SCCM Resource Library-Is POCUS as Reliable as Formal Echocardiography in Screening for Shock in Patients Requiring Temporary Mechanical Circulatory Support?

Video Transcription

Good morning. I feel honored today presenting the lecture, Is POCUS as Reliable as Formal Echocardiography in Screening Shock Patients Requiring Mechanical  Circulatory Support? We have a prerequisite for this lecture, which is understanding the definition of point-of-care ultrasonography, and perhaps the most critical  element in that definition is to acknowledge the immediate clinical integration of ultrasonography imaging performed by that treating clinician at the bedside.  The two objectives that I have today include, number one, describe a contemporary POCUS framework in critical care medicine, and contrast the diagnostic accuracy of both qualitative  and quantitative echocardiographic assessment for left and right systolic ventricular dysfunction.  I want to clarify the term of critical care echocardiography now, because it implies advanced  levels of knowledge and skills in the application of trans-thoracic or even sometimes trans-esophageal  echocardiography in critical ill patients. In this lecture, I will be mainly utilizing cardiac POCUS for the screening of shock in patients that require mechanical circulatory  support. This is a contemporary POCUS framework in critical care. Whenever we are evaluating  patients in shock, we can use ultrasonography for these different purposes. And in this case,  if I would like to summarize my talk, I would be able to state that the screening application of POCUS is valid, and it can equate the majority of times the diagnostic assessment  that we obtain whenever we apply formal quantitative echocardiography. It's absolutely  valuable and reasonable to utilize POCUS as a screening in the initial management and treatment  of patients in shock. In 2019, we created this video for the assessment of left ventricular systolic function. We were able to do the video after analyzing the existing literature  that correlated qualitative and quantitative echocardiographic measures.  We understood that the application of those echocardiographic parameters with  visual estimation will be extremely practical and applicable at the bedside.  So, what we have so far? Based on previous investigations, when performed by trained  emergency medicine and critical care physicians, POCUS correlates well with quantitative assessment  of left ventricular function when performed by echocardiographers. These are the four parameters  These are the four parameters we will use for estimation of left ventricular systolic function.  First, the longitudinal shortening of the left ventricle, and more specifically, the mitral annulus. Second, the anterior mitral leaflet motion.  Third, the thickening of wall segments. And fourth, the area cavity change.  The first parameter we will analyze is the longitudinal shortening,  which is represented by the movement in systole by the mitral annulus from the base of the heart  towards the apex. That movement should be more than one centimeter, and you can appreciate here  how that happens. So, you might say, well, it's not clear to me. You are just guessing that centimeter. In this case, you have a scale here, and each of these dots or small lines  are representing one centimeter. And for sure, it's easy just to recognize that this movement of the mitral annulus is more than one centimeter based on this scale.  Once again, longitudinal shortening is our first parameter to recognize. I just removed the dots, and I want you to try to determine whether or not you have more than one centimeter  movement by the mitral annulus. The second echocardiography measure that we're using for estimation of left ventricular systolic function is the recognition of the appropriate  movement, anterior movement, of the mitral leaflet, that motion in systole. For that,  we will put this imaginary line in the middle of the left ventricular cavity. Normally,  the anterior mitral leaflet should have a motion beyond that imaginary line in systole. This is  normal. So, this is the second parameter for estimation of left ventricular systolic function.  The third parameter is the thickening of wall segments. So, in systole, you are expected to have  an increase in the thickening of each wall segment by one third, 30%. We will be able to appreciate  the same change in other views, not only the parastellar long axis view or the apical view.  Change in area of cavity is the fourth echocardiographic measure that we will use to  estimate left ventricular systolic function. In my opinion, this is that echocardiographic measure  that is more used in the clinical practice.  The change in area of cavity should be determined also in the apical view or  the parastellar long axis view. And in that way, we can have a more complementary assessment of  the left ventricular systolic function. In this table, we present the four echocardiographic  measures that will allow us to classify the left ventricular systolic function either as normal,  with more than 55% ejection fraction, or severely reduced left ventricular systolic function with an estimated left ventricular ejection fraction under 30%. Of note,  all four echocardiographic measures must be normal or abnormal. All of them must be present in order for the operator to determine that the patient has normal or abnormal  left ventricular systolic function.  In 2020, I served as the editor of the second edition of the SCCM Critical Care Ultrasound  Testbook. Therefore, I will be using the chapter I volunteered to write with my highest esteem  colleagues, Dr. Mira Avendano, Billard-Baron, and Mojaver on right ventricular function.  We proposed five echocardiographic measures as a practical approach to evaluate right ventricular  systolic function. The first measure is the ratio between the right ventricular end diastolic area and the left ventricular end diastolic area. And whenever the ratio is over one,  that correlates with severe right ventricular enlargement and systolic failure.  Then we try to determine which ventricle is more predominant in the formation of the apex.  And if the right ventricle predominates, that correlates as well with enlargement of the right  ventricle and systolic failure. The third measure is that excursion, the motion from the mitral  and the tricuspid annulus. Normally, the tricuspid annulus has more excursion than the mitral.  