All right. Good morning, everyone. Thanks for attending today. My name is Patrick Northup, and I'm a Hepatologist Director of Liver Transplantation and Hepatology Services at NYU Langone in New York City. And it's my pleasure to welcome you today to this webinar on point-of-care ultrasound. I do this on behalf of the Portal Hypertension SIG that came up with the idea and invited these two world-class speakers to update us and give us information on how we can introduce this technology as hepatologists into our practice. So we've arranged this in a very introductory fashion. Our first speaker will give us very basic background information on a little bit of the physics. Don't worry, it's not too much physics, and the practical uses. And then our second speaker will give us information on how this is used specifically in the critical care units and in the evaluation of advanced liver disease as well. So if you have questions, feel free to type them either into the QA tab. There's a tab on Zoom that says QA. You can type them directly into there, we'll see them. You can also put them in the chat and we'll keep an eye on those as well. So yes, and we'll aim for about an hour. We'll finish a little early for questions or comments, and we'll try and finish right on time. Also, for those of you who have to back out earlier, have another thing that comes up, this will be available as a recorded session online over about the next 24 to 36 hours, it'll be posted online. You don't need to be an ASLD member to visualize it. So you can feel free to send it to your friends as a link. I mean, anyone else who might be interested, we'd like to distribute this knowledge as broadly as possible. So it is my pleasure to welcome Dr. Brian Buchanan and Dr. Konstantin Uddin-Karvelas. Our first speaker will be Dr. Buchanan. I'll read his bio. It's long and very distinguished, but Dr. Buchanan graduated from the University of Alberta in Human Physiology in 2006, and MD in 2010. He went on to complete training in medicine at, boy, I will mispronounce the name of this, but Dalhousie University. Dalhousie. Dalhousie, in critical care at McMaster. And he completed concurrent fellowship training in critical care ultrasound and a master's in medical education. So he is uniquely positioned to help us with introductions to this technology. He practices general systems intensivists at the University of Alberta Hospital in Edmonton, and is a flight physician as well. We had some discussion about that before we logged on here. He is associate professor and the director of Alberta Sono, a critical care ultrasound education program, and directs the critical care ultrasound fellowship there. And he lives with his wife, Lindsay, in Edmonton, so, and two children. So with that, I will turn it over to Dr. Buchanan, and he will give us the intro. So thank you. Excellent. Thank you very much. I'll get my presentation here started. Bit of a busy screen here to start, just to double check everybody can see the presentation. Yes. Yes, perfect. Excellent. Again, thank you for that introduction. So yeah, we're gonna talk about essentials and point-of-care ultrasound for the hepatologist. So I made this talk thinking, what would someone wanna know to get started with using ultrasound, and beginning with a solid foundation? My disclosures, I do advise for a company called Echo Imaging. This is mostly with machine learning and AI in cardiac and lung imaging, so unrelated to this talk. And what I hope is at the end of this session, you'll understand some of the key principles of ultrasound and acquiring 2D images, and really using that to understand where POCUS can potentially improve care of patients with cirrhosis and liver failure, and compare and contrast some key false positives, false negatives, and some cognitive pitfalls. So yes, there will be some physics. However, I have tried to keep this as practical as possible. So I will try to consistently relate any physical property back to how we acquire images in the clinical realm, and talk about how we detect complications. Here's some solid reference material. If you have any questions about some of the underlying principles, I recognize that physics is not everyone's cup of tea. And again, I've tried to keep it as practical as possible. So just some references there for you, should you wish to elaborate or explore more. But when we talk about ultrasound, we talk about frequencies above human hearing. So greater than 20,000 Hertz or 20 kilohertz. So that's in the acoustic range here. And we talk about ultrasound, we're talking about two to 20 megahertz. So one megahertz equals 1 million Hertz. And really we're talking about this diagnostic range, which is as low as two megahertz, okay, which is a much lower frequency, upwards of 20 to 50 megahertz. 50 being more research applications, but certainly this higher range, we call kind of a higher frequency, in some cases, ultra high frequency, which just gives us different properties of our images. When we think about sound waves, we think about several different properties. So we think about wavelength. So for the length it takes between the start and finish of one complete wavelength, the amplitude, okay, that's the overall height of each sound wave. And also the propagation velocity, recognizing that these are really mechanical properties of longitudinal waves. And when we think about the frequency, we think about how many cycles per second. So they talked about being in that two to 20 megahertz range in most occasions. And again, this is a longitudinal wave propagating through a medium. How we generate the sound waves is through applying an electrical charge through piezoelectric material. Now, some of the more recent probes, for example, the butterfly, which is a commonly known one, I have no affiliation with butterfly, but they use silicone chip technology. So it's a bit different than this, but most conventional transducers would use piezoelectric crystals. So it deforms the crystal, okay, and this deformation leads to these pressure waves, something called a reverse piezoelectric effect. Okay, so we generate these sound waves, they propagate, they have reflections and attenuation across soft tissue. And some of those sounds get returned to the transducer, resulting in deformation of the crystal, producing electrical charge, kind of the direct piezoelectric effect. This is how we generate these two-dimensional maps. And really the object appearance on a two-dimensional ultrasound screen, when we think about the time it takes for that sound wave to travel out and then return, so obviously it makes sense that the longer it takes to return, the deeper it is, and that's something to do with a property called time of light. There's also that strength or amplitude of returning echo determines the level of brightness, okay? So some things can be very bright, and that's because of their specific acoustic properties. But we often think about how these maps are generated is there's these series of different tissue interfaces, okay, and then a certain proportion of those sound waves are reflected back. And of course, the deeper these sounds have to travel, the more you have attenuation, and that's that loss of that fundamental properties of things like energy and amplitude as the sound waves transmit at greater depths. So you'll notice that, for example, you lose some of the quality of imaging at greater depths, which makes sense as you have attenuation. But these are our 2D maps that we effectively generate. So on the left, we see apical four chamber and cardiac imaging. On the right, we see an image of the right upper quadrant with the, we can see here the liver and the kidney here and the paternal space or Morrison's pouch. So these are our 2D maps that we generate. There's also something called M-mode imaging, which is slightly different. So M-mode imaging is one tissue plane, this gray line, okay, and that is generated over time to generate motion. The reason why M-mode is often used is it actually has a higher frame rate than 2D imaging or brightness-mode imaging. 