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Scientific Basis for the Selection of Vascular Closure Sutures Released: June 2008 Sponsored by Dannemiller Memorial Educational Foundation  Supported by an unrestricted educational grant from 
Faculty: Kant Y. Lin. M.D. Professor of Plastic Surgery Chief of Division of Craniofacial Surgery University of Virginia Health Systems Charlottesville, VA William B. Long III, M.D. Medical Director, Trauma Specialists, LLP Legacy Emanuel Hospital Portland, OR Richard F. Edlich, M.D., Ph.D. Distinguished Professor Emeritus of Plastic Surgery Biomedical Engineering, and Emergency Medicine Founder of the DeCamp Burn and Wound Healing Center University of Virginia Health Systems Director of Trauma,Prevention, Education and Research Trauma Specialists, LLP, Legacy Verified Level I Shock Trauma Center for Pediatrics and Adults Legacy Emanuel Hospital, Portland, OR Statement of Need: Continuing research into present and future methods of wound closure techniques makes it important for surgeons and surgical specialists to stay informed about the most up-to-date findings concerning all types of modern wound closure techniques. Surgeons must be able to restore the physical integrity and function of the injured or diseased tissue with the lowest incidence of infection and the most aesthetically pleasing result. Moreover, surgeons must have a scientific basis for selecting the most appropriate surgical suture and needle. Goal: The broad mission of this course is to train the participant to perform wound closure technique using appropriate sutures and needles. Objectives: At the completion of the training, the participant will be able to:
To receive credit, participants should, in order, view the objectives, read the educational material, then click on the link at the end of the activity to complete the post-test, evaluation, and then print the CME certificate. This activity should take approximately 1 hour to complete. This activity is available through June 30, 2011. No credit will be awarded after this date. Target Audience: This educational program is intended for general surgeons as well as other surgical specialists or physicians involved in wound closure. Accreditation: The Dannemiller Memorial Educational Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The Dannemiller Memorial Educational Foundation designates this educational activity for a maximum of 1.0 AMA PRA Category 1 Credit(s),TM. Physicians should only claim credit commensurate with the extent of their participation in the activity. The Dannemiller Memorial Educational Foundation is an approved provider of the California Board of Registered Nursing. Provider approved by the California Board of Registered Nursing, Provider Number 4229 for 1.2 contact hours. RNs outside California must verify with their licensing agency for approval of this course Disclosure Policy: The Dannemiller Memorial Educational Foundation requires that the faculty participating in a continuing medical educational activity disclose to participants any significant financial interest or other relationship (1) with the manufacturer(s) of any commercial product(s) and/or provider(s) of commercial services discussed in an educational presentation, and (2) with any commercial supporters of the activity. The presenting faculty reported no financial interest or affiliation that impacts on this activity. Dr. Long has nothing to disclose. Dr. Lin has nothing to disclose. Dr. Edlich has nothing to disclose. The content and views presented in this educational activity are those of the authors and do not necessarily reflect those of the Dannemiller Memorial Educational Foundation or U.S. Surgical. This material is prepared based upon a review of multiple sources of information, but it is not exhaustive of the subject matter. Therefore, healthcare professionals and other individuals should review and consider other publications and materials on the subject matter before relying solely upon the information contained within this educational activity. FOREWORD If this educational program heightens the surgeon's, resident's, and student's interest in the biology of wound closure and infection, the long years occupied in my search for improved methods of wound management would more than fulfill my expectations. Through the ages, selection of surgical sutures, needles and gloves has been an important consideration for surgeons. Despite these important historical considerations, some surgeons perceive surgical suture, needle and glove selection more as an art than as a science. For those artisans, the use of methods and materials for suturing and glove selection is usually a matter of habit, guesswork, or tradition. This approach to suturing has contributed to a growing concern that the suture selection as well as knot tying techniques employed by many surgeons are not optimal and that they incorrectly select sutures and use faulty techniques 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 surgeons used the appropriate knot construction.1 Of the twenty-five gynecologists, mostly department heads, who were polled about their knot tying technique, most were