 Hi, I'm Alex Cavaias from the Université de Montréal. Today, we're going to discuss what can TE tell us about lung function. I have no conflicts of interest to declare. Our objectives will be to discuss the use of point-of-care real-time transesophageal lung ultrasoundography to quickly establish the etiology of acute hypoxemia and to define the advantages and disadvantages of transesophageal lung ultrasound versus transterrastic lung ultrasoundography. Together, we'll go through image acquisition and we'll discuss the general principles of lung ultrasound, including A-lines, B-lines, lung sliding and lung pulse. We'll discuss the different diagnoses that can be made with lung ultrasound, including pleural effusions, consolidation, pneumothoracies, and alveolar interstitial syndrome. We will discuss an integrated approach to hypoxemia using both the findings from cardiac examination and lung examination. Finally, we will discuss advantages and limitations of using the transesophageal lung ultrasound. Now let's get through image acquisition. Any standard 2 to 8 megahertz multiplane transesophageal probe can be used to perform transesophageal lung ultrasound. Pending studies comparing various imaging settings, we recommend using a frequency of 4 megahertz with no post-processing. Harmonic imaging, automatic tissue optimization, and any other forms of post-processing should ideally be turned off as they can suppress the artifacts that are rely upon for image interpretation. The depth of the field should be set at approximately 20 centimeters. The main point here is to aim to examine the lungs in the systematic fashion as we do with the heart when we perform echocardiography. In our 2016 paper in the Canadian Journal of Anesthesia, we proposed to examine the lungs in a longitudinal axis with a multiplane angle at 90 degrees. The same could be done by examining the lungs in short axis with the multiplane angle at 0 degrees. The technique we proposed consisted of locating the left subclavian artery origin in order to examine the apical regions of the left and right lungs by turning the probe slowly clockwise. Then the probe could be advanced to examine the middle lung regions which correspond to the left superior pulmonary vein origin. Finally the lungs would be examined the basal regions of the lungs would be examined by pushing the probe down to the inferior vena cava origin and again turning the probe clockwise examining the left lung and then the right lung. At each of these three levels images of the anterior regions lateral regions and posterior regions of both lungs could be acquired. Let's now go through the general principles of lung ultrasound. Lung ultrasound generally consists of analyzing ultrasound artifacts. A-lines are normal horizontal repetitions of the pleural line generated by a phenomenon called reverberation. They should be absent with lung consolidation erased by B-lines but may be present even in the presence of a pneumothorax. The second lung artifact that we need to be able to recognize are the B-lines. These are abnormal shiny vertical lines arising from the pleura. They move along through the respiratory cycle and erase other artifacts. They also do not fade. They may appear in processes associated with increased lung peranchyma density such as pulmonary edema, interstitial diseases and ethylactasis. Now let's discuss lung sliding. This is the normal sliding motion of the visceral and parietal pleura against each other with inflation and deflation of the lung. The absence of lung sliding is associated with the presence of a pneumothorax or could also signify selective contralateral intubation. Lung pulse is the normal rhythmic movement of the pleural line induced by pulsatile blood flow through the pulmonary vessels. Here we see this phenomenon in M-mode imaging. The absence of a lung pulse is associated with the presence of a pneumothorax. Now let's go through the different diagnoses that one can make using lung ultrasound. First, we see a simple pleural effusion. An effusion made out of fluid generally appears as a dark area. The fluid allows the ultrasound to travel further than the normal AR rated lung which dissipates the ultrasounds and hides everything behind it. Here, surrounding the effusion, we can see the diaphragm, the liver and the ribcage. Now we proceed to a complex pleural effusion. Again, we can see the same structures. The diaphragm, the liver, the ribcage and in the middle here, a dark area composed of fluid, the effusion, but we can also see this time some some fibrin strands creating locules of effusions. This is sometimes called the jellyfish sign. In this image, we again see the ribcage, the diaphragm, but we also see these small debris floating around in the the effusion. This can be caused by either blood or pus. In this case, it was a hemothorax. This phenomenon of debris floating around in sometimes is sometimes called the plankton sign. We can use transcephageal lung ultrasound to quantify the effusions. The method described by Howard's at all, the effusions are examined here in a short axis view of the lungs, meaning at a multiple angle of zero degrees. The level in the esophagus where the effusion looks the biggest is located. The maximal surface area of the effusion is then calculating by tracing the effusion. And a maximal surface area of less than 20 square centimeters is generally a mild effusion of less than 400 mils. An effusion between 20 and 40 square centimeters generally corresponds to a moderate effusion of 400 to 1.2 liters. And a surface area of more than 40 centimeters square is generally considered severe and corresponds to more than 1.2 liters of fluid. Another method has been described in the British Journal of Anesthesia in 2007. In this method, the depth of the probe at the most proximal level at which the effusion can be seen is noted. Then the probe is pushed down to the level that the most distal level where the effusion can be located and this depth is again noted. The surface, the maximal surface area as measured previously is also calculated. The volume of the effusion then corresponds to the distal depth minus the proximal depth times the surface area, the maximal surface area of the lungs. Let's now move to our second diagnosis, consolidation. Consolidation is a generic term