 Thank you for giving me the opportunity to speak on the topic of transesophageal echo for patients with ARDS and ECLS. In the next 20 to 25 minutes I will describe and illustrate the role of transesophageal echo in patients with ARDS and ECLS and describe the common pitfalls and challenges. I will cover three points. First, the role of TE in the diagnosis of ARDS. Then the role of TE guidance for ECMO cannulation and then the role of TE once the patients are on ECMO. My first comment is that you don't necessarily need a transesophageal echo. You may be able to obtain the information with a trans thoracic but assuming that you've attended a trans thoracic echo and you have poor ecogenicity then you may have to perform a TE. So first, what is the role of TE for the diagnosis of ARDS? So I know I'm going to be stating the obvious here but it is not infrequent that despite the fact that it's part of the definition of ARDS that will receive patients that are considered for ECMO and who have had no cardiac assessment. So this is going to be the first role of our echo to make sure that you don't have any left-sided valvular disease or significant LV dysfunction that could be explained in the hypoxia. This was the example of a patient who was transferred for consideration of ECLS. He was known to have a bicosperal aortic valve and an endocortitis. And on his previous echoes he was reported that he had mild aortic insufficiency. So when he was transferred, we repeated the trans thoracic echo and as you can see the views were suboptimal so we elected to perform a TE. So you can see that the AI that was described as being mild was in fact severe and needless to say that in that case ECMO was not the solution. So the next indication of a TE and again if you can get the information with the trans thoracic you may be able to not do a TE but sometimes you may have to proceed to do a TE to roll out intracardioction. This was the example of a patient who was transferred to us also for consideration of ECLS and as you can see she had a tricuspid valve endocarditis and she had a very drastic response to positive pressure. By that I mean that every time that the PEEP was above three or four she became profoundly hypoxemic which made us suspect that she may have an intracardioction. And that's what you can see here with the color with a significant PFO there and even more striking with the bubble study that she had. As a reminder the incidence of PFO for patients with ARDS is about 16% and another 26% of the patient have intrapulmaration so it's not negligible. The next indication for an ECOL in someone with ARDS is to assess their right ventricular function Assuming that their RV is normal and giving them fluids without assessing the right ventricular function may be deleterious because they may have developed some acute right ventricular failure due to the high ventilatory settings, severe hypoxemia and hypercapnia and we know that the incidence of acute RV failure in that setting is between 20 and 25%. So the last thing is that you may be wondering what if your patient is prone. As I'm sure you all know we manage patients with ARDS with prone positioning for duration between 16 to 18 hours a day. So what if you just put your patient prone and they're unstable and you need to assess their cardiac function. Should you wait until they are put supine? Should you put them supine again? I would say it really depends on the situation. Obviously you can always attend to do a trans thoracic but it's usually limited to the apical window if you see anything at all. So if your patient is extremely unstable and also doesn't tolerate to be put back supine you may have to perform your transesophageal echo in the prone position and that's been described and it's not been shown to be more dangerous or more complicated in a series of cases. They actually showed that the insertion of the probe was quite straightforward. This is the example of a patient who was transferred for consideration of ECMO for COVID ARDS was transferred in the prone position. On arrival he was quite hypoxenic, hemorrhaginically unstable despite an illustration of fluid and my poor apical for chamber already showed that the right ventricle was quite dilated and overloaded but our main question was whether we should anticoagulate this patient. So we elected to perform a transesophageal echo and as you can see still significant dilation of the right ventricle and some masses in the RV that in that context were highly suspicious to be a cloud. So we studied this patient on inhaled nitric and studied him on therapeutic anticoagulation and those RV clouds are something that we've seen a lot in patients with COVID ARDS. So just to summarize on this first point echo is an integral part of the diagnosis of ARDS you need to make sure that you roll out a left-sided disease and it's also crucial to roll out shunt and assess RV function and if you have to perform a TE in the prone position it's been shown to be actually very safe. So my next point is the role of TE guidance for ECMO cannulation. So just a reminder for those who are not familiar with ECMO we have two main different types, venous-venous ECMO mainly for respiratory support where you drain the blood from the venous system and you re-inject in the venous system. That assumes that your right ventricular function is good enough that it can pump the blood into the pulmonary circulation and then you have venous arterial ECMO where you drain the blood from the venous system and you re-inject in the arterial system. In the sake of time I'm only going to refer to venous-venous ECMO because this is what we use the most for patients with ARDS and you have again different types of configurations so one where you have two cannulation sites in the femoral and the jugular but you may also have seen some of those bi-cable dual-dom cannula where you have one insertion site and you have one cannula and two lumen with one port that drains from the IVC one port that drains from the SVC and the re-injection is in front of the tricuspid valve. And more recently some physicians have diverted the use of what's meant to be an RV support device known as protodual with a drainage from the right atrium and the re-injection in the pulmonary artery by passing the right ventricle. These are ECMO parameters that you want to assess before ECMO. As I mentioned before you want to make sure that you don't have any left-sided valvular disease that are significant or any significant LV systolic dysfunction. The