Two studies presented at the 2008 Clinical Congress of the American College of Surgeons demonstrate how surgeons are using existing materials in innovative ways. The two techniques are safer and more cost-effective than previous approaches, getting patients out of the operating room faster than before. One method even opens the door to procedures currently impossible to perform before its introduction.

At Stanford (CA) University School of Medicine, microsurgeon Geoffrey C. Gurtner, MD, FACS, is working with chemical engineers to perfect a technique for sutureless microvascular anastomosis using thermoreversible poloxamers. “Anastomosis” is the term used to describe connecting both ends of cut blood vessels, so that the blood can flow through unrestricted. However, working under a microscope to connect the tubes of these tiny blood vessels is tedious, time-consuming, and requires a skilled microsurgeon. Dr. Gurtner and his colleagues invented a way to connect blood vessels without sutures that can shave a stunning 15 to 27 minutes off a 30-minute procedure.

“This technology makes vascular anastomosis surprisingly easy,” Dr. Gurtner, associate professor of surgery at Stanford, said. “In our experience, it has made procedures that were impossible before possible—even in inexperienced hands. Also, anastomosis is the hardest thing to do with robotic or laparoscopic techniques, and our technology trivializes those connections.

“What this approach means to patients is that we may be able to do more and more things less invasively—including heart bypasses and things like that. For example, this technique might lower the incidence of amputation in peripheral vascular disease and it might allow us to more completely revascularize a blocked heart in coronary artery disease,” he explained.

Dr. Gurtner described his new technique by first explaining that when he is trying to sew tiny blood vessels together, they tend to collapse because there is no blood in them, as clamps have been applied to hold blood back. As these floppy, hollow vessels become smaller and smaller, he has increasing difficulty putting sutures into them. One thing that is easy to do, however, is to fill them with fluid.

Instead of attempting to stitch hollow, floppy vessels together, Dr. Gurtner explained, he fills the blood vessels with a liquid poloxamer already approved by the US Food and Drug Administration (FDA) for other human-delivery purposes. He describes this material as a clear, colorless, hair-gel-like synthetic polymer. When the blood vessels are filled, he heats the liquid polymer using a convection blower, like a hair dryer. The liquid phases into a solid at 38 degrees Celsius (100.4 degrees Fahrenheit) and is solid at 40 degrees Celsius (104 degrees Fahrenheit). The floppy vessels stiffen like straws, and he lines the vessels up end to end. He seals the vessels together with Dermabond®, a liquid skin adhesive used by doctors to close wounds, then releases the clamps. The normal body temperature blood rushes into the vessels and hits the thermoreversible polymer. The polymer dissolves within one to two seconds and is excreted by the kidneys.

Dr. Gurtner has been performing sutureless anastomosis since early 2006 in animals and has seen no evidence of embolization, toxicity, or end organ damage. Particularly because this solid melts into a liquid within seconds after returning to normal body temperature, he believes there is a large margin of safety with its use. Follow-up angiograms and other tests demonstrated equivalent open and unblocked vessels and vessel diameters, burst strength, and volumetric flow between the sutureless group and the control. Inflammation and scarring were dramatically decreased in the sutureless group, however.

“Much of what we do in medicine is try to restore blood flow to parts of the body that don’t have blood flow,” Dr. Gurtner explained. “Currently there are limits to how small or how diseased a vessel can be before we would conclude it is impossible to sew it together. This technology will extend what we can do to those things that cannot now be sutured. It will have a profound effect on the field of microsurgery.”

Dr. Gurtner and his colleagues who are pioneering this technology with him are now working with Synvascular, Inc., Palo Alto, CA, to complete the final regulatory groundwork to assure the FDA that this technology is safe. They anticipate beginning human trials in 2009.

Farther along in development is a clever FDA-approved device called the INSORB® absorbable dermal stapler that Jeffrey A. Ascherman, MD, FACS, Columbia University Medical Center, New York, NY, has been using for about a year. He reports that the stapler works well, and he has provided significant data showing that this device gets just as good cosmetic results; saves time and operating room expense; and is safer for patients than the usual practice of suturing the dermis.

Dr. Ascherman, who is chief of plastic surgery at the Columbia University campus of New York-Presbyterian Hospital, explained that plastic surgeons normally close incisions in layers, which takes tension off the outer surface of the skin, known as the epidermis, allowing a less noticeable scar. Traditionally, the epidermis as well as the deep layer underneath called the dermis are closed with sutures. This new dermal stapler, however, allows a novel way to close that deep dermal layer of skin.

“We found that the cosmetic results were comparable with staples,” Dr. Ascherman said. “We didn’t have any wound infections or separations in any of our groups, so we really couldn’t compare that, so there were no overall complication rates. The scar results were roughly the same. The stapler was more than three times faster than sutures, so there was a very statistically significant savings in time and, therefore, in cost.”

Dr. Ascherman and his colleagues designed a prospective, randomized, blinded study to follow 18 patients with abdominal incisions. Of these patients, 10 were randomized to dermal closure with the INSORB® stapler and eight received sutures. At follow-up, no difference was found for scar vascularity, pigmentation, pliability, or height. The dermal stapler closed wounds approximately 33.6 seconds per centimeter faster than sutures (21.7 minutes of time saved per abdominal closure). With an operating room cost of $2,000 per hour, overall savings for abdominoplasty on these particular patients with staples was about $658 per patient.

As Dr. Ascherman explained at the Clinical Congress, the dermal stapler works well for most standard incisions, but cannot be used everywhere. In order to use this stapler, the surgeon must evert the skin. The surgeon inserts the staples with special forceps. One hand is on the stapler and the other hand is on the four-pronged forceps. Normal forceps are two pronged, he explained, but these have four prongs because the surgeon lifts up the skin on both sides of the incision at the same time in order to be able to get the staples in. Some types of closures do not evert so well, so the surgeon cannot lift up on both sides. With those types of closures, it would be more difficult to use the stapler. There is a learning curve, according to Dr. Ascherman, but he said he caught on within five minutes.

With both of these novel approaches to closing wounds there is less of a risk of injuries to staff in the operating room because needles are not used. Importantly, the less time a wound is open, the less the risk of infection. Also, the longer someone is under general anesthesia, the greater the risk that person has of developing pulmonary and circulatory problems, blood clots, and so on, so both of these procedures are safer for patients.

“The INSORB® dermal stapler is a safe and reliable technology,” Dr. Ascherman says. “It saves operating room time and cost and gives equally good results as the standard sutures—and that’s a pretty big plus.”

Edward I. Chang, MD; Michael G. Galvez, BA; Cynthia D. Hamou, MD; Jayakumar Rajadas, PhD; and Michael T. Longaker, MD, MBA, FACS, assisted Dr. Gurtner in this work at Stanford. Dr. Gurtner’s research was funded by the Bio-X Interdisciplinary Initiatives Program at Stanford.

Shannon L. Wong, MD; Kevin J. Cross, MD; Esther H. Teo, BSc; and Christine H. Rohde, MD, worked with Dr. Ascherman at New York-Presbyterian Hospital. They are on the staff of Cornell or Columbia Universities.

Source: American College of Surgeons (ACS)