to have an actual pain-relieving effect, whereas some others may have a placebo effect; Debride the wound – to remove slough and foreign objects from the wound; Protection from infection – to defend the wound against germs and mechanical damage; Promote healing – to contribute to recovery via granulation and epithelialization; and Reduce psychological stress – to obscure a healing wound from the view of others.

64. Provide mechanical and bacterial protection Maintain a moist environment at the wound-dressing interface Allow gaseous and fluid exchange Does not adhere to the wound Safe in use – nontoxic, not sensitive and non allergic (to patient and medical personnel) Well acceptable to patient (relieve pain and allow movement) Highly absorbable It absorb wound odor Be sterile Easy to use Needs infrequent changing Available in a suitable range of forms and sizes Cost effective. Properties /qualities of surgical dressing :

65. Gauze : a thin cotton fabric used for covering and protecting wound. Yarn : thread spun from fibers. Warp and Weft: threads that run lengthwise – warp (ends); those crossing them at right angles – weft. Plain weave: thread pass alternatively over and under the thread running at right angle. Naps : loose fluffy fibers of cotton cloth in plain weave. Technical Terms

66. Woven Dressings Cotton, silk and animal wool are used to prepare some woven dressings e.g.: Absorbent Lint: cotton cloth of plain weave, a nap is raised from warp yarn. Flannel Bandage: raised fabric of plain weave made entirely from animal wool. Demotte Bandage: combination of fabric of plain weave, warp yarn are cotton and weft from animal wool. Crepe Bandage: fabric of plain weave, warp threads are cotton and wool, weft threads are cotton.

67. Classification of Surgical Dressings Primary Wound Dressings : Designed to be placed on wound surface; Supported by absorbent. It should allow passage of fluids and non adherent to the surface. E.g. Gauze compresses of suitable mesh and thickness; petroleum impregnated gauze; absorbent pad . Absorbents : Used specifically to absorb large quantities of exudates that may drain from an incision or wound in form of balls or pads. Absorbent cotton, rayon wool, gauze pads, laparotomy sponges, eye pads, nursing pads, sanitary napkins etc are some examples of absorbent dressings.

68. Bandages : Material that holds dressing at the required site, applied pressure or supports an injured part or check bleeding. May be elastic (crepe) or non-elastic (common gauze roller and muslin ). Adhesive Tapes : Made in many different forms, varying in type of backing and formulation of the adhesive mass. Commonly used adhesives are rubber based or acrylate adhesives. Rubber tapes are cheaper and provide strength of backing and superior adhesion e.g. used in athletic strapping. Acrylate adhesives are used in operation or post operation to reduce skin trauma.

69. Protective : Employed to cover wet dressings, hot or cold compresses Also as covering for poultices and for retention of heat. Prevent the escape of moisture from the dressing or compresses. Commonly used: plastic sheets, rubber sheets and waxed or plastic coated paper or cloth.

70. TYPES OF SURGICAL DRESSINGS : Dry Dressings: These dressings are typically composed of a gauze material and used for wounds with a small amount of drainage. These dressings are good for keeping the wound covered after cleaning, and to promote healing, as well as taking out small amounts of infections. Wet-to-Dry Dressings: These types of dressings are used mostly for post-surgical wound care, as well as debridement of wounds. They take out necrotic areas, as well as infections. The gauze is soaked in saline, placed lightly inside of the wound, and covered with a dry dressing. Once the gauze dries, it can be removed. The dressing lightly, but continuously, pulls and sucks exudates and fluids from the wound. Chemical-Impregnated Dressings: These are provided by manufacturers and they contain chemicals and agents that promote the healing process. Some of these dressings come in sheets and require secondary dressings.

71. Foam Dressings: Dressings that require additional padding utilize foam pads to help absorb and provide a moist healing environment. They also act as a shield to the wound and prevent any damage from friction or pressure. Alginate Dressings: These dressings are composed of calcium, sodium salts and also provide a moist environment for the healing process. They are better used with a larger wound such as ulcers or donor sites . Hydro-fiber Dressings: These dressings are similar to alginate dressings when it comes to absorbing characteristics, but they do not affect hemostasis. They are composed in sheets which contain polymer carboxymethylcellulose and can be cut according to wound size and severity. However, when using these dressings, a secondary dressing is almost always required .

72. Transparent Film Dressings: This specific type of dressing is more like a plastic covering for the wound. It allows oxygen to reach it and help heal but does not absorb any fluids. With this being said, transparent film dressings are more used towards dry wounds . Hydrogel Dressings: This type of dressing is more directed towards infected areas and those in need of a moist environment to heal properly. It helps promote the body's own natural functions of removing necrotic tissue. It is advised not to be used on dry wounds . Hydrocolloid Dressings: This type of dressing does not allow oxygen to reach the wound. It is a wet-to-dry technique but is not recommended for infected areas. This type of dressing can last up to 7 days with a close eye and must be removed with care.