ECMO may help you choose the appropriate configuration meaning VV ECMO versus VIA ECMO. If your patients have acute RV failure in the setting of ARDS you will place them on VV ECMO and if you decide to go on VIA ECMO you want to make sure that you don't have any contraindication such as ARTIC dissection or ARTIC insufficiency. These are other ECMO parameters to be assessed before cannulation. You want to look at the anatomy of your superior and inferior vena cava. You want to look at your right atromorphology. You want to make sure that you don't have any signs of chronic pulmonary hypertension because in that case VV ECMO may not be indicated. It may be more VIA ECMO. You want to make sure that you don't have a pericardial effusion or if you do have one to have a baseline measurement for your pericardial effusion. You also want to make sure that you don't have any atrial septal defects and I'll show you why in a later case. This is the example of a patient who was referred for ECMO for COVID-A RDS and as you can see there are some masses located at the junction of the SVCRA junction so we were a bit nervous to proceed with the regular femoral jugular cannulation and the patient instead got VV ECMO with the femoral-femoral cannulation. This was another patient also COVID-A RDS who was referred to as for ECMO and as you can see also has some masses in his right ventricle which were clouds and it's extremely important in those cases to make sure that the wires do not go into the right ventricle during cannulation and I'll show you some examples of that a bit later. When it comes to the cannulation itself you want to make sure that you have a good visualization of your IVC, of the bicable and of the SVC. On the left hand side you can see the wire being advanced through the IVC and on the right hand side you can see the bicable with both wires going through both vena cava so the femoral wires coming from the IVC and going all the way up to SVC and the jugular wire coming down from the SVC through the IVC. In my opinion this is the safest position for these wires to be because even if the operator inadvertently advances the cannula too far you are still in a vein but if the wire has gone into the right atrium or in the right ventricle and the operator advances the cannula too far then there's a risk of cardiac perforation. Unfortunately the wire is not always what you want it to be. This is an example where the wire had gone through the posterior wall of the jugular vein through the carotid artery and was in the aorta and obviously it's very important that you pick that up before they start the dilation. So once the wires are in the appropriate position you still want to keep your eyes on these wires during the dilations and until the cannulas are fully inserted because what may happen as in this example is that when the wire is being pushed in a little bit during dilation or when they are advancing the cannula is that the wire may bend in the right atrium and eventually either coil in the right atrium or flip out of the vena cava and end up in the right atrium or in the right ventricle. This is an example where you can see the wire in the right ventricle. The fact that the wire is in the right ventricle is not so much the problem unless you have a clot and you don't want to dislodge that clot but it's mainly that if you advance the cannula and the wire is in the right ventricle you have a risk of perforating either your right atrium or your right ventricle. This was an example of a patient who had COVID-A RDS who was diagnosed with a nasty at the time of the cannulation so as you can see it's left to right so that was not necessarily significant in terms of worsening oxygenation but initially you could see that both wires were in the right position from both vena cava but then during iterative dilations you can see that the wire was bending in the right atrium and eventually flipped out of the superior vena cava and when they wanted to reposition the guide wire unfortunately the guide wire kept on going through the ASD in the left atrium so we had to guide them to make sure that the cannula was not going into the left atrium. It's important to be aware that the cannula comes with an obturator and you see the different holes but on echo you cannot discriminate the end of the cannula if the obturator is in place so some operators will slightly withdraw the obturator as soon as they are deep enough in the vessel but you want to make sure that before you ascertain the final position of the cannula that the obturator is not in place anymore because you won't be able to know the end of the obturator from the end of the cannula and this was an example of the cannula being advanced in this case the obturator was not on but you can see we're moving from the IVC and in the right atrium and just following the cannula up until the SVC and that's the ultimate position of the cannula so you can see that the drainage cannula is at the SVC re-junction and the re-injection cannula it's in the SVC about 3-4 cm above the SVC re-junction and we've changed that with our experience with COVID patients we used to put the drainage cannula at the IVC re-junction but I will show you a case later to explain why we put it much higher now even though we know that we may have some degree of recirculation when it comes to the bicavel cannula depending on the comfort of your operator depending on your own comfort with TE it may be done under TE guidance only and this is an example where you see the cannula being advanced and in this case it's absolutely crucial that you make sure that the wire is staying in the IVC at all times really it's not in frequency that you have the wire in the IVC in the right position when you activate or advance the cannula the wire flips out of the IVC and then goes into the ventricle and if you keep on advancing the cannula while the wire is in the ventricle unfortunately you have a risk of having cardiac perforation so this is those protect duos again, drainage in the right atrium and bypassing the right ventricle and re-injecting in the pulmonary artery they look like pa catheters only bigger so you see the wire lining along the right ventricular wall in our center they place them with both fluoroscopy and TE and you will need a TE because the tip of the cannula need to be past the pulmonary valve but only two or three centimeters and cannot be selective in one of the branches of the pa so on 2D it's actually very difficult to image those cannula all at once