We have five minutes for questions, and either to Alex or to Norio, or to any of the faculty, please go ahead and just use your microphone when... I'll ask our colleagues from Japan, the water immersion or underwater technique, do you change your settings on the electro-surgical unit because you're working underwater? Same setting, because we use the dual knife, it has a very thin needle, so the concentration of the electric current, so we don't change the setting. Thank you. That's a very important point, and I definitely don't want to steal Dr. Juan's thunder because he's going to give a lecture on electro-surgery, but if by the end of this course you have grasped one concept, and that concept is of current density, that will be great. That is probably the most important concept in electro-surgery and TSD. And what he said, thin knife, high current density, water doesn't change it. If you're using the hybrid knife, and you're working underwater, good luck of cutting underwater. You will not be able to, because, and I have tried it in pond, the knife is much thicker, which drops your current density, and the fluid actually drops your current density, and cutting becomes problematic. So I don't want to spoil it anymore for Juha, but we'll have a dedicated lecture on that. As far as, yeah, guys, questions on anything, not necessarily just of what we discussed. Just a follow-up question for clarification. Is this underwater ESD, or is it under saline ESD? Because I think a lot of people get confused on that. Yeah, for the EMR, underwater is acceptable. However, in ESD, saline must be used, because saline of the water jet, of the endoscope, go into the sub-mucosal layer. If we use water, we cannot dissect the sub-mucosal layer, including the water. Water don't have the, yeah, yeah, yeah, sorry, thank you. Thank you. Yeah. There was a question there. So, about the mucosal fat, I just wanted to make one comment. You make your initial incision, and obviously you can't guide the depth of that, but I've noticed that after you've done your initial incision, you have an incision going from left to right. It's very important to, you know, before creating that fat, to go a little deeper in the sub-mucosa. I know there's someone that said you have to do superficial dissection, but I feel like there's penetrating vessels that go up and then laterally spread in the middle third of the sub-mucosa. So, if you keep dissecting superficially, you get a lot of bleeding. It's better to create like a little groove right after your initial incision, and then continue the dissection just beneath the middle third of the sub-mucosa to get like a good, clean, bleeding-free dissection. This is a great point. So, that refers to that concept of trimming or retracing your initial mucosal incision, and you do get bleeding sometimes because you don't see the vessels. It's kind of a difficult situation. So, what do you do? Usually, and not always, but it's a good idea to continue cutting to free some space for you, because if you say, okay, I have bleeding, let me get the quag grasper, you cannot identify the vessel because everything is collapsed, so actually opening up the incision, it's a good idea. Injecting more can help you. The second thing that you mention is where do you make the incision? So, the first incision is the mucosa. The first retracing after that should be right underneath the mucosa, usually using a cutting current, in my opinion. I mean, the way Juha puts it, if I want to cut, I use cutting current. If I want to coagulate, I use a coagulating current. This is a big point of debate, but that very first retracing should be right underneath the mucosa, because if you go too deep at that point, you can easily perforate. But then you very quickly want to get deep into the mucosa, into the submucosa, after you have done that first retracing underneath the mucosa. Hiro, make some comment on that. The mic. Oh, yeah. So, the next hands-on session, three hours from 9 o'clock, we have all need to type it into the ESD knife. So, as Dr. Schlachtermann showed in the slides, the angle of the knife is very important. So, to cut into the submucosa, you need to be perpendicular to the submucosa layer. And then once you create the mucosal incision, your knife will kind of like become parallel to the muscle to prevent any muscle injury. So, just adjust your angle. So, I think you will work on this aspect. Yeah. So, we'll have three hours to work on exactly on that point. Also, one last thing for a beginner that sometime, because you're so close and you hit a blood vessel and then you start to see blood, your immediate reaction is you step in the blue pedal. A lot of time that too much charring, too much black in the beginning is not a good idea. And sometimes even like you're anxious that you keep going up on your watts, nothing will happen. These are all minuscule, little tiny vessels. A lot of time, even if you wait a couple of seconds, they stop on their own. So, don't char too much in the beginning because you get muscle injury. It makes everything so fibrotic and black so quickly and it makes it harder. I want to add about this charring issue. You have to watch that your knife is clean because if the knife covered with char, then the electrical circuit will go unpredictably from the area which is not covered by char. So you think that you are touching it and cutting, but in reality, it can be that you are burning completely different portion of it. So do not hesitate. If you see that the knife is getting charred, for whatever reason it is, you have to pull it out, you have to clean, and then you will predictably create the electrical circuit right where you touch the tissue which you intended to cut. But when it is charred, then it will not be where you cut. You may be cutting in a completely different area, just simply where the knife is not covered by the tissue which is not conducting. Or your current density will be really low. Low, right. And you just won't be able to cut. Exactly. Yeah. You'll be very imprecise. That's a great way to wrap this.

electro-surgery

current density

submucosal dissection

dual knife

saline