Advances in Keyhole Surgery

Before minimally invasive surgery was widely available, major surgery usually meant large skin incisions and prolonged recovery times. Over the past 10 years, technology has evolved to the point that many major surgeries can now be done with the assistance of minimally invasive techniques. Smaller incisions now mean less time in the hospital after surgery and fewer days away from normal activities. Minimally invasive and computer-aided surgery is rapidly growing because of the obvious advantages for both the patient and the physician. These new advanced technologies have been referred to as "laser surgery", "keyhole surgery", or "laparoscopic surgery." Many different types of physicians, such as general surgeons, urologists, heart surgeons, gynecologic surgeons, and orthopedic surgeons, all use minimally invasive techniques to treat their patients.

How does minimally invasive surgery work? The major advance occurred about the same time that video cameras began to spring up in consumer use. A thin instrument with a camera on the end is used to peer inside the human body without using large incisions. The camera gives the surgeon a clear picture of the area needing surgery. Then under this view, surgeons use miniaturized graspers and scissors to perform standard surgeries without large scars. In the 10 years since this technology has been applied widely in the US, much has changed. The ability to suture (place stitches) inside the abdomen, remove diseased segments of bowel then connect bowel back together with metal clips, and stop bleeding by coagulating or "melting" blood vessels, are just some of the new technologies. Surgeons can now remove diseased gallbladders, spleens, kidneys, adrenal glands, ovaries, sew bowel together and repair hernias all through incisions no bigger around than a pencil eraser. Hysterectomy (removal of the uterus) and removal of donor kidneys for transplant can also be assisted using minimally invasive techniques. Patients now can go home hours after having these procedures and return to work in just a few days.
Even more exciting is the new robotic surgical technology that allows the surgeon to sit at a console and guide a surgical robot through minimally invasive surgical procedures. The robotic arms, as well as the special video camera, are all controlled from a remote console thus allowing the surgeon greater ease and precision during complex surgical tasks. Current uses for the robotic-assisted minimally invasive techniques include heart surgery, weight reduction surgery, and anti-reflux (heartburn) procedures. The daVinci Robot is currently being used here at the University of Nebraska Medical Center, as well as several other centers around the country, for both patient care and research applications. At UNMC a number of surgeons are using the above described skills in order to better treat their patients. Whether it is abdominal, orthopedic, gynecologic, urologic, or transplant surgery, patients can be assured that locally trained specialists can apply these new technologies today.

WHICH would you prefer: a surgical procedure that left you in pain, incapacitated and scarred, or one that was virtually painless, involved no recovery time and left no visible scar at all? It may sound too good to be true, but a radical improvement in surgery is the promise held out by a new technique, called “natural-orifice translumenal endosurgery”, or NOTES. Rather than operating on the abdomen by making incisions in the skin, it involves passing flexible instruments through the body's orifices and entering the abdomen from the inside.

One of the most widely studied approaches is “transgastric” surgery, in which the instruments are passed through the mouth and into the stomach. From there, the surgeon cuts a hole in the stomach wall to enter the abdominal cavity and perform the operation. Once it is complete the instruments, along with any removed tissue, are drawn back out through the stomach and mouth and the access incision is stitched up. Similar approaches involve entering through the rectum, the vagina and even the penis.

It may sound somewhat drastic, but the rationale for doing this goes well beyond the desire to avoid leaving a scar. NOTES could have many medical benefits over conventional surgery, and even over laparoscopic or “keyhole” surgery, in which the operation is performed via a small number of external incisions. NOTES could reduce the risk of post-operative infections. It does not require a general anaesthetic, making it an attractive option for the elderly or infirm.

Post-operative convalescence normally involves recovering from the access incisions made in the abdomen. NOTES should mean shorter recovery periods, since the stomach wall has relatively few pain receptors, says Paul Swain, an endosurgeon at Imperial College London who is one of the British pioneers of the technique. “Patients theoretically would be able to go back to work the next day, rather than taking a week or two off,” says Lee Swanstrom, director of minimally invasive surgery at the Oregon Clinic in Portland, Oregon.

Beyond the keyhole
In recent months several surgical groups have reported early successes using NOTES to carry out procedures such as gall-bladder and cancer-tumour removals, and diagnoses of pancreatic cancer. In animals even more complex procedures have been demonstrated, such as fallopian-tube resections, organ-bypass procedures, reconstructive stomach-reduction procedures and even the draining of coronary arteries. Yet for NOTES to become as widespread and successful as traditional laparoscopic surgery, an arsenal of new surgical instruments will be needed. Answering this call, physicians and medical-device companies are falling over themselves to develop innovative new tools. “There's an explosion in patent filing in this area,” says Dr Swain. “This is one of the great periods of medical innovation.”

What makes NOTES so difficult is having to carry out surgery via a single and very narrow point of access. Open surgery doesn't have this problem, because the abdomen is laid bare to the surgeon, and even laparoscopic surgery involves placing at least three (and sometimes as many as five) separate instruments into the abdomen from different directions, through different incisions. This makes it possible to triangulate when cutting, sewing or manipulating tissue, says Eugene Chen, the boss of USGI Medical, a surgical-instruments firm based in San Clemente, California. “We have to create instruments that allow us to do the same thing,” he says.

