Tool, Not "Smart" Machine
Robotics and long-distance "telesurgery" are increasingly being used to give surgeons a helping hand in the operating room, especially for unusually complex procedures or those that require greater dexterity. But the trans-Atlantic surgery is the first time a robot has held the surgical instruments and done a complete operation.
The surgical robot is not a "smart" machine, guided by artificial intelligence, but only a tool, the researchers emphasized. "All judgments and movements must be done by surgeons," Gagner said. "The robots were doing exactly what we told them to do from here in New York."
Two surgeons were by the patient's side in Strasbourg to intervene if there were complications. One had his foot on an emergency pedal, said Steven Butner, a professor of electrical and computer engineering at the University of California-Santa Barbara who helped Wang and others at Computer Motion design the robotic system. "If he took his foot off the pedal, the robot would freeze and he could take over," Butner said.
The trans-Atlantic surgery was done after nearly two years of work to refine ZEUS, overcome technical limitations, and get approval from oversight agencies in France and the United States to use the remote robot to operate on a human patient.
So far the technology is allowed only for investigational use. The medical team obtained the patient's consent and also had to acquire the go-ahead from an ethical committee that reviewed the proposed procedure.
Gagner said a gallbladder operation was chosen as the first test procedure because it's a "landmark" step in training doctors to perform laparoscopic surgery. "When trained in laparoscopy, it's usually the first procedure doctors do because on average it's a relatively simple operation," he said. "It involves removing tissue only, not reconstructing."
One of the most important issues the engineers had to address was a time lag in the transmission of signals from the surgeon's console to the operating room and backa problem known as latency.
This latency, or delayed response, is critically important in remote surgery, Butner noted, because the operating physicians are able to use only vision to guide their movements. They lack an advantage we have in performing most physical tasks when we rely in part on sensations to guide our actionsapplying a bolt, for example, and knowing from a sense of touch when it's tight enough.
Any electronic signal entails some delay in transmission of the data and conversion into a form that's readable to the recipients. The researchers had to determine how much of a delayed response surgeons could tolerate and still do a remote operation effectively. "We needed to minimize the time lag so the surgeon sees the motion of the robot with minimal latency," Butner said.
Data travelling between the two locations made a round trip of more than 14,000 kilometers.
To determine the acceptable threshold of latency, the researchers artificially altered the time lag of the operations between New York and Strasbourg as surgeons used the robotic technology to remove the gallbladders of several experimental pigs.
"From those experiments we found that surgeons had great confidence in the procedure, the robots ran well. So we wanted to test the procedure in a human operation," Butner said.
The time required for the transfer and video-coding of data meant that movements executed by the operating surgeon in New York were visible to him on his video screen 155 milliseconds later. That delay beat the estimated safe lag time of 330 milliseconds.
Laparoscopy revolutionized the field of medicine over the past decade. It's now widely used for many common surgical procedures, such as treating colon, prostate, and fertility problems.
The technique is popular because it's minimally invasive, usually requiring only a small incision through which to insert a camera scope and surgical tools.
Flexible fiber-optic scopes are typically used to examine or treat ailments of organs such as the throat and colon. For thoracic and abdominal procedures, in which body cavities are larger and surgeons have more room to manipulate tools, the scopes are often rigid and use fixed lenses to transmit light. The ZEUS robot uses a rigid scope with fixed lens, which has the advantage of producing higher-resolution images.
Further improving the quality of surgical treatment today is the power and precision of robotics.
"Robots enhance the capability of surgeons by enabling them to do procedures more evenly and precisely," said Butner. Robots can be programmed to perform micro-motions such as making sutures that are much smaller than those of human surgeons and filtering out inherent human tremors for "rock-steady movement," he pointed out.
Moreover, automation enables surgeons to do more complicated and intricate procedures, Gagner said. "Robots will work beautifully at different angles, locations, and cavities where it may be difficult for human surgeons to maneuver or work without becoming fatigued," he explained.
The trans-oceanic gallbladder operation sets the stage for the next level of sophistication in laparoscopic surgery. "This is very much the leading edge of minimally invasive surgery," said Butner.
Until now, long-distance surgical assistance has been limited mainly to "telemonitoring," the researchers say. And only parts of the surgical process have been automated.
"In the past, a remote surgeon has been able to collaborate with an on-site surgeon, consulting with that [operating] surgeon and providing assistance such as guiding the camera," said Wang. "But this is the first time a complete remote telesurgical operation has been done."
Wang and his collaborators are especially hopeful that the new technology will help raise health standards around the world and make medical expertise more widely available.
"This could be especially important in Third World countries where there are no surgeons or very few," said Gagner. "We could have surgeons donating their time operating in other countries."
To overcome the lack of sufficient cable connections, he suggested, it may be possible in the future to send signals by satellite or microwave. And once the technology is portable enough to be transported by boat or plane, nurses and physicians in other regions of the world could be trained to position the surgical robot.
Said Gagner: "It will be a kind of laptop technology in the future."
SOURCES AND RELATED WEB SITES