convinced that they made square knots, even though their knot-tying techniques resulted in slipped knots that became untied.2 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. This 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 extensive clinical experience's of the gifted plastic surgeon, Dr. Kant Lin and trauma surgeon, Dr. William B. Long, were essential ingredients of this empowering continuing education program. Dr. Kant Lin a internationally recognized craniofacial surgeon and Dr. William Long, Medical Director of Trauma Specialists, LLP, have been viewed by many of their colleagues as the Paderewski's of the scalpel who has brilliant results in trauma. It is my belief that these surgeons have transformed surgical suture and needle selection from a ritual practice to a surgical discipline. Early in my career, surgical selection of sutures and needles was largely based on testimonials and anecdotal experiences of senior surgeons. Today, modern surgeons select sutures and needles on the basis of well-controlled, randomized clinical and experimental trials. Having a keen appreciation of surgical education, they have modeled the format of this course to be an individualized learning environment. The course is designed to teach each participant the scientific basis for suture and needle selection as well as to illustrate the appropriate surgical techniques involved in vascular wound repair. Richard F. Edlich, M.D., Ph.D. Distinguished Professor Emeritus of Plastic Surgery and Professor of Biomedical Engineering Founder of the DeCamp Burn and Wound Healing Center University of Virginia Health Systems Editor-in-Chief of the Journal of Long-Term Effects of Medical Implants Director of Trauma Prevention, Education and Research Trauma Specialists, LLP, Legacy Emanuel Hospital Portland, OR VASCULAR SUTURE CLOSURE Biology of vascular repair The description of wound repair of blood vessels will be confined to arterial surgery in which the surgeon attempts to establish a new non-wettable intima and to reestablish a strong elastic muscular media. There are four possible origins of neoendothelial cells after injury: (1) circulating macrophage mononuclear cells; (2) medial smooth muscle cells; (3) circulating endothelial cells; and (4) junctional zone, that is graft/post pannus extension of the anastomosis. The origin of the new elastic fibers for the subintimal elastic lamina is the medial smooth muscle (myointimal) cells. The biology of vessel healing can be divided into three phases: substrate, proliferative, and resorptive (maturation).3 The substrate phase lasts 3-4 days. During the initial two to three days, fibroblasts appear in the wound and begin producing collagen shortly after their appearance. The substrate phase is overlapped by the proliferative phase where collagen is laid down in the wound. By the fifth or sixth day, new collagen synthesis accelerates, and wound strength enhances quickly. This proliferative phase continues for several weeks. The process of wound repair becomes a balance between the synthesis of collagen and the lysis of collagen. Imbalance of lysis and repair results in a failure of wound healing. In one case, excessive collagen lysis will result in anastomotic failure. In contrast, excessive collagen production may result in stricture formation. In the resorptive phase, tissue macrophages and fibroblasts disappear and excess collagen is removed. During this phase of absorption, the amorphous mass of collagen is transformed into an interlocking connection of collagen fibers. Blood vessels contain a special type of collagen (type III) that possesses special properties that allow some elasticity of the collagenous tubing, thereby enhancing its performance as a vascula conduit. Wound repair will now be examined in vessel wall wounds. Repair of Vessel wall wounds Repair of vessel wall wounds is encountered in arteriotomy for vascular access as well as in artery-to-artery anastomoses. In both circumstances, wound repair is primarily at the suture line. Both of these surgical procedures are usually performed in areas of relatively normal arteries that augur for the best wound repair. It is important to point out that the endothelium of artery-to-artery anastomoses and arteriotomies heal by pannus extension that is continuous autogenous endothelial growth across a suture line, rather than by cellular ingrowth from within the lumen of the vessel. Humans are able to extend an endothelial pannus for only 6 to 10 mm from either direction from the suture line. Replacement of this endothelial cell layer is rapid and likely to be complete in ten days. Orientation of the new endothelial cells appears random. By twenty one days, the endothelial cells resume their normal orientation that is parallel to the blood flow. Regeneration of the elastic lamina is not as rapid or as successful as endothelial repair. The elastic lamella defect is repaired by four to six weeks. The origin of the new elastic fibers is from medial smooth muscle cells. Collagen synthesis begins to exceed lysis and suture line strength begins to enhance within three to four weeks.4 On the basis of these observations, surgeons recommend