So i'm going to take this baton and i think in concept we are Going to make this practical for everybody because not Everybody has an eit machine. So let's see if we can't give You some tools to take back that everybody can use. And we can all use these driving pressure tools. All right. I'm not advancing. Okay, next slide. I have a lot of animation, you'll hear me. All right, so next slide. So we're gonna talk just briefly about these prevailing concepts. This isn't gonna work out with this animation. You wanna switch to the third one and bring me? Okay, I'll think of something too. All right, so here we go. All right, so if we put the total lung volume up on here, I think clearly we all really, really understand and take to heart the idea that we can put too much volume, total lung volume into the lung and we come away with volume trauma. Nope. All right. I swear I didn't break it. You didn't break it. Are you doing that? All right, here we go. Cool, there we go, excellent. All right, so we have up top volume trauma clearly and down at the bottom at the lower lung volumes, we have this risk of adelect trauma, take away from that. The physiologic parameters that we put on these limits are clearly plateau and peep down at the bottom. And we try to find this magic window, this target like we had just talked about. And then we developed this kind of roadmap, which is really, really fuzzy sometimes, especially kind of when you're at the bedside here. And we take our cues from these latest guidelines from 2017 that have just been recently updated, but we'll take the two really strongly supported recommendations that came out of that, low volume and low pressure ventilation, and we'll kind of put them onto this graph. And I think the point that we wanna bring home here is that we end up with this roadmap. You put it in ways, it's a direction on how to get there, it's a recipe, right? Which is the greater good for everybody, but you're gonna run out of room really, really quickly in a whole bunch of patients, right? And so I think this is where we are and this is who we're talking about. Who can we benefit that this protocolized mechanism isn't working for? Because that's what we're dealing with. And as much as I can completely support protocolized medicine, I think at this point, pulling them off and understanding how we're going to individualize this care, not breaking the rules, but applying the same ideas and same parameters and same mechanisms to an individual patient. And so I think our first dip of a toe into this water of personalized mechanical ventilation was driving pressure, right? And so what we do in between the bottom and the top makes a difference. How much we stress the alveolus on inspiration makes a complete difference, right? And so if we take PEEP down at the bottom and its function into opening it up and we're attempting to put a volume into this little teeny tiny space that is available to us, clearly we're gonna exert a bunch of pressure and that results in an increase in driving pressure. This is the landmark paper clearly, and I just wanna point this out, bring us all onto the same page, that if you follow my light blue bars with a decrease in driving pressure all across the resampling of this patient cohort, that it is associated with a decreased risk. And if we pull apart the ideas here that the title volume really didn't make a difference, nor did the plateau pressure above or below a median value make a difference. It was the plateau. So it's not the plateau, it's not the volume, and it's not the PEEP individually. It is how you craft your breath, how you design as an architect, the mechanical breath profile that produces the lowest driving pressure that is going to make the biggest difference and be the most closely associated variable in mortality. So if we put it on this relative risk here, we come out with this idea that our driving pressure should now be somewhere below 15 or so, right? And so now we're pulling this target that we had initially set really, really, really tight. And we understand this with this recipe now that we got to achieve the bottom, we got to achieve the top, and it would be really great if you could achieve the middle portion of this lung protective strategy as well. And this has been kind of taken away in several different meta-analyses that high driving pressure is injurious. And so now we come to the practicality and the pragmatic portion of this, like, how do I do this? Like, should we do it, right? And there's clearly ongoing studies, prospective randomized control trials, but these concepts you have to take away back to the bedside here. Should I influence the volume? Should I dose volume in some way to influence driving pressure? Or should I scale my PEEP to influence the driving pressure, right? And so if we take this same CT image, if we use more PEEP and open up the space, you can put the same volume in to a larger space now and drive down driving pressure, or you put in a smaller volume. So if we take this volume across all these different types of patients and we make the point that that same fixed tidal volume, which you may check the box and give each other a high five for achieving that goal of safe protective ventilation is going to achieve several different results in this heterogeneous