Satellite Latency No Problem For Surgeons

Recent advances in minimally invasive robotic telesurgery — now being performed via satellite — are taking on greater significance now that space agencies are planning flights to the moon and perhaps Mars that will last considerably longer than missions conducted today.

NASA is conducting robotic telesurgery and sensor support experiments under its NASA Extreme Environments Mission Operations (NEEMO) program. The tests are taking place 60 feet below the surface of the Atlantic Ocean at Aquarius, the agency’s underwater habitat and laboratory facility 3 miles off Key Largo in the Florida Keys National Marine Sanctuary.

In order for a surgeon to perform and monitor a surgical procedure while maintaining voice contact with medical and technical staff in another location, the correct amount of satellite bandwidth must be allocated to support high-quality video as well as a direct link for providing robotic control.

Using satellite capacity provided by Telesat Canada, Canadian researchers found attempts to perform robotic telesurgery via satellite links operating at less than 3 megabits per second (Mbps) to be unsuccessful and recommend that any satellite communications link for this purpose must be at least 5 Mbps.
While there are numerous challenges when performing surgery while relying on satellite communications, signal delay, or latency, is not viewed as a significant problem, according to researchers from the University of Western Ontario’s Department of Medical Biophysics and the London, Ontario-based Canadian Surgical Technologies & Advanced Robotics (CSTAR). Despite delays of more than 500 milliseconds, surgeons were not distracted by this latency once they became accustomed to it.

“Without any predictive or virtual reality software, dealing with the raw data of delayed video signals would be difficult in urgent clinical surgery. During real surgery in the lab, there was no significant difference in productivity or quality of surgery when ground and satellite [Internet Protocol] were compared, even though satellite delays were about 10 times longer (approximately 600 milliseconds),” says Dr. Reiza Rayman of the University of Western Ontario and a co-author of “Robotic telesurgery: a real-world comparison of ground- and satellite-based internet performance.”

“Overall, the experiments to date have shown that both ground and satellite based robotic telesurgery are quite feasible, but predictive virtual reality software methods would greatly help with clinical procedures,” Rayman says in the article published in June in The International Journal of Medical Robotics and Computer Assisted Surgery.

Evidence from other CSTAR experiments suggests that satellite network jitter is not an issue either, says Christopher Schlachta, medical director of CSTAR. Earlier research teams often injected jitter into their landline connections to see how disruptive it might prove to be.

“Experienced surgeons simply learn to move more slowly and make more definite and predictable actions. Most studies suggest that experienced surgeons can accommodate a delay of 300 milliseconds for complex tasks, and from our evidence, up to 600 milliseconds for simpler tasks,” says Schlachta. “It actually increases the efficiency of surgery to a certain extent.”

Robotic prototypes requiring no human intervention and suitable for use in hazardous environments that preclude the presence of a surgeon and health care team are “a very hot and active area of research,” says Schlachta. NASA, the U.S. Defense Advanced Research Projects Agency and the U.S. Army’s Telemedicine and Advanced Technology Research Center are among those funding this research.

This advancements would be a boon to the field, as current robotic systems remain large, awkward and very mechanical, according to Charles Doarn, deputy director at the University of Cincinnati’s Advanced Center for Telemedicine and Surgical Innovation, which is participating in several NEEMO projects.

“These systems are being trimmed in size and enhanced with more capability. Telecommunication and information technology systems require continued improvement,” Doarn says. “Evolving technologies and capabilities will enable systems to be used autonomously at distant sites (such as Mars where one-way communication to Earth takes as long as 22 minutes).
“Autonomous function, minimizing latency and the introduction of haptics — the application of tactile sensation to human interaction with a system — are key to moving forward with wider adoption,” says Doarn. “In addition, human clinical trials will be vitally important to early adoption and sustainable business models.”