Whenever you see that this is equal, you can start suspecting there might be issues with the right ventricular function. And when the mitral annulus has more excursion  than the tricuspid, that correlates with right ventricular enlargement and failure. And we will see those examples next. Next one is the presence of free wall hypokinesis,  and it is present. You have systolic failure and the flattening of the interventricular septum.  If there is flattening only during part of the cycle, the cardiac cycle or throughout the cardiac cycle. When it's continuous, continuous flattening of the interventricular septum,  that correlate with right ventricular systolic failure.  Okay, now let's go over some examples. Here you can observe how the right ventricular end diastolic area is less than 0.6 than the left. This is a normal,  this correlate with normal ventricular function.  In contrast, you have this patient that now has a right ventricular end diastolic area that is larger than the left. That correlates with right ventricular systolic failure  and enlargement, of course.  Utilization of sucostal view is important. In this example, we are able to see how the right ventricular end diastolic area appears larger  than the left ventricular end diastolic area. This is the same patient and is important to use different echocardiographic windows to obtain this value.  Let's discuss the second echocardiographic measure, which is the apex forming ventricle. In this case, we have a left ventricle that is forming primarily the apex. This is normal.  On the bottom, we have a patient that has a right ventricle that is predominant in the apex.  The right ventricle is forming the apex, and we are ensuring that the quality of this apical view is optimal. You can see how vertical the heart is,  what they are procuring the view, and there is no doubt that the forming ventricle of the apex, in this case, is the right ventricle.  Now, we can analyze the third echocardiographic measure, which is the right ventricle versus left ventricle based to apex contraction.  And the way we do this is comparing the motion, the excursion of the tricuspid and the mitral annulus. I said before that normally the right ventricle,  the tricuspid annulus, has a much longer range of motion. In this case, from the base to the apex, the longitudinal contraction is much,  much higher in the tricuspid than in the mitral. You can see here on the bottom, in this case, this tricuspid annulus barely moves.  So the longitudinal contraction of the right ventricle is gone. And this is a good example of severe right ventricular enlargement and failure.  In fact, by definition, the longitudinal contraction of the right ventricle has been considered much better than the left ventricle.  The left ventricle has better circumferential contraction. The right ventricle has much better longitudinal contraction. So this is a very important, very important sign,  at least for me in the clinical practice, always, always comparing the tricuspid and the mitral annulus excursion during systole.  I have mentioned before that we use alternative echocardiographic windows. And in this case, I want you to recognize that the movement,  the motion of the tricuspid annulus in the succostal view can be recognized easily as well. So we have here a comparison between a patient with normal  to increase right ventricular systolic function versus a patient that do not have good right ventricular systolic function.  Now it's time to discuss the fourth echocardiographic measure, which is the right ventricular free wall hypokinesis. And it's very obvious here how the motility  of this right ventricular free wall is appropriate versus in this case, there is obvious hypokinesis. So this will be the fourth parameter  and is suggestive of right ventricular systolic failure.  As I mentioned it before, we can appreciate that motion of the free wall also in the succostal view. And here we are able to determine that the patient  has a free wall without hypokinesis versus in this case is hypokinetic, barely moves.  The fifth echocardiographic measure that we use for estimation right ventricular function is the intraventricular sectum flattening. It's absolutely crucial for me  because it gives you a very good idea about interventricular dependence. So in this case, you can see the tendency that most of the cardiac cycle,  the intraventricular sector is flat. That means that the pressures inside this right ventricle have been just elevated and more elevated. And for that reason, the distinction,  whether you have mild or moderate right ventricular dysfunction or severe right ventricular dysfunction will be based on how much of the cardiac cycle this flattening is happening.  I'm using these two cases to make that contrast, to see how a patient that might have primarily diastolic strain or volume strain  is because in diastole is when the flattening happens. But in systole, this ventricle has a more circular shape versus a patient that is always exposed  to this high pressure, which is continuous. This is very typical of patients with pressure strain  and because throughout the cardiac cycle there is flattening in the interventricular septum that put this patient in the category of right ventricular systolic failure.  Lastly, I want to share with you the only semi-quantitative assessment for right ventricular systolic function. And in this investigation,  we intended to have an alternative to TABSI. The name of the measurement is called a CTAC and it stands for subcostal echocardiographic assessment of tricuspic annular kick.  You can see here this similar, like when you are kicking, for instance, a soccer ball. So we are able to obtain the subcostal IVC view and we will be measuring with a mode  that excursion of the tricuspid annulus between systole and diastole. So in this case, we have a CTAC of 2.4. In our investigation, we found a 0.3 delta between TABSI and CTAC,  meaning that the normal cutoff for TABSI is 17 millimeters or 1.7 centimeters, for the CTAC is 1.4 or 14 millimeters. Figured you can see how we obtained a good correlation  between CTAC and TABSI and it was preserved even in severe decreased right ventricular dysfunction or mild to moderate right ventricular dysfunction.  So I want to conclude this presentation. Stating again that when performed by trained emergency medicine and critical care physicians, focus correlate well,  correlate well with quantitative assessment of the right ventricular systolic function. And we have evidence for that. Thank you so much for your attention.  I really hope that you can put in practice this qualitative assessment for screening of shock in patients that need mechanical circulatory support.

