[Music] all right you guys welcome back to another video lesson in this lesson we're gonna be taking a look at the different basic ventilator modes that you're commonly gonna come across these are the modes that you're gonna see more often than not and it's gonna be imperative that you guys have a good understanding of these so that in the future when we talk about and you also come across some other alternative modes of ventilation you have this as a baseline in which to understand some of these other modes and my name is Eddie Watson and I welcome you to ICU advantage my goal here with ICU advantage is to take these complex critical care topics and really break them down for you and make them easy to understand for you guys I hope that I'm able to do just that and perhaps by the end of this video I'll have learned a subscription from ya if you do make sure you hit that Bell icon and select all notifications that way you guys will never miss out on a new lesson as always a special shout out to all of our awesome subscribers who continue to watch like and support our Channel really without you guys in your support this channel would be nothing once again another quick shout out to respiratory coach another channel here on YouTube he was super helpful in reading through the notes on this lesson and making sure that I had all of the key points that I really needed to get across to you guys if you haven't seen this channel yet he's got a bunch of really awesome videos on topics related to respiratory therapy so make sure you guys head on over there check out some of his videos and subscribe to his channel alright and with that said let's go ahead and get started here and let's really start this lesson off and begin with a quick introduction to the topic of our basic ventilator modes so in the previous lesson which if you haven't watched it yet I'm linking to it up above and down in the description I provided you guys with an introduction into the world of invasive mechanical ventilation in that lesson I talked about how pretty much all of the ventilators that we use today are all forms of a positive pressure ventilator and within the world of positive pressure ventilation there really are many different types or modes as we call them that our ventilators can really operate in in this lesson here I'm gonna be covering the basic vent modes to try to really give you guys a good understanding of the most common modes that you're gonna come across in a future lesson I am gonna take a look at some of the more advanced modes that you may very well come across now when we take a look at our different vent modes there's really two main categories that you're really gonna come across the first of these is something that we call volume control and the other is something that we call pressure control so first let's take a look at volume control here and I'm actually going to take a look at some of these modes here in just a minute but really the basis of this category is that we're gonna be setting and controlling the volume of air that our patients get and the way the vent does this is it delivers this volume by providing pressurized air causing it to move into the patient's lungs now depending on many factors the pressure that's required to deliver this volume can and certainly will change from patient to patient and from breath to breath this right here is a very important fact for you to remember so now if we move over and quickly talk about pressure control here the reverse is taking place in pressure control we're going to be controlling the pressure that we deliver to our patients and there are many benefits to pressure control which we are going to discuss in the next lesson on those advanced modes but the thinking and understanding of these modes is different than our natural intuition now similar to like we had just talked about with volume control depending on many factors the volume of air as opposed to the pressure of air that is going to be delivered can and will change from patient to patient and breath to breath once again this is going to be a very key point and this really summarizes the main difference between our volume control and our pressure control as I mentioned here volume control our volume is constant and our pressure is the changing variable whereas in pressure control our pressure is constant and the volume is our changing variable so a very key important distinctive concept to know now within each of these main categories there really are many different modes and even some that kind of cross in between both of these modes here but for the purpose of this lesson we're gonna be sticking to just talking about volume control so like I said the main principle for volume control here is that we want to ensure that our patients are receiving a set volume of breath each minute and like I said within this category we have different modes that are ultimately play a different role in the impact on our patients work of breathing in order to understand the differences between these modes though we really need to talk about some of the settings and some of the things that we're going to be looking at on our vent alright so the first thing that we're going to talk about in our settings is something that we call our tidal volume and this you'll see in the setting VT and essentially our tidal volume is the volume of air that set to be delivered with each breath to our patient all right the next setting that I want to talk about is something that we call frequency also known as our respiratory rate and this will no usually find abbreviated as either F or RR and this one should be pretty self-explanatory but it's how many breaths per minute are being delivered to our patient now it's important understand how this works and how this triggers for a breath to be given is it will actually