but you can see on the top left the part where you have the drainage holes and then you can see the cannula lining along the right ventricular wall and you can see that the tip is just past the pulmonary valve two to three centimeters and with the color you see that the blood is being injected in the main pa so the summary on the TE guidance part really you want to keep your eyes on these wires at all times it seems like it's not a huge procedure and most of the time it's actually straightforward but if you don't keep your eyes on the wires they may be at the right position in the first place but then with dilations be in the right ventricle and if you advance the cannula while the wire is in the right ventricle then unfortunately you may have a catastrophe and as I say to my trainees it's better to take a couple of minutes and check that the wires are in the right position than to have a hole in the heart so my last part is the TE monitoring once the patient is on ECMO so some situations where you made an echo is persistent hypoxemia despite the fact that the patient is on ECMO obviously you want to rule out that this is not due to an oxygenator failure but then it can be because you have a mismatch between your cardiac outputs and your ECMO flows which you can assess with your echo and it can be a problem of position of the cannula and recirculation so recirculation is the fact that you just re-injected is immediately being drained by the drainage cannula and that can be because the cannula are too close to each other could also be a direction problem but you may have to readjust the position of this cannula the example of this patient the cannula were really close so we had to pull the drainage cannula a little bit and that was followed by a significant improvement in oxygenation when it comes to those dual domain cannula so you want to make sure that the direction of the re-injection is actually towards the tricuspid valve and not towards the septum so in this case you can see the re-injection is actually going towards the interatrial septum and is actually not directed at all towards the tricuspid valve so they had to turn the cannula around to allow the blood to be directed towards the tricuspid valve this was an example of a patient who had COVID RDS and who had a dual domain cannula that was placed under eco-guidance and initially you could see that the direction of the flow was directed towards the tricuspid valve and the patient oxygenation improved as soon as we placed heronectomy but a couple of days afterwards the cannula had not budged in terms of the measurements on the cannula itself but the patient was still profoundly hypoxemic despite the fact that we were increasing the ECMO flows so we repeated a TE and we could not see the re-injection flow in the right atrium anymore but instead when we advanced the probe the re-injection flow was actually seen in the sacipatic vein and in the liver and the explanation for that is the fact that initially the tip of the cannula in relationship to the diaphragm was about 4 cm but what happens usually is that as soon as the patient is on ECMO we tend to decrease the ventilator settings so that they are not injurious anymore and that is associated with a significant loss in lung volumes and when that happens the diaphragm may actually shift upwards and the relative position of the tip of the cannula and the diaphragm is significantly different to the point that the re-injection hole which was initially in the middle of the right atrium was now intrahepatic and that's the reason why as I mentioned before we tend to put the drainage cannula much higher than what we used to do because we expect that once the patient is on ECMO we decrease the ventilator settings we will have a loss in lung volumes so when the cannula is at the IVC or re-junction then your diaphragm will ascend in the chest and at the end your cannula is only in the IVC and as soon as the patient starts to wake up coughs then you lose your flows completely but when it's a bit higher in the right atrium you have a little bit less of dropping flows when the patient is a little bit more awake and we've not actually seen that much more recirculation, at least clinically relevant in our patients since we've changed that so again now the drainage cannula is more at the SVC or re-junction and the re-injection cannula again is in the SVC but 3-4 cm above the SVC or re-junction so talking about dropping flows it can be obviously an oxygenated failure that you want to rule out, it can be hypervolemia or it can be a problem with cannula position thrombus or tamponade this is an example where the cannula was stuck in the septum with dropping flows every time the patient was coughing so it had to be reposition in some centers they will never advance the cannula sometimes we do but if you have to do so it needs to be under eco-guidance this is an example where the cannula was advanced without any guidance and as you can see the cannula ended up crossing the interritorial septum and was in the left atrium lastly, tamponade is a possibility in those patients especially because they aren't therapeutic anticoagulation the main point I'm going to make on this is that obviously if you're on VVAC mode you will have some hemodynamic compromise but be very careful because many of the signs of tamponade, ecosigns of tamponade will be missing you may not have a positive paradox you may not have any respiratory variations because as I said before, those patients may not have any tidal volumes or negligibles, something like 50cc and in these cases you will not have any respiratory variations and depending on the location of the effusion or the clout you may not actually have a dropping flux on VAC mode you can be even trickier because you may not have any hemodynamic compromise so to summarize on this point, the fact that the cannula was in the appropriate position on day 1 does not mean that you will not have to reassess it and again be very wary about ruling out tamponade on someone on eco and this is the summary so really eco is an integral part of the diagnosis of ARDS it's going to be useful to rule out shunt to assess your RV function, if you have to do a TE while the patient is prone, it's actually safe and once the patient is on ECMO make sure that if you are guiding a procedure you are following the wires at any given times and eco will be really helpful to assess causes for refractory hypoxemia and drop symptoms and on this note, I thank you for your attention