Good morning. I'm Herbert Patrick, presenting session 11.17. The four of us are presenting. There is one slide deck that will take you all the way through with some ARS. But the surprise will be at slide number 58, our audiovisual team is going to present videos of a ventilator with ARS questions based on what you've seen in the prior three lectures. So the panel is made up of myself as the moderator from Pennsylvania, Ilana Roadcloud from New Jersey, Rich Wettstein from Texas, and Dave Vines from Illinois. For the conflicts of interest, there's none, except with Dr. Vines, with funding from Teleflex, Rice Foundation, and Triamin Health Services. The way we'll run this will be all four of us are panelists. There will be the first lecture on basics with Ilana, the second with Rich presenting synchrony, and then the special video system with Dave getting this info out. And for the presentation, if there's still empty seats, we'll take extra members. This turnout is wonderful. So to begin, Ilana will present the waveform basics and take you through the language and the nomenclature of mechanical ventilation. Ilana? Thank you, Dr. Patrick. Thank you all for coming. And today my goal is to hopefully help everyone look at a waveform and be like, oh, I remember this. I remember this from chest. Dr. Roadcloud showed me. Hopefully you guys can appreciate that at the end of this talk. All right, so waveforms are confusing, whether it's the bedside monitor, the echo, the EEG. We look at waveforms and we're like, I just don't want to do it anymore. How do I get out? But after today, I'm hoping that you guys are able to understand the modes of ventilation using graphics, and we're going to specifically go over pressure, flow and volume. So I'm going to be specifically looking at the Medtronic Covidian Puritan Bennett 980 ventilator for majority of my slides. And as we go forward, you'll also see that echoed amongst our panel. So just to orient ourselves, what we're seeing right now is the common triple screen, pressure, flow and volume. And I just want to point out that this is something that could be changed. So if you go into the room and you're trying to distinguish what waveform you're looking at, just start with the panel on the side here, which gives you your units, pressure at the top, flow, volume at the bottom. In addition to that, I want you to be able to determine what mode of ventilation is the patient in. Is our patient in assist control? Is our patient in PSV or pressure support ventilation? So very quickly, assist control. Assist control can be either volume targeted, pressure targeted or hybrid, a hybrid being that I feel like most people probably have seen, PRVC or VC plus or auto flow. And if you're looking at an SIMV or synchronous intermittent mandatory ventilation, that's usually a patient, quote, on a wean, end quote, then that's something you'll see here with an SIMV or pressure support mode. And the distinguishing factor between the two is that the SIMV is combined with the spontaneous breaths. But you do have a backup just in case our patient is not able to sustain breathing on their own. And this is just a little summary to kind of say everything that I just said. So if you guys wanted to get a snapshot of what's going on, that's basically what this is here for. It's a little busy, but I just wanted it as a summary. All right. So we are going to select our mode. So on a Puritan Bennett 980, we're going to go ahead and press the bottom. I guess it's your guys' left, my right side of the screen where you see the ACVC plus circled in white. And then it pops up for us all of our modes of ventilation that we can set for our patient. And then everything underneath that are settings in some cases that are required and other cases may not be required. Something I want you to note that you need to understand when you see a screen for the first time is, is my patient being assisted with their breath? Is my patient undergoing a controlled breath? Or is my patient breathing spontaneously? One way to note that is by looking up here at the top right-hand corner on my right. There's an A. The A stands for assisted breath. The C here stands for controlled breath. So what's the difference? Well, in the assisted breath, and I'll just go back, our patient is trying to trigger their breath. And they do that usually by signaling to the ventilator that they want to take a breath. And our ventilator is set so that it gives a set tidal volume. In this particular mode, VC plus, we will have set the tidal volume that they will get. Whereas in a controlled breath, our patient did not trigger this breath. And this is something that is already set and we're going to give this controlled breath to the patient. And it's timed. It's usually something that you set, you preset before. The spontaneous breath is the patient breathing on their own. So this is spontaneous breathing. And our patient is taking their own breaths and initiating the breath and getting the tidal volume that they are able to obtain. All right. So this slide is a little busy, but this is probably the most important slide up here. This is mainly going to very quickly go through the equations that you need to be able to use in order to better help your patient. So we're going to specifically look at what do you see when you look on the ventilator? You'll see a peak pressure. That's the top one, P peak. That's the maximum airway pressure during inhalation. The next part is the P plat. This is not something you may see right away, but this is something you will be able to see once we do an inhalation pause. This is a point of no flow, and we'll talk about it in a little bit more detail later. The main thing I