 Hello, my name is André Deneau, thanks for the invitation to talk about TUs during immunodynamic instability outside the cardiovascular operating room. I will be giving this presentation with Dr. Jean-Vierve Riendoux-Bolac. Those are our disclosures, and our objectives are the following. First, to appreciate the essential role of TE in cardiac arrest, to identify the key findings in unstable and hypoxic patients using TE. And finally, to identify key findings in unstable and hypoxic patients using extracardiac TE. So my name is Jean-Vierve Riendoux-Bolac, and I'm an anesthesiologist at Montreal Sacrifice Hospital. As you all know, hemodynamic instability and hypoxemia can rapidly lead to cardiac arrest. And management of cardiac arrest outside of a controlled work environment like the cardiac OR can be really challenging. So TE can play an essential role during rest station, even when the probe is not already in place. We'll start this presentation by exploring together the reasons why TE is useful in cardiac arrest and how we would use it in this particular context. So a little quiz to introduce the reasons why TE is useful in cardiac arrest. Which statement is true? A. Ultrasound should always be used during cardiac arrest. B. TTE and TE offer the same possibilities during cardiac arrest management. C. Data show that TE reduces mortality following cardiac arrest. And D. TTE provides chest compression feedback in real time during rest station. So the answer is D. As demonstrated here on this TTE midisophageal long-axis view, obtained during chest compression of a 50-year-old patient in cardiac arrest. You can see how CPR has been optimized to allow LV ejection through an open LVUT and aortic valve during compression phase. But be mindful that this is not always the case during TTE blind rest station. And this is one of the reasons why TE can play an essential role during cardiac arrest. So let's dive into the subject. So point of care ultrasound is a bedside tool that is now widely used during cardiac arrest. In fact, the recent 2020 American Heart Association guidelines for CPR states that if an experienced sonographer is present and use of ultrasound does not interfere with the standard cardiac arrest treatment protocol, then ultrasound may be considered as an adjunct. Focus in cardiac arrest relies mostly on cardiac ultrasound, and TTE during cardiac arrest has been described in multiple review articles. However, the use of transterrastic approach may be challenging for many reasons. Image acquisition using TTE may be difficult when acoustic windows are limited due to patient factors or due to limited access to the chest and abdomen by, for example, wound dressings or defibrillation pads. Moreover, in the setting of cardiac arrest, cardiac massage creates motion artifacts precluding TTE image acquisition, thus only allowing intermittent cues during chest compression pauses. Observational studies comparing manual versus ultrasound guided pulse check durations have also suggested that use of TTE may cause prolongation of compression pauses, exceeding the 10 seconds recommended by the AHA guidelines. TTE overcomes many of the challenges of TTE due to its retrocardiac location, which provides a superior acoustic window and better visualization of many structures which expands its diagnostic reach. It also allows for continuous imaging throughout resuscitation, which eliminates the challenge of developing an ecocardographic window within the recommended 10 seconds. A retrospective study of video recordings of cardiac arrest cases comparing TTE and manual pulse checks show the significant prolongation of pauses with TTE, but not with TTE. TTE also helps achieve two critical steps of the AHA chain of survival in cardiac arrest. To this end, the first two goals are meant to provide CPR quality feedback in real time and provide rhythm identification assistance that could help reduce delays in defibrillation. Then, the ultrasonographer can proceed with a search for an underlying reversible cause and provide guidance for life-saving endovascular procedures. So let's go through these four goals. First, to assess quality of chest compression in real time, the midisophageal long-axis view is used to identify the area of maximal compression, or the AMC, because it may lead to individualized adjustments of hand placement. The AHA guidelines recommend providing chest compression on the lower half of the sternum and the entering nipple line. However, several radiology studies have shown that LVUT and ascending aorta were located underneath the recommended chest compression location in 46-80% of patients. Supporting these radiologic findings, two TEE studies identify the AMC at the LVUT or ascending aorta in more than half of the patients. More importantly, a retrospective study of TEE in refractory cardiac arrest showed that no patient with a closed LVUT had a successful resuscitation. So in