73. Sutures and Ligatures Suture : threads or strings use in sewing or stitching tissues, muscles and tendons with a needle. Ligature : when thread or fiber is used to tie a blood vessel to stop bleeding without a needle. Materials used include intestinal tissues, tendons of animal, vegetable fibers, horse hair, synthetic threads and metallic wires. Qualities of sutures: well sterilized, non irritant, good mechanical strength, fine gauze and minimum time of absorption (if absorbable ). Classified as absorbable or non-absorbable, natural or synthetic, and braided or monofilament. Most are available in standard 18- and 27-inch lengths. Some are provided in 8-, 9-, and 10-inch lengths.

74. Absorbable sutures: Defined by the loss of tensile strength within 60 days after placement. Used primarily as buried sutures to close the dermis and subcutaneous tissue and reduce wound tension. Surgical gut or catgut (natural). Polyglycolic acid and Polyglactin (synthetic, braided). Polydioxanone , polytrimethylene carbonate and Polyglytone (mono-filamentous).

75. Surgical gut: First absorbable suture material available. Made by twisted fiber from collagen of intestines of sheep, cattle, or goats. It is packaged in alcohol to prevent drying and breaking. Three forms are available plain, chromic, and fast-absorbing. Plain elicits inflammatory reaction in tissue and maintains its tensile strength for only 7-10 days. Generally, it is completely absorbed by 70 days.

76. Chromic gut Plain gut treated with chromium salts to slow absorption and decrease reactivity by cross-linking the collagen. Its tensile strength is maintained for 10-21 days, and complete absorption does not occur until at least day 90. Used in the closure of mucosal surfaces or as ligatures for blood vessels. Fast-absorbing gut (Ethicon) Plain gut treated with heat to facilitate more rapid absorption. Maintains tensile strength for only 5-7 days. It is completely absorbed within 2-4 weeks. Useful for percutaneous closure of facial wounds under low tension and for securing split- and full-thickness skin grafts.

77. Polyglycolic acid ( Dexon S; Syneture ): Introduced in 1970 as the first synthetic absorbable suture; available as clear or green suture. High tensile strength, 60% retained at day 7, 35% at 14, and only 5% at 28. Completely hydrolyzed by 90-120 days. A fast-absorbing dexon S is available (maintains strength for 7-10 days) and hydrolyzed by 42 days. Useful in wounds requiring short-term support.

78. Introduced in 1974, the second synthetic absorbable suture material available. The initial tensile strength of polyglactin is slightly greater than that of polyglycolic acid and is absorbed more quickly. Polyglactin retains 60% of its tensile strength at day 14 after implantation and only 8% of its original strength at day 28. It is completely hydrolyzed by 60-90 days. Both of these suture materials may be transepidermally eliminated if buried too superficially in the dermis. Although used primarily as a buried suture, polyglactin has been used for percutaneous closures without adverse outcomes and with resultant cost savings. Polyglactin is available as a clear or violet suture. Others : Polytrimethylene carbonate ; Poliglecaprone ; Glycomer 631; Polyglytone 6211 Polyglactin

79. Non-absorbable sutures Resistant to degradation by living tissues. Most useful in percutaneous closures. Natural: surgical steel, silk, cotton, and linen. Synthetic: nylon, polypropylene, and polybutester (commonly used in cutaneous procedures).

80. Silk First suture material; in 1890s; it is braided. Although non-absorbable, gradually degraded in tissue over 2 years. High tissue reactivity, suture removal difficult and painful. It is soft, pliable, comfortable for patients and unlikely to tear even delicate tissues. A good choice in mucosal tissues and as a temporary suture to elevate or retract tissues for improved visibility during surgery. Available in black.

81. Nylon: Introduced in 1940 as first synthetic, most commonly used. Available in mono-filamentous and braided forms. High tensile strength, but loses strength when buried in tissue. Braided forms lose strength after 6 months, but mono-filamentous retain two thirds after 11 years. Monofilament relatively inexpensive, available as black, green, or clear. Although mostly use as a percutaneous suture (low tissue reactivity) clear suture can be used buried in situations where prolonged dermal support is necessary.

82. Polypropylene: Monofilament introduced in 1962. Tissue reactivity is extremely low, gradual absorption does not occur if buried. An excellent choice for long-term dermal support. More expensive than nylon, available as a clear or blue suture. Polybutester : T he newest monofilament non-absorbable synthetic suture. It is available as a clear or blue suture. Its cost is comparable to that of polypropylene.

83. Conclusion In conclusion, the role of fibres and surgical dressings in Pharmacognosy is pivotal. Ongoing innovations in these areas are essential for enhancing wound care, promoting healing, and improving patient outcomes in modern healthcare.

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