want you to take away from this is that the desired P plat or plateau pressure is less than 30, and this is all in an effort to decrease lung injury. PEEP, or our positive inexpiratory pressure, is the main thing that we all know and love, because we usually set it to like five in some cases or eight. And in those scenarios, it's a set PEEP. But there's also an intrinsic PEEP or an auto PEEP that we have to keep in mind, and we'll go over how we can then calculate our auto PEEP and move forward in terms of how to treat our patient. In addition to that, we have our driving pressure. Our driving pressure is our plateau pressure minus our PEEP, another way for us to determine whether or not we are causing injury to the lung, where our goal is to keep our driving pressures less than 15. Finally, our compliance and our resistance. So our compliance comes in two. There's dynamic and static, where our dynamic equals the tidal volume divided by the peak pressure minus the PEEP, and the static equals the tidal volume divided by the plateau pressure minus the PEEP. Our resistance is our peak pressure minus our plateau pressure divided by our flow in liters per second. This is important because you may not have the opportunity to do the liters per minute conversion to liters per second, and you may come up with the incorrect number. So just keep that in mind. All right. So we have our ventilator. We're walking up to it, and we're saying, okay, inspiratory pause. How do we do that? Inspiratory pause on a PB980 is going to start with looking at the bottom portion of our screen as notated right here. Let's see if you guys can all see that. So I just zoomed in a little bit. So here we are. We have two lungs. One is for our inspiratory pause, and the other is for our expiratory pause. And for right now, we understand that the pause button is pretty straightforward. So you just press the pause button, and if we're trying to get our peak pressure and our plateau pressure, we want to do an inspiratory pause. So in this scenario, we've initiated an inspiratory pause. Our patient has a peak pressure and a plateau pressure. And luckily for us, our PB980 will calculate it for us, which is really nice, and will display it right here over to the side. All right. So now in our expiratory pause. So we're going to try to figure out what our intrinsic peak is with an expiratory pause. We go to our PB980. We initiate an expiratory pause. And upon doing so, we realize that there's no intrinsic peak. Our intrinsic peak here is zero, and the peak that we set is eight. So looking here, we can see that there's no additional peak present, and it's just our expiratory pause has just shown that there's no intrinsic peak. So in an example using an AVEA, I was able to come up with what it would look like if we did have intrinsic peak present in the system. So we're going to do our expiratory pause. And again, this is a different ventilator, so it may look a little different on your ventilator in your institution. First, I get my expiratory pause, which will show me my total peak, as indicated right here where my marker is. And that's 19. In addition to that, my set peak is five. And then I take my 19 total peak, and I subtract it from five, and I'll get my intrinsic peak. My intrinsic peak in this case is 14. All right, so what if you don't do an expiratory pause, or you're trying to find something called a dynamic auto-peak? So in this scenario, you're looking at the flow portion of our graph, and you're saying, is flow at the end of exhalation returning to zero or not before inhalation? That's the question you want to ask. The important part about this is understanding that this is not going to give you a number. This is just going to say whether it's present or absent. In this scenario, I'm looking at my flow graph, and I'm noticing that it is returning to zero right before inhalation, and that indicates during a point of zero flow that there is no dynamic auto-peak present. However, in this scenario, there is dynamic auto-peak present. As you can see right here where my marker is, our patient is exhaling, exhaling, and right before inhaling again. All of this is not returning to zero. That means that there is auto-peak present in our system. All right, so we're almost there. Lung compliance, as we discussed earlier, is also important, and this is an additional term that I would like you guys to keep in the back of your minds. It's the lung volume divided by the change in transpulmonary pressure. So there's two parts to it. There's the static compliance, the compliance at a fixed volume without airflow, and then there's dynamic compliance, compliance as a continuous measurement. The static compliance is calculated, as I mentioned earlier, as the tidal volume divided by the plateau pressure minus the peak, and normal in this scenario would have been 60 to 100 approximately. For dynamic compliance, it's calculated as tidal volume divided by the peak pressure minus the peak, so just so you guys don't get confused, okay? All right, so in this scenario, if we wanted to, our PB980 nicely calculates it for us, but again, we could calculate our static compliance given the things that the ventilator allows us to see, so we hit our peak pressures, we get our plateau pressures, we get our PEEP, so we're able to calculate our static or our dynamic compliance. An additional term that I want you to know is the resistance. So resistance is the change in transpulmonary pressure that's required to produce airflow, and that's divided by the flow. Important part about resistance is knowing when your patient is not responding the way you would expect them to. Is there a problem in our system? Is there too much airway