2D is brightness-mode imaging, but this allows us to resolve things that are moving really fast. Like for example, in the heart, we'll use this to look at valve motion, for example, but this can also be used to look at the diaphragm, let's say, to look for how much excursion do we have, which can be important in a patient who has respiratory failure. So that's M or time-motion mode. Further, when we think about capturing images, we often have to recall that an ultrasound transducer is really like a cut plane technique. It's a two-dimensional assessment. And so it's really critical to understand where the probe marker is and where the beam is, okay? So when you're using a transducer, one thing to try to understand for yourself is where does that plane cut through, okay? And to go back to your typical planes of, say, transverse and coronal and sagittal and parasagittal are really important properties that you have to kind of bend your mind around again if you've lost any familiarity with those, because usually when we're looking at structures, we have to look at them in multiple planes. We talked a bit about attenuation as well. So as I mentioned, as sound waves travel through a medium, they kind of weaken, and distance and frequency are really the two largest contributors. So in one case, on the far left, we see reflection. So for example, when there is a high amount of calcium in an object, we'll see a pretty intense reflection. It can be very, very bright. So a high proportion of those sound waves are reflected. In some cases, we'll see some refraction, which can be like light passing through a prism, okay? So there's loss of energy, but not in necessarily a productive plane. Scatter, okay? When you have a bunch of different materials, different impedances, you see a big loss of energy, okay? This can happen with air throughout tissue, for example. And then absorption, where a lot of the energy is lost in the form of heat, okay? This happens a lot in bone, and you just see a loss of transmission of sound waves through the bone. So again, here we see a tissue air boundary on the left, which produces a lot of intense reflection and scatter. In the middle here, we see probe air tissue. So imagine if we're holding a probe up to the air, trying to intonate something, obviously we're not gonna get a good signal there, because we have a big difference in acoustic impedance of the probe itself and the air. And so we can't insonify through that, okay? And so we use gel as what's called a coupling agent, which helps basically align the acoustic impedance between mediums. That way sound waves can adequately propagate. So here's an example, probe gel tissue. So here's the tissue, this is lung, this is rib, this is the pleural line, okay? And what we're seeing here is that we see there is a big difference in impedance between the tissue and the air. The air impedance is much lower, okay? And this leads to fairly intense reflection and scatter. This is bright, okay? And in fact, you're not getting propagation of sound waves past the pleural line here. All of this is frankly fiction, okay? So that would be until, for example, you have consolidation or say an effusion where you properly allow propagation of the sound waves. Now, when we think about attenuation, we also think about ecogenicity. And this is where I think the rubber hits the road talking about physics and trying to bring all these items together. So for example, when we see a high amount of reflection, we can get these very hyper-echoic tissues. These are lymph nodes, for example. Some fat, some calcium in there leads to these highly echogenic structures, chronic thrombus, for example, can produce a similar phenomenon. Okay, we can also see hypo-echoic. So this is just, it's less echogenic than the surrounding tissues, okay? So this, you can see hypo-echoic internal reflections, for example, in more acute or sub-acute thrombus, for example, and then, or even blood that's congealed, for example. And on the right, we see anechoic, which is most internal structures. And arguably the biggest property of ultrasound in liver patients is actually just finding fluid, okay? Finding fluid spaces it doesn't belong, okay? Whether it's in the belly or the chest, sometimes around the heart, for example. But it turns out this is a really strong property of ultrasound across all fields, whether it's medicine, intensive care, emergency medicine, palliative care, or whatever. But this is just basically smaller and smaller amplitudes of sound returning. So when it's anechoic, there is no internal echoes, okay? So anechoic, no internal echoes, or echo-free. So that's another term that's used. So here we see just the scale. So anechoic is this blue star. We see here that that's the internal structure here. This is the internal jugular vein, okay? So we see that it's, again, anechoic because it should be free-flowing blood. Oh, free-flowing blood. The yellow star here is hyperchoic, okay? That's the vessel wall and some of the fascia, for example, around the muscle, okay? So it's a different acoustic impedance, and therefore, it becomes a bit bright, okay? In the abdomen, we can see here the blue star, again, is anechoic. That's fluid around the liver, okay? And then the yellow star is actually the diaphragm. And so in this case, the diaphragm is straddled equally by anechoic spaces and actually might be a bit brighter than usual because of a property of ultrasound called acoustic enhancement, okay? So we can really see the diaphragm really well here because there's fluid on either side. So this is, you know, being able to look for fluid above and below the diaphragm is a really helpful tool to have at your disposal when assessing patients with liver disease. In this case, this is a bit more subtle. So this is looking in the abdomen. This is a patient who actually just had a TIPS procedure and came back to our ICU and quickly became unstable. And if we look at the kind of pinkish-brown star, we see here that there's this, it's kind of hypoechoic. It's not quite anechoic. Like there is some internal echoes here and there's some stranding in there, okay? And then the yellow star is really just bowel. Again, it's more bright here because of that property of acoustic enhancement. But the point that I want to get across here as I have the text on the slide, that something's not quite right with echogenicity here. It should be dark, okay? And, you know, we do adjust the gain here, which amplifies signal and noise. And so we try to turn it down to make sure that the internal echoes are black in fluid-filled spaces. But here we can see that actually this is more echogenic and this is actually blood. So this patient was actually bleeding and had hemoperitoneum. This is called the hematocrit sign for those who are kind of more interested in figuring out what this is. But this should not really be seen typically in a patient who has floating free fluid. So I'm just showing here in the white box, we can see here that this is the fluid above the chest. So this is the diaphragm, this is a bit of the lung. See how it's quite black? That means, you know, your gain's adjusted well. That regular fluid's black, but in the belly it's not quite, okay? And it's kind of coalescing here in the lower quadrant. So, and then on the right we see a typical appearance of anechoic fluid, okay? We see, again, the bowel's bright here because of that acoustic enhancement. But this is fairly characteristic of an anechoic space. Now, you must be careful because sometimes