April 8, 2011 (San Antonio, Texas) — Will endoscopic snakes — fully articulated and self-propelled — be the next technological advance in minimally invasive surgery? Three researchers from the divergent fields of bioengineering, surgery, and gastroenterology think so.

A team made up of Michael Awad, MD, a general surgeon at Washington University at St. Louis, Missouri; Shayam Thakkar, MD, from Allegheny General Hospital in Pittsburgh, Pennsylvania; and Howie Choset, PhD, professor at the Robotics Institute, Carnegie-Mellon University, Pittsburgh, presented a study here at the Society of American Gastrointestinal and Endoscopic Surgeons 2011 Annual Scientific Session and Postgraduate Course. They used natural orifice transluminal endoscopic surgery (NOTES) to perform a transrectal distal pancreatectomy with their robotic snake in a porcine model.

The investigators inserted the snake transanally through an overtube after a rectotomy was performed. At that point, a retroperitoneal dissection was performed, using instruments passed through the snake's 3 internal channels to gain access to the distal pancreas. There, with the aid of 5 mm ports for laparoscopic monitoring and retraction, a distal pancreatectomy was performed using endoscopic biopsy forceps and needle knife cautery. Subsequently, the specimen was retrieved transrectally, using an endoscopic snare. Total procedure time was less than 2 hours.

Dr. Michael Awad

Although endoscopic surgery has made huge strides in the past 20 years, many surgical procedures are still done in an open method because of limitations in the technology, Dr. Awad noted. Until now, robotics has been thought of as the surgeon using fixed tools remotely. However, the new field of "mobile robotics," used in this study, has been developed by 2 surgeons and a bioengineer, who combined their different professional perspectives to create what might be the very first endoscopic robot snake.

Dr. Awad told Medscape Medical News that the 3 brains on his team have proven better than 1. "It helps to have 3 different perspectives on the same problem. From the surgical side, we're biased to doing things the same way we have for the last 25 years. By bringing in these new eyes, we're bringing in new ways of looking, ways we could not have even imagined. For example, a lot of the new tools and new approaches we're looking at are using natural orifices. To get through those natural orifices, for example, from the mouth to the stomach, requires a tool that would be flexible and long, and these are tools gastroenterologists have used for the past 40 to 50 years — that is, the flexible endoscopes. So Dr. Thakkar's experience with endoscopy really is invaluable."

"Obviously, from the engineering side of things, we can only dream of what these tools would look like, and the fascinating thing is that many of these tools were not developed for the medical realm at all. In fact, they were developed for search-and-rescue operations and archeological expeditions, so these perspectives overlapped and were applied to the problems we're trying to solve."

The Endoscopic Snake

Dr. Thakkar discussed the background of the new endoscopic snake with Medscape Medical News. "NOTES is a new type of surgery being practiced in research hospitals and facilities around the world. . . . It basically involves accessing a natural orifice, such as the mouth, the vagina, or the rectum, creating a perforation in the luminal cavity, and then driving the endoscope — or in our case, our snake robot — through that perforation to the organ of interest, and then performing the resection and removing [the robot snake] through that same orifice."

"Benefits [of using NOTES] include decreased wound infections, decreased complications, less postoperative pain, and incisionless surgery for patients. Other benefits might include lower cost; rather than having a sterile environment such as an operating room, you could have just sterile instruments, such as NOTES-specialized equipment, and potentially less anesthesia requirements. Finally, it could be important for patients who are critically obese or morbidly ill that are not good candidates for surgery."

Dr. Choset added: "I work in the world's largest robotics research center. There's no other place like it. The things that my group is famous for are these . . . snake robots. These are highly articulated mechanisms that can use their many internal degrees of freedom of movement to thread through tightly packed volumes and get to places that people and machinery cannot otherwise access."