take the respiratory rate that you set and divide that into 60 to figure out the amount of time that we should have between each individual breath and we'll talk about it more here in a minute but when that amount of time has elapsed then it triggers another breath to be given all right the next setting that we're going to cover here is going to be our oxygen concentration and this is what we refer to as our fio2 and fio2 really means our fraction of inspired oxygen this is important to know because when we are referring to our fio2 oftentimes we'll say we're on 50% we're on 80% but really we need to understand that this number is being expressed as a fraction or a decimal so when we say we're on fifty percent our fio2 setting is actually going to be 0.5 if our patients on a hundred percent fio2 then we have an fio2 of 1.0 so the next setting that I want to talk about in the world of volume control is a setting called positive end expiratory pressure this is something that we more commonly referred to as peep so thinking back to one of our previous lessons where we covered non-invasive ventilation think of peep as being really similar to CPAP or BiPAP on a BiPAP machine essentially this is a constant pressure that's going to be applied throughout expiration to really help an open and keep open alveoli now it's peep along with our fio2 which is how we really help to improve our patient's oxygenation and so for this setting it's really important that we maintain at least 5 centimeters of water to help to provide what we call physiological peep and the reason for this is because of the ET tube that we have in our patient that this can actually allow the intrathoracic pressure to fall to zero which would not be a good thing now the range of settings that will usually see for a peep is typically in the range of 5 to 20 and since they didn't mention in a minute ago for our fio2 we typically aren't going to find that any lower than 35% or 0.35 and this can obviously go up to a hundred percent alright and so the final setting that i want to talk about here in this world of volume control is something that we call pressure support this one you'll see abbreviated as PS and the best analogy that I can really give you for pressure support is if you really think about this as a spotter at the gym so this is really an extra push of air to assist our patients when they're taking spontaneous breaths so if you think about that spotter is there to kind of help provide a little bit of pressure and support as you're going through doing some sort of exercise that's kind of the same thing that's happening with our pressure support only in this case we're helping our patients take a breath so if you really think about this the more pressure support that we apply the larger the spontaneous breath that a patient's going to be able to take with Morris's our settings usually for pressure support you're gonna find in the range of five to twenty typically though we're gonna keep it at a minimum of anywhere from eight to ten and this is really to help overcome the resistance of having to breathe through that ET tube actually out there if you take the time to look for it there is a chart that does a breakdown based on the ET tube size and how much pressure support it really requires to overcome that resistance if I happen to find it I'll link to it down in the description but it's an interesting chart and it really drives home the point that just because of the size and the resistance of that ET tube we're already gonna have to give them some sort of assistance because if we gave them nothing breathing through that ET tube would actually be harder to breathe through than if they were normally breathing alright so those are all the settings that you're gonna need to know when we're talking about these different modes of volume control lastly I do want to talk about a couple of the different things that we're going to be looking for in the monitoring of our patients on the vent and I'm gonna go through a couple different parameters that you're gonna see on your vent but just know that these parameters that I'm listing here are far from all of the parameters that are really important in truly understanding how your patient is tolerating being on the vent but again this is where the respiratory therapist comes in because this is their area of expertise over time it certainly is great to learn about a lot of these different settings and different numbers that you get on there but for a basic understanding I'm gonna give you a couple things that are going to be really important the first of these is going to be something that we call our minute ventilation and this you'll see abbreviated as ve now this one's probably the most important one for you to understand and that's because this is a measure of the amount of air that's being delivered to our patient per minute so it's important to know how we get this number and really in a perfect world our minute ventilation would be our tidal volume times our frequency and if you really just kind of think about that for a minute if we take the volume of air that we're delivering with each breath and then multiply that by how many breaths were giving per minute should tell us what our volume of air that we delivered to our patient over the course of a minute would be now as we know we don't live in a perfect world so we have to deal with things like inefficiencies triggering pressure limits and really the patient's own response can and do impact the actual delivery of air that they get but if you do have to increase or decrease your patients minute ventilation to do something like let's say control our PA co2 on an ABG then we're going to be looking to adjust our patients minute ventilation and again because we should be keeping our tidal volume set based off our patients ideal