 Good morning, I'm Dr. Phyllis Biliah from the Peter Monk cardiac center and I'll be talking to you about echo ramp studies to guide weaning of patients from ECMO support I have nothing to disclose My tasks today are to discuss the role of echo and weaning from ECMO support and how to integrate this information with other clinical data as Well as to discuss some of the pitfalls and diagnostic challenges that we face There are two separate issues when we're looking at afterpatients that are supported with VA echo The first one is when should patients be considered for decannulation and I think that this is a daily assessment Second is how to assess for decannulation and that is with a weaning trial However before proceeding towards concept the conception of decannulation Effort has to be made to optimize the patient and you have to demonstrate that there's evidence of clinical stability That would include no evidence of compounding factors such as the presence of tamponade Bleeding, distention of the LV for example And the patient should be on optimal then settings The timing of decannulation can also be affected by complications acquired while on ECMO support Such as serious bleeding either from the cannula sites or elsewhere and other complications would include development of ischemic limbs and or strokes Clinical stability is demonstrated by the following parameters Resolution of the pulmonary edema normalization of lactate And improvement of end organ function In addition patients should only require minimal vasoactive support To maintain a mean arterial pressure of greater than 65 millimeters of mercury. This should be a minimal then settings And the pulse pressure should be greater than 20 millimeters of mercury This would indicate that there is evidence of some degree of LV ejection also also states that before attempting weaning There should be signs of biventricular recovery and they suggest assessment of aortic pulsatility And myocardial contraction for recovery in addition to end organ recovery This is where echo is key But the problem is that there are no guidelines with respect to how often one should image These patients and having looked after enough patients by now. My message to you would be to use Echo cardiography as a daily assessment tool for looking for the potential for ventricular recovery and to rule out complications That would change the course of treatment One thing to keep in mind in relation to decannulation and liberation from ECMO Is that while that this may seem to be a binary outcome Of whether or not a patient is decannulated and this is clinically important This outcome alone is potentially more reflective of patient selection As opposed to the liberation process itself or the protocol used Some of the strongest determinants for high success rate and removal From ECMO comes from the presence or absence of unmodifiable factors Making this difficult to integrate it into liberation protocols And some of the unmodifiable factors that i'm referring to Would include age and comorbidities such as ischemic heart disease diabetes and chronic kidney disease And the presence of these factors does pretend worse long-term outcomes As do clinical characteristics at the time of cannulation Such as acid-bait disturbances and acute renal or liver dysfunction And then there is the recovery of the biventricular function. This is critical to success In clinical practice the removal of any temporary support must take into account The hemodynamic effects of both the right ventricle and the left ventricle as support is slowly withdrawn Looking at the LV is obvious But as ECMO support is weaned RV function is no less important in determining a patient's course In the bridge to the next step and this is where ECMO is crucial Let's consider a patient being supported by VA ECMO We know that VA ECMO flows increases afterload and decreases preload and as such intrinsic LV function is marked Is massed sorry at flow full flows Therefore a period of lower support to fully assess the patient's hemodynamics and clinical status is needed Consideration of weaning should be done as part of daily rounds But also thought should be given to the safety and utility of doing it on that particular day Overall the aim is to optimize the patient's clinical state as much as possible before considering weaning and then Decisions about weaning may vary And are likely a combination of the circuit factors, which we won't discuss Further in this talk by chemical parameters That you see in the blood work renal function lactate liver function to the name of few Also hemodynamic data with the use of an arterial line to provide pulse pressure Pulsatility and mean arterial blood pressure and finally a pulmonary arterial catheter The use of a pa catheter is controversial in some centers And the last but not the least is is an important way to monitor these two patients is by echocardiography There have been some parameters that have been shown to predict success for decannulation And I will try to show you some of that data A bit later in the talk Why is it important to wean as soon as possible? This is related to the accrual of opportunity For complications while a patient is cannulated and receiving optimal support The complication rate is not small and some of them pretend to worse prognosis and make support futile Others are a result of the hypertension associated with the presentation of cardiogenic shock such as renal replacement therapy And a longer support that is greater than four days is associated with the higher mortality Weaning from actual support should be considered as part of a patient's journey rather than the specific outcome Goals of weaning will vary with the exit strategy and the exit strategy should be defined before proceeding At the peter monk cardiac center We start with the process ensuring a few of the things that I've already mentioned That