population. And so that's the point. I think you have to weigh the risk and benefit of this though. So I'm not gonna say here at any one point, go back and turn everyone down to five and four cc's per kilo, because that isn't the answer. There is a risk benefit balance to this that has tentacles to it. And it makes a big difference as you start to drive down the volume. And so you have to take the question, should I decrease the volume in this particular patient? This group published in the Blue Journal, they're out of Toronto. They normalize the elastance to the individual patient by taking the driving pressure and dividing it by the dosing of volume, right? And so this is just a simple calculation that they use to normalize the elastance of the lung, right? And so in this case, what they were able to do is kind of stratify these patients into low intermediate and high elastance. And the effect of volume had a different treatment effect depending upon the elastance of the lung. Patients with a higher elastance, meaning a much stiffer lung, had a much higher probability for a treatment effect in terms of decreasing the volume. Those patients that did not have such a low elastance or may have a bit of a higher compliance had a much different treatment effect. In fact, almost no effect whatsoever at all. And this played itself forward in terms of mortality that you see that the change in volume didn't make a difference until you had a normalized elastance ratio that was much, much higher. Yours and mine is one, all right? And so these elastance ratios are triple of what yours and mine are sitting here today. And so you can't just indiscriminately decrease the volume. It has to be appropriate for that patient. And so you step away with, well, when is it appropriate? How do I determine it? And so a normalized elastance ratio is one way to kind of elucidate out. Maybe it will work in this patient. Maybe I should go forward in this patient, but not in this one. We can further stratify this into kind of cohorts with obese patients versus non-obese patients in this particular group here that these non-obese patients had a very drastic effect versus the obese patients that did not in terms of their driving pressure and the effect of mortality at 90 days there. And if we partition the respiratory mechanics out and taking the idea, well, obesity presents all of these different problems with chest wall, what this group of research has found is that the airway pressure, driving pressure perform equally to the transpulmonary driving pressure, right? And so even in the absence of your balloon, right, that you can measure transpulmonary pressures in this morbidly obese patient population, that airway driving pressure performs pretty well for you and is equal to that transpulmonary driving pressure, right? And so we come back to this idea, the second one, should we increase the PEEP on these particular patients? And again, I'll pull up the same four patients. And if we increase the PEEP in these same four patients, you are going to get a drastically different result in terms of recruitability versus non-recruitability, which my friend here just kind of touched on. So this part will be kind of short. We're gonna take those same exact ideas. That same group that I showed you with the tidal volume and the driving pressure versus the transpulmonary pressure also looked at PEEP guided according to transpulmonary pressure. And in non-obese patients, it performed much differently than in the obese patient. So when you're contemplating, should I go up on the PEEP? It had a much different effect in obesity versus non-obesity. Take that into account. And this is your bedside test. This is a group of researchers out of Toronto, the Center for Excellence in Mechanical Ventilation. And they validated this recruitment to inflation ratio, which is a single breath maneuver. It takes me about 10 seconds to do it. We can do it on every single patient, every single day in the stream of care. I don't have to manage neurologically in terms of doing slow flow pressure volume loops and all of these other ideas to predict recruitability of the lung, right? And so this is the idea. If I understand the compliance of this baby lung, which the units of measure of milliliters per centimeter of water, and we changed the PEEP, we should, even though we're changing pressure, we should expect volume gain out of that, right? Because of the compliance. And so if we know how much we changed the PEEP, then we should be able to understand how much volume we should gain with that change in PEEP, right? That's a difficult ask if you are going upwards in PEEP, right? And so this, during a single breath maneuver, we're going to drop the PEEP, right? And so in total here, what ends up happening is that when you drop the PEEP, there will be a big release of volume. And that volume is partitioned into a couple different aspects. One portion of that big drop in volume is your set title volume. The next portion of that volume is the volume that you gained by the change in pressure of PEEP. And then any additional volume over top of that is what you recruited or is beneficial, right? And so that's the concept behind this. And so when I do this, when we perform this recruitment-inflation ratio, we put them on 15 of PEEP, and