this area, if you have very dilated bowel, like you have a large colonic distension, this can give a similar appearance because, of course, the colon, when stretched and filled with fluid, will be anechoic internally and will have walls that can be kind of relatively thinned. That's right against the peritoneum. So you do have to be cautious that you're not looking at, you're not just looking at colonic distension and bowel. So this is a fairly typical appearance here of just ascites, okay? And the bottom right, this is a patient who had some chronic ascites and some organization and some complexity, okay, that you can see here, some highly kind of organization and pockets here of fluid. There are some mimics to be aware of, okay? These are all things that I've seen before. So this image here, for example, we are scanning the right lower quadrant down this big pocket of what appeared to me may be free fluid, okay? As we scan more medial, we discovered that, in fact, this was bladder. Okay, on the bottom here, we see this is the liver. This is actually, you know, this is a kidney with hydronephrosis. Now, if you have severe hydronephrosis, you know, the actual cortex medulla can be really slimmed out, and this can give you the false appearance of free fluid in the hepatorenal space. On the top right, this is the left upper quadrant. Okay, this is the diaphragm here. That's the spleen there. And this is the stomach. Okay, believe it or not, we can see this highly congenic material that's kind of sloshing around, and that's actually gastric contents. So the left upper quadrant can be a tricky place where the stomach can kind of get into and mimic free fluid. The bottom right, we have some free fluid and then bowel here, okay? So this just gives you a sense of what bowel can look like when there is fluid between the bowel wall and the peritoneal lining, and this patient had a bowel obstruction. So fluid is kind of going back and forth, this kind of to and fro sign we talk about. The wavelength also impacts image resolution. So a high frequency, a high frequency and shorter wavelength imaging can produce really high quality imaging, but frankly at much lower depth because high frequency sound waves undergo a lot of attenuation. So with attenuation, you don't get very deep. You might get kind of three to four or five centimeters depending on the exact frequency. And low frequency, here we talk about getting much better penetration, but maybe your quality imaging is a little bit less depending on what we're looking at. So here's an example here of a linear probe. Again, we're looking at depths here of three and a half centimeters, really high quality imaging, okay? But lots of attenuation and therefore reduced penetration because the sound waves simply just don't get deep enough. And on the right, we see a curvilinear probe and a phased ray probe, which work a little bit differently in a nuanced way, but both have lower frequency sound waves that allow propagation fairly deep compared to a high frequency probe. So when we talk about selecting probe type, you know, there is a lot of crossover. Like it's a very big Venn diagram of how these probes can operate. For example, in the lung, we could use a linear probe, but we could also use frankly any of these probes will offer different acoustic properties. But when you're looking at vascular specifically, linear is your best bet. Although in some cases in patients who are morbidly obese, you might actually find that a curvilinear probe might offer you a better depth, okay? Because you need that depth, okay? Because you do have a lot of soft tissue, then you need a lower frequency probe to reach down there. But there is a lot of things you can do with these probes that maybe are considered to be classical probe selection. On the top left here, we see this is the lung, okay? So again, high frequency, shallow depth, 4.2 centimeters, okay, really high quality image here. But again, this is a high frequency probe with low penetration and high resolution. On the bottom left, we see the curvilinear probe and phased array. This is from a curvilinear probe. We see, you know, a great depth, 16.2 centimeters, and offers a fairly large sector here to give you a nice broad perspective. We can see fluid and some bowel floating in there mesentery. But on top right, we can also see that there's, this is a curvilinear probe applied to the chest. So, you know, it's not that this image itself is unusable. In fact, you can still see sliding here, okay, in this patient while it's subtle. And so there is, again, a lot of shared features you can have with these sets. And this is just showing that, you know, when you're looking at the right upper quadrant, you can use the curvilinear probe as well if you're examining the pleural spaces, for example. And the bottom, as we can see, again, curvilinear probe with the right lower quadrant. So here is just the lung. This is with a phased array probe now, okay? So what people would call the cardiac probe, but it is the phased array probe, just in terms of the activation of crystals produces a different kind of image. But we can see here, we can make out lung sliding, these A lines, okay, which are these reversion artifacts. Okay, so this gives you a sense that you can do, you can do, you can be quite versatile with these probes. So I would commonly do the lung exam, thoracic exam with either phased array or curvilinear. And if I really have questions, I might apply the linear probe, if I have questions about, you know, lung sliding, for example. And then here in the thorax, this is where, you know, you really want to use your low frequency probes because the depths here, you know, 19 centimeters. So you need to propagate all the way through essentially down to the spine okay because if there is fluid or consolidation there you'll need that low frequency to get down there so this is acquired in the effectively kind of position four or five here at the level of the diaphragm. The probe orientation when we think about non-cardiac imaging if you press the exam type on your machine usually if it's non-cardiac it'll go the marker will go to the left and that'll correspond here to a little bump on the probe but each vendor has they may have a light or a ridge but just be mindful that these things do line up and we think about cardiology with echo most facilities have the screen marker right so there is some subtle differences between cardiac and non-cardiac imaging when we think about just describing our findings we think about those in the near field and far field okay that's just kind of generic spatial terms it's also the property as I alluded to earlier of gain so the difference between these two images as you can imagine is gain so on the right the gain is up so we see amplification of signal and noise the cavity itself in the heart is kind of white okay whereas it should be black typically okay and then on the left it's appropriately adjusted there there is good gradation between fluid and tissue and on the right it's a bit messy so you do want to just gain that being said you can imagine if blood slows down let's say because of heart failure then you may have some more hypoechoic findings because the blood has become itself more echogenic so on this machine you can see here that there's different ways to adjust gain this is an auto gain and then there's also what's called time gain compensation this is adjusting gain in different parts of the field okay so here's some examples on the right we can see here that gain is turned up too high thus amplifying signal and noise the next thing too is want to make sure we adjust the the depth so here we just at 14 centimeters looking at the kidney so this just kind of to remind you to think about how we adjust the depth that way we don't