resistance present? So some ways that we can figure that out is by calculating how much resistance is in our system. The formula we use for that is our peak pressure minus our plateau pressure divided by our flow or liters per minute. In this case, we need it to be transitioned to liters per second, so as I said earlier, make sure you do that before you start using this formula. So our liters per minute transitioned to liters per second, LPM divided by 60, and then we come up with our final units, which is the centimeters of water over liters per second. Our goal here is to have an airway resistance of less than five. All right, so I'm not sure how I'm doing on time. I might be a little bit over. But I would like to see how you guys do in this scenario trying to calculate this. One thing of note that I want to make sure you guys understand is that in order for you to have all of the variables that you need to do this calculation, your patient has to be in a volume control setting. So if you notice here, my patient's in ACVC, which is a volume control setting, and this will allow us to have our flow set at 60 liters per minute. But just remember to convert that to liters per second. Do you guys want to give it a try and see what you get? Hint, the answer is on the screen. Anybody want to give it a shot? I can go back to the formula if you need it. I think I heard it. Yes, very good. That's awesome. Thank you. So I'm just highlighting this. You did a great job. Thank you. Using our formula and basically plug and chug, we were able to come up with an airway resistance of 20. So I think we have some problems. All right, and just as a transition, I want you guys to understand something that's important when looking at volume. So, for instance, when we're looking at our title volume, we want to know whether or not it returns to zero at the end of exhalation. And why is that important? Because in addition to looking at the other parameters, there may be something as simple as a circuit leak going on with our patient, and that's an easy fix. So this is something that I want you guys to be aware of, that if you're looking at a patient and you're looking at the volume portion of our graph and you're saying to yourself, well, why is their patient not pulling their title volumes, then this is one place I want you guys to look. As you can see, our patient is trying to pull their volumes but not really getting very good ones. And all of these arrows are indicating exactly what I mean when I say there's a circuit leak present. So this is just a way for them to remember if you ever see it in a patient. All right, so as of right now, and I'm going to move to the next portion of our talk, and we're going to start talking about RISE time, and I'll hand it off. Thank you, guys. All right, well, I get to have more fun. David Vines will have the most fun at the end with actual movies, what we would actually see graphically. But what I'm going to be doing is looking at a lot of stills. We don't have time to do all audience response, although I've got one coming up for you here pretty quick. But, again, if you hear things, see things, look, feel free to call it out because I am going to be asking you. So we're going to start looking at some of those dis-synchronies, like the last one Alana just showed you, right, was looking at you had this 400 title volume. Just by looking at that volume curve, right, you could see that all that volume wasn't coming back, only 177 of the 400 mils, right? And the rest was just lost, right, because they had some mammoth leak, whether a proximal sensor fell off, something happened, right? Well, at a glance, you see it, right? So that's where we see, when we look at these graphics, they are 1,000 words, right? I mean, they really are. There's 1,000 things to see or 1,000 words we could use to describe all the stuff that we're seeing. So when I look at this, right, of course we've got all of our data at the top, which is very helpful, right, because that's showing in real time. Yeah, we've got our settings, which I didn't show at the bottom, but it's telling us at the top what's happening right now with this patient. So to me, the first thing I would look at is notice we've got great peak pressures, right? Our peak pressure is only 18. So we know, before we look at anything else, like our driving pressure has got to be great, right? Even if we had a peak of only three, which I don't think on the adult side, I've seen three in a long time. But even if you only had it set at three, we've got a driving pressure of 15, right, plateau max, right? Because our peak is 18, our plateau is going to be at least slightly lower, even if we had hardly any airways resistance. So we know right away, okay, we're in a safe place for our driving pressure. We're in a safe place for our plateau, right? It's definitely under 30, even under the ideal of 27. So right away, without even doing a plateau pressure, we're like, whew, this patient's looking pretty good, right? And we can see we've got an expired tidal volume of 500 mils. So that puts us in the ballpark of where a lot of our patients are ventilated. And so I'm already going, okay, we're looking pretty good. Now, when we look down at the actual graphics, notice that we have one waveform that's square. And that means that's the one that's limited, right? It's constant. So here we've got a square flow wave pattern, so we know we're in volume ventilation, right? So we're in some form of volume ventilation. And as Alena mentioned, notice that C up there. So we know that this was not a patient-triggered breath. Now, with just what we see there, we don't know if we're in volume assist control or volume SIMV, right? But we