He continued: "In all the applications in which we are using snake robots, the common denominator is some kind of action in a defined space. Whether it be manufacturing for the aerospace industry, search and rescue, archeology — we're doing minimally invasive surgery on a structure. So why not do minimally invasive surgery in a human body? The critical breakthrough was a few years ago, when we figured out how to make our snake robots small. Up until then, almost all snake robots were 40 mm in diameter or larger. There were some smaller devices, but they were made out of exotic actuation technology that wasn't robust. Our breakthrough came when we figured out how to make functional, small, articulated snake robots . . . using proven actuation — that is, motors and fishing wire."

After 5 years of work, the research team put their robotic snake to work. "With the minimally invasive cardiac surgical snake," Dr. Choset said, "we've operated on 30 pigs, 2 cadavers, and 3 live humans. These 3 people on whom we operated received a diagnosis for which normally they would have had to have their breastbones cracked open and they would be recovering for months. Instead, they went home the next day and did fine."

How exactly does the robotic snake work? Dr. Choset was happy to describe the device's working method for Medscape Medical News. "It's an articulated computer-controlled probe. It's not being pushed in by a person: There are electric motors that are marionnetting the links of this robot to assume whatever 3-dimensional shape you want, and there are 2 more motors that push the robot in. So a doctor has a joystick that he aims."You drive it as if you're flying a plane. You can think of it as a floating ball in space. That's the tip of the snake, and you can make it go anywhere. The rest of the snake is just to position that ball. You aim the robot and the mechanism, and the underlying computer algorithms coordinate the degrees of freedom of the robot and do all the magic for you. What I call the 'fundamental path-planning science' makes the robot go where you want," Dr. Choset said.

"The robot has, inside of it, 3 working channels through which we can pass anything. We use 1 of those channels to pass visualization info — a regular endoscopic view. We use the other 2 channels for endoscopic tools, whether they be an ablation tool, a cutting device, a colonoscope, or forceps."

Dr. Awad was enthusiastic about this new technology: "I really do think we are reaching the limit of what we can do in a minimally invasive fashion. For example, surgeries on the pancreas, the bile ducts, and the liver are highly complex surgeries that require advanced levels of precision and articulation that we simply can't get with current laparoscopic technology. To make those surgeries truly minimally invasive, we do need new tools, such as this, that will allow us to break that barrier. I believe this it will be a game changer."

"There's a platform called TEM, which requires rigid instruments that we still liken to chopstick surgery, where there's a lot of so-called 'sword-fighting,' with instruments gnashing against each other. The ergonomic requirements there are extreme," Dr. Awad noted.

The field of ergonomics is an area that is ready for the advancements offered by this technology. As Dr. Awad suggested, "there have been studies comparing the ergonomics of laparoscopic surgery vs open [surgery], which is roughly a 5-fold increase in the amount of work for a surgeon. If you then go through the jump from laparoscopy to NOTES, it's been quantified as 10 times more [work] than laparoscopy. So it makes for an extremely arduous case. Our technology, the robotic snake, offers an alternative, with its extreme ease of use."

Pierre Theodore, MD, associate professor of surgery at the University of California–San Francisco, approves of the new invention. "I think it's an important move . . . toward increasingly minimally invasive technologies," he said. "To have an endoscope with full functionality — the end of the endoscope is really critical. The robotic snake in many ways is the Holy Grail: To make not only the incisions very small, or to make the endoscope able to reach the deepest recesses of the body, but also to have real functionality at the end of the endoscope."

Richard Satava, MD, professor of surgery at the University of Washington, Seattle, and a senior scientific advisor for research and development at the US Army's Medical Research Command, also praised the team's advancement and had some concrete suggestions.

"I think this is a significant step forward in flexible endoscopy," Dr. Satava told Medscape Medical News. "In particular, I think it's time for mobile robots to finally move into general surgery. All of our robots today are, for all intents and purposes, fixed. So this will give us the first opportunity to get into an area of mobile robotics. There are some issues at this point in time with the control motion of them, as opposed to the fixed robots, where you have a nice console that's ergonomically designed. The researchers have been focusing on the instrument itself, and now we have to take the next step and decide what's the best way to control this flexible robot."

Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) 2011 Annual Scientific Session and Postgraduate Course. PresentedApril 1, 2011.

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