order to avoid complete obstruction of the LVUT as shown here and preclude resuscitation success, CPR quality must be monitored whenever possible and TEE is an excellent monitoring tool for this purpose. So remember that the first goal is to make sure that the LVUT and aortic valve open during the compression phase to allow left ventricular ejection. The second goal is to assist in rhythm diagnosis when no shuckable rhythm is noted on the CARJAC monitor. CARJAC ultrasound can identify fine ventricular fibrillation initially missed on CARJAC monitors due to low signal amplitude. This can impact decision-making and lead to defibrillation without further delay. Moreover, in patient presenting with a non-shuckable CARJAC arrest, TEE can help distinguish pseudo-pulseless electrical activity from true pulseless electrical activity using CARJAC ultrasound to evaluate the presence or absence of CARJAC contractions. With pseudo-PEA, CARJAC electrical impulses produce ventricular contraction but it is ineffective to generate a palpable pulse. It is essentially severe hypotension. Patient presenting with pseudo-PEA often have a reversible cause of arrest that can be treated if identified promptly. With true PEA or acestely, ecocardiography shows CARJAC standstill which is a consequence of electromechanical dissociation when CARJAC electrical impulses are unable to generate ventricular contraction. The differentiation between pseudo- and true PEA could potentially help prognostication although data is still insufficient to change ACLS management on this basis. AHA 2020 guidelines recommend against the use of focus to decide whether resuscitative maneuvers should be stopped based on the absence of CARJAC activity on ultrasound. The third goal is to identify mechanism and etiology of the CARJAC arrest. Ultrasound is useful to rule in or out most of the 5 H's and 5 T's of the ACLS checklist and our evaluation should not be limited to CARJAC views only. Of importance, TE is very limited for tension pneumothorax diagnosis so long ultrasound is essential. Dr. Dhanou will explore these diagnosis with more details later on in this presentation. The last and fourth role of TE is for various endovascular procedural guidance. TE is commonly used to confirm venous position of guide wires when inserting central venous access catheters and to guide positioning of intraerotic balloon pump. TE has also been successfully used at the bedside as an alternative to fluoroscopy for emergent placement of temporary transvenous pacemaker and it is also essential during ongoing chest compression to guide venous and arterial cannula placement for initiation of ECPR. TE also facilitates careful examination of the thoracic aorta to rule out aortic dissection in the setting of endovascular interventions. To resume, TE has many advantages compared to TTE. TE offers superior CARJAC acoustic windows, continuous imaging allowing more time for image acquisition and no prolongation of pulse check pauses. It also offers chest compression quality feedback in real time and superior endovascular procedural guidance. As you can see, rhythm identification assistance and reversible causes diagnosis can also be achieved using TTE and TTE should be used if it is the only available modality that can rapidly provide assistance. In terms of competency, we believe that the most experienced physician should perform the examination and that TTE should never be performed without proper training. We also believe that simulation-based learning is key and that even non-experienced ultrasonographers can achieve competency in acquisition and interpretation of basic TTE views. Finally, concerns exist about the safety profile of TTE during CARJAC arrest because of its invasive nature. As for safety issues, no specific literature is available regarding risk of injury during CPR so we can only infer from ambulatory TE studies. In an emergent setting, probe insertion might not be as smooth and concerns exist about the possible mechanical compression of the probe against the spine during CPR potentially increasing the risk of isophageal complications. Given the fact that TTE during chest compression may require more probe manipulations due to a higher level of difficulty in image acquisition, it might be reasonable to consider that TTE during CARJAC arrest may increase risk of injury as compared to other settings. Even though the emergent setting of the examination does not allow time to verify contraindications or obtain consent, we still believe that benefits probably surpass risk in a life-or-death scenario. So now how do we proceed? Institutional implementation of protocols can facilitate TTE use during CARJAC arrest and we think it is especially important in settings outside of the CARJAC OR where a TE probe is not already in place. A multidisciplinary collaborative approach is also important since TTE-skilled physicians can be part of the emergency