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The robot surgeons

In some German clinics it is already a common view: The patient lies on the operating table. Above him are four sterile robot arms. A few feet away from the table, the surgeon sits in a kind of cockpit, concentrating his head in an opening in the apparatus, where he sees images of the patient’s body magnified up to tenfold. With control handles, the surgeon operates the arms of the robot, performing mainly prostate, bladder and kidney surgery. The logo always says “da Vinci” on the robots. The US company Intuitive Surgical has built a monopoly since its approval in 2000 with this system and made a huge business.

Now, however, a whole series of robots are in the starting blocks, which make da Vinci competition with more intelligence. One reason for this is that relevant patents have expired. However, caution should be taken with the coming robot boom: Surgeons say that the robots make some operations easier, but not all, and the high cost of a robot could lead clinics to use the technique for balance sheet reasons, not just for the benefit of the patient.

About 877,000 patients were operated worldwide with the help of da Vinci last year. 684 of these systems, the manufacturer sold in the same year – depending on the equipment for up to two million Euros plus a maintenance contract with up to just under 150,000 Euros per year. In addition, there are 500 to 3,000 Euros of consumption costs per operation.

The benefits of da Vinci are still debated after 18 years. In the USA clinics advertise offensively: There are fewer complications, less pain, less blood loss, shorter hospital stays. But so far, there are no independent studies that provide sufficient evidence. Benjamin Chung, a professor of urology at the University of Stanford, found neither convincing arguments for a surgery with da Vinci in one of the few long-term studies nor against it.

Chung said in a press conference that there are no significant statistical differences in the outcome of the surgery or the length of hospital stay. The study covered a period of 13 years. What is certain is that robotic-assisted surgery costs more – about € 2,000 more per patient. Also, the likelihood of a longer operating time with robots is higher.

Researchers at the University of Illinois came to another conclusion with da Vinci: in 14 years there were 144 deaths, 1391 injuries and 8061 device errors. Hot parts of the instruments fell in the patient, the instruments carried out unwanted actions, there were system crashes and problems in the image display. However, these reports affect older versions of the device. In addition, the study does not reveal how many complications there were in the same period without robots.

Today, surgeons say that the system actually makes their surgery easier, including Professor Sören Torge Mees, Managing Director of the Department of Visceral, Thoracic and Vascular Surgery of the Dresden University of Technology. “We use the robot primarily for oncological surgery, when we need to be particularly subtle, for example, deep down in the pelvis in a rectal resection – the rectal removal.” Due to the spatial tightness and bleeding, the view can be significantly limited. Da Vinci helps with his visual enlargement, but also with his four arms: one arm leads the camera, three arms work and an assisting surgeon at the operating table can intervene in addition.

In esophageal surgery, the seven so-called degrees of freedom of the robotic instruments are useful for sutures: The robots have more joints than a human hand and, according to Mees, are clearly superior to the classical minimally invasive instruments. For surgeons, the system is ergonomically advantageous because they can sit in the chair and do not have to dislocate over the patient, as is necessary in some minimally invasive surgeries.

“On the other hand, you work so concentrated in a small area that it can still be exhausting in a multi-hour operation,” says Mees. But the device also has disadvantages: The surgery time can indeed extend, since the operation takes time. It will take a long time for surgeons to get involved. In a gastric surgery, an experienced surgeon needs in about 20 procedures to achieve the same quality with the system as without, in pelvic operations rather 50. Also, the device is technically not yet mature. Mees says, “when I work between the upper abdomen and lower abdomen in larger areas, I have to be careful that the robot’s arms do not collide.” That could be prevented with sensors.

Another disadvantage is the lack of feeling. An experienced surgeon can palpate a tumor with minimally invasive surgery because he senses the resistance of the nodule. In a robot-assisted surgery, surgeons need makeshift mechanisms – such as pre-marking the tumor with ink or clips so they know exactly where it is.

“There are, therefore, operations where the da Vinci Surgical System has clear advantages in my opinion, such as in prostate surgery, deep down in the pelvis, or in the chest,” says Mees. “For other OPs, the system is unlikely to prove superior to traditional minimally invasive surgery.” Indeed, initial studies indicate that the system is no better for gallbladder or uterine removal, for example. In addition, it has not yet been proven to what extent the benefits for surgeons also bring which for patients.

The manufacturers of new robots therefore want to do something different than at da Vinci and steal from him market share. There is, for example, the TransEnterix “Senhance Surgical Robotic System”, which consists of three robotic arms and is suitable for the same operations. It has force eedback: The surgeon can roughly feel the resistance of the tissue being touched by the robotic arm. By eye tracking – the measurement of eye movements – the surgeon can control the endoscope with his eyes so that he has his hands free to control the other instruments.

The system was recently approved by the FDA in the US. Other robots that are coming soon or have already arrived are from companies such as Versius, Medtronic, CMR Surgical, Auris Health, Smith & Nephew, Stryker, Mazor Robotics and Zimmer Biomet.

However, these systems do not bring major innovations into the OR. The haptic feedback, for example, has to become much more precise, for instance in order to be able to differentiate automatically healthy tissue from tumor tissue. Alexander Schlaefer, Professor of Medical Systems at the Technical University of Hamburg is working on this problem. One challenge is to do this without additional sensors on the instruments. The integration would otherwise be too expensive, as well as the cleaning too difficult.

His team relies on a combination of endoscope and optical coherence tomography. “It allows us to see how the tissue in the body reacts when it comes into contact with an instrument – how it deforms on the surface and below,” says Schlaefer. The difficulty is to deduce from this information the exact force acting on the tissue and the software must be as fast as possible to minimize latencies during surgery. Pinpointing the force would be helpful in providing the surgeon with more accurate haptic feedback than before, but also to better isolate tumors – helping surgeons to completely remove the tumor and damage as little healthy tissue as possible. It will probably be years before robots get that done reliably.
 
As long as there are no such significant advances and independent studies are lacking, it is not easy for patients and clinics to opt for or against surgery with one of the new robots. There is a risk that clinics will purchase an expensive system and use it for operations that it may not be ideal for – to get the cost back. The company CMR Surgical even plans not to sell a robot to the clinics, but instead to offer a service contract – the clinics would have to commit to a minimum number of missions, so that it is worthwhile for all. The company keeps the system up to date.

“Ultimately, it is extremely difficult to evaluate such technologies,” says Jörg Raczkowsky, Head of the Medical Group at the Institute of Anthropomatics and Robotics of the Karlsruhe Institute of Technology. From a neutral point of view, a system is worthwhile only if it prevents reoperation or complications or, for example, exposes the patient to less radiation during the operation. “But only statistics can prove that in the long run.”

(This is a translation of my article that was published in Süddeutsche Zeitung.)

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