Surgery News - November 2008 - (Page 6)

NEWS SURGERY NEWS • N O V E M B E R 2 0 0 8 Poloxamer Makes Sutureless Anastomosis Possible BY ROBERT FINN Else vier Global Medical Ne ws S A N F R A N C I S C O — Imagine making an anastomosis on a blood vessel that is 0.3 mm in diameter in less than 10 minutes, without using needle or thread. That’s the promise of a new technique revealed by Dr. Edward I. Chang and Dr. Geoffrey C. Gurtner at the annual clinical congress of the American College of Surgeons. Although the experiments to date have been in animal models, the investigators plan to begin human studies in Europe sometime in 2009. A specialist in microsurgery, Dr. Gurtner explained that connecting small blood vessels is difficult because they are floppy and tend to collapse when empty. His solution is to make the cut ends of the vessels stiffen like drinking straws. He lines the vessels up end to end and seals them together with Dermabond. The technique takes advantage of poloxamer, a material that has the odd property of turning from a liquid to a solid when its temperature is raised—a phase transition that’s the opposite of what is normally seen in water and other liquids. Poloxamers have been approved by the Food and Drug Administration for use in depot medications and other applications. Although surgeons have expressed interest in the technique, concerns remain about its safety. The investigators will have to prove that the material is nontoxic and never turns back into a solid, potentially causing a dangerous embolus. Dr. Gurtner, an ACS Fellow with Stanford (Calif.) University, and Dr. Chang, who is currently at the University of California, San Francisco, and their colleagues designed a poloxamer that is liquid at body temperature (37° C) and is solid at Scanning electron micrograph shows sutureless anastomoses 6 months following surgery. Scanning electron micrograph shows hand-sewn anastomoses 6 months following surgery. just a few degrees warmer (42° C). They inject the liquid poloxamer into the lumens of the cut vessels and then use a heat lamp to raise the temperature enough to turn the material solid. Then they dock the vessels and apply Dermabond. Once the Dermabond has set, the heat lamp is removed. Within a few minutes the poloxamer cools down, turns to liquid, and is flushed away with the blood flow. The poloxamer is eventually excreted by the kidneys. At the meeting, Dr. Chang presented data from a rat model demonstrating 30 end-to-end anastomoses of the infrarenal abdominal aorta and 5 end-to-side anastomoses of the left iliac artery ligated and anastomosed to the right iliac artery. The investigators have also conducted experiments on pigs, dogs, and sheep, and have followed the animals for up to 1 year, Dr. Gurtner said during a press conference. The patency of the poloxamer anastomoses and their volumetric flow rate showed no statistically significant differences when compared with hand-sewn, end-to-end anastomoses. The investigators were unable to complete any of their attempts at hand-sewn, end-to-side anastomoses, but they were successful 100% of the time using the poloxamer technique. Furthermore, the poloxamer procedure took an average of just over 8 minutes, compared with an average of 47 minutes for the needle-and-thread procedure, a significant difference. “Not only have we enabled ourselves to do anastomosis without needle and thread, we may be actually getting anastomoses that are better than can be achieved even in easy ones using needle and thread. We’ve eliminated the foreign body of the suture material [and] we’ve decreased the risk of inflammation, which leads to gradual narrowing of cardiac bypass grafts or peripheral bypass grafts,” Dr. Gurtner said. Histologic studies on anastomoses up to 1 year old show no evidence of inflammation, no evidence of fibrosis, no narrowing, and no “purse-stringing.” Burst studies show that these anastomoses do not fail even at pressures of 1,000 mm Hg. work failed to notice a severe fungal infection in one patient’s groin, requiring the operation to be postponed. In response, Dr. Gawande said, “If [the checklist] is understood to be a regulation, then we’ve failed. If we instead understand this to be a tool to help people obtain the best possible results they can get then “It looks actually like there was never anything done to this artery,” Dr. Gurtner said. “When we open up these animals, generally we can’t even find where the anastomosis was performed.” If proved safe and effective in humans, the technique may open up new vistas of microsurgery, Dr. Gurtner said. It may be possible to do more with the very small vessels at distal