body weight then really we know that if we need to be making changes to our minute ventilation we probably want to be adjusting our respiratory rate the core concept here is if we have more minute ventilation we're gonna have more co2 clearance hence less minute ventilation less co2 clearance and the goal for a patient's minute ventilation is going to be from 5 to 10 liters per minute all right the next thing I want to talk about it's actually going to be the first of two different pressures here it's gonna be something that we call our peak inspiratory pressure and this one you'll see abbreviated as our pip now I'm not going to go too far into some ventilator Theory here but essentially our pip is the maximum pressure that's reached during inspiration and the goal here for our pip is to have this less than 35 with the goal of preventing lung injury now the last setting and the last pressure that I actually want to talk about here is something that we call our plateau pressure and this one's abbreviated RP plat and when we talk about some of these pressures and volume control the plateau pressure is going to be probably one of our most important ones to keep an eye on because this one's going to be an indication of our lung compliance so we measure this one at the end of inspiration with an inspiratory hold or pause maneuver and we really want to be shooting to have our plateau pressure under 30 and this is really to help prevent Barrow trauma so important to know plateau pressure means lung compliance if we see an increasing plateau pressure this can signal that there's some sort of problem with our patient's lung compliance all right so those are the settings and some the major important things that we want to be monitoring for in terms of numbers on the ventilator and so now let's go ahead and move on and talk about the different volume control modes so I'm going to go through and talk about a few different modes that we're gonna see here and it can really help to think about these modes as being from the most supportive to the least supportive in terms of our patient's work of breathing alright so the first of these modes that I want to talk about is something that we call assist control this is something that you'll see abbreviated either AC or VC for volume control now you may also see people interchange this with CMV but there actually is a very important distinction and I'll kind of explain that difference here in a minute when we get to that so when we talk about assist control there's a couple settings that are going to be really important for this mode obviously we're going to have because it's a volume control we're gonna have a predetermined volume set for each breath so a VT or tidal volume and we're also going to set the number of breaths per minute or the frequency for our patients in addition to that we're also going to set an fio2 as well as a peep important distinction here is we are not going to have a pressure support now let me try to explain why so we know based on our tidal volume and our frequency that every so often we're gonna give the patient a set volume of breath so if we had a tidal volume of let's say 500 and a respiratory rate of 12 we know every five seconds we're gonna give this patient a breath of 500 MLS and this is essentially what CMV or control ventilation does whatever the set number of breaths are and the volume to be delivered the vent just continues to pump that out one after another after another and there is no derivation from that no matter what the patient needs or what they're trying to do they're just going to continue to get at the same frequency the same volume of breath where assist control comes in is this actually will take into account the patient trying to take their own breath so what happens here in assist control is if a patient attempts to take their own breath this is what we call spontaneous breath that the ven is gonna recognize this breath but it's going to deliver the full set tidal volume so the vent is either gonna deliver breath to the patient when it's time or if the patient tries to initiate their own breath the vent is going to recognize it but say I know you want a breath here have the full breath and because of this this is why we don't have a pressure support because we're not gonna aid the patient in taking a spontaneous breath we're just going to detect that they want a breath and then give them a full breath so this sounds wonderful except the fact that this can actually lead to excessive ventilation especially if our patients are too kipnuk for non respiratory related reasons so here this to Kipp Nia will lead to blowing off too much co2 and ultimately lead our patient into a respiratory alkalosis if you want kind of a review on this I'm gonna link to ABG lesson up above as well as down in the description but here if you think about if your patients in pain if they have anxiety or even if they have some sort of central nervous system dysfunction causing them to have this abnormal - Kipp Nia that this can ultimately lead to blowing off too much co2 when we physiologically normally wouldn't want that now often times though we will initially use AC when we're intubating a patient as we really have the full control over our patients minute ventilation as well as fully taking over their work of breathing alright so because of some of these problems that we just talked about with assist control and also because of a desire to want to be able to have a mode that can really help with weaning our patients down off the ventilator another mode was developed and it's something that we call synchronized intermittent mandatory ventilation something that goes by the name simv so essentially with simv we're still going to determine or mandate hence the name mandatory that a patient gets at least a set volume and a set