know we're in VC with machine breaths, right? And we're not going to get into stress indexes, but a nice little factor here, we can see that nice straight line rise to our peak pressure. So we got a stress index of 1, which is optimal. We're happy. When we look at this, if you went back and saw some of the slides that Alena showed, you would have noticed that our expiratory flow returned to baseline very quickly. Here, it takes a while. So we're thinking, even though our peak pressure is really low, and remember, peak reflects both that pressure needed to overcome airways resistance and static compliance, even though we have increased raw, it's not too bad right now, right? It can't be. Without even doing a plateau, we know it can't be because we return to baseline fairly quickly. I mean, our PIP isn't too high. And notice, in a second and a half, about we're back to baseline. So as long as our patient doesn't get really tachypneic, or we turn the rate really quick, the patient's going to do okay. Now, I talked for a long time about that slide, right? I could keep going because there's so much that we see there. But what's happened here compared to the last patient? I know the quality went down, but I just didn't have time to go back and re-film another one for this. What did you think? What's going on here? What took forever? That reflects high expiratory airways resistance, right? So this would be like our asthma patient or COPD, CF patient, right, that comes in with something going on. They've got a lot of raw right now, right? Now, if we talk about problems occurring, is this currently a problem besides the fact they have obstructive process going on? Based on the graphic, are we running into what Elena called dynamic auto-PEEP? No. I can see some head shaking, right? It gets back to baseline just before the next machine-triggered breath, right? You can see there's no dip. So even though we can't see the C, there's no dip in the pressure curve. So this is a time-triggered breath. Again, tons of information out there, right? We're still in a volume mode, nice square flow wave pattern. Right now, we're not running into problems. But what will happen if the patient becomes tachypneic? Yeah, we're going to start doing this, right? So remember, Elena showed you this, not this picture. I took this one separately, but essentially the same picture, right? When we see this, we know we have gas trapping, right? And if we know we have gas trapping, what else is present? So you should be able to go to a live slide here. Do we have an audience response there or not? Okay. It's not going. Oh, it is. I'm sorry. I'm seeing it on my screen. Sorry about that. Okay. So let's take a moment. Yep. All right. Still going up. I apologize. We have multiple versions of this out there, and I actually thought the next question was where the vote was, so I kind of gave it away. 99. Wow. We got a lot of people. 100. Nice. Okay. So as most of you picked, air trapping is what's going on, right? And we can actually, even without looking at graphics, if you're listening to them, you're going to hear this as well, right? You'll hear the expiratory sound going on forever, and then the inspiratory sound right away, right? They're blowing out, and then immediately, right? Where normally you're going to hear a pause between those. So you can hear it. Sometimes you can see the chest still moving in an expiratory direction when the next breath comes, right? So lots of clinical data, and this is where I actually thought the audience response was, was the auto-peep option, okay? So remember, any time we have gas trapping, we can't quantify auto-peep, but we know it's present. So if you ever see that expiratory line not return to baseline, we know that gas trapping is there, and any time there's gas trapping, there's auto-peep. Until we quantify it, we don't know how much it is. Now, this is the actual quantification from the last slide. When I saw gas trapping, I went and did the auto-peep measurement, so I did an expiratory hold and measured what it was, and we can see that the auto-peep associated with this was only 3.5, which doesn't sound like a lot compared to Elena's slide of, well, 19 was total peep, right? This one is total peep of only 7, but, you know, the patient at 14 of auto-peep is crazy, right? Like, I mean, that's a crazy amount of extra pressure on top of the set peep. So why is this important? What happens, we're talking about asynchrony here and looking at slides, what happens when to, how does this impact the patient when we even have an auto-peep of 3.5? So this is a little delay here, sorry. So this is showing that 3.5. And with this, you can see that... Sorry. There we go. This is answering... I don't know how we've got some duplicate slides there, so sorry about that. But this is showing what this gentleman just shared, right? Is notice this patient is trying to draw, to initiate a breath, but because, you know, these are compromised patients, right? So even though the auto-peep is only 3.5, it's indicating the patient, the ventilator doesn't know, even though you measured it, it doesn't, it's not a static number. So it doesn't compensate for that. So it just keeps saying, okay, if you have your trigger, let's just say you're in a pressure trigger of 0.5, right? So it's nice and sensitive. Even though it says 0.5, if they have an auto-PEEP of 3.5, they have to draw 4, right? Because they have to draw 3.5 above PEEP down to 0.5 under, and we end up with missed triggers in compromised patients. And you can only imagine if it's even worse, like Elena was seen, right? So then we say, well, let's correct this. Let's make our eye time shorter. Maybe we turn up our flow. If it's