Well, I'd like to talk about the water pressure method, which is a kind of natural traction technique. Usually some kind of traction technique is very helpful, especially for the difficult situations such as very big lesions or lesions with fibrosis. But it's sometimes cumbersome to bring some device into the room and or prepare devices. It's time consuming. That's why I made it much simpler. Just using the power of the water, we can easily open the submucosal space. For doing the water pressure method, it is mandatory to use the ST food, which was originally made by Dr. Yamamoto. I usually use classical ST food, which has a little bit longer length. And of course, I use the normal saline to emerge the entire region and conduct procedure with underwater condition. Well, this is a very simple technique. Just suck the air from the lumen and emerge the entire region with the normal saline. Then right after making mucosal incision, I flush the normal saline through the irrigation channel of the endoscope. Then we can easily open the submucosal space. Usually initial submucosal dissection is the most challenging part for the beginners to do ESD. We usually struggle to open the submucosal space. But by using water pressure method, we can easily open the submucosal layer by giving active pressure of the normal saline. This is the beauty of this technique. As a result of opening the submucosal layer, we can easily recognize the true dissection plane and we can easily continue the submucosal dissection in a safe manner. We can visualize the muscle layer as well as the beautiful submucosal layer like this. Then we calculated the complication rate and procedure time and compared standard ESD and water pressure method. And we found that the procedure time is much less with the water pressure method. And of course, we can reduce the complication rate by using the water pressure method. I would like to show you actual clinical case, which I removed by the water pressure method. This is not a super difficult region because of the small region size. But it was located in between the two Haussler's holes at the ascending column. And unfortunately, my maneuverability of the endoscope was a little bit poor. But because we completely sucked the air from the lumen, therefore we can relatively easily keep the straight endoscope position. That is the merit of the water pressure method. By keeping straight endoscope position, we can control the direction much better. In this particular case, I checked the maneuverability of the endoscope from the anal side in a straight position as well as the oral side in a little flexed position. But unfortunately, both of the directions were a little bit difficult to control precisely. But by sucking air and immerse the entire region using normal saline, it becomes much better. And after injecting glycerol solution to the target area, I started initial mucosal incision within the underwater condition. And by conducting the procedure underwater condition, we can visualize the target region much better because of the magnification effect underwater. And we can avoid smoking effect or dirty situation. But we should carefully wash the lumen before starting actual procedure. Otherwise, it just becomes dirty. Of course, air bubble always coming, but we can easily flush away the bubbles during the procedure by giving additional water irrigation through the endoscope. And of course, it becomes quite easy because we can widely open the submucosal space. After completing the part of the submucosal dissection, I completed the circumferential mucosal incision. Again, by keeping the straight endoscope position, I could easily control the direction by twerking my wrist. We don't have to control right-left channel or up-down channel so much. Just keeping straight position and gently torque our wrist of the left hand, we can easily control the direction. As a result, even for the difficult situation, I could easily complete the circumferential mucosal incision. And right after completing circumferential mucosal incision, I gave additional water pressure to the submucosal layer, then opened the submucosal space. As a result, it becomes quite easy to continue the submucosal dissection. And if we found the tiny blood vessel, we should go relatively slowly in order to give additional, give adequate thermal effect to the exposed blood vessel. Usually it is okay to go through the vascular network because they are really tiny vascular network. And of course, I'm using DualKnifeJ. I can give additional submucosal fluid cushion at any time if it is necessary. And I usually include small amount of indigo calming for the injection solution, even for the knife injection. I can visualize the dissection plane as a blue color much easily. So this is almost the end of the procedure. Although maneuverability was initially very poor, I could finish the procedure quickly. This is the resection bed. Actually, I finished this procedure just 11 minutes for the four centimeter region. This is reality. You don't have to worry about the difficulty of