cardiology intensive care or anesthesia team. It is important to highlight again that the use of TTE should never interfere with a CLS protocol. Also, a dedicated physician different from the leader running the code should perform TE. For first, an ultrasound machine equipped with different probes including a properly sterilized TTE probe should be called as soon as possible. Since long ultrasound is the only way to rule out tension in pneumothorax, it should be performed rapidly as an adjunct to TE. To reduce the delay to first-image acquisition and to help prevent over-ferential injuries, we recommend inserting the TTE probe under direct visualization during the same laryngoscopy used for tracheal intubation. Although airway management should never be delayed if a TTE probe is not available for simultaneous placement. To achieve the four goals that we talked about, the physician in charge starts by performing basic TE views and as a last step, the physician can perform extended TE views if ROSC is achieved or as an adjunct to the basic views. So the basic TE views are meant to achieve the four goals with the midisophageal long-axis view as the only view to provide adequate CPR feedback in real-time. Previm identification and diagnosis of reversible causes can be achieved using many views. And finally, venous and arterial endovascular procedural guidance can be achieved using the midisophageal bicable view and the descending aerodash red-axis view, respectively. The extended TE views are essentially based on the ASE 2013 guidelines with bonus extracardiac views based on the TE GUS and TELUS techniques. In the next part of this presentation, Dr. Dono will detail how these views are useful during management of unstable and hypoxemic patients, including cardiac arrest patients. Let's now discuss about the role of extracardiac TE in unstable and hypoxic patients. Among the reversible causes of cardiac arrest, rodent fluidalitation is not specific of pulmonary embolism and can be seen in cardiac arrest in the absence of any obstructive physiology. Maccordial infarction diagnosis is challenging because organized cardiac activity is needed to visualize regional wall motion abnormalities. Regional wall motion abnormalities may be unrelated to the underlying coronary artery disease as a result of hypoprofusion or stress-induced cardiomyopathy, or it may be already present before the cardiac arrest. Ultracell plays an important role in the diagnosis of tamponade. Loculated regional effusion may be missed with transuracic echo, but TE is much more sensitive. Tension pneumotorax is an important diagnosis, but it will be diagnosed with surface-long ultrasound. And finally, hypovolimia can be very similar in terms of ultrasound findings compared to a distributive shock. And there are some issues regarding the diagnosis of hypovolimia. There was an animal model where they identified RV dilatation during arrest induced by hypovolimia. So extracardic views might be needed to identify potential bleeding source, and this is when we talk about transgastric abdominal ultrasound or transavagil lung ultrasound. So when we look at the heart with TE, we often think that TE can only diagnose the heart, but there's no reason why we cannot look around to the right and to the left and also below the diaphragm. So the extracardic TE applications have been classically for lung and upper GI cancer differential diagnosis, for celiac blockade for pancreatic cancer. But in terms of perioperative application, this is useful technology to determine the cause of hypoxemia, which is most of the time pulmonary, extracardic cause of hemodynamic instability or cardiac arrest, and to monitor splangnic and renal perfusion. So in the guidelines for perioperative TE, it is mentioned that TE is indicated for unexplained persistent hypotension or hypoxemia. These two conditions can be absolutely of a non-cardiac origin. So Dr. Carayas will talk a little bit more in detail about the transophageal lung ultrasound. But what is very important to understand is when you use a TE probe outside the heart, the orientation of the image will change. So for instance, when you do a trans-gastric view, what you are seeing on the right side of the screen is the left side of the heart and what you see on the left side is the right side of the heart. So whenever you turn mechanically rotate the TE probe, the appearance of the image will be different. For instance, at six o'clock, what you see on the right is the right of the patient, what you see on the left is the left of the patient, and the orientation will change as you rotate mechanically the TE probe. The same way as if you turn, go to 90° and you turn to the right or to the left, what you always see on the right side is the cephalade portion of the anatomical structure. So TIGAS is called trans-gastric abdominal ultrasound and with TIGAS we can identify the most of the upper abdominal