have you know if we put the depth here at you know five centimeters we wouldn't see the kidney it was at 20 centimeters we would smudge the kidney in the near field here's adjusting dynamic range so we can increase the gray scale okay of of how much we're seeing on the bottom here we have a you know fairly appropriately adjusted blacks and whites but as we go up we see a blending of the tissue because now where our gray scale is increasing so we do want to be mindful on the image right for example the high dynamic range we actually find this more challenging to separate blacks and whites and grays so dynamic range is one property you can also adjust to optimize imaging and most often it could be just a downwards to help you better see things to quickly just remove some artifacts um so we talked about acoustic enhancement but some other things to be aware of when you look at the lungs we're talking about reverberation artifacts most often because the the probe itself can act as a mirror and so does the plural line because there's lots of reflection there as we talked about earlier so that can generate these a lines which are a reverberation artifact they're equidistant from the probe to the plural line repeated over time at depth okay so that's very normal for healthy tissue to generate a lot of reflection so a lines are often seen as being normal but they can be seen as well as pneumothorax because you are still a tissue interface on the right we see different kinds of reverberation artifacts which is generated from interstitial edema these are called b lines these are more hyperchoic uh go from the go from the plural line all the way down and move here i'm not sure this is coming across screens very well here but these are um vertical hyperchoic lines we also think about acoustic shadowing so on the right we see a gallbladder with a gallstone again generating that shadow okay because there's lots of reflection here off this echogenic structure and then finally uh we think about mirror image artifacts which occur at boundaries where there's lots of reflections so on the left here we see that there's this liver lesion which is replicated above the diaphragm because the diaphragm acts as a mirror effectively with the probe and on the right here we can see actually that the pericardium acting as a acting as a mirror okay it's generating an additional heart below the pericardium and we know that there's not two hearts in this patient finally some additional tools we can use things like color doppler can add additional features so looking at the kidney here for example we can look at kidney perfusion um this is looking at the radial artery okay looking at pulsatile flow so these are additional skill sets you can use but they are they do come with their own unique challenges and generally i would reserve this for people who have become more familiar with the foundations of ultrasound so that's the summary um so i hope i covered some principles here again i want to provide you with the foundation to think about ultrasound to think about how we can change the properties of ultrasound talk about some false positives some false negatives some pitfalls and we talked about some of the physics like wavelength frequency amplitude how we generate you know uh echogenic structures from being anechoic to hyperchoic we talked about beam mode and some m mode imaging attenuation and some imaging artifacts and how we use this to generate uh pictures of you know obviously fluid and other structures so that's all i have and uh yeah i'll pass the torch back all right thank you brian that was a wonderful introduction to uh the technology and that that's so there's a lot to digest there so to speak uh in um a short amount of time so any of you looking to learn more about this um there are classes available and there's entire um societies and industries now designed to help introduce folks to this technology so again thank you brian um the next speaker is dean carvalho and i am going thank you brian um the next speaker is dean carvalho and i am going to read his um his also very uh distinguished um bio he is a professor of hepatology and critical care medicine at the university of alberta he's been an attending intensivist um since 2009 he also is involved with the liver transplant program as a hepatologist as well um and his his training was from the university of alberta 2001 completed residency in gi in 2006 critical care um in 2009 he's a clutton for punishment um and a chronic student uh at least until the late 2000s he received the cag sharing cihr research fellowship and completed advanced training in hepatic failure at the institute of liver studies in king's college in london and he has been a member of the asld for many years and is the chair of the acute on chronic liver failure sig and co-chair of recently published aclf clinical practice guidance he's also an associate editor for the journal of hepatology and the only canadian co-investigator of the nih funded acute liver failure study group and he's got two numerous account publications um essentially so dean we're honored to have you uh thank you for agreeing to participate in and i think dean's goal looking at his slides is to translate what we just learned about these physics into how it can be used in the at the bedside in the critical care unit for patients with liver disease uh thank you patrick uh and uh brian is always a tough act to follow uh so first thing is i just want to make sure that everybody can see my slides yes perfect okay um so i uh i'm gonna try to follow up with uh with brian with some clinical examples that are kind of relevant to the hepatologist either on the ward or in particular in the icu i want to give the uh the acknowledgment that everything i know about this i learned from the course i took with dr buchanan so uh my successes are his and my my failures are my own so um in terms of uh what we'll cover we'll kind of evaluate the role of focus and detection of ascites and procedural guidance characterize how focus can help troubleshoot shortness of breath and respiratory failure which is a big challenge that we deal with and also look at focus for volume status and stock shock states and finally one other thing i wanted to kind of just kind of explore is particularly in acute liver failure show us some techniques uh from focus particularly transcranial doppler can help us in a non-invasive fashion look at things or surrogates of intracranial hypertension so i want to compliment brian who recently uh um as an educational and research tool put uh several of our mid and late career intensivists through a through a rigorous ultrasound course and uh this study just recently concluded in august of 2023 and we look forward to the the results of this being published so i'm starting with ascites and procedural guidance which is something that that the hepatologists are very kind of aware of you know the advent of focus primarily here improves the success rate decreases the rate of complications decreases the rate of aborted procedures and also kind of identifies uh you know patients where where this is not appropriate and furthermore it saves time and there is a large body of literature that kind of shows that that paracentesis is is better with with focus and ultrasound techniques brian has already covered this but we talked about uh changes in appearance of fluid where where fluid can be anechoic um for example being cirrus fluid or fresh blood but over a period of time as as blood clots it can become generally more gray or hyperechoic or even hyperechoic so in terms of the particular areas of the abdomen we will and and brian kind of went into details about the the different uh probes that you can use predominantly we are we are in the mid axillary line looking at the right