on the PB, we're going to turn up our flow, which shortens our eye time, makes more time for exhalation, and maybe we turn down our tidal volume, right? We've got some options out there. But when we do that, we might see what's happening here. So what do we do? We turned our eye time down to 0.7 of a second. And you can see over here, we've actually now got enough time. We're just hitting baseline before the next breaths come along. But what happened here? We've got into this, right? Double triggering. The patient's neural eye time is longer than the eye time we have set. Once we get below especially 0.8 of a second, this isn't uncommon in adult patients. Now if you're pediatric, of course, another world, right? Especially neonates, right, and preemies. But for adults, the lower that gets, the more likely we are to get into trouble. OK. Well, what's another thing that you'll see out there? If you use volume ventilation all the time, we are the ones, I'm saying we as health care professionals are the one controlling their patient's peak inspiratory flow rates. So when we look, remember I showed you that graph which we saw a nice straight line acceleration to PIP? That's ideal. When we, to peak inspiratory pressure, sorry, PIP, peak inspiratory pressure. So here we are, constant flow, but that constant flow isn't meeting the patient's inspiratory flow requirements. And so we see sags in the curve. These can be dramatic. I mean, I've seen them pull below PIP because we are so deficient on setting that peak inspiratory flow high enough. And this can take all kinds of, you know, it just depends on the patient effort, what that looks like. So this one looks a little different. We see exactly this one's pulling much stronger here. And we can see, though, that in all of these cases, the patient's flow is insufficient. So we can, again, turn up flow. As we turn up flow, remember, eye time gets shorter. Now we've got to think about neural eye times. We may, in some patients, are really tricky. We may need to go to a pressure-limited ventilation where they can get as much flow as they want, but we set their eye time so they're not double-triggering the vent. OK. Well, this was the last thing at the end of Elena's talk. We were kind of going to double up here, and we decided to just leave here. But again, when we're in pressure ventilation, does that solve all the problems? Well, maybe, but it depends on how we set it. So if we look here, this is setting rise time to our peak inspiratory pressure. Every ventilator out there, all your mainstream ICU vents, doesn't matter if you use Servo or GE or whichever one out there, even the niche ventilators, they have a rise control. Where you set, they can call it slope, they can call it all kinds of things, inspiratory rise time. They set how quickly you expose the patient to the full amount of pressure. And this was that same patient when we had the rise set to 70%. Look what's happening here. We still see that we're not meeting the patient's inspiratory flow requirements, and you can see how it's kind of bumpy all the way through. So we have a range of 1 to 100%. If you guys are old timers, 840 is always called this FAP, flow acceleration percent. On the 980, their new data says rise time, but it's still that same percent. 1% gets you there super slow, 100% gets you there really quick. And if we look at this, we can see when we increased it to 80, it looks a little better, but we're still got some variation there. When we go to 100%, it's looking a little smoother. This is the transition here was 80%. This is to go to 100%. And you can see when we went to 100%, we get a tiny little pressure overshoot. We were already getting it actually back here, but notice how much smoother that is. We're actually meeting or exceeding the patient's inspiratory flow requirements. And you could try 90%. You could say we went quick, but that will get us where we need to be. Now, we're going to do a whole bunch of other things with David Vines, but key thing is we have a lot of control based on the way we set our patients. And the easiest thing for people to do is say, oh, they're asynchronous with the ventilator. Let's sedate them using drugs. But if you know your ventilator, the more you know your ventilator can play with it, you can change the settings and meet their needs and help them to become synchronous. Mechanical sedation, right? Where we are troubleshooting and solving the problems on the mechanical side. And that's where I would encourage you. That's what's fun about graphics is we can use what we're seeing to keep fine tuning and actually meet the patient's needs instead of just our standard settings. And we're like, oh, they're not happy, sedate them. All right. Dr. Vines. Yes. No. There we go. Thank you. Great. So now we're ready to change over, which is done. Sorry on that side of the room, we can only, I don't think it can show on both sides the video, right? Yeah, but we have set up as the lecture will continue on the left screen with ARS, but the right screen will be showing the video of a manic in a simulation of a patient on a 980. And this is a first. What we used to do was had a 980 here and the 980 would attach to a test lung and that opportunity enabled a demonstration and then you might ask a question and Dave would set up that question into an answer and you'd see the video running. Okay. The 980 didn't make it across the Pacific Ocean. But you're here, Dave's here, and with audiovisual's help, we're ready to start a video. The ARSs will be built into these videos. So, I mean, the joke would be Dave is a puppeteer, but his brain will be the 980 for this demonstration. Okay. Do you want to click forward a couple of