that stress on the anastomosis or arteriotomy should be kept at a minimum for at least two weeks. The growth of the vascular suture line has been studied extensively in a large number of experiments. Although some felt that body growth ultimately resulted in a slight relative stenosis at the suture line, all investigations reported that the suture lines grew fairly well as the parent artery increased in size. However, it was evident that the tendency toward constriction at the suture line was considerable if continuous nonabsorbable sutures were employed. Moreover, constriction was minimized by the use of continuous monofilament absorbable suture or interrupted nonabsorbable suture. Consequently, it is generally agreed that in infants and growing children that vascular anastomotic repair can be accomplished by two different techniques to avoid late anastomotic stenosis. In one technique, one-half of any anastomosis with nonabsorbable suture should be made with interrupted sutures.5 In the other technique, a continuous monofilament absorbable suturecan be used clinically with a low incidence of stenosis.6 Some surgeons use monofilament synthetic absorbable suture for anastomosis repair in infants and growing children. When surgeons make tucks in the suture line, these tucks may result in disruption of the laminar flow and may lead to progressive stenosis of the sutural repair. Finally, in the adult, the surgeon should use the least reactive nonabsorbable suture, monofilament polypropylene, because this suture maintains anastomotic strength, causes the least fibrosis of the suture line and facilitates a more rapid resolution of the suture line inflammatory response. There has been some debate regarding the various types of suture techniques. On the basis of investigations by Schumacker and Lowenberg,7 they concluded that everting mattress suture techniques were preferable to techniques into which an end-on approximation of the artery was accomplished by a continuous suture. However, Sako and colleagues8 reported no essential difference in the incidence of thrombosis with the mattress technique and with suture passed through all layers. Opinions remain somewhat divided as to the relative merits of the mattress suture and the end-on approximation. The ease with which end-on approximation can be accomplished has caused most surgeons to rely exclusively on the continuous end-on approximation technique. Lowenberg and Shumacker9 conducted further studies on the healing characteristics of divided and then sutured carotid arteries in dogs. The breaking strength at the anastomotic site was evaluated with the original silk suture intact. The same type of healing curve was observed as had been established by similar experiments for the healing of other tissues, such as the abdominal wall. It was concluded that arteries gained strength much in the same fashion as did all other tissues which had been studied. The actual force, which disrupted the recently sutured artery during the "lag" period was as little as 2 lbs. It was evident that a small force at that time could pull apart a recently completed arterial anastomosis and that it was important to approximate blood vessels without tension. Their observations indicated that while the force necessary to break the recently sutured artery by direct pull was not great, the sutured artery rapidly regained resistance to intraluminal pressures and that after 14 days or longer could withstand, without leaking, intraluminal pressures in excess of normal systolic blood pressure. Preliminary studies by these authors demonstrated that the circumference of the artery at the anastamosis increased in the growing animal comparable to the increase in the circumference of the unsutured portion of the artery. The investigators pointed out that many of the healed suture lines failed to break or burst at pressures which ruptured the artery itself. There are two important considerations in making vascular incisions: the direction of the incision and the manner of the closure. Longitudinal incisions provide excellent exposure because they can be easily extended. This benefit must be weighed against a distinct disadvantage. Closure of a longitudinal incision in smaller (< 4 mm ) vessels narrows the lumen over a great distance and thereby causes significant stenosis and turbulence that may lead to thrombosis. This narrowing is not encountered in closure of a transverse incision. Consequently, a transverse arteriotomy is recommended in smaller vessels. Continuous suture closure of longitudinal arteriotomy The chosen area for the femoral arteriotomy is exposed, mobilized, and isolated. Partial occlusion of the artery by two silicone loops is not undertaken until everything is ready for the arteriotomy, thereby minimizing the occlusion time. The silicone loops are now positioned at sites proximal and distal to the planned arteriotomy (Fig. 1).  