Colon Surgery Without Staples -- In-Depth Doctor's Interview

What is NITI?

Dr. Daniel Marcus: The NITI, or N-I-T-I, is a combination alloy of nickel and titanium, which is where the term NITI comes from. It is what we call a compression astomosis ring, or CAR. It's a way of joining two segments of bowel, primarily colon, in a way that is very different from what's been done for the last 30 years.

When would you use it?

Dr. Daniel Marcus: We use this for resections of the colon, either for cancer or for inflammatory diseases like diverticulitis. Traditionally, people would just resect or remove the portion that was diseased, and sew the two ends back together again. About 30 years ago, a revolution of stapled anastomosis -- the term for connecting the two parts of bowel together -- was introduced, and that enabled surgeons to do this technique much more quickly, and pretty consistently, with very little variability between surgeons, and that's been the mainstay, basically the way of connecting two pieces of tissue together. What's changed is trying to look at some of the complications and some of the potential benefits of doing that technique without staples, which has been the standard way of connecting those tissues up until now.

How does this work?

Dr. Daniel Marcus: NITI enables metal to be formed into different shapes at cold temperatures. It is as flexible as rubber, and you can shape it into something and then shock it at a higher temperature where it will form its original, preferred shape, it is a shape memory metal.  Interestingly, it was actually developed by the Russian Navy some 20 years ago, to deal with submarines that were going into deep, cold water, and had to have an ability to have a malleable, or a shapeable type of metal So we use this type of technology to reshape and create a constant pressure between the two rings which bring the two pieces of bowel together. The two rings are on either end of the bowel, and there is a way of connecting them that continues to compress the tissue. After about ten to twelve days, it completes the healing process and is passed out the bottom, leaving behind a connection or an astomosis which is completely without any permanent  foreign material – there are no staples, no sutures, nothing. We think there is less potential  for that tissue to narrow down, which is always a problem when you form two bowel pieces together.

Why does that usually happen?

Dr. Daniel Marcus: If you think about, you have two pieces of bowel that are very flexible. As soon as you bring in a piece of metal joining those two, it is a rigid component in that connection, so with time -- even though those staples are very small and they will separate -- there is a rigid piece of material there and that can cause a bit of a waist, or a narrowing at that one point, which we call a stricture. Often that's not a problem, but sometimes that stricture can become so narrow that it causes a bowel obstruction. That's one of the problems. The other main concern, which is a more immediate and a bigger concern to surgeons, is the staples that are used to connect the bowel, especially very low in the pelvis sometimes can cause micro-perforations, or very small holes in the connection. Clearly, that can be bad, because it can create what we call a leak. And if any of the material from inside the colon leaks, it can cause an infection or an abscess or other complications that can cause the patient to need another operation or antibiotics. So the ability to form a union with less potential for a leak is very attractive.

Explain how this ring prevents it.

Dr. Daniel Marcus: By the ring forming basically a joining of two parts of the bowel, there is a rigid solid union initially for the first seven to 10 days, because the bridge is a solid metal ring. Once that ring cuts through the bowel and passes, it's sort of like the hem on a skirt or a pair of pants -- the only thing there is the tissue itself, so there are no small holes, whatsoever. There are pins that hold the two bowel pieces together, but beyond that it passes and there is very little potential for a leak. We know this because we can do what's called a pressure, or burst test. And if we take in an animal model, we can test what kind of pressure is required to force a leak in different materials. So if we do it in a staple anastomosis, or a staple connection, that leak rate is somewhere between 30 and 50 millimeters of mercury pressure.  If we do it with the compression and astomosis ring, that is about three times higher a number that you need to cause a burst, or a leak, so clearly, that translates to much of a lower incidence of leaks and abscesses.

What have you seen as far as the benefits for the patient and their recovery?

Dr. Daniel Marcus: We're doing a lot of laparoscopic colon resections, which has already lowered the length of stay of the patients in the hospital. Our average length of time in the hospital for a colon resection is about two-and-a-half to three days. There have been studies that have proven that laparoscopic colon resection has the advantage of shortening the length of time that a patient is in the hospital. This device is not limited to laparoscopic or open, as we call it, but we do think that there's a possibility that patients may also get out of the hospital sooner, whatever technique is used, because the ring itself enables less swelling around the tissue because it's almost like a stent -- it's a solid material. Usually what keeps a patient in the hospital is the return of their G.I. function. As soon as they can eat, then they can go home. This is all what we call anecdotal -- we don't have large numbers to substantiate this, but we think that there may be a potential for patients to get out of the hospital sooner. The most important thing really though, is that if it can in fact reduce the leak and the abscess and the stricture complications, that is a significant improvement over what we've seen so far.

In general, would you say this is moving in the right direction?

Dr. Daniel Marcus: I think so. This is not the first time people have tried other techniques, but this is relatively new. The concept of having a connection without a permanent product material remaining is very attractive. That by itself wouldn't be enough to push it along. But this also has the ability to reduce these complications and more importantly without it costing any more financially or without it causing a great learning curve, so surgeons can use this technique and learn how to do it very quickly. It's not any different than what we currently do. The platform is very similar, meaning it's like driving a Ford versus a Lincoln. If somebody can do one, they will be able to learn the other quite quickly.

Are there any risks in using this?

Dr. Daniel Marcus: It's still relatively early. Worldwide, there have been 0ver 1000 of these colon anastomosis cases done, and so far, the initial data is very impressive. The risks are like with any surgery. There still is a potential for leaks, there is potential for a disruption of the anastomosis, meaning a breakdown of that connection. But so far, those have occurred at less of a percentage, less of an incidence than we've seen with staple anastomosis. The other potential benefit, which we haven't talked about, is bleeding. Sometimes the staples themselves can cause some bleeding at the connection, at the anastomosis because there is a series of very sharp staples that is connecting these two ends. That usually does not require a return to the operating room, but sometimes it does require a transfusion. Again, with a compression anastomosis we would expect to markedly reduce that incidence of bleeding.

Is colon surgery fairly common?

Dr. Daniel Marcus: Colon surgery, over the years as we've seen, is quite common. Colon cancer, unfortunately, is on the rise. Diverticulitis, which is the other reason people would have their colon operated on, is relatively common. There are about 400,000 colon resections or colon surgeries done a year, and of that number, at the lower part of the colon, probably about 110,000, so they're pretty big numbers. There's a significant rise because of the increase in awareness of colon cancer. Many more people, as you're aware, are getting colonoscopies now. So we're much better at getting to patients much earlier, when of course, colon cancer can be cured if we get it at an early stage.

If this proves to be successful, when do you think it could be fairly commonly used?

Dr. Daniel Marcus: I think in a relatively short period of time. Much of it depends on clinical data, of course, and initially having some idea that we're going to see an advantage, which would then prompt larger centers and larger multi-center studies to be done. Sometimes that takes a long time to get started. This study from the NIH and Mayo Clinic which looked at laparoscopic and open colon surgery took almost eight years to complete because it was a numbers issue. If we can first establish that there's no negative impact of using this device, and that we're at least as good, I think it will encourage more people to be interested in it. Certainly, I think surgeons, primary care physicians, and patients themselves would be very interested in anything that might reduce complications that we currently are seeing on a daily basis.