upper quadrant um in the in the left upper quadrant and also suprapubic in the in the pelvis so you know traditionally we've um you know this this is an article from the new england journal we we talk about in prepping the patient for ascites that you can go either in the left or the right lower quadrant the main reason for this is you're trying to stay away from the intercostal vessels that are are midline particularly inferior epigastric artery but there are advantages you know besides traditional landmarking whether you go in the left or the right lower quadrant that you can get with with ultrasound so the first thing being is that we know that there are superficial vessels that you're more likely to see with ultrasound and to avoid a bloody tap this will help you landmark with regards to not only avoiding superficial vessels but staying away from the from the bowel the second thing is also that you're able you know ultrasound affords you the opportunity to detect free fluid in in several spaces throughout the abdomen and not only just the left and right lower quadrant so the example here is with that with the kidney and the in morrison's pouch in the hepato-renal space so um and then here is an example this is kind of a standard view that um that you'll get with looking in the left lower quadrant in the paracollar gutter where you see the the you know fluid differentiating from the from the lining of the peritoneum and the bowel so just to know that there are false positives and one of the challenges in some cases can be are you looking at fluid in the below or above the diaphragm so just a couple of examples here that this at first glance looks like you could be looking at both a plural effusion as well as looking at ascites but if you actually look in more detail you've got atelectatic lung uh with with fluid both above and below the lung and actually above the diaphragm so in this situation if you you would likely end up with a with a with a dry tap if you went into the abdomen and at worst you might end up with a complication so this is probably where where ultrasound is helping us um uh the most in the in kind of the critically ill setting particularly in patients with aclf it gives us a lot of information at the bedside with regards to patients with respiratory dysfunction you can detect pulmonary edema pleural effusions differentiate this from pneumonia or lobar collapse it also allows the detection of complications of procedures such as a pneumothorax or or bleeding as a result of a central line insertion it also facilitates the detection of structures around the external chest vis-a-vis abdominal fluid and diaphragmatic function which we'll talk about as well so um you know we'll we'll kind of uh you know tag this on to a case you've got a um a 54 year old male with with uh mazzled uh slash alcohol cirrhosis awaiting transplant admitted with aki um for continuous renal replacement therapy developing worsening shortness of breath prior uh pigtail was inserted in the thorax for a chronic infusion he's now been on the ventilator for six days uh the chest tube pigtail is still draining but has worsening respiratory status and you can see here that you have uh you know quite significant uh you know white out on the on the right lung so one of the things to mention this is where uh you know uh ultrasound gives you a lot of information and and brian has kind of touched on this already that normally when you have a normal um interface between the uh parietal and the uh sorry the um the the the parole line between the parietal and visceral pleura you will see lung sliding so you can see this here in this video um and furthermore you'll get as as dr buchanan mentioned the reverberation artifacts or the a lines which you would have with essentially reflecting that you have uh reflection from the healthy tissue air interface and you reflecting also normal lung parenchyma meaning that in this setting you don't have a laurel uh pneumothorax or pulmonary edema there are three places on on on the chest that you can look at there is you know classically it's the mid clavicular line between the second and third intercostal space the anterior axillary line between the third and fifth intercostal space and then at the level of the of the diaphragm the other is you can also go posteriorly um on the posterior axillary line both at the third to fifth intercostal space and at the level of the diaphragm so the difference here um is that uh what you're seeing on the left we show our normal video again where you have lung sliding and a lines as opposed to the second video where you've now lost this lung sliding and you've also lost the a lines where the concern here potentially could be a pneumothorax and the the the hint with this uh particular patient was the fact that they had recently had a central venous catheter inserted on that side so the the other thing to look at here is is is uh people are symmetrical so so we see on the right side um looking in the uh at the right chest in the mid clavicular line that you are seeing a space that shouldn't be here between the parietal and visceral pleura and this is fluid and in contrast you don't see this space on the left side of the chest implying that you likely have a pleural effusion uh on the right the other thing that you can use with ultrasound is that you can you can go up the chest from different views so what you're seeing here is is what's known as a meniscus sign where in in the more uh sorry about that in the more dependent areas uh uh you have uh you know a larger space reflecting kind of more fluid at the at the base of the lung um and as you go uh up on the chest that you see that this kind of levels out to a to a meniscus where there's less fluid and this will obviously identify where potentially you might put in a a pigtail catheter this is also just to kind of mention that uh what we're looking at here uh potentially is that you've got a large fluid pleural effusion here but you're also looking at the diaphragm here and realize that you've got some fluid below the diaphragm as well and this is uh not uncommon in the setting of ascites with a patient with a hydrothorax so generally if we are going to uh you know define the size of a um of a pleural effusion you want to do it in a in a cross-sectional fashion and you want to do it in the in the dependent part of the lung one thing to note is that generally for every one centimeter that you measure this can be approximated to about 200 cc's of fluid so in this setting where you have a patient with about 12.6 centimeters this equates to almost two to two and a half liters of fluid that's actually in the chest and as you can see post insertion of a of a pigtail drain you can see that there has been resolution of this pleural effusion slash hydrothorax so at the other end of it there are other things that we look at as well so this is now a post-transplant patient that is having difficulty weaning off the ventilator and we're trying you know generally the the lung fields look fairly symmetrical so the question is that what could be explaining this and uh what i'm kind of highlighting here is that you notice the diaphragm here the liver but the the diaphragm is kind of doing something funny here and just to kind of highlight again in these two videos this is what normal diaphragmatic excursion should look like where you get uh essentially with with uh to generate negative intrathoracic pressure you get the diaphragm pushing down into the into the abdomen increasing the intrathoracic space but on top of that also that's what you see on the left but also on the right you see thickening of that muscle of the diaphragm and also you see some uh confounding uh because of air that's in the in the lung so if you look at the you know at the normal diaphragm