slides? There's some objectives there. Maybe move forward a slide or two. Oh, I'm sorry. Okay. Yes. All right. So if you can see the video here and my little arrow moving around, I'll orient you for just a second because it's a little hard to see. So we're in volume control ventilation. That's the mode. Whether you see that blurred out or not and can't see it, you always know you're in volume control if you have a square flow waveform. As you can only control flow waveforms really in volume control ventilation, so if you have control over a flow waveform, you know you have to be in volume control ventilation. We have a total volume set. Our flow is default, so sometimes restorative therapists or people are trained to default to set flows at a particular setting. That's 30 or 40 liters a minute in a square flow waveform, 60 liters a minute in a decelerating one. So we're in a square flow waveform. You can see we have an ARDS patient with 70% oxygen, 10 a peep right now. And our rate and total volume, so we're an 80-kilogram patient, so we're right at 6 mLs per kilogram, and around, what, 96 liters per minute of a minute volume. So I'm going to play this screen for you for just a second, and you can see the waveforms run across the screen. You see this run here. Okay, next slide, Dr. Patrick. Next slide. So you'll see there, you're going to see a question. I'll let that run again. So tell me what type of asynchrony you're seeing on the screen there. Well, the ones who had answered there, that's pretty good. They keep going. Great job. So we know there's some flow to synchrony there. Yeah. It's okay. Just leave it. They're voting right now. You can see it on our screen. That's the next one. Yeah, you have to watch over here. You can watch right here. Okay. So if we look back at the screen, how I know there's flow to synchrony as Richard and Alana was showing you earlier in square flow waveform, volume control ventilation, we'd expect this line to be straight, right? We would expect it to start here. Anytime you see a dip or scooping out, they actually call it scooping. If you see a scooping in the pressure waveform, which is the waveform that will change in volume control, right? This waveform is set. So is the volume. So the inspired volume is set, the green line. So is the green flow. So in volume control, you set those settings. They will not change. You shouldn't expect them to change. The only thing that can change in volume control is the inspiration here is the pressure waveforms. So the patient's pulling them down. So we know that here's our possible solution. I'm going to start to increase flow. So we're going to solve that problem by turning up flow. So are we good? Is that enough? Enough flow? What do you think? No, not enough flow, right? So we're going to give them some more flow. We would like that waveform to, again, we'd like that waveform to become more straight. Great. This looks better, right? Maybe a little dip here. So how many people like 60 liters a minute of a square flow waveform? I use it. Some people like to use that all the time. Look at this. So here we are at this point as we run across the screen. And I'll let that go just a little bit more. Okay, next question. So the answer is actually it's a premature cycle is how some would term that, and we will explain. So if you come back and watch the video here for a minute, our patient is actually starting to breathe into the expiration. And so sometimes when you get the inspiratory time too short, it can result in a double trigger as Richard was showing you in the slides before, but most often it's going to resort in a premature cycle, meaning the patient will still be breathing in when the vent cycles into expiration. So can you imagine about the end of your breath, all of a sudden the valve opens up and the air leaves? Can you imagine what that might feel like? So sometimes it can make the patients be more tachypneic, or certainly it's a type of desynchrony. So I'm going to show you how you would diagnose that. So if you see these sort of waveforms, if you actually add a pause to them in volume control, you will start to see this symbol as you're, you will see this, something that looks like this. So we added a pause and I paused the screen for a second. So we added a pause in the breath. So we go to zero flow, but notice it doesn't flatten out as Alana was showing you earlier. It actually dips down and then comes back up. So this is the patient continuing to make effort into the pause, and then they actually stop and the vent starts to, as they stop making an effort, the pressure will suddenly rise. Sometimes this looks just like the Batman symbol. So I tell students a lot of time, that's a Batman. So it starts to look like a Batman symbol. You know that you have too short of inspiratory time set. The patient's neural time is actually longer. To figure that out, you would actually have to set a pause in volume control and you would begin to recognize that if I back this back up just a second. You would start seeing this point where they begin. You don't see a sharp point in exhalation. You begin to see them decrease the exhalation. So it doesn't have really a peak expiratory flow to it. So that's your first clue. Then just add the quick pause to check it. If they are making this sign where you start to see whether you're from Texas and it looks like a longhorn or you like Marvel comics and it looks like a Batman, your choice. But you would then begin to identify those depending on your patient. And then you could make potential changes. And so we're going to roll into some of those changes now as we move this forward here just a little bit. So one of the changes we could make is to change