this procedure. Well, I would like to show you another case. This is a much more challenging case, which is a little bit bulky mass located at the sigmoid column. And as I mentioned during the morning talk, there is a whole convergence going to the big nodule. It suggests a kind of muscle traction. Therefore, this seems very difficult and looks like invasive cancer. So initially, this patient was planned for surgery, but this patient refused surgery because taken biopsy by the previous doctor just revealed a high-grade adenoma. That's why this patient refused the surgery. Therefore, my surgical colleague asked me to do ESD. It looks really difficult. And also, there was a tattoo. Fortunately, it was opposite side from the target region. And there was a remarkable non-lifting sign after injection, but I conducted ESD using the water pressure method. As I mentioned, I sucked the air completely from the lumen and immersed the target region with the normal saline. Then started the mucosal incision from the anal side and dissected both sides and exposed the retracted muscle. Then tried to dissect here, visualizing the muscle fiber and carefully cut through the muscle fiber. This is a little bit challenging, but as a result of dissecting muscle layer, I could widely open the submucosal space. Now we can see the regular submucosal tissue behind the fibrotic area. This is a wonderful aspect of the water pressure method. I could widely open the submucosal layer. Now it turns to standard ESD procedure, just gave additional submucosal fluid cushion through the knife and completed the circumferential mucosal incision and completed the submucosal dissection for the rest of the submucosal tissue. It was quite smooth, even though it was a really tough situation because of the muscle traction sign with severe fibrosis. This is the final result. And the final histopathological evaluation revealed deeply invasive cancer with lymphobascular infiltration. Therefore, this patient finally accepted surgical treatment. So this is a good overview of the water pressure method. It's relatively simple, very cheap, and we can perform really aggressive procedure by using this technique. Thank you very much for your kind attention. Any questions? Yes, please. Yes, Nakhisa, your patients are remarkably clean inside. If there is any stool and you put this water immersion, everything becomes murky and difficult to see. So how do you achieve cleaning like that? We usually wash your room again and again until it's completely clean. It's very, very important. Then the time of your removal of the polyp should include that one. It would not be 11 minutes. It would be two hours, 11 minutes probably. Usually, Japanese patient is much... Compliant, more compliant. Yeah, that's right. And they take bowel prep very effectively. So usually, we don't have so much dirty cases. But would you say that you would not attempt it if there is a stool inside? Would it prohibit you from using water immersion? That's right. That's right. Peter? Nakhisa, there's a question from virtual audience. Oh, okay. After answering to the virtual audience, I will take a question from Peter. I noticed Dr. Ehag is using the new ST-HUD with an Olympus scope. He used the same system, but I find the instruments tend to sometimes get caught at the end. Any tips for using the new ST-HUD with Olympus scopes? There is no problem. Just insert the instrument first through the working channel and try to fix the ST-HUD along the working channel. I mean a device. So you adjust first before you go in. Yeah, yeah, that's right. And fix with the tape. Thank you. Peter? Yes, my question is how to adjust this technique, which on your hands works beautifully with the dual knife, if you were to use any different knife, let's say the pro knife or the hybrid knife, which are thicker. So can you share your settings? Underwater, the settings are different because you get current dispersion. Do you have to increase your settings if you're using a thicker knife or you stick with your standard settings? For the thicker knife, you should increase the setting of the electric current. It is mandatory. But for the dual knife, I can use standard setting because electrode is quite small. Therefore, it cuts very well even under water condition. But it is mandatory to use normal serine for water irrigation. Otherwise, it doesn't cut well. And what are your standard settings? If you don't mind repeating this again. For the dual knife water pressure method, I usually use dry cut effect 3, 30 watt for mucosal incision and the swift quark effect 3, 30 watt for the submucosal dissection, which is for bio 300. Thank you. And yeah, using the dual knife, that is good enough. But as Peter said, if you use a pro knife or a bigger knife, I recommend you to use the dry cut for the submucosal dissection as well. If you increase the effect with the coagulation current, it causes a lot of bubble. That's right. That's right. Using dry cut to end cut cutting mode causes less bubble. So please use dry cut to end cut. This is very astute observation