that we use when the lungs become solid. They have, they then have a similar echo texture to the spleen and liver. This is why it is sometimes called hypnotization of the lung. We can see this with both pneumonia and atelectasis. Some more subtle signs can help us differentiate pneumonia from atelectasis. Analogous to chest radiograms, we can sometimes see air bronchogram in consolidations. In this image, these small hyperachoric areas that appear bright white, it represents air that is trapped in the consolidated lungs. This is generally more in favor of pneumonia rather than atelectasis. But what is even more pathognomonic of pneumonia is dynamic hair bronchogram. When you can hear see the bubbles moving around in the bronchi with the respiratory cycle. In trans thoracic imaging, a pneumothorax is characterized by the absence of lung sliding, B lines and lung pulse. The absence of these three elements has a hundred percent positive predictive value for the for pneumothorax. The identification of a net transition point between absent and present lung sliding termed lung point is pathognomonic with a positive predictive value of a hundred percent. However, none of these signs have been validated with trans esophageal lung ultrasoundography and it is unlikely that they will. In fact, air tends to accumulate in the non-dependent area of the thorax which is inaccessible to trans esophageal lung ultrasound in the supine patient. It is therefore highly unlikely that a trans esophageal approach could be of diagnostic value for most non-tension pneumothoracies. With tension pneumothoracies, heart-long interactions may be observed. More specifically, one can sometimes observe a mass effect causing compression in this case of the right atrium and the right ventricle and in this case of the right ventricular apex. The last lung ultrasound diagnosis that we will discuss is the L. Vehler interstitial syndrome. The interstitial thickening produced by pulmonary edema or fibrosis results in the appearance of vertical beeline described previously. In an acute setting, pulmonary edema is often responsible for the appearance of beelines. This extravascular lung water may be the product of increased hydrostatic capillary pressure as in the ventricular failure or increased capillary permeability as in ARDS. Cardiogenic edema usually results in a beeline distribution that is gravity dependent bilateral and homogeneous. A noteworthy exception is the mitral regurgitation which can be strikingly localized as an eccentric regurgitation jet can cause selective congestion of lung tissue corresponding to a single pulmonary vein receiving the regurgitant jet. On the other hand, ARDS is characterized by a patchy distribution of beelines and areas of reduced or absent lung sliding. The number of beelines seems to be proportional to the amount of extravascular lung water. Indeed, in an oleic acid animal model of acute lung injury, a strong correlation was found between the number of beelines and the wet and dry ratio of the lung tissue. Beelines respond very quickly to changes in extravascular lung water and thus allow real-time follow-up of the effect of diuretic therapy. In our experience, left-sided beelines are present in a significant proportion of cardiac surgery cases under pre-procedure transesophageal lung ultrasound exam. While others have also have reported the presence of this artifact using TE, the exact meaning of the presence remains unknown. We should be cautious before extrapolating the associations and scores described with transerastic imaging to transesophageal lung ultrasound. While the transerastic approach allows interrogation of a wide surface of the pleural interface where beelines originate, transesophageal approach only allows interrogation of the pleura immediately opposed to the posterior medius dyneum. As there is often a gravitational gradient in the edema distribution, this could potentially render tell you over sensitive. Further clouding the issue at the lektasis, a common occurrence in the dependent lung zones of patients under general anesthesia has also been associated with the presence of beelines. In our cohort of 115 patients undergoing cardiac surgery, we could find left-sided beelines in 80% of patients. However, right-sided beelines were less common and could only be found in 38% of patients. Again, in our experience, patients with right-sided beelines had slightly more elevated pulmonary artery occluded pressures than patients without right-sided beelines. One of the main advantages of transesophageal lung ultrasonography is the ability to combine the valuable information provided with the one already provided by transesophageal echocardiography. Here we'll discuss an integrated approach using elements from both exams in order to make the differential diagnosis. A pneumonia could present as consolidation with dynamic air bronchogram. It could be accompanied with ipsilateral pleural effusions that are either simple or complex. Sometimes we can even see lung abscesses on lung ultrasound. The impact on the left and right ventricular function will depend on the presence of septic cardiomyopathy. Obstructive atelectasis should present with consolidation but no dynamic air bronchogram. It should have no impact on the left ventricular function and a variable impact on the right ventricular function depending on the degree of associated pulmonary hypertension. ARDS is generally presents as bilateral heterogeneously distributed beelines with skip areas. One can see focal areas of reduced or absent lung sliding and posterior consolidations either unilateral or bilateral can be seen. It generally does not affect left ventricular function but can greatly affect right ventricular function with increased pulmonary vascular resistance and core pulmonary. The presence of a pneumothorax on translerastic lung ultrasound is generally suspected in the absence of lung sliding and lung pulse beelines but also the presence of a lines or a lung point. These elements can rarely be seen on transness of a geolung ultrasound as discussed previously. However, the impact, the heart-lung interactions caused by them by attention pneumothorax can present as small left-sided cavities, small right-sided cavities, inferior vena cava dilation and inspiratory collapse of the