parts of the hands and feet that are often damaged in diabetes or atherosclerosis, as well as with larger vessels. Although the investigators haven’t chosen the exact experimental model for human trials, one possibility is the repair of arteriovenous fistulas. Work on the poloxamer anastomosis technique was supported by grants from the National Institutes of Health and Stanford University. Stanford owns patents on the process, and has licensed them to Synvascular Inc. Dr. Gurtner disclosed that he is on the board of directors of Synvascular, and that Dr. Chang and several of the other coinvestigators are consultants for the company. ■ it’s likely to be very successful.” “I don’t want to sound like a zealot or an absolutist, but please use a checklist when you operate on me, no matter what operation you’re doing.” Dr. Flum said. Dr. Gawande and Dr. Flum said they had no conflicts of interest related to their presentations. ■ Can Be Completed in 90 Seconds Checklist • from page 1 parts. The first part, administered before rates (from 9.6% to 6.5%). All differences the induction of anesthesia, confirms such were statistically significant. “So intuitive is the concept of a checkthings as the patient’s identity, any allergies, list that I doubt if there’s a lot and the presence of a difficult of disagreement that this is a airway. The second part, adgood thing,” said Dr. David R. ministered before the skin inciFlum, an ACS Fellow with the sion, requires that all team University of Washington, members introduce themselves Seattle, who described his efand that the surgeon, the anesforts to implement a similar thesia team, and the nursing checklist in hospitals in Washteam discuss anticipated critical ington state. (See box.) events. The third part, adminBut during the question-andistered before the patient leaves answer session, one physician the operating room, requires ‘Please use a the team to confirm sponge checklist when you expressed concern that checkcounts and specimen labeling, operate on me, no lists would add to already burdensome paperwork requireand to ensure that equipment matter what ments. “I just came out of the problems have been addressed. operation you’re [Veterans Affairs] system, and to (To see the complete checklist, doing.’ do a shave biopsy, the consent visit www.safesurg.org.) DR. FLUM process and the paperwork took The checklist was designed to be completed in 90 seconds or less, Dr. probably three times what it took to actuGawande said. After it was implemented, ally do the procedure,” he said. “We realoverall adherence to the six safety mea- ly need to stop and think about whether or sures rose from 33.5% to 67.4%, whereas not everything that you’re doing for 100% reductions were seen in death rates (from compliance becomes cost effective and re1.3% to 0.7%), surgical site infections ally rational.” He then cited a case in which (from 4.3% to 3.0%), and complication nurses who were preoccupied by paper- Wash. State Steps Up Checklist Initiative surgical be the major grassroots Implementingfocus of achecklistsinwill organization in Washington state 2009. The Surgical Care Outcomes Assessment Program (SCOAP), a peer-led collaborative, is dedicated to improving surgical outcomes through education, surveillance, tracking, and data analysis (SURGERY NEWS, August 2008, p. 1). Currently, 35 hospitals throughout the state are enrolled in the collaborative, which Dr. David R. Flum described as a “bare-bones initiative” that receives little outside funding. Dr. Flum, an ACS Fellow, is the medical director of SCOAP. “SCOAP focuses on processes of care and getting data back to surgeons in hospitals about the way that care is delivered,” Dr. Flum said. “Not just, ‘Did the patient live or die?’ but how did [the surgeons] deliver the care compared with their colleagues? How long were patients on ventilators? How often do they use transfusions? The data are collected locally [and] put through a Web-based system.” This system provides quick feedback so that physicians can make changes right away. SCOAP is using the World Health Organization’s checklist as a model, and seven hospitals have already implemented the checklist. A major public relations campaign starting in 2009 will aim to have the checklist displayed as a large poster in ORs statewide. PHOTOS COURTESY DR. EDWARD I. CHANG http://www.safesurg.org

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Surgery News - November 2008 Contents News:�Without a Stitch The 20/20 Vision:�Med School Mix News From the College:�New President General Surgery: Diabetes Debate

Surgery News - November 2008

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