we drop the PEEP to five. We look at the volume that is released at that change in pressure, and it should be a big old release of volume. And we capture that volume. Here's kind of the math underneath of it. There's online calculators for us to be able to do this, but this is the math concept underneath of it. If I understand the compliance of this baby lung to be 20 at this point, and then I change the pressure here up to 15, and I allow the drop in pressure from 15 down to five, I get that big volume. And I look at that volume. We'll make it up at 700 CCs. I know my volume was 400, and I know my change in pressure was 10 for a compliance of 20. So my predicted volume gain is 200. That means I got an extra 100 CCs out of that change or increase in PEEP. And so this is predicting recruitability of the lung. It's a validated tool. And we use this quite often to understand when should we increase the PEEP to influence this driving pressure? Because that's where we are right now, optimizing driving pressure in some way, shape, or form. That is one tool. I'm not going to spend very long because my friend over here did this particular study. This is the recruit study, the 108 patients, 109 patients that they published. These are the recruitability different curves. So a little bit different of a graph than what he showed you. But I do want to point out here down at the bottom, it is a cautionary tale about driving pressure, as he pointed out here, because the driving pressure did not match the best recruitability versus over distention in about 81% of these patients. So it is kind of a blunt instrument without the idea being how much am I over distending this patient as I increase the PEEP. The driving pressure alone as a global number has a difficult time pulling that out for you, different than the EIT. This is the last tool that I'll give you here because everything prior to this was in passive patient. So if your patient is active, you're going to have a little bit different time trying to figure out what I should do in terms of volume versus PEEP. This is a single breath maneuver. Again, it's the most simplest thing. It takes us about 10 seconds in order to do it. We perform an expiratory hold and we get this occlusion pressure, this change in occlusion pressure. We pause the screen and we mark this, how much this changes. What this same group of researchers out of Toronto has been able to validate is that that occlusion pressure estimates your PEMAS and more importantly, it estimates your change in esophageal pressure. With those two ideas, knowing from a single expiratory hold, how much the patient pulls down during that expiratory hold is an estimation of change in esophageal pressure. What that unlocks for you is a dynamic inspiratory transpulmonary pressure because if I know the airway pressure and I know the estimated esophageal pressure, I can understand my inspiratory transpulmonary pressure and then guide my volume in that way. All right, so two tools there for you that are pretty novel, pushing the frontiers, the recruitment inflation ratio and the single breath PEOC here, all right? And those enable you to understand the mechanics and try to help you answer the question, should I be dosing volume downwards or should I be scaling PEOC upwards in that patient laying before me in the bed because they are going to vary widely in their recruitability. And finally, this is where we're looking out from right now. There's a large study database essentially that has four different domains here that they're looking in and they're organizing their research efforts. We're gonna pull the invasive ventilation, the perspective randomized control trial that is ongoing is called DRIVE-RCT right now. It's a driving pressure limited ventilation study. This is the protocol. So these are very, very highly selected type of patients that will benefit from the individualized approach as opposed to a protocolized approach, high PEEP for everybody, low PEEP for everybody, low driving pressure, high driving pressure, low volume, et cetera, et cetera. They individualize it according to this study protocol here for driving pressure as well as what I just told you that occlusion pressure and that dynamic inspiratory transpulmonary pressure. So this group is really, really selectively in individualizing mechanical ventilation and studying it in a perspective way. All right. So my sum up here, every driving pressure is important. You gotta take it away. It should be your modus operandi, your conversation all the time. What is it? All right. The dosing of volume is different for every patient. And so you gotta figure out when do I dose volume lower or when do I leave it alone? The high elastins, very low compliance patients are most likely to be benefited from a lower tidal volume. Scaling PEEP should also be selectively applied in those patients that have a high chance of recruitability as determined by EIT or anybody can do it that RI ratio. All right. And then these perspective trials are ongoing with a careful selection and application of therapy going on. All right. So that's what I got for you for practical driving pressure and optimization. All right. Thank you.

mechanical ventilation

driving pressure

individualized care

lung recruitability

personalized strategies