The possibilities and challenges created by “smart” machines replacing humans have been a staple of science fiction for nearly 150 years, beginning with Samuel Butler’s novel Erewhon. Since then, the theme of smart machines has been developed in numerous books and films, some of which portray smart machines as mankind’s helpers like Isaac Asimov’s Robot books.
In a development that sounds right out of one of Asimov’s books, surgeons and scientists recently demonstrated that supervised, autonomous robotic soft tissue surgery on a live subject (in vivo) in an open surgical setting not only is feasible, but also outperforms standard clinical techniques.
The research study, published last month in Science Translational Medicine, reports the results of soft tissue surgeries conducted on both inanimate porcine tissue and living pigs using proprietary robotic surgical technology, Smart Tissue Autonomous Robot (STAR), developed at Children's National. This technology removes the surgeon's hands from the procedure, instead utilizing the surgeon as supervisor, with soft tissue suturing autonomously planned and performed by the STAR robotic system.
Soft tissues are the tissues that connect, support or surround other structures and organs of the body such as tendons, ligaments, fascia, skin, fibrous tissues, fat, synovial membranes, muscles, nerves and blood vessels. Currently more than 44.5 million soft tissue surgeries are performed in the U.S. each year.
"The intent of this demonstration is not to replace surgeons, but to expand human capacity and capability through enhanced vision, dexterity and complementary machine intelligence for improved surgical outcomes,” Kim adds.
WHAT ARE SMART MACHINES?
Smart machines are hardware or software systems that can accomplish their designated task even under conditions of uncertainty and variability.
According to BCC Research analyst Andrew McWilliams, smart machines also are able to:
- Operate autonomously (without direct human supervision) or at least
- semi-autonomously.
- Adapt to and learn from changing conditions in real time.
- Communicate with other machines.
McWilliams divides the global market for smart machines into five segments: expert systems, eurocomputers, autonomous robots, smart embedded systems and intelligent assistants.
He says expert systems made up the largest share of the market in 2015, followed by autonomous robots and intelligent assistants. However, by 2026 intelligent assistants are expected to be the largest market segment, followed by autonomous robots, McWilliams anticipates. Expert systems should fall to third place.
McWilliams estimates the total market for these technologies, which reached $6.6 billion in 2015, to increase to more than $7.4 billion in 2016, nearly $15 billion in 2021, and $40.3 billion in 2026.
STAR SYSTEM MAKES ROBOT-ASSISTED SOFT TISSUE SURGERY A REALITY
While robot-assisted surgery (RAS) has increased in adoption in healthcare settings, the execution of soft tissue surgery has remained entirely manual, largely because the unpredictable, elastic and plastic changes in soft tissues that occur during surgery, requiring the surgeon to make constant adjustments.
To overcome this challenge, STAR uses a tracking system that integrates near infrared florescent (NIRF) markers and 3D plenoptic vision, which captures light field information to provide images of a scene in three dimensions. This system, which enables accurate, uninhibited tracking of tissue motion and change throughout the surgical procedure, is combined with another STAR innovation, an intelligent algorithm that guides the surgical plan and autonomously makes adjustments to the plan in real time as tissue moves and other changes occur.
The STAR system also employs force sensing, submillimeter positioning and actuated surgical tools. It has a bed-side lightweight robot arm extended with an articulated laparoscopic suturing tool for a combined eight degrees-of-freedom robot.
"Until now, autonomous robot surgery has been limited to applications with rigid anatomy, such as bone cutting, because they are more predictable," says Axel Krieger, technical leader for Smart Tools at the institute. “By using novel tissue tracking and applied force measurement, coupled with suture automation software, our robotic system can detect arbitrary tissue motions in real time and automatically adjust."
HOW STAR’S EFFECTIVENESS COMPARES WITH OTHER SURGICAL PROCEDURES
To compare the effectiveness of STAR to other available surgical procedures, the study included two different surgeries performed on inanimate porcine tissue (ex vivo), linear suturing and an end-to-end intestinal anastomosis, which involves connecting the tubular loops of the intestine. The results of each surgery were compared with the same surgical procedure conducted manually by an experienced surgeon, by laparoscopy, and by RAS with the daVinci Surgical System.
Intestinal anastomosis was the surgical procedure conducted on the living subjects (in vivo) in the study. The Children's National research team conducted four anastomosis surgeries on living pigs using STAR technology and all subjects survived with no complications. The study compared these results to the same procedure conducted manually by an experienced surgeon using standard surgical tools.
"We chose the complex task of anastomosis as proof of concept because this soft tissue surgery is performed over one million times in the U.S. annually," says Kim.
All surgeries were compared based on the metrics of anastomosis including the consistency of suturing based on average suture spacing, the pressure at which the anastomosis leaked, the number of mistakes that required removing the needle from the tissue, completion time and lumen reduction, which measures any constriction in the size of the tubular opening.
STAR PROVES SUPERIOR TO HUMAN HANDS AND RAS TECHNIQUES
The comparison showed that supervised autonomous robotic procedures using STAR proved superior to surgery performed by experienced surgeons and RAS techniques, whether on static porcine tissues or on living specimens, in areas such as consistent suture spacing, which helps to promote healing, and in withstanding higher leak pressures, as leakage can be a significant complication from anastomosis surgery. Mistakes requiring needle removal were minimal and lumen reduction for the STAR surgeries was within the acceptable range.
In the comparison using living subjects, the manual control surgery took less time, eight minutes versus 35 minutes for the fastest STAR procedure, however researchers noted that the duration of the STAR surgery was comparable to the average for clinical laparoscopic anastomosis, which ranges from 30 minutes to 90 minutes, depending on complexity of the procedure.
Kim says that since supervised, autonomous robotic surgery for soft tissue procedures has been proven effective, a next step in the development cycle would be further miniaturization of tools and improved sensors to allow for wider use of the STAR system.
He adds that, with the right partner, some or all of the technology can be brought into the clinical space and bedside within the next two years.
