How Robotic Surgery Will Work

In today's operating rooms, you'll find two or three surgeons, an anesthesiologist and several nurses, all needed for even the simplest of surgeries. Most surgeries require nearly a dozen people in the room. As with all automation, surgical robots will eventually eliminate the need for some personnel. Taking a glimpse into the future, surgery may require only one surgeon, an anesthesiologist and one or two nurses. In this nearly empty operating room, the doctor sits at a computer console, either in or outside the operating room, using the surgical robot to accomplish what it once took a crowd of people to perform.

The use of a computer console to perform operations from a distance opens up the idea of telesurgery, which would involve a doctor performing delicate surgery miles away from the patient. If the doctor doesn't have to stand over the patient to perform the surgery, and can control the robotic arms from a computer station just a few feet away from the patient, the next step would be performing surgery from locations that are even farther away. If it were possible to use the computer console to move the robotic arms in real-time, then it would be possible for a doctor in California to operate on a patient in New York. A major obstacle in telesurgery has been latency -- the time delay between the doctor moving his or her hands to the robotic arms responding to those movements. Currently, the doctor must be in the room with the patient for robotic systems to react instantly to the doctor's hand movements.

Having fewer personnel in the operating room and allowing doctors the ability to operate on a patient long-distance could lower the cost of health care in the long term. In addition to cost efficiency, robotic surgery has several other advantages over conventional surgery, including enhanced precision and reduced trauma to the patient. For instance, traditional heart bypass surgery requires that the patient's chest be "cracked" open by way of a 1-foot (30.48-cm) long incision. However, with the da Vinci system, it's possible to operate on the heart by making three or four small incisions in the chest, each only about 1 centimeter in length. Because the surgeon would make these smaller incisions instead of one long one down the length of the chest, the patient would experience less pain, trauma and bleeding, which means a faster recovery.

Robotic assistants can also decrease the fatigue that doctors experience during surgeries that can last several hours. Surgeons can become exhausted during those long surgeries, and can experience hand tremors as a result. Even the steadiest of human hands cannot match those of a surgical robot. Engineers program robotic surgery systems to compensate for tremors, so if the doctor's hand shakes the computer ignores it and keeps the mechanical arm steady.

Let's take a look at the different approaches to robot surgery, starting with supervisory-controlled systems in the next section.

Of the three kinds of robotic surgery, supervisory-controlled systems are the most automated. But that doesn't mean these robots can perform surgery without any human guidance. In fact, surgeons must do extensive prep work with surgery patients before the robot can operate.

That's because supervisory-controlled systems follow a specific set of instructions when performing a surgery. The human surgeon must input data into the robot, which then initiates a series of controlled motions and completes the surgery. There's no room for error -- these robots can't make adjustments in real time if something goes wrong. Surgeons must watch over the robot's actions and be ready to intervene if something doesn't go as planned.

The reason surgeons might want to use such a system is that they can be very precise, which in turn can mean reduced trauma for the patient and a shorter recovery period. One common use for these robots is in hip and knee replacement­ procedures. The robot's job is to drill existing bone so that an implant fits snugly into the new joint.

Because no two people have the exact same body structure, it's impossible to have a standard program for the robot to follow. That means surgeons must map the patient's body thoroughly so that the robot moves in the right way. They do this in a three-step process called planning, registration and navigation [source: Brown University].

In the planning stage, surgeons take images of the patient's body to determine the right surgical approach. Common imaging methods include computer tomography (CT) scans, magnetic resonance imaging (MRI) scans, ultrasonography, fluoroscopy and X-ray scans. For some procedures, surgeons may have to place pins into the bones of the patient to act as markers or navigation points for the computer. Once the surgeon has imaged the patient, he or she must determine the surgical pathway the robot will take.

The surgeon must tell the robot what the proper surgical pathway is. The robot can't make these decisions on its own. Once the surgeon programs the robot, it can follow instructions exactly.

The next step is registration. In this phase, the surgeon finds the points on the patient's body that correspond to the images created during the planning phase. The surgeon must match the points exactly in order for the robot to complete the surgery without error.

