Материал: surgical knot tying manual covidien

(Surgipro™ II) has been developed that has increased resistance to fraying during knot rundown. Polypropylene sutures are extremely inert in tissue and have been found to retain tensile strength in tissues for a period as long as two years. Polypropylene sutures are widely used in plastic, cardiovascular, general, and orthopedic surgery. They exhibit a lower drag coefficient in tissue than nylon sutures, making them ideal for use in continuous dermal and percutaneous suture closure.

Monosof™ and Dermalon™ are monofilament sutures composed of the long-chain polyamide polymers Nylon 6 and Nylon 6.6. They have a high tensile strength and low tissue reactivity. The pliability characteristics of these sutures permit good handling. Because nylon sutures are more pliable and easier to handle

than polypropylene sutures, they are favored for the construction of interrupted percutaneous suture closures. However, polypropylene sutures encounter lower drag forces in tissue than nylon sutures, accounting for their frequent use in continuous dermal and percutaneous suture closure. Nylon sutures are also available in a braided construction. Only nylon sutures are available both as monofilament and multifilament sutures (Surgilon™). These braided nylon sutures are relatively inert

III. scientific basis for the selection of surgical sutures (cont’d)

in tissue and possess the same handling and knot construction characteristics as the natural fiber, silk sutures (Sofsilk™).

Polyester sutures (Surgidac™, TiCron™) are comprised of fibers of polyethylene terephthalate, a synthetic linear polyester derived from the reaction of a glycol and a dibasic acid. Polyester sutures were the first synthetic braided suture material shown to last indefinitely in tissues. Their acceptance in surgery was initially limited because the suture had a high coefficient of friction that interfered with passage through tissue and with the construction of a knot. When the sutures were coated with a lubricant, polyester sutures gained wide acceptance in surgery. This coating markedly reduced the suture’s coefficient of friction, thereby facilitating knot construction and passage through tissue. The TiCron™ polyester sutures are coated with silicone, while the surface lubricant for Surgidac™ is polybutylene adipate. Because some surgeons prefer to tie sutures with a high coefficient of friction, the Surgidac™ sutures are also available without a surface coating.

The polybutester suture (Novafil™) is a block copolymer that contains butylene terephthalate (84%) and polytetramethylene ether glycol terephthalate (16%).

Polybutester suture has unique performance characteristics that may be advantageous for wound closure.8 This monofilament synthetic nonabsorbable suture exhibits distinct differences in elongation compared with other sutures. With the polybutester suture, low forces yield significantly greater elongation than that of the other sutures. In addition, its elasticity is superior to that of other sutures, allowing the suture to return to its original length once the load is removed. In a study by Trimbos et al.9 they compared the cosmetic outcome of lower midline laparotomy scars using either nylon or polybutester suture for skin closure. A randomized clinical trial compared polybutester skin suture with that of nylon for lower midline laparotomy wounds in 50 women undergoing gynecologic surgery. Scar hypertrophy, scar width, scar color, the presence of cross-hatching marks, and a total score was assessed in all patients at 18 months following surgery and compared by nonparametric statistical tests. The wounds closed with polybutester suture were significantly less hypertrophic than those closed with nylon. Regardless of the suture material used, the lower part of

the laparo-tomy scar showed an inferior cosmetic result compared with the upper part underneath the umbilicus for scar hypertrophy, scar width, and the total scar score. The surgeons concluded that polybutester skin suture diminished the risk of

III. scientific basis for the selection of surgical sutures (cont’d)

hypertrophic scar formation because of its special properties allowing it to adapt to changing tensions in the wound. Increased closure tension of the skin in the midline region above the pubic bone may be caused by a relative immobility of the skin. In 1997, Pinheiro et al.10 compared the performance of polybutester sutures to that of nylon sutures in 70 male and female rats in which they examined the clinical response of the skin in abdominal wall muscle to the use of these sutures. Under general anesthesia, standard wounds were created in the dorsum and abdomen of the animals and subjected to suture closure with either polybutester or nylon. The animals were sacrificed immediately, 12, 24, and 72 hours and at four, five and seven days to evaluate the impact of the sutures on the wounds. They found that polybutester produced some advantages such as strength, lack of package memory, elasticity, and flexibility which made suturing quicker and easier. They concluded that Novafil™ suture can be used safely on skin and mucosal wounds because it is less irritating to tissues than nylon.

The clinical performance of polybutester suture has been enhanced by coating its surface with a unique absorbable polymer (Vascufil™).11 The coating is a polytribolate polymer that is composed of three compounds: gylcolide, e-caprolactone,

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and poloxamer 188. Coating the polybutester suture markedly reduces its drag forces in musculoaponeurotic, colonic, and vascular tissue. Knot security with the Vascufil™ suture was achieved with only one more throw than with comparably sized, uncoated polybutester sutures. On the basis of the results of our investigations, coating the polybutester suture represents another major advance in surgical suture performance.

2. Absorbable surgical sutures

The absorbable sutures of Covidien are made from either collagen or synthetic polymers. The collagen sutures are derived from the serosal layer of bovine small intestine (gut). This collagenous tissue is treated with an aldehyde solution, which cross-links and strengthens the suture and makes it more resistant to enzymatic degradation. Suture materials treated in this way are called plain gut (Plain Gut). If the suture is additionally treated with chromium trioxide, it becomes chromic gut (Chromic Gut), which is more highly cross-linked than plain gut and more resistant to absorption. When this treatment of collagen sutures is limited, the result is a special form of chromic gut (Mild Gut) that is more susceptible to tissue absorption. The plain gut and chromic gut sutures are composed of several plies that have been twisted

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