on this side you see that happening here there's probably a little bit of fluid around the lung however on the other hand uh as Dr. Buchanan has described as the as the winking sign of the diaphragm you get abnormal movement of the diaphragm in fact it's moving paradoxically and there is very little diaphragmatic thickening so obviously in the setting of a transplant where there might be a diaphragmatic injury you're noticing here that there could potentially be diaphragmatic paralysis and uh you know kind of an example here again this is just doing it through a through a version of m-mode that essentially you can see here that with normal diaphragmatic uh excursion on the left hand side you will get a positive inspiratory peak where on the other hand in a patient with dysfunction of the right hemidiaphragm you are actually getting a negative inspiratory peak uh indicated of paradoxical diaphragmatic movement so uh this is another example here where you're actually in the um in the axillary line between the third to to fifth intercostal space which normally is described as as the triangle of safety that the question here is uh you know um you know am I safe to put in a chest tube because the initial concern here is that we're thinking that this patient might have a pleural infusion but in fact when you examine the patient um with um with ultrasound you see this raised um hemidiaphragm uh with a large amount of acidic fluid and the concern here is that potentially if you had put in a blind uh chest tube here you would have ended up potentially with a diaphragmatic injury even though this you know would have been done with traditional landmarks so another cautionary tale one of the benefits of ultrasound is that even in a patient where where you think you might be doing something blindly in a in a safe fashion that that ultrasound really affords you a benefit to avoid complications. So moving over to to volume status uh you know this is where I I think really one of the big changes for us is using these dynamic techniques. It should be noted that ultrasound is not a binary tool of yes or no um whether to give or withhold fluids and as you can understand cirrhosis and ACLF patients can be very challenging to assess volume status and this is just another two uh tool in our toolbox. Particularly we're looking at somebody if if they are volume tolerant so the example being somebody they may have a significant amount of third space fluids but they might actually be intravascularly deplete and respond to fluid or other patients where they're truly volume intolerant where their where their total body fluid overloaded where where they may actually uh tolerate either diuresis or or or removing fluid on ultrafiltration with renal replacement therapy. Essentially the idea here is we're using this to kind of point us in one direction or another, and the primary issue is to know is there, you know, first of all, from a failing point of view, and secondly, from a pump point of view, do you have pump failure, or is this due to circulatory failure due to shock, to hypertension, or to systemic vasodilatation, or distributive shock that's common in patients with liver failure? So, what essentially you have here is this is a parasternal long axis on the left, and then you have a parasternal short axis where you're cutting through the left ventricle, and really what you're seeing here is that this heart is contracting very slowly. If anything, it's hyperdynamic. If anything, kind of reflecting a state of low afterload, which is kind of a classic feature of distributive shock, or in patients with acute or chronic liver failure, and if anything, you're seeing a patient where the right ventricle might be underfilled, and furthermore, you see it even more on the parasternal short axis with near kind of, you know, closure of the of the LV cavity. So, this is somebody where we're potentially with a hyperdynamic EF that you could consider giving volume to, and just looking at it, you know, from a different point of view, this is the same, you know, a similar hyperdynamic patient where you're now looking at the apical four chamber view, and you can see here today, you know, again, you know, a fairly aggressively contracting left ventricle, you know, the right ventricle is reasonably filled, and one other measure that you can use is actually looking at the velocity time integral, which is measured with a cursor here, and this is another one of these measurements of blood flow where you get an area under the curve, and really you're getting a, you know, a product of the of the velocity time integral, and the cross-sectional area of the valve gives you an approximate, you know, measure of stroke volume, and you can see here because the patient has a high VTI, they have a true high cardiac output state, and they're reasonably well filled. But one of the things to mention here is having a hyperdynamic heart does not necessarily mean that you have high cardiac output, and this is the example of the patient, for example, post, you know, having a liver lack in the setting where they have a hyperdynamic LV that's almost collapsing, and here if you look at the velocity time integral, it's the overall area is depressed with a VTI of only 10 centimeters, so this is a patient obviously that needs to be resuscitated. It's not a primary pump problem, but this is somebody that needs to be resuscitated due to hemorrhagic shock. One of the other challenges that we deal with is, you know, we see patients with portal pulmonary hypertension, which in some cases can be reflected in the setting of tricuspid regurgitation. Here we have a, you know, a patient where we're doing a doppler over the tricuspid valve, and you can see that there's a lot of, there's a significant retrograde jet here, and this is one of the challenges in a patient with TR, you know, assessing volume status and furthermore response to fluid. This is somebody that's going to have significant venous congestion and on clinical exam and elevated JVP. So, you know, there, another kind of setting here that you can have in a patient with significant TR is right ventricular dysfunction and RV overload, and you can see here that you've got this big massive right ventricle that is now, you're getting some intraventricular dependence where you get kind of bowing of the intraventricular septum that's now kind of impeding on the left ventricle and will likely impact left ventricular filling, and this can lead to a form of an obstructive shock state, and here you can see this kind of, once again, this large kind of tricuspid regurgitant jet, and in terms of another method of, you know, assessing venous congestion is here you're looking at this large inferior vena cava on your subcostal view, where normally if this is greater than two centimeters, which this is, and you don't get any respiratory variation, it implies that you're volume overloaded, but to take it even a step further, you can see a very well demarcated hepatic vein that's coming off, sorry, a portal vein that's coming off, and hepatic vein coming off the internal jugular vein, which normally you should not be able to see with such prominence. The other thing is, which is also relevant, you know, particularly in the setting of somebody that you're considering for liver transplant, is a depressed ejection fraction, so once again here we're looking at the parasternal long axis, and now you're seeing a big baggy left ventricle with very little kind of myocardial thickening with contraction, and you're seeing very minimal movement of the mitral valve. Here you're looking again in short axis at the LV, where once again you're seeing very little, you know, thickening of the LV wall, and furthermore, or, you know, contraction of the ventricle. You can also see this down