to a—we're going to take out that pause—is to change to a decelerating flow pattern. So if I choose a decelerating flow pattern, then that automatically will lengthen my inspiratory time because it's going to take longer to deliver that breath because now that flow decreases over time. And you can see we have this little dip. So you know, you could say, maybe that's not enough flow in the beginning of the breath. And remember, 60 liters per minute, a decelerating flow is kind of a starting point. So you could turn this up. The same time you would worry about the inspiratory times getting too short here in that process, you would not want that to happen. I would tell you we certainly wouldn't go more in that. Still have these. It is a little short. If we meet our patients here, hopefully as we meet their demand, they will begin to slow their effort a little bit. And look, let's check it with a pause. Let's see if they're pulling into it. Doesn't look too bad. A little bit. But then they stop. Another alternative is that you could choose to change modes. You could choose to go to a pressure-limited mode such as PRVC. And if you have PRVC, I will pause this just a second to point out just a couple of things here is that you see this little alarm, and I realize most of you probably don't. You have someone, a respiratory therapist, someone set up that ventilator. But this little alarm right here, limit, this actually limits the inspired volume. So everybody's like, hey, I don't like PRVC because I have no control over how high the inspired volume gets. That's actually not true. This little alarm right here will let you set that no more than eight mLs per kilogram if you want. I would give a little variability in it. I wouldn't put it right at the six because then it'll be cutting off the breath each of the time. You want it a little bit higher than your total volume, maybe around 100 higher or something like that in them. We'll see more as this runs. So certainly here, you can limit how high the volume will go. It is a cycle. It's like hitting a pressure limit or on a volume mode. It will end the breath. So if you hit that alarm, you hit that limit, the breath ends, it will cycle at that point. That always needs to be set. That should always be set, in my opinion, somewhere no more than eight mLs per kilogram when you set them and should be part of them. And so I'm going to let this run for just a minute. A lot of times, it depends on your institution. This flow acceleration percentage that you see there, you're setting a rise time. If you set that rise time, then some places, the ventilator company defaults usually to 50% unless you're a place that sets that or has that adjusted. The other thing here that is worth a mention is that you see something that I did that I noticed earlier. Look, we have a very short inspiratory time. I want that to run just a minute. Okay, so we went into PRVC and pressure control. Notice in a pressure-limited mode, how that works is even in this mode, even though we're targeting a volume, the vent has calculated a targeted pressure related to the volume you have set. So the vent does a mathematical calculation and says, hey, here we go. We've measured this plateau to begin with. This plateau should work in this volume, and it targets that pressure. Every breath is pressure-limited. It can have a slight variability in volume if you do use, obviously, a pressure-limited mode, but at the same time, this flow pattern assumes a decelerating pattern. The vent's job is just to hold the pressure constant for that period of eye time you have set, and as pressure equilibrates in the lung and gets closer to the pressure on the ventilator, it's physics. Once two equal, flow would be, nobody answered that, zero, right? When two pressure sources equal each other, flow is zero. So when you look at these waveforms, and you can see this moving forward here, as I begin to play it, our choice here would be, and patients typically tolerate more, would be an increase in eye time. Like volume control, my flow is now variable. I can get away with longer eye times for my patient to tolerate them, and you will probably see pressure drop by one, because now the pressure in the lungs is closer to that pressure on the ventilator as this flow approaches zero here in inspiration in a pressure-limited mode. There is a very small air leak in this patient right there, as we can see. Now the question is, let's click to our next question. We talked about it. We'll get into four minutes. Yep. This is the four-minute one. Yep. Next question. Mm-hmm. All right, let's, you begin to answer this. I'm going to let this play for a minute so you can begin to see them. This is the, you're looking at currently the 50%. We're going to go to 100. There's a rise time at 100%, which is this vent's fastest. Some of them are in seconds. Now let's, we're going to turn that down a little bit to those three options you can see over here on the other screen. So this is going from 100 to 90. Go to 80. So you saw the three of them. This is 80, 50, 100, or 90. Which one do you like the best? So perfect. No use for me going in there. This is the point the overshoot stops, in my opinion. So if I backed up to 90 real quick, I would tell you there's still a little bit of pressure overshoot, which is the one I use the most. Instead of looking at the flow waveform, I do want this to square up more. Realize some people become concerned about shear forces in that. You're feeding a vacuum. If the patient's not breathing, that may be a different point. You can't really argue shear forces when you feed a vacuum. That's mostly reflection of what's in the endotracheal tube in the overshoot. The patient