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CHICAGO -- A capsule endoscope steered by magnets attached to an external robotic arm successfully performed automated retroflexion maneuvers in the porcine colon, researchers reported here -- a critical early step in developing a fully autonomous capsule device that can outperform conventional colonoscopes.
As explained by senior investigator Keith Obstein, MD, of Vanderbilt University in Nashville, the small capsule -- 18 × 21 mm at the head, tapering to 6.5 mm -- should be capable of more complete visualization of the colon's interior surface.
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
Obstein, speaking to reporters at Digestive Disease Week 2017, where the research was presented during a poster session, said the ability to turn the device completely around -- that's the retroflexion maneuver -- would allow the operator to look behind colonic folds that would otherwise be out of view with a standard endoscope.
He also said the capsule should be less prone to distend the colon during complex maneuvers, compared with conventional colonoscopy, with consequent lower risk of perforations, as well as less discomfort to patients and need for sedation. That, in turn, would make it more attractive for patients with inflammatory bowel disease (IBD) who typically undergo colonoscopies annually.
Indeed, Obstein said, IBD patients are likely to be the first patient population to be targeted in clinical development.
Described in the poster as an "autonomously controlled capsule robot," the device so far has been tested ex vivo and in vivo in pigs. Obstein estimated that a live human trial could begin in about 18 months, although he declined to speculate whether it would involve healthy volunteers or patients.
The control is exerted by a robotic arm hovering over the abdomen, using magnets to pull the capsule through the colon and execute turns. The "autonomous" part is that the arm's magnetic control is computerized to perform a retroflexion maneuver, which Obstein said would be exceedingly difficult for the human operator to manage on his or her own.
"Any repetitive or complex maneuver is ripe" for robotic automation, he said.
In essence, the operator issues a command to perform the maneuver, at which point the computer takes over control of the arm and thus the capsule. This has been technically difficult to pull off with magnetic control because of the high field gradients: the arm must remain at a very nearly fixed distance from the capsule to avoid losing contact (if it gets too far away) or pulling it too hard against the colonic wall (if too close).
The pig studies reported here indicated that the desired amount of control was achieved, with every one of 30 attempts to perform a retroflexion successful. Completion times ranged from 9.4 to 17.1 seconds in a constrained setting and from 11.8 to 19.2 seconds unconstrained. Necropsy studies afterward showed no signs of leakage or trauma.
The capsule includes a soft, thin tethering cable for transmitting video. Also, through it, the operator can perform conventional colonoscopic function such as insufflation, irrigation, and biopsy sampling.
Obstein said the next phase of development would be to give the capsule forward-looking vision, allowing the operator to drive it as if he or she were inside, like a car.
Disclosures
The work was funded by U.S. government grants and the Royal Society.
Obstein and co-authors disclosed no relevant relationships with industry.
Primary Source
Digestive Disease Week
Sarker S, et al "The first autonomously controlled capsule robot for colon exploration" DDW 2017; abstract Mo1962.