Video Summary

In this lecture, the speaker discusses the use of point-of-care ultrasonography (POCUS) in screening shock patients who require mechanical circulatory support. They describe a contemporary POCUS framework in critical care medicine and compare the diagnostic accuracy of qualitative and quantitative echocardiographic assessment for left and right systolic ventricular dysfunction. The speaker explains four parameters for estimating left ventricular systolic function: longitudinal shortening, anterior mitral leaflet motion, thickening of wall segments, and change in area of cavity. They also present five echocardiographic measures for evaluating right ventricular systolic function, including the ratio of right and left ventricular end diastolic area, apex forming ventricle, tricuspid and mitral annulus motion, right ventricular free wall hypokinesis, and flattening of the interventricular septum. The lecture concludes by stating that POCUS can be used as a valid screening tool in the initial management and treatment of shock patients.

Asset Subtitle

Cardiovascular, 2022

Asset Caption

The incidence of cardiogenic shock is increasing. In the hopes of improving outcomes, clinicians are increasingly turning to percutaneous left and right mechanical circulatory support devices. The widespread availability of these devices and a multidisciplinary approach that combines expertise from cardiologists, heart failure specialists, cardiac surgeons, and critical care specialists may help pair the right patient with the right device at the right time. Echocardiography is essential in all advanced hemodynamic support stages in the adult and pediatric ICU. This session will demonstrate the most relevant echocardiographic features in the initial assessment, continuous monitoring, and recognition of complications that the critical care team can face at any time with commercially available devices— venoarterial extracorporeal membrane oxygenation, intra-aortic balloon pump counterpulsation, various heart pump system models, and percutaneous left ventricular devices in adult and pediatric patients with shock. Experts in the field will provide the most practical didactics for immediate clinical practice application.

Meta Tag

Content Type Presentation

Knowledge Area Cardiovascular

Knowledge Level Intermediate

Knowledge Level Advanced

Learning Pathway Cardiothoracic Critical Care

Membership Level Select

Tag Echocardiography

Tag Hemodynamic Monitoring

Year 2022

Keywords

POCUS

shock patients

echocardiographic assessment

left ventricular systolic function

right ventricular systolic function

initial management

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