right atrium and or right ventricular outflow tract. A pulmonary embolism in the acute setting should not result in any abnormal abnormalities on lung ultrasound but patients may eventually develop pleural effusions and or areas of consolidation. However, patients can often present with the McConnell sign inferior vena cava dilation, right ventricular dilation, increased estimated systolic pulmonary artery pressure. Sometimes a trombone in transit can even be seen. Left ventricular failure can present as bilateral homogeneously distributed be lines with or without simple bilateral pleural effusions. This diagnosis can readily be made by associating these findings with findings of decreased left ventricular ejection fraction and or evidence of increased left atrial filling pressures such as the e to a prime ratio. A left valvular pathology can lead to bilateral homogeneously distributed be lines or localized be lines with eccentric MR. So we've discussed some of the advantages and disadvantages but let's so the main advantages of transasophageal lung ultrasound is that it can be performed at the bedside without the need to have access to the chest. This is most often useful in the operating room. It may provide real-time feedback for interventions such as effusion drainage fluid and ventilation management. The probe is closely opposed to the posterior regions of the lungs where pleural effusions consolidations and by be lines primarily occur. The probe also allows access to the posterior superior zones of the lungs that are considered the blind spots of trans thoracic ultrasoundography because of the presence of the scapula. Transasophageal lung ultrasound also has several limitations. It's more invasive than trans thoracic ultrasoundography. It has significantly less supporting evidence. It is less sensitive to right-sided pathologies. The anterior and lateral aspects of the lungs are also largely inaccessible. In general it often relies on artifact interpretation to gain insights into the lung and is operator-dependent but not more so than trans thoracic lung ultrasound. Now that we've seen all the theory let's get into our case. The case we're going to discuss is a 65-year-old male with no past medical history. He presented four days ago with an anterior ST elevation MI. Coronary angiogram revealed severe three-vessel disease. Pre-entra and post-op echoes all revealed a left ventricular ejection fraction of 55% with an anterior wall motion abnormality. The right ventricular function was normal. The patient underwent coronary artery bypass graft, a left internal mammary artery to LED graft and venous graft to the posterior descending artery and the second marginal artery. There were no intraoperative complications. The patient came off bypass easily. There was a 300 milliliter blood loss intraoperatively and the overall fluid balance in the operating room was plus 1.3 liters. The patient arrived in the ICU on 0.05 micrograms per kilo per minute of norepinephrine. After a first hour of stability in the ICU the patient experienced progressive hemodynamic deterioration with the norepine climbing from 0.05 to 0.45 micrograms per kilo per minute. The patient received generous fluid resuscitation with 1.5 liters of crystalloids and one packed red blood cell with only transient blood pressure response. CVP was 8 centimeters of water and cardiac index 1.9 mils per minute per square meter. The arterial blood gas on 80% FiO2 revealed a pH of 730, PaCO2 of 36, PaO2 of 65 and bicarbonate of 17. The lactates went up from 1.7 to 3.9 millimoles per liter. The urine output was 100 mil in the first hour but just 20 mils in the second hour. The mediastinal drain output was 50 mils in the first hour and 150 mils in the second hour. The left pleural drain gave 50 mils in the first hour but nothing in the second hour. The ACT you ordered was 120 and the rotem was normal. What's your differential diagnosis? What is your next investigation? You decide to perform TE to rule out cardiac tamponade. There is no pericardial effusion. Ventricular function is unchanged but then remembering this course you decide to turn the probe towards the lungs. Here is your middle lung view in the posterior region of the left lung. What is your diagnosis? I think you guessed right a hemothorax. Here we see debris floating in a generally darker area between the aorta and the rib cage towards the bottom. In the beginning of the clip we see the diaphragm and here we see a little bit of lung consolidated lung floating in the hemothorax. So what do you do next? After discussion with the surgeon the decision is made to go back to the EOR for re-exploration. The source is identified failure of a surgical clip on one of the bypass grafts. This is quickly corrected by the surgeon. A massive left hemothorax is found and 2.5 liters of fresh blood is drained. There is minimal medistinal blood hemodynamic stabilization quickly occurs. The patient is brought back to the ICU where he's extubated during the night. The patient is then discharged from the ICU on post op day one without any further complication. So in conclusion I hope I've convinced you over the last few minutes that anesthesiologists and intensivists routinely performing TE can gain important information by simply turning the probe to look at the lungs. Transis of a geolung ultrasound is a point-of-care real-time tool that can provide valuable information to make some common diagnoses such as lung consolidation, pleural effusions and pulmonary edema. It allows to integrate both cardiac and pulmonary examinations. The main limitation however is that it's still supported by limited evidence and relies mostly on extrapolation from the translerastic literature. I'd like to thank the organizers of this conference for the amazing opportunity to present among this great panel of experts and also I'd like to acknowledge the work of André Danot. He's a great clinician, an amazing teacher and an extraordinary mentor. He dedicated his career to the development of echocardiography and point-of-care ultrasound in cardiac anesthesia in the ICU and he's the one who provided the inspiration for this presentation and most of the clips in the presentation. Here is my contact info in case you want to reach me. Thank you for your attention. Have a great conference.