Future Endoscopic Tools and Platforms for Endoluminal Surgery

Fig. 23.1

Computer-mediated automatic insufflation unit for flexible GI endoscopy (GW-200, Fujifilm Corporation, Tokyo, Japan)

Fig. 23.2

The SPACE system

Fig. 23.3

Add-on insufflation line (Impact Shooter, Top Corporation, Tokyo, Japan)

Preclinical Evaluation of Space

We have preclinically evaluated the feasibility and safety of SPACE technology in the upper and lower GI tracts [8–10]. In the esophagus, we successfully demonstrated that SPACE is feasible and safe in porcine models, without causing massive gas migration into the downstream bowel. In addition, SPACE significantly reduces operating times of esophageal ESD compared to manually insufflating endoscopy, by stabilizing the exposure, providing uniform tissue tension onto the mucosa at cutting, and reducing time to regain exposure after each suction [8]. In the lower GI tract, we also successfully confirmed that SPACE colonoscopy is feasible and safe in canine models [10]. SPACE colonoscopy provides stable and highly reproducible endoscopic exposure without causing massive retrograde gas migration [10]. Interestingly, the gas migration into the upstream bowel was even more significant in conventional (manual) insufflation than in SPACE, when the insufflation pressure is adequately set in advance (Fig. 23.4) .

Fig. 23.4

Multipoint pressure monitoring during conventional (blue squares) vs. SPACE (red circles) colonoscopy at (a) insufflation site (cecum), (b) 50 cm proximal, (c) 100 cm proximal, (d) 150 cm proximal bowel, respectively. Note: significant pressure elevation (i.e., gas migration) in proximal bowels during manual insufflation whereas minimal or no elevation during SPACE

Implication

The clinical feasibility and safety of SPACE using commercially available surgical insufflator (not GW-200) were validated in the esophageal ESD for patients with esophageal cancer [11]. The GW-200 insufflator and related accessory devices gained approval of their manufacture and sale pursuant to the provisions of the Pharmaceutical Affairs Act in Japan in 2015. The system is now under clinical evaluation in Japan and will be officially released in the market soon. Further clinical assessments are needed to apply this new technology to wider range of advanced endoluminal surgery worldwide .

Improvement of Endoscopic Smoke Evaluation

Potential Hazards of Smoke in the GI Lumen

It is known that the smoke generated by energy devices not only reduces visibility in laparoscopic surgery but also increases chemical/biological hazards to patients, surgeons, and operating room personnel [12, 13]. This fact has led to recent improvement in smoke evacuation system in laparoscopic surgery. However, less has been known about the smoke generated during flexible GI endoscopic intervention . Recently, we have demonstrated that the smoke generated by endoscopic mucosal/submucosal ablation contains harmful substances as well [14]. The effective smoke evacuation system not only may improve performance and quality of endoluminal surgery but also may reduce potential risk of health hazards in patients and medical professionals .

Automatic Smoke Evacuation System

The automatic smoke evacuation in the GI lumen is only possible under automatically pressure-controlled environment; otherwise, each activation of evacuation almost always leads to significant collapse of the pneumoviscera [14]. Our SPACE technology can provide virtually “non-collapsing” exposure as long as the insufflation pressure and evacuation power are optimally set. An evacuation line is dedicated to the standard flexible endoscope, and any kind of automatic smoke evacuator for surgical use, equipped with a smoke absorptive membrane, is connected to the evacuation line (Fig. 23.5). To accomplish effective evacuation in the GI lumen, a simultaneous evacuation and insufflation at a well-balanced power is required. In the above experimental setting, the setup intraluminal pressure was 8 mmHg in SPACE, with the mode of evacuator of 100% power with delay time of 10 sec.

Fig. 23.5

Simultaneous insufflation/evacuation system

Preclinical Evaluation of Evacuation System

The system was preclinically evaluated in terms of visualization and dense of residual smoke after endoscopic session (mucosal ablation) in a porcine stomach [14]. The endoscopic visualization was significantly clearer in animals with automatic evacuation than that of animals without automatic evacuation (Fig. 23.6). The residual smoke inside the GI lumen was denser in animals without automatic evacuation than that of animals with automatic evacuation [14]. The semi-quantified relative carbon concentration was significantly lower in evacuation group than that of no evacuation group. During the activation of automatic evacuation, the actual fluctuation of intraluminal pressure remained within 6–8 mmHg, and no significant luminal collapse was observed [14].

Fig. 23.6

Endoscopic visualization after mucosal ablation with or without automatic smoke evacuation

Implication

Although still in its “POC” phase , the automatic smoke evacuation in the GI lumen has been proven feasible and promising. The data above has encouraged industry to develop ideal automatic smoke evacuators and related peripheral devices for flexible GI endoscopic intervention s. Ideally, future endoscopes and/or related platforms should provide dedicated insufflation/evacuation channels.

Improvement of Endoscopic Working Space

Need for Stable Endoscopic Working Space

In addition to stable endoscopic visualization/exposure , the stability of working space is another major factor to the success of advanced endoluminal surgery. Although SPACE technology can provide a stable pneumoviscera, the flexible endoscope is still floating freely inside the GI lumen . It needs to be kept in the correct position by an operating endoscopist or assisting endoscopist. The precise surgical actions needed for advanced endoluminal surgery are technically difficult without fixing/stabilizing both the endoscope and the intestine .

The ESP System

To obtain a stabilized endoscopic working space, various “platforms” have been proposed to date [15]. Some systems are robotic , having integrated optics and independent instrument manipulation function. The other systems are more mechanical, using conventional flexible GI endoscopes for visualization, and instrument manipulation being integrated with the use of a flexible, often lockable, multichannel access device [16]. It is easy to imagine that these platforms have been originally developed for more extreme conditions such as NOTES (natural orifice transluminal endoscopic surgery) , where the stabilization of working space is more technically demanding. Each system has then been trickled down as a spin-off for current endoscopic intervention . As a result, most systems, especially robots, are too bulky and complicated to be applied inside the GI lumen .

The endoluminal surgical platform (ESP, Lumendi Ltd., London, UK) is also an endoscopic platform but has several unique features . The system has been designed for colonic use from scratch, as an add-on sleeve over the scope. It has two balloons (fore balloon and after balloon) and can be easily attached on virtually any colonoscope (Fig. 23.7). The ESP is advanced with both balloons not inflated into the colon. At the surgical site, the after balloon is first inflated to stabilize the system; then the fore balloon is pushed out beyond the point of pathology to manipulate the colon and to create an isolated, stable, and workable space called the “therapeutic zone ” (Fig. 23.8). The distance between the two balloons may be adjusted, therefore smoothing out folds, straightening the colon between the balloons (by extending the fore balloon), or pulling the wall of the colon more directly in view (by pulling back on the fore balloon ) (Fig. 23.9) .