is not generating negative pressure in the beginning of that. You want that rise, you want that pressure waveform to square up, or you're not giving them an adequate amount of flow. And so then if we move to our patient here, we'll just give it a second. All right. Hold right there. You're going to see. So our patient's SATS was less than 88, so we had to turn up the PEEP following lung protective ventilation protocol here. Notice we're going to turn up the PEEP again. Following that protocol, 270%, 14 of PEEP. As we know, 14 of PEEP, a pretty common PEEP for ARDS. So looking at these waveforms, what would you recommend? So looking at this screen and waveforms, what would you recommend from the choices there? We have less voting. Less voting. They're thinking about it. All right. We can click forward. I'm going to run out of time. Our time is shorter, but I believe it closes if I can close it together. I think they keep voting. They're still voting, but I can close it with the page down. While we go, we can't run. Okay. So, back to the waveforms just a minute, because this is an important point for you to understand. You can't, in a pressure-limited mode, you can't use that PIN. It's not most likely real. You actually have to do a plateau, or flow needs to hit zero. If flow hits zero, remember I said earlier, if flow goes to zero, pressure on the ventilator and in the lung are equivalent. And since they're equivalent, this peak is reflective of a plateau. So, anytime flow hits zero in a pressure-limited mode, the pressure on the ventilator is the pressure in the lungs. In this case, the patient has to have a TATA volume reduced, because essentially their plateaus are 32. Don't trust the number that may have been recorded earlier from an inspiratory hold, or you could redo the inspiratory hold if you don't remember whether or not flow hits zero here. So, this point's telling me that that peak is a plateau, and I don't need to do an inspiratory hold, which is an important point here. So, I know I have to turn down the TATA volume in that situation. And so, you're going to see that happen. And look, you could do what I just did, hit an inspiratory hold. You can see there the inspiratory hold will show you the same thing, my plateau's above 30, and you would need to turn that down. So, if you don't remember what I said about inspiratory flows going to zero, then you would want to do that to be able to generate them. Okay. So, we're going to turn down the TATA volume. We're going to go to 5 mLs per kilogram, and we should see as the ventilator make an adjustment to lower the TATA volume down to that 400. Remember, this TATA volume is inspired TATA volume, which is targeted on most of the ventilators. This expired volume is what is being measured on the expiratory side. That's not what's targeted. Inspired volume is what's targeted. So, we've progressed. You want to go ahead and click to the next question, right? Okay. So, our last point of the day, which is one, I noticed this change that just happened to the patient here as we begin to see this change. As you see them across the screen, I'm going to freeze it here at this point. And then you look at this change. So, what is that change? What caused that change in waveform? Again, a decrease in our compliance, decrease in airway resistance, increase in static compliance caused that, increase in airway resistance caused that. Which one? And you go, can you tell that in a pressure-limited mode? I'm going to show you in just a second. Notice peak pressures have massively increased, right? Very good. My job's done. I don't even need to explain. So, you know, just to make sure we're all on this same page, remember this, how long it takes for this flow to hit zero is based on time constants. Time constants is calculated by compliance times airway resistance. So, the increase in airway resistance, right, or increase in compliance both take longer to fill the lung. And so, here you can see flows no longer going to zero. And not only that, the pressure had to go up. That's equivalent to meaning that we've had to have some type of increase in airway resistance. Also, you're going to see drops in peak flows. It's going to take a lot longer to get back to baseline. They even may start to air trap in this. But I can tell you in this scenario what happens is the patients in PRBC get rolled over, and then their A2 tubes gets pinched. Now, I want you to watch what happens when you roll them back. Pay attention to what happens to this volume right here. So, you can see if you roll someone without setting, this is the important part of the alarm setting here. Did it pause? If you notice here, then we're going to roll the alarm went off. So, I'm going to back that up just a second because that was not quite what I wanted there. So, if you notice as this runs, the patient was rolled over, caused an increase in airway resistance. That went away. That alarm saved my patient from getting a very large tidal volume. And now it will keep cycling. If you notice, it even created an alarm because it won't let them get to that volume. It stopped it. And then it will come back, adjust pressure down, fix it without exposing my patient to a higher tidal volume or them losing significantly. But that is it. And so, in conclusion, hopefully you found that helpful today in recognizing some types of synchronies and optimizing patient ventilator settings. And we'll be glad if you want to come ask us questions or we'll be glad to answer questions for you if you have any. Thank you.

asynchrony

mechanical ventilation

patient-ventilator settings

volume control ventilation

flow waveform

flow asynchrony

premature cycling

pressure overshoot

rise time