The final phase is navigation. This involves the actual surgery. The surgeon must first position the robot and the patient so that every movement the robot makes corresponds with the information in its programmed path. Once everyone is ready, the surgeon activates the robot, which carries out its instructions.

­The next type of robot can only act under the direction of a human surgeon. Let's go to the next section and learn about the da Vinci Surgical System.

A product of the company Intuitive Surgical, the da Vinci Surgical System is perhaps the most famous robotic surgery apparatus in the world. It falls under the category of telesurgical devices, meaning a human directs the motions of the robot. In a way, this makes the robot a very expensive high-tech set of tools.

On July 11, 2000, the U.S. Food and Drug Administration (FDA) approved the da Vinci Surgical System for laparoscopic procedures, making it the first robotic system allowed in American operating rooms. The da Vinci uses technology­ that allows the human surgeon to get closer to the surgical site than human vision will allow, and work at a smaller scale than conventional surgery permits. The $1.5 million da Vinci system consists of two primary components:

In using da Vinci for surgery, a human surgeon makes three or four incisions (depending on the number of arms the model has) -- no larger than the diameter of a pencil -- in the patient's abdomen, which allows the surgeons to insert three or four stainless-steel rods. The robotic arms hold the rods in place. One of the rods has two endoscopic cameras inside it that provide a stereoscopic image, while the other rods have surgical instruments that are able to dissect and suture the tissue. Unlike in conventional surgery, the doctor does not touch these surgical instruments directly.

Sitting at the control console a few feet from the operating table, the surgeon looks into a viewfinder to examine the 3-D images being sent by the camera inside the patient. The images show the surgical site and the two or three surgical instruments mounted on the tips of the surgical rods. The surgeon uses joystick-like controls located underneath the screen to manipulate the surgical instruments. Each time the surgeon moves one of the joysticks, a computer sends an electronic signal to one of the instruments, which moves in sync with the movements of the surgeon's hands. Working together, surgeon and robot can perform complete surgical procedures without the need for large incisions. Once the surgery is complete, the surgeons remove the rods from the patient's body and close the incisions.

The final category of robotic surgery devices is the shared-control system. We'll learn more about this kind of robot on the next page.

Shared-control robotic systems aid surgeons during surgery, but the human does most of the work. Unlike the other robotic systems, the surgeons must operate the surgical instruments themselves. The robotic system monitors the surgeon's performance and provides stability and support through active constraint.

Active constraint is a concept that relies on defining regions on a patient as one of four possibilities: safe, close, boundary or forbidden. Surgeons define safe regions as the main focus of a surgery. For example, in orthopedic surgery, the safe region might be a specific site on the patient's hip. Safe regions don't border soft tissues.

In orthopedic surgery, a close region is one that borders soft tissue. Since orthopedic surgical tools can do a lot of damage to soft tissue, the robot constrains the area the surgeon can operate within. It does this by providing haptic responses, also known as force feedback. As the surgeon approaches the soft tissue, the robot pushes back against the surgeon's hand.

As the surgeon gets closer to soft tissue, the instrument enters the boundary region. At this point, the robot will offer more resistance, indicating the surgeon should move away from that area. If the surgeon continues cutting toward the soft tissue, the robot locks into place. Anything from that point on is the forbidden region.

Like the other robots we've looked at, shared-control system robots don't automatically know the difference between a safe region versus a forbidden region. The surgeons must first go through the planning, registration and navigation phases with a patient. Only after inputting that information into the robot's system can the robot offer guidance.

Out of the three kinds of robot surgical systems, the telesurgical approach has received the most attention. The success of the da Vinci Surgical System caught the attention of doctors and the media alike. We may see more examples of shared-control and supervisory-controlled systems in the future.

While surgical robots offer some advantages over the human hand, we are still a long way from the day when autonomous robots will operate on people without human interaction. But, with advances in computer power and artificial intelligence, it could be that in this century scientists will design a robot that can locate abnormalities in the human body, analyze them and operate to correct those abnormalities without any human guidance.

To learn more about robots, medicine and related topics, take a look at the links on the next page.