structures. We can see all those solid organs, the orta, the branches. We can detect free fluid and we can also monitor signs of venous congestion and renal perfusion also. So this is an article we published last year on this topic and there are basically 10 views that can be used that we've described that can provide you with information on the upper abdomen. Basically these views can be divided in those in which the ultrasound beam will be at 12 o'clock, like the trans-gastric view. If you turn to the right, you'll see the inferior vena cava, the portal vein and the apathetic vein. If you continue turning and you're at 6 o'clock this is when you're going to see the large vessel of the abdomen and the pancreas and then as you turn to the left you'll see the spleen and the kidney. So I will have time to go over all these views but I'll give you an example of how this can be useful in the context of cardiac arrest or immunodynamic instability. This is a 50-year-old man who was unstable after cardiac arrest and what you can notice once the patient was resuscitated there's a very empty left ventricle and there's almost awful truck obstruction in those patients. So in this case, the cause of immunodynamic disability is definitely not the heart. So this is why it's important and when you do this then you can see there's free fluid in the abdomen. If we look in more detail this is the stomach, this is the left lobe of the liver, this is the heart and this is the free fluid so this patient is basically bleeding into the abdomen. This is a free peritoneal fluid. So another view that it can be useful when you have unstable patient is the inferior vena cava in the apathic venous view. You can diagnose RV systolic and dastolic dysfunction, pulmonary hypertension. You can look for IV cystinosis and I'll show you an example. You can see if there's a tumor or trombus particularly after ECMO patient because this is a high risk for this type of trombus. You can diagnose abdominal compartment syndrome and it's also been used as an interpretive monitor during renal cell carcinoma surgery involving the IVC. So this is an example of a patient in which we're coming back on bypass difficult to wing. He had a redo aortic valve replacement and mitral valve replacement and I'd like to point your attention on this high velocity signal just at the interatrial segment and in fact we had a similar case which was given to us by Anadvegas in Toronto. So this patient had an empty left ventricle but the inferior vena cava was highly distended and again on the same view you can see this high velocity signal at the level of the interatrial septum but when you look closer here what you see is an inferior vena cava stenosis and this was the cause of the chronic instability which can lead in some cases to a cardiac arrest. So you can, we've been seeing those in any surgery that involve the inferior vena cava in liver transplantation it's not uncommon. This is an example, a 37 year old man with a fauna procedure and this is the IVC before and after bypass in fact it's just before the correction so what you can see before is the IVC is distended and you can see almost the red blood cell barely moving and then on the other side you see the red blood cell are much faster. So basically this patient had a neatrogenic inferior vena cava stenosis and one of the way you can diagnose this condition is to use pulsewave Doppler of the apathetic vein so this was the apathetic venous Doppler before bypass and this is when this patient was unstable. So if you have an IVC stenosis you'll barely have any Doppler signal in your apathetic vein. This is another example a very unstable patient this was a case done in 2004 and were difficult to win from bypass he's unstable and we insert an intratheic balloon pump remember at that time people were not using very much ultrasound to do vascular access they were inflating and deflating in the inferior vena cava and basically that's the intratheic balloon pump in the inferior vena cava. Finally this is an example of a patient who has an abdominal compartment syndrome and in those patients what you will see, and this is a transtheracic image but would be the same with T you barely can see the inferior vena cava it's completely collapsed and sometimes the only way you can see it is by using Doppler signal and you see a color air basically an airline aspect on the inferior vena cava So in conclusion, T is an essential tool to optimize chest compression and cardiac arrest Levintercular alpha-trach obstruction during cardiac massage will lead to an unsuccessful resuscitation. During cardiac arrest T can rule out fine ventricular fibrillation between true PEA versus pseudo-PEA T can provide endovascular procedural guidance for ECPR and finally, cardiac and extra-cardiac causes resulting in cardiac arrest or hemodynamic instability can be identified with T, telus and T-Gas Thank you for your attention