Материал: surgical knot tying manual covidien
II. introduction
Through the ages, the tying of knots has played an important role in the life of man.1 Most of the ancient civilized nations, as well as savage tribes, were accomplished rope makers. Because rope could have served few useful purposes unless it could be attached to objects by knots, man’s conception of the rope and the knot must have occurred concomitantly. Knotted ropes played many important roles in the ancient world, being used in building bridges and in rigging ships.
Because rope and knots have been two of man’s most useful tools since the dawn of history, it is not surprising that they also have symbolic and even magical connotations. It was the custom of Roman brides to wear a girdle tied with a square (reef) knot, which their husbands untied on their marriage night, as an omen of prolific offspring. Moreover, it was believed that wounds healed more rapidly when the bandages which bound them were tied with a square (reef) knot.
This mythology of knots may have contributed to some surgeon’s perception of surgical knots more as an art form, than as a science. For those artisans, the use of methods and materials for suturing is usually a matter of habit, guesswork, or tradition.2 This approach to suturing has contributed to a growing concern that the knot construction employed by many surgeons is not optimal and that they
3. Individualized Self Instruction
use faulty technique in tying knots, which is the weakest link in a tied surgical suture. When the recommended configuration of a knot, ascertained by mechanical performance tests was compared to those used by board-certified general surgeons, only 25% of the surgeons
correctly used the appropriate knot construction.3 Of the 25 gynecologists, mostly department heads, who were polled about their knot tying technique, most were convinced they they made square knots, even though their knot tying technique resulted in slipknots that became untied.4 When a knotted suture fails to perform its functions, the consequences may be disastrous. Massive bleeding may occur when the suture loop surrounding a vessel becomes untied or breaks. Wound dehiscence or incisional hernia may follow knot disruption.
As with any master surgeon, he/she must understand the tools of his/her profession. The linkage between a surgeon and surgical equipment is a closed kinematic chain in which the surgeon’s power is converted into finely coordinated movements that result in wound
closure with the least possible scar and without infection. The ultimate goal of this linkage the perfection of the surgical discipline. This manual has been written for medical students, nurses, nurse practitioners physician assistants, surgical residents and surgeons who view themselves as scientists cultivating and practicing the science of surgery.
III. scientific basis for the selection of surgical sutures
There are several different suture materials and needles that provide an accurate and secure approximation of the wound edges. Ideally, the choice of the suture material should be based on the biological interaction of the materials employed, the tissue configuration, and the biomechanical properties of the wound. The tissue should be held in apposition until the tensile strength of the wound
is sufficient to withstand stress. A common theme of the many reportable investigations is that all biomaterials placed within the tissue damage the host defenses and invite infection. Because surgical needles have a proven role in spreading deadly blood borne viral infection, the surgeon must select surgical gloves that reduce the risk of accidental injuries during surgery. 5
Important considerations in wound closure are the type of suture, the tying technique, and the configuration of the suture loops. Selection of a surgical suture material is based on its biologic interaction with the wound and its mechanical performance in vivo and in vitro. Measurements of the in vivo degradation of sutures separate them into two general classes.6 Sutures that undergo rapid degradation in tissues, losing their tensile strength within 60 days, are considered absorbable sutures. Those that maintain their tensile strength for longer than
60 days are nonabsorbable sutures. This terminology is somewhat misleading because even some nonabsorbable sutures (i.e., silk, cotton and nylon) lose some tensile strength during this 60-day interval. Postlethwait7 measured the tensile strength of implanted nonabsorbable sutures during a period of two years. Silk lost approximately 50% of its tensile strength in one year and had no strength at the end of two years. Cotton lost 50% of its strength in six months, but still had 30-40% of its original strength at the end of two years. Nylon lost approximately 25% of its original strength throughout the two-year observation period.
1. Nonabsorbable surgical sutures
The nonabsorbable sutures of Covidien (formerly Tyco Healthcare, Norwalk, CT) can be classified according to their origin. Nonabsorbable sutures made from natural fibers are silk sutures. Sofsilk™ silk sutures are nonabsorbable, sterile, non-mutagenic surgical sutures composed of natural proteinaceous silk fibers called fibroin. This protein is derived from the domesticated silkworm species Bombyx mori of the family bombycidae. The silk fibers are treated to remove the naturally-occurring sericin gum and braided sutures are available coated uniformly with a special wax mixture
III. scientific basis for the selection of surgical sutures (cont’d)
or silicone to reduce capillarity and to increase surface lubricity which enhances handling characteristics, ease of passage through tissue, and knot run-down properties. Sofsilk™ sutures are available colored black with Logwood extract.
Metallic Steel sutures are derived from monofilament stainless steel. Modern chemistry has developed a variety of synthetic fibers from polyamides (nylon), polyesters (Dacron™), polyolefins (polyethylene, polypropylene), polytetrafluoroethylene, to polybutester.
Polypropylene is a linear hydrocarbon polymer that consists of a strand of polypropylene, a synthetic linear polyolefin. All polypropylenes begin with a base resin and then go through the following steps: extrusion, drawing, relaxation, and annealing. Each step in the process will influence the ultimate biomechanical performance of the suture. Biomechanical studies demonstrate that the manufacturing process (i.e., annealing, relaxation) can dramatically influence the surface characteristics without altering its strength. Changes in the surface characteristics can facilitate knot construction of the suture. Polypropylene sutures (Surgipro™) that have a low coefficient of friction will facilitate knot rundown and suture passage through the tissue. A new polypropylene suture