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Remote Surgery

A common robotic surgical system generally consists of one or more robotic arms (controlled by the surgeon), a surgeon console, and a sensory system giving feedback to the user [1]. Usually, the robotic surgical system consists of a surgeon's console that is typically in the same room as the patient, and a patient-side cart with interactive robotic arms controlled from the console. The surgeon uses the console's master controls to maneuver the patient-side cart's robotic arms. The instruments' jointed-wrist design exceeds the natural range of motion of the human hand; motion scaling and tremor reduction further interpret and refine the surgeon's hand movements. The robotic surgical system always requires a human operator, and incorporates multiple redundant safety features designed to minimize opportunities for human error when compared with traditional approaches. Figure 1 indicates one robotic surgery scenario using robotic surgical system.

Figure 1 Example of robotic surgical system
In the robotic surgery prototype, the surgeon before the console is seated at a 20-foot distance from the patient cart and surgical robot as the shown in the Figure 2.

Figure 2 One Example of Robotic Surgery Prototype
Remote surgery (also known as telesurgery) is the ability for a doctor to perform surgery on a patient even though they are not physically in the same location. It further includes the high-speed communication networks, connecting the surgical robot in one location to the surgeon console at another location manipulating the robot through an operation. 
Remote telesurgery allows the specialized surgeons to be available to the patients worldwide, without the need for patients to travel beyond their local hospital. This is illustrated in the following Figure 3. Think of an injured soldier needing immediate, specialized surgery on a battlefield. Then consider a reality where a surgeon wouldn't need to enter said war zone to operate on a soldier, but could perform the surgery from thousands of miles away. Or, imagine a doctor in an urban city, performing an urgent procedure on a patient in an inaccessible rural area.

Figure 3 Remote Telesurgery
The concept of telesurgery is certainly not a brand new one. In fact, it's been around for more than a decade. Back in the early 2000's, the first complete trans-atlantic robotic surgery happened in 2001 [2], Dr. Jacques Marescaux in New York removed a 68-year-old woman's gall-bladder as she lay across the ocean in Strasbourg, France, more than 7,000 kilometers away shown in Figure 4.


Figure 4 Dr. Jacques Marescaux was operating remotely
The Communication networks between the New York and Strasbourg were done through asynchronous transfer mode (ATM) technology (France Telecom/Equant's, Paris, France). ATM network nodes are interconnected through a high-speed terrestrial fiber-optic network that transports data through virtual connections dedicated per customer, providing a low transport delay, high reliability and low packet loss ratio [3]. However, the expense of dedicated ATM network is highly costly, there was no practical way to transmit large amounts of data quickly or reliably enough to make the concept a reality, it will be preferable to use conventional network infrastructures for the future expansion of telesurgery.

Impacts on the Network

With the development of 5G research, a recent 5G White Paper deliverable from Next Generation Mobile Network (NGMN) releases several 5G characteristics [4]. Remote surgery is part of what is characterized as "Ultra-reliable Communications". In order to ensure a telesurgery procedure to be highly safe, we would require a particularly unique demand on the network, at least including very reliable connection (99.999% availability), sufficient bandwidth to ensure adequate video resolution as required by the remote surgeon controlling the robot, as little as possible latency allowing the feel of instantaneous reaction to the actions of the surgeons and of course as little as possible latency variation (i.e., jitter) allowing system or human correction of the latency.
The Nicholson Center at Florida Hospital has successfully tested the latency time created by the Internet for a simulated robotic surgery in Ft. Worth, Texas, more than 1,200 miles away from the surgeon in Orlando hospital campuses [<ac:structured-macro ac:name="anchor" ac:schema-version="1" ac:macro-id="8dc6c2ad-06a3-4f10-a62e-6b823da96df0"><ac:parameter ac:name="">_Hlt492042456</ac:parameter></ac:structured-macro>5]. The experiment aims to determine the end-to-end latency threshold--that is, the amount of delay a surgeon can experience between the moments they perform an action to the moment video of the action being carried out at the surgery site reaches their eyes. The problem has less to do with the speed of light at which electrons travel via fiber optics and more to do with Internet provider processing times. To find the E2E latency threshold, the team used simulators to introduce a video delay while having surgeons perform basic surgical tasks.
Findings show that at 200 milliseconds, surgeons could not detect a lag time. From 300 to 500 milliseconds, some surgeons could detect lag time, but they were able to compensate for it by pausing their movement. But at 600 milliseconds, most surgeons became insecure about their ability to perform a procedure.

Figure 5 the effects of lag times on remote telesurgery
From above scientific study, that E2E latency beyond 200 milliseconds affects the performance of surgeons and beyond 250 milliseconds it is very difficult for surgeons to operate at all. The system immanent latency of a modern operating robot is already around 180 milliseconds (Da Vinci System) [6]. That means the transmission latency for remote telesurgery is around 20~30 milliseconds.
Based on above latency requirements analysis, and the current performance of broadband networks, it is clear that some changes need to be made to the current broadband network in order to successfully incorporate telesurgery service in the near future.

Reference