With NOTES, however, all the instruments have to be fed in parallel through a single orifice, and then through a single internal incision. This makes manipulating tissue much more difficult and also limits the surgeon's viewpoint. With existing instruments designed for gastro-intestinal procedures, the camera is attached to the same instrument tip as the grasping and cutting tools, which creates problems. “As soon as you have to move your instrument to grasp something, it changes your view,” says Per-Ola Park, another pioneer of NOTES who is based at Sahlgrenska University Hospital in Gothenburg, Sweden.

Furthermore, surgical tools for NOTES need to be able to manipulate, cut and repair kinds of tissue that are very different from those normally found in the gastro-intestinal tract, says Kurt Bally of Ethicon Endo-Surgery, another surgical-tools firm, based in Cincinnati, Ohio. So Ethicon, USGI and other firms are developing entirely new instruments.

Stephen JeffreyOne device developed by USGI, called the ShapeLock TransPort, consists of a flexible “access platform” through which other devices can be fed. Other flexible gastro-endo-surgical devices have existed for some time, but what is novel about this latest device is that once in place it allows its shape to be locked. This has huge benefits because normally if you try pushing a tool or lifting some tissue, the entire instrument will move, says Dr Park. But by “rigidising” the device and fixing its position the surgeon can operate from a stable platform that is almost like being inside the abdomen itself. The ShapeLock device was recently used with great success in America's first transgastric procedures on humans.

Having gained access to the abdomen, surgeons need to be able to cut, grasp and suture tissue. To this end Dr Swain has developed a novel form of suturing that involves poking folded T-shaped fasteners through the tissue on either side of a tear or incision, each connected to thread. The fasteners act like anchors so that when the two threads are drawn together the incision or tear closes up. The threads are then fixed together using a small clasp, rather than being tied, and the loose thread is cut. This remarkably simple technique allows suturing to be carried out very effectively with access from only a single flexible scope. USGI has developed a similar approach which uses umbrella-like fasteners, and Olympus Medical Systems, another firm working in the field, has devised a system based on curved hooks.

Hooks and graspers are also being used to manipulate tissue. When passed through flexible scopes, pairs of them can move independently of the tip, so that they can oppose one another, making triangulation possible. This concept has been further elaborated upon by Dmitry Oleynikov at the University of Nebraska Medical Centre, in Omaha. His approach involves the insertion of self-assembling, remote-controlled surgical robots into the body. During insertion these devices are cylindrical in shape, but they then unfurl two opposable arms for grasping and cauterising, and two cameras to give the surgeon stereoscopic vision.

The tiny devices, which are called natural-orifice miniature robots, are tethered to allow the surgeon to control them and to provide power (though Dr Oleynikov has developed wireless versions, too). Dr Oleynikov has already used his robots to carry out a number of operations on pigs, including gall-bladder removals, liver biopsies and the ablation of tumours. He believes it should be possible to place two robots into a patient at the same time. “We have filed a number of patents for devices which are inserted in the mouth and through the stomach,” says Dr Oleynikov. The technology is now being commercialised by Dr Oleynikov's spin-out company, Nebraska Surgical Solutions, which has filed applications with American regulators for experimental use in humans.

Dr Park warns that there is a danger of over-engineering these surgical instruments. Robots can be expensive, he says, and if these new tools are to be successful they will have to be cost-effective. One way to keep costs down but to enable triangulation could simply be to insert devices through more than one natural orifice, he says. “You could have one coming in from the stomach and one coming in from the rectum or vagina,” he suggests. Put perhaps the biggest challenge is to develop better cutting tools, says Dr Park. Ultrasonic scalpels are popular tools in keyhole surgery, but they are rigid—so finding ways to make them flexible enough to insert transgastrically would be a big step forward.

A surgical gold rush
Someone will probably work out how to do it soon enough. “I can't believe things are accelerating as fast as they are,” says Mr Chen. There are now half a dozen billion-dollar companies developing new instruments for NOTES, he says. The number of patents filed by Ethicon Endo-Surgery has quadrupled over the past ten years, with a particular surge in the past couple of years. This is largely due to NOTES, says Mr Bally.

Needless to say, the needs of the surgeon are not the only reason for this. It has become a “gold rush”, says Dr Park. When laparoscopic surgery was first developed there was a surge in the development of new surgical instruments. This time round everyone is keen not to be left behind. But unlike the free-for-all in laparoscopy, in which many surgeons insisted on using their own proprietary devices, doctors and device-makers today appear to be working together to make tools that will be commercially feasible.

Some companies are canvassing doctors for such partnerships. In October the Natural Orifice Surgery Consortium for Assessment and Research, a joint effort of the American Society for Gastrointestinal Endoscopy and the Society of American Gastrointestinal and Endoscopic Surgeons, offered $1m for NOTES-related research proposals. The money will be provided by Ethicon Endo-Surgery, which is part of Johnson and Johnson.

Amid the hype the fact remains that the medical benefits of NOTES remain unproven, so there is an undercurrent of caution. “It's not a revolution, it's an evolution,” says W. Scott Melvin, the surgeon who carried out the first transgastric procedures in America, and who is also the director of the Centre for Minimally Invasive Surgery at Ohio State University Medical Centre, in Columbus. NOTES is really just the next step beyond laparoscopy, in other words. But, he says, adoption has been slow “because of a lack of adequate instruments”. That now seems to be changing fast.