relate to clinical stability Improvement and cardiac function alone for viability Pulsatility with evidence of the aortic valve opening Lower dose of basal pressure support and improvement in And organ function And if there are no confounding variables we then assess for recovery with echo looking at lvo tv ti ejection fraction tricuspid s prime and assess the rv when we can I say when we can because the assessment of the rv is complex in the situations where transisophageal echocardiography is not being Used the patients cannot be optimally positioned suboptimal images can be common Having said that if we see that that we have the criteria outlined as shown in the blue box Then we would reduce the flows by 50 for 30 minutes and redo the echo Following that again if we see that we're moving in the right direction and we have the goals out as outlined below We then would Reduce the flows to a minimum first reduce the flows by 25 further And then repeat the echo and then do reduce the flows to minimally allowable flows We also assess the rv along this route with a trial of volume if needed an inotropic challenge To see if we can improve rv function and see if there is recruitable work that can be done by the right ventricle In these patients echocardiography Particularly serial echoes is an incredibly important component of management of patients supported with ECMO Because it allows us to assess so many important parameters that will affect management such as Providing information on chamber sizes is a surrogate of lv decompression aortic valve excursion as surrogate for severity of of contractile dysfunction the presence or absence of intracardiac or aortic rupthrombus aortic valvular valvular regurgitation and pericardial effusion with or without tamponade Finally, it allows us to look at cannula position, which is problematic When when we see that flows are dropping with no other explanation Trans thoracic echo can confirm cannula placement and identify certain causes of circuit obstruction But trans thoracic echo may also fail to provide adequate septal spatial resolution And in these cases trans esophageal echocardiography should be considered Things that affect the performance of a trans thoracic echo include presence of chest tubes making good getting good acoustic windows difficult Ventilator interference and restriction in the positioning of the patient When trans thoracic echo is problematic, therefore because of the poor acoustic windows or clots are suspected Trans esophageal echo is then preferred However, I do have to say that there when there are good windows with trans thoracic echo I do start that with that as our my first approach This figure is great in that it highlights the main TEE views used to assess hemodynamics and sick patients Not just those supported by VA ECMO And it shows the types of images we can acquire with the progression of the tip of the probe from the upper esophagus into the stomach If we look at the level of the upper esophagus We have a view of the great vessels on the left The middle panel shows us the MO to demonstrate the respiratory variation of the superior vena cava And then at the level of the mid esophagus at 40 degrees We can easily find the aortic tricuspid and pulmonary valves as well as the right atrium and right ventricle on the left panel The middle panel shows us the view at 20 degrees with the left ventricular alfaltrac and both aortic Um In mitral valves and on the right panel at 20 to 60 degrees. We can now assess for tricuspid regurgitation We have here a four chamber view on the left a two chamber view in the middle and both Left and right ventricular systolic function and size can be assessed and the mitral inflow on the right And finally in the trans gastric views We have the short axis view of the heart to assess left ventricular systolic function and intraventricular septal motion Is seen on the extreme left And then at 120 degrees we can measure Doppler velocities in the lvot tracked middle left panel And the arrow indicates Where? Which gives us time velocity integral reflecting stroke volume, which is the middle right panel To assess repertory variation of maximal Doppler velocity. We use this as an index of Fluid responsiveness, which is on the extreme right The place where there's a role in addition to this for VA ECMO is in relation to the cannula placement And this is seen quite nicely from the T. This is not a TEE on the left How there it is a trans thoracic study to show us the placement of the cannula From the groin with the mouth With the mouth of the cannula at the junction between the IVC and the right atrium But also it's important to be able to look for clots Smoke is as shown here on the second case and this is done by trans esophageal echocardiography The aortic valve is not opening in this study And there is stasis of blood in the lvot, which is a concern for very early clot formation Let's talk about a case Hmm This is a case of a 34 year old man with Bechet's muscular dystrophy who presented with cardiogenic shock The upper row of images are trans esophageal images acquired at the time of cannulation The lower row are trans thoracic images at five or six days later The cannula placement Sorry, if we look at the time of cannulation It is evident that there is severe bibrantricular failure as seen in the upper left panel The cannula placement is confirmed in the upper middle panel where we see the cannula From the peripheral side traveling from the IVC To the opening of the svc And in addition this patient needed a subtostomy and this shows so nicely In the top right panel We have flow created from the subtostomy the cannula here is not well seen Five to six days later the te was repeated And we started to see Recovery of the rv function, but not lv function and the lvot vti sub optimal at 6.5 centimeters While the tap c is 1.2 centimeters About a week later a ramp study