Robots are a growing presence in operating rooms throughout the U.S. as surgeons embrace the technology to help them remove damaged organs or cancerous tissue. These systems have improved greatly in recent years but still need hands-on surgeons to guide their instruments and make critical decisions. Turning a robot loose on its own to cut and sew delicate tissue inside a human body would be a massively complex undertaking requiring advanced imaging, sensor and artificial intelligence technologies—not to mention a lot more acceptance from the medical community and federal regulators.
But those hurdles have not stopped scientists at Children’s National Medical Center’s (CNMC) Sheikh Zayed Institute from developing a robotic system that has successfully sutured and reconnected portions of pig intestine in a living animal with little or no human intervention, according to a report in the May 4 Science Translational Medicine.
Soft tissue surgeries like this one, which is called intestinal anastomosis, are especially challenging for robotic systems because the tissue changes shape and moves around during the procedures. CNMC’s Smart Tissue Autonomous Robot (STAR)—although not yet completely autonomous—is designed to compensate for this by using a 3-D and near-infrared fluorescent imaging system, a force sensor and a preprogrammed algorithm to determine the appropriate type, tension and location of sutures.
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In the pig experiment the researchers placed markers, which fluoresced under infrared light, in the intestinal tissue. STAR’s imaging system tracked their positions down to the millimeter during the surgery. The robot’s computer developed and adapted its suturing approach—a combination of knots and running stitches—as it received information from the imaging system. Researchers had programmed the system with data about ideal suturing practices including spacing and tension, which could be consulted throughout to prevent leaks.
To test STAR’s performance the researchers recruited surgeons to perform the identical procedure on pig intestines using three other methods: hand-sewn sutures, laparoscopy and the robot-assisted da Vinci Surgical System approved by the U.S. Food and Drug Administration in 2000. According to the researchers, STAR outperformed these other techniques in terms of ideal spacing between sutures—and this enabled the STAR-repaired intestine to withstand nearly twice as much pressure before leaking, compared with the intestines sutured manually.
There were, of course, several caveats to STAR’s success. The robot system actually operated autonomously for only 60 percent of the experiment, with researchers making minor adjustments to the equipment as the robot worked. The intestinal suturing could been performed without human intervention, Peter Kim, professor of surgery and the lead for the Sheikh Zayed Institute, insisted at a press conference Tuesday—but “we were like parents with a young child that was about to walk.” STAR also sutured more slowly than its human counterparts, although Kim and colleagues Axel Krieger and Ryan Decker said it could be programmed to work faster. They acknowledged at the conference that their experiment was mainly a proof of concept, designed to determine that a robot could perform a particular surgery alone under specific conditions.
The idea is not to replace surgeons, the researchers said, but to add machine intelligence that improves surgical procedures. “Anytime you have a significant anastomotic leak, as [in] your intestine leaks, the risk of dying from it goes up by three to 10 times,” Kim said. “So if you have a technology that can potentially mitigate or reduce that, I think that's a very clear value.”
STAR’s ability to work without human intervention, while limited, makes it unlike any other robotic option available to surgeons. So far, Intuitive Surgical Inc.’s da Vinci system is the only general-purpose robotic surgery platform with FDA approval. Since 2000 da Vinci has helped surgeons perform a number of laparoscopic soft-tissue procedures including hysterectomies, gall bladder and kidney removals, prostate cancer treatment and heart valve operations. The key to da Vinci’s acceptance thus far has been the hands-on role the surgeon plays, controlling the robot’s four arms while sitting at an ergonomically designed console and aided by a high-definition 3-D camera. Despite its nearly $2-million price tag, da Vinci’s popularity has grown steadily. In 2012 doctors used the system to perform more than 350,000 surgeries in U.S. hospitals, a 60 percent increase from 2010. Based on its success, sales of surgical robotic systems are expected to climb from $3.3 billion in 2014 to about $6.4 billion in 2020, according to a report that Allied Market Research issued in January.
CNMC’s work is a “technical breakthrough” because of its integration of various technologies, rigorous animal testing and the quality of the suturing, says Blake Hannaford, who was not involved in the pig surgery and is director of the University of Washington’s BioRobotics Lab and co-founder of Applied Dexterity, a start-up developing an open-source robotic surgery system called the RAVEN. Hannaford, however, points to STAR’s current limitations and questions whether such a technology will have much value to surgeons in the near term. “While in a technical sense semi-autonomous suturing is a ‘grand challenge’ problem of surgical robotics, clinically much suturing and bowel anastomosis is done by [surgeons using] staplers, which can do the whole thing in seconds,” he says.
The success of autonomous operating room robots will ultimately rest with surgeons and their patients, says T. Sloane Guy, director of Robotic Cardiac Surgery at Weill Cornell Medical College’s Department of Cardiothoracic Surgery. Guy, who has used da Vinci to perform cardiac surgeries for the past several years, says patients frequently express concerns about how much control surgeons cede to robotic systems.
“I’m thrilled to hear that this type of research is being done,” Guy says of CNMC’s latest experiment. But he adds that this work is one of several stepping-stones that could take robotic surgical systems to full autonomy. “Part of my job as a doctor is to bring technology to patients that is beneficial to them as well as educate them regarding both the technology’s advantages and limitations. As a doctor, I have to be 100 percent convinced that I can trust a given technology and that it’s not some sort of gimmick.”