because I have tried underwater poem. I have not tried underwater ESD. And bubbling was a terrible problem to a point that I abandoned doing it. Yeah, that's right. With end cut, you get too much cavitation. Yeah, yeah. Therefore, I carefully observed submucosal tissue. And if there is no vascular network, I usually use end cut, end cut eye. That is much better because it doesn't cause so much air bubbles. And if we flush the normal saline too much, sometimes it cause extension of the organ. Therefore, we should suck the ricket in between the procedure. Otherwise, it becomes a little bit difficult. And another tip to prevent bubble formation, the duration of the current should be short. If you apply too long duration and coagulation current, a lot of bubble. But a short time, then it prevents bubbling. Yeah, that's very important technical tips. When you're doing these underwater dissections, if you encounter bleeding during the procedure, it goes to Sergei's same question. Does it muddy your entire field? Of course. Major bleeding is really a big problem when we conduct water pressure method. That's why I carefully check the blood vessel when we conduct submucosal dissection. And if there is sick blood vessel, I always try to seal it before cutting there using very low setting of force quark. That is the very, very important technical tip. And in case of having minor bleeding, it doesn't cause any problem. We just touch to the bleeding point with the closed tip of dual knife. We can immediately stop it. Major bleeding is the really big problem. If unfortunately got major bleeding during the procedure, I press down the bleeding point tentatively with the tip of the SD foot. That is the best way to tentatively stop the bleeding. Then prepare the coagulator and flush away the blood from the operating field and catch the bleeding point quickly with a coagulator. That is the very important technical tips. Very nice. Sort of tamping out. Yeah, that's right. I wanted to share one thing that I found very useful during, again, underwater point, but probably will relate very well to ESD when you're dissecting. The technique that Dr. Toyonaga showed with the low power, that does not work underwater. You need much higher power and you will still preemptively coagulate the vessel. For the dual knife technique, we can use exactly the same. It works very well. Yes, because of the small electrode, I just use 0.3 post-coag for vessel sealing, even underwater condition. Interesting. I was using hybrid knife, by the way, and I had to double the power in order to get preemptive coagulation. Yeah, probably you need to coagulate a little bit much longer time. Yes. Then it works very well. Do you agree, Dr. Toyonaga? In case of using thicker electrode, we should increase the power a little bit and take a little bit longer time. Yes, theoretically, that will be correct, but I don't have my experience by myself. And as I mentioned again and again, it is really necessary to use normal saline. Yes. Yeah, I have experience using a flash knife underwater condition and pre-coagulation with spray coag and 0.5. It works well. Is that same setting when you use the CO2 insufflation? Same setting or different? We can use the same setting in the CO2 as well, but in the CO2, your setting could be better. Forced coagulation. Also good. Are you using forced content? But for the underwater condition, you prefer to use spray coag with 0.5. Yes, yes. Yeah, I have a quick question. So during the air ESD, we usually concern about the direction of gravity. So once you are underwater, you wouldn't worry about... Yeah, we can ignore the gravity effect. Thank you. Therefore, we don't have to change the patient position. We don't have to care about the direction of the gravity. Just go. Okay, thank you. Combining water pressure with pocket method. Any benefit or does that make any difference combining both? We can have much more freedom by using the water pressure method. We can control any direction much easily. And by suctioning the gas from the lumen, we can keep straight position much easier. Therefore, I can control endoscope much easily. That is one of the merit. May I answer the question? Yeah, I think that's a good idea to combine the underwater water pressure and the pocket creation method. Especially the region is located on the dependent side of the gravity. Water pressure and pocket creation method combination works very well. Yeah, yes, your question is the combined technique. Yes, it works very well. Yes, please. For the pressure part, does it make a difference if you try to close the hole on the cap? Because it's going to allow... If you don't close the hole on the cap, it might allow the water pressure to be released from the side. And if you close the hole, you can have more forceful pressure to help with dissection as well. Hole means the... You don't have to care about it. Just flush the water. It doesn't matter. Thank you very much.

water pressure method

endoscopic submucosal dissection

normal saline

submucosal space

clinical cases

complications