was performed These are clusters of four echo images on the left which are baseline at 2300 rpms Which provided almost two liters per minute of flow, however the tap c, vti and ts prime are not optimal But the rv function has improved as compared to the initial cannulation When the speed is reduced and the flow dropped to as low as possible at 0.6 liters per minute The only parameter that changed with this ts prime by 50 percent There has been some observational studies that have discussed The utility of using specific echo parameters to predict success from weaning from va-echmo support The importance of improvement in the rv function cannot be understated Some groups have shown less rv failure in those patients surviving weaning from va-echmo And some of the key parameters for that include 3d rv ejection fraction Which has the highest predictive value for success and a cutoff of 25 And other rv parameters would include rv free well strain rv fractional area change and all of these seem to be additive to the assessment of the right ventricular ejection fraction But from a practical perspective obtaining the types of echo images that are required can be problematic To extend this out further a paper was published last year in jace from a group in korea This paper was a detailed echo assessment of parameters that change as patients were being assessed for weaning with a reduction in speeds As recommended by also They did this for 92 patients and interestingly two-thirds of the patients were weaned from echo successfully And from this analysis, we were able to identify specific echo parameters that met with success namely lvot vti lateral e prime And indicators of rv function namely tricuspid valve s prime and rv fractional area change And we're looking at a change of 50 increase in these measure parameters Conventional parameters would include an ejection fraction of the left ventricle greater than 20 An lv vti greater than 10 centimeters and a mitra annulus s prime greater than six centimeters per second This paper added to those initial values but Stated that the percentage change that is predictive for with weaning is a 50 increase in lateral e prime 50 increase in lvot vti And 25 increase in the tricuspid s prime As well as a 10 increase in the fractional area change of the rv in the same study We see that that using the traditional criteria was not that predictive of successful weaning for echo With the addition now in the percentage change of the lateral e prime and the tricuspid s prime We now start to see that the presence of both of these parameters leads leads to a 80 percent of patients being successfully weaned With respect to the need for monitoring We also need to consider complications And what we're showing here are trans esophageal echo images Which shows the presence of clot on the left are Associations of clot with the aortic valve on the top the Approximal aorta on the bottom and then with Septostomies and the cannulas left and present in in the left atrium we can see Clot formation on the tip of the cannula and two separate views of the same patient Marker bubbles have also been validated as a safe and effective method to evaluate cardiac chamber Um size and function and to rule out cardiac masses are thrown by in difficult and technically difficult studies There's limited information on the utility and the safety of contrast in ECMO patients However, I did find an abstract from the Mayo clinic that looked at their experience from 2001 to 2016 and and in close to 2000 echoes that were performed Definity contrast was used only four times with no serious issues The circuit alarmed one out of the four times But the flow didn't stop and with the use of contrast they were able to detect thrombus and intercardiac clot in three out of the four studies Sometimes you can use echo contrast like divinity to help with with this But there is very little data other than this that I could find on the safety and utility of this approach In real world experience, we are limited Each of us by what we do at our institutions and the patient related factors that may allow for good imaging There can be limitations to using echo to evaluate hemodynamics and critically ill patients supported by ECMO And there's no standard criteria for recovery or for helping to assist in timing of weaning Has already stated the improvement LVEF or VTI through the LVOT are the initial parameters However, assessment of the LVEF can be subjective and there is high intra-observer variability Also preload is changing according to ECMO flow therefore preload sensitive variables such as EF and VTI may not represent contractility of the native heart The RV has also an important role in the process of ECMO weaning as we've already spoken about And it's it's important to assess the RV as as much as possible So that we can then have some Evidence of feasibility of weaning once decanulated Patients with premature RV and LV recovery are likely to experience some deterioration of RV function after ECMO weaning And as the ECMO flows are reduced during the weaning process the RV has to adapt to increase RV preload The prematurely recovered RV may not tolerate this and for those patients with premature LV recovery reducing ECMO flows Could result in increased pa arterial pressures, which then leads to increase RV afterload In summary then weaning I think should be considered on a daily basis I think it's critical to optimize the patient prior to thinking about weaning from ECMO strategies And ECMO is definitely a critical part of this assessment for readiness for weaning from ECMO support I think that there is utility in using both trans esophageal and trans thoracic surveillance for intracardiocomplications And should be used as necessary And the principles of weaning protocols that we discussed Are currently based on echo parameters, but there's a lot more work that needs to be done