Sufficient tension is applied to the ends of the suture loops to temporarily obstruct the flow of blood into the artery. Tension is applied first to the ends of the silicone loops to occlude partially the vessel lumen. Both ends of the silicone loops are then clamped between silicone covered jaws that maintain vessel occlusion. The longitudinal arteriotomy is initiated with a short opening of the lumen with the cutting-edge of a No. 11 blade, rather than its point. The arteriotomy is then completed by cutting the vessel wall with a 7 inch. DeBakey vascular scissors whose jaws are positioned at a 45º angle to the scissor handles. The length of the longitudinal arteriotomy is 3cm long. In this psychomotor skill station, the arteriotomy will be closed with a continuous polypropylene suture. A 36 inch length 4-0 polypropylene double-armed suture swedged to taper point needles with subtended arcs of 180º are used for continuous sutural closure of the arteriotomy. This needle is grasped between the smooth jaws with rounded edges of the T-C Crile Wood needle holder 1.5mm beyond the end of its laser drilled hole. The surgeon begins the arteriotomy closure at the proximal end of the arteriotomy farthest from the surgeon. The vessel wall is everted with the 6 inch long smooth DeBakey forceps to permit needle passage through the intima and overlying vessel wall 1 mm lateral to the end of the arteriotomy. With eversion of the opposite wall, the needle is passed through the intima and overlying vessel wall 1 mm lateral to the arteriotomy. Using an instrument tie, a three-throw square (1=1=1) knot is constructed. After knot construction, the knot is positioned at a point farthest away from the surgeon. One fixed suture end with attached needle is cut 3mm from the knot, leaving one 3mm knot ear. The other fixed suture end attached to the needle is then passed through the adventitia and intima at a point 1mm from the last interrupted suture and 1mm from the divided vessel edge (Fig.2).  The needle is then passed out through the intima and overlying vessel wall 1mm from the vessel edge on the opposite side of the arteriotomy. The sutural closure is then continued with similarly positioned sutures 1mm from each other and 1mm from the divided vessel wall perpendicular to the suture line. The polypropylene suture must be pulled taut continuously to maintain approximation of the vessel wall and avoid later suture line bleeding. A fine nerve hook with a blunted point inserted through the end of the arteriotomy can be used as a safeguard as the final suture is passed. At this point, tension is released from the proximal suture loop, allowing blood and air to escape from the remaining opened end of the longitudinal arteriotomy (Fig 3).  After passing the final suture 1mm lateral to the end of the arteriotomy, knot construction is accomplished with the suture loop and free suture ends using a six throw square (1=1=1=1=1=1) knot construction. The suture loop and ear are cut 3mm from the knot, leaving three, 3mm long suture ears (Figure 4).  Tension is now removed from the distal silicone loop, allowing blood flow to return to the femoral artery. When closing a longitudinal incision in small ( 4mm diameter) vessels, stenosis of the approximated lumen will occur with a continuous suture. This stenosis may be obviated by the insertion of an elliptical vein graft. The surgeon's ultimate selection of surgical sutures and needles will be dependent on his/her perception of the performance of the suture and needle during surgery. Realizing the importance of understanding the surgeon's perception of the performance of suture and needle products, two large multicentric evaluations of suture and needle products have been reported in peer reviewed publications.10,11 The guidelines used in the development of this multicentric evaluation of surgical suture and needle products should be replicated in any hospital setting to assure that the surgeon has a superior needle and suture product. CONCLUSION Your success in achieving optimal wound closure using sutures and their attached needles will depend on several factors. First, you must have all of the appropriate sutures and attached needles that are necessary to achieve wound closure. Inadequate instruments will defeat the efforts of even the master surgeon. Second, mastery of surgical skills using sutures and needles requires repetitive practice. Surgeons who do not have adequate psychomotor skills will not achieve an excellent result even with the finest sutures and their attached needles. Third, select the most appropriate sutures with their attached needles based on the biology of wound repair and infection and the biomechanics of sutures and needles. Finally, you must always use a double glove hole indication system that accurately detects holes in the gloves. In the event of a needle stick exposure during surgery, operating personnel must follow carefully the postexposure prophylaxis plan against blood borne deadly viral infections. As you perfect your surgical discipline, share this information with your colleagues and encourage them to participate in this training program. In addition, we encourage each of you to evaluate carefully the clinical results of your wound closure with sutures and strive to devise new and improved techniques that are based on scientific investigations rather than testimonials. References
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