here, this is now on an apical five chamber where you can also see the LVOT, and this is also reflected in the setting of hepatic congestion on the subcostal view with a dilated IVC, which is also reflecting now because you have a low flow state. I kind of mentioned that one of the new innovations is looking at non-invasive methods, particularly in acute liver failure, of determining intracranial hypertension without the use of a direct intracranial pressure monitor, and I think these techniques really hold a lot of promise. So one measurement is the optic nerve using the linear probe to measure the optic nerve sheet diameter. This is done by essentially placing gel over a closed eyelid and then using, as mentioned, the linear probe. The idea here is that you want to measure it both on the left and the right side, and you want to get perpendicular images. This is generally measured three millimeters behind the posterior of the orbit, and as mentioned, generally these measurements will be done in duplicate. And this is kind of highlighting here that you will measure here approximately three millimeters behind the orbit, and one thing to mention is that you're not measuring the nerve, but the nerve sheet. It should be noted here that, you know, there is some intra-observer variation and that's why you will see this intra-observer agreement, you know, reported in multiple different studies when looking at optic nerve sheet diameter. This is an example which is fairly obvious, where you get papilledema of the optic nerve and swelling secondary to intracranial hypertension and elevation of the optic nerve, which is essentially buried in the optic nerve head, which is obviously an extreme example of this. Obviously, the goal of measuring optic nerve sheath is trying to kind of identify this before its terminal, and you're able to intervene with ICP-directed therapies. This is one good study that showed that, you know, when you look at receiver-operated curve analysis in vented patients, you know that a cutoff of optic nerve sheath of about five millimeters has been validated in non-ALF brain injury patients. You know, it should be noted that there's a couple of small studies in ALF that have also shown that an optic nerve sheath greater than five will discriminate between survivors and non-survivors, but truth be told, these are small studies and this needs further investigation. But probably what's here used more widely is actually transcranial Doppler, which offers a non-invasive method to evaluate blood flow, and it should be highlighted that it complements also direct intracranial pressure monitoring, because we're looking at cerebral blood flow and we're getting blood flow measurements and it's not just a pressure measurement. So, it allows for gross prediction or indirect prediction of ICP and evaluate changes in blood flow, you know, potentially looking at somebody who could be progressing to circulatory arrest from severely raised ICP. You know, why we do this is that we can do this as a bedside assessment and also permits assessment in low resource settings. And one example of using this is in a setting with ALF that potentially is on the transplant list, where you might do this as an initial screening test in determining whether somebody has raised intracranial pressure, where certainly if you're considering proceeding with liver transplant, that's somebody that you might proceed with putting in a bolt or a direct intracranial pressure monitor. So, this is a very nice technique where you use the cardiac probe and you're looking at the middle cerebral artery. And once again, you can look at other vessels as well, but classically the one that's used most commonly is the middle cerebral artery. And once again, you're getting an area under the curve when you look at flow velocities. If you're to boil it down to one variable, people talk about the pulsatility index, which is looking at the difference between systole and diastole. And one of the ideas here is as the tighter the brain gets and you lose capacitance in the brain and the loss of what they call the Winn-Kissel effect, that this waveform will become more sharp and you will kind of lose the broadening out. And with that also, you will get a decreased area under the curve. So, there have been some studies that have shown that even a pulsatility index of greater than 1.2 might discriminate patients with acute liver failure, although certainly a pulsatility index has been published more broadly in the neurocritical care literature of greater than 2 is associated with a worse outcome. I will say, though, that with transcranial Doppler, looking at blood flow really adds a lot of value on top of the pulsatility index. And really what you're looking at here is a patient that's slowly progressing to cerebral circulatory arrest, where initially you lose the diastolic waveform and then it can become paradoxical to eventually, as you can see here, that you get a decrease in the area under the curve prior to circulatory arrest. So, as mentioned, in our setting, we really like to use this. You are able with mathematical software to approximate an intracranial pressure and a cerebral blood flow and a pulsatility index. And this might give you information on either continuing your current therapy or okay to go ahead with transplant. Is it concerning where you might initiate more aggressive intracranial pressure therapies? Or finally, is this a stop sign where, you know, if you're getting a predicted ICP of greater than 50, that either is it a stop sign or do you really want to measure this with an ICP monitor where it might be a decision to delist somebody for liver transplant? So, in summary, I know that this is a lot to cover, but really the role of POCUS is really increasing over time, particularly for abdominal ultrasound, for ascites and procedural guidance, chest ultrasound, not only looking at hydrothorax, but also the identification of lung pathology. It is very valuable in the assessment of volume status in the ACLF patient and in particular in terms of guiding resuscitation. And then the area in particular of neuro POCUS, particularly in the acute liver failure patient, I think is really going to evolve over the next few years. And with that, I thank you very much. All right. Thanks, Dean. That was a great insight to what you're doing at the bedside in these critical care patients, especially. We have Brian back. And if anyone has questions, feel free to type them in either chat or the Q&A box. I see none currently, but if I'm missing them, please someone let me know. We'll give people a minute to type in. So, you know, I think I can pose this to both of the speakers as a open question, especially on the ascites and the cardiac findings. How does being able to have this technology in our hands differ than getting a formal echo? For instance, when looking at cardiac function, how have you found an advantage to POCUS versus, you know, the full echo? No, I was gonna leave this to you. I think you've got it. Sure. So I think, you know, oftentimes when we order an echo, like in our ICU or on a ward patient, for example, there's often like a considerable delay. And not to mention that the person who does the imaging is kind of divorced from the clinical context. And I think there are strengths to that, like to having no bias per se. There's also fairly immediate weaknesses too, because you're not obviously with the patient and you may have to make an intervention. For example, if your patient's hypotensive, well, you may have to make a move and that could be a big move, for example, like you may have to call ICU or start inotropes, for example, in a patient who's in the emergency department. So I think having the feedback at your hands, but that does require good training and a lot of thought and consideration. And there, you know, the benefit to someone who has kind of a more robust experience is they can really help make decisions in a short time to help keep a patient resuscitated. There's also the risk, though, that if somebody doesn't have adequate training, that they may make erroneous decisions. Or for example, you can imagine a patient who, as Dr. Carvello spoke about, a patient who has a high ejection fraction, hyperdynamic EF, who has a high output. And the thought is, well, we should just increase their inotropes, like their heart's not beating strong enough for when, for example, it's really just high output is kind of the problem, like a low systemic vascular resistance. So there's definitely immediate benefits, but there are also risks too. Yeah, that makes a lot of sense. How, one of the questions that is often posed in these types of situations in an institution or a unit even looking to implement this kind of technology, either of you could comment on this. How, what's the usual initial investment for the technology? And then how do we go about getting people trained in a controlled fashion? So I think that the actual costs of this technology are fairly low. The costs are coming down over time too, and machines are becoming increasingly affordable. So I actually don't think the costs are very high in comparison to other items. Like for example, our machines, somewhere between 50 to 80,000 for a fairly high quality machine that's fairly versatile. Our machines are used frenetically, like every hour in our units. And so the cost is not high. Now the biggest barrier to entry, I think, is having a champion, having a person or group of people to support the program. And I think that's where you're talking about having somebody who has the training. And when it comes to getting someone trained, having someone who has dedicated training, like for myself, I went for a fellowship, which I was able to do during my ICU time, but having someone with at least kind of four to six months at minimum, even upwards of a year, who can really wield the probe, understand the kind of knowledge piece of ultrasound, but also the technical piece. And I think that that will bring most programs much further than others. Yeah, I think one thing I want to comment too, is that there's a huge difference for somebody doing a course versus somebody that is a true, you know, true expert. And I think also the fact that the luxury we have in our unit is I call it that you have the phone a friend, that you can say I'm seeing something. This isn't something that's run of the mill. And before I do something that the door is only one way it might be worth getting advice from somebody. You know, and I think that's one of the important things, like you said, is continuing competence. And you know, we have the luxury now that we have at multiple ICUs in our city, we've got intensivists that have all done the kind of the one year fellowship. And Brian's actually trained several of them. Yeah, we, many larger institutions have entire even subdivisions of folks that have, you know, a skill set that can lend itself to helping others learn. Are there published or, you know, available resources for training, either online or in person training that people can go to and seek out? Yeah, so it kind of depends what you're looking for. Now, in terms of online learning resources, the site that we have created is albertasono.ca. So there's lots of resources on there. And a lot of the resources will cite evidence for assertion. So I think that's a worthwhile site to look up. I can put that in the yeah, it's just albertasono.ca. So I think that's worthwhile. There are also other, there's plenty of educational resources out there, the American College of Physicians or ACP produces some educational resources as well. And in terms of curricula, like so it depends on where you are and where you want to travel to, I think some of the biggest trainers in ultrasound, the American College of Chess Physicians or ACCP has an ultrasound curriculum that they have where they can offer, I believe it's some kind of credential certification, which does have kind of more a longitudinal element, which I'm definitely a proponent of. And then we have training here at our site called the Canadian Resuscitative Ultrasound Course West. So you can find the link to our site. And we do also offer electives to trainees and increasingly electives to even faculty who are interested. Great. Those are great resources. And the American College of Chess Physicians, I think has even information on pathways to credentialing and that sort of thing. So that's useful for for many. I think we have time for one more question. One on the QA tab asked, maybe I'll target this to Dean, can ultrasound help predict or identify AKI in ACLF or triage the cause of it in even in post-transplant patients? So that's a really good question. So I think you probably get around it indirectly, but a couple of pieces of information you'll get. So if this is pre-renal, you're going to likely have somebody that very clearly is underfilled and you'll see a collapsible IDC. So that will give you some information. And secondly, in that situation, often, you know, when looking at the kidney, the kidney will look normal in size. You don't have, you don't see evidence of hydronephrosis. Where on the other hand, obviously with obstruction, you'll probably see hydronephrosis. And if you see it, and this is something obviously that takes a lot of training. So if you're going to be looking at things like whether it's a shrunken kidney due to medical renal disease, these are really the indirect pieces of, of information that you will get. But I think also furthermore, where it probably, where it probably helps you is along with some of the other biomarkers or things that you'll, you'll use in the clinical picture. And I highlight what Brian says too, that a lot of the real benefit with this is we're coming in with a pretest probability. We know the information and yes, it's good to be agnostic sometimes, but, but really that's how we get the answer to the, to the, to the problem. And what, what is the action item as mentioned? Is it fluid? Is it norepinephrine? Is it something else? Yeah, I've seen some literature out there on the use of IVC compressibility or collapsibility and even resistive index and the renal blood flow system. So there, there are lots of there's lots of options out there. And the literature is growing in this area, especially in liver disease patients. So I think we're about out of time. There's a question about using POCUS for liver stiffness or steatosis measurement. And I, I don't know the answer to that. They're either of, you know, other than Fibroscan, which is an ultrasound based technique. Yeah. You know, people are doing this, but, and obviously that is got certainly more relevance to the, to the clinics and, and some people are doing this, like, oh, we're not doing this in a critically ill setting, but that is actually something that's come up in terms of, can you actually use liver stiffness, not just in cirrhosis, but will it give you information in an ALF patient as well? Yeah. Great. Well, thank you doctors for your talks. They're very insightful. And this is just dipping our toe into the waters of POCUS. Anyone interested, I'll go ahead and say, please email myself or either of the speakers here, and we can point you in directions that might help you. Thank you gentlemen for the time and thanks to the ASLD and the Portal Hypertension SIG. So we'll end it there. And thank you very much.

Point-of-Care Ultrasound

POCUS

Critical Care

Diaphragmatic Function

Volume Status

Cardiac Function

Intracranial Hypertension

Liver Disease

Resuscitation Decisions

Clinical Decision-Making

Portal Hypertension