number of breaths per minute again for this we also will set an fio2 and a peep so so far this is looking just like a sis control the big difference now when we compare this to AC is what happens when a patient takes their own spontaneous breath in simv instead of delivering the set volume of air the patient's actually going to be allowed to take whatever size breath they can and so now the breaths that were delivering through the vent are actually going to be synchronized with the patient's own spontaneous breaths to really help to increase their vent compliance so essentially as long as they take a breath in a predefined window between each of the two mandatory breaths then if they go to initiate that breath then whatever breath they take the size the volume that they get is what they get if they happen to take that breath right about the time that another mandatory breath is going to come the vent is going to recognize this but similar to AC is it's then going to go ahead and give that full set tidal volume this ensures that we're maintaining at least that mandatory minimum level of minute ventilation so because the fact that our patients are able to take their own spontaneous breath that this is where we actually are going to set a pressure support here and again the point of this pressure support is to assist them in taking their spontaneous breath if we notice that our patient is taking too small of the spontaneous breath we can increase this pressure support to really help them achieve a larger spontaneous breath so now a quick test of understanding here let's say you have a patient who has just been intubated and they are currently sedated and paralyzed still from the intubation if you were to put this patient now in to assist control or if you were to put this patient into simv with all of the same settings other than the pressure support that you'd set in simv what would be the difference that you would see in your patient on the vent now well hopefully you realize that that was a trick question because there's going to be no difference between these two so if a patient is taking no spontaneous breaths simv is going to be indistinguishable from AC and if you really kind of think this one through if they're paralyzed and they're not taking their own spontaneous breaths we do have a frequency and a tidal volume set so again if we think of that example of a volume of 500 and a frequency at 12 every five seconds we're gonna give this patient 500 tidal volume and this is just gonna go over and over and the patient doesn't take any spontaneous breath that's all that they're gonna get well if they were an AC again they're gonna still be getting every five seconds of volume of 500 and again they're not taking any spontaneous breaths so that's all that they're gonna get as well and these two modes are going to be completely indistinguishable from one another now simv is really good because it can actually allow patients to gradually take back over their work of breathing over time and so the less support that we give them with the mandatory breaths the more work of breathing that the patient is going to need to take on on their own and so like I said simv was initially developed with the help of really weaning patients from the vent but often we find it as one of our primary modes of ventilation because of the fact that some of the work of breathing is on the patient it really requires close observation of our patients physiologically as well as psychologically to see how they're responding to this work of breathing now our patients may be at risk of becoming tachypneic hyperventilating and leading themselves into a respiratory alkalosis but again because we're relying on them for some of the work of breathing if they're minute ventilation just isn't sufficient for what they need they're not taking enough breaths or large enough breaths then we can go to the other side of things and be retaining co2 leading to a respiratory acidosis all right so the last mode that i want to talk about here is something that we call pressure support now oftentimes you'll hear this referred to as CPAP let me tell you this is not CPAP please don't call it that and in talking about pressure support this actually technically isn't a volume control mode of ventilation because in volume control we are setting and controlling the volume that our patient is getting and pressure support is a form of spontaneous breathing so for patients in this mode we're only going to set an fio2 a peep and a pressure support so there's not going to be a tidal volume or a rate set for the patience although that said most vents do have a safety mechanism in place something that we call backup rate so in the event that our patient goes APNIC this backup rate is gonna kick in and take over until we reset it now here in pressure support minute ventilation and thus our patients work of breathing will be almost entirely dependent on the patient's effort with the assistance of whatever we set our pressure support at so oftentimes you'll see this used as our last step or trial before excavating patients typically if we do have our patients and pressure support and we are doing this spontaneous breathing trial we usually have them set at 10 over 5 which is 10 of pressure support and five of PEEP or for a very short run sometimes we will run them 5 over 5 and again this is going to be a short run just prior to excavating all right so that finishes up our discussion here talking about the different vent modes hopefully these modes make sense you can see that we're looking at some of the same settings were functioning very similar in terms of volumes that were being delivered but where some of the key differences come in is how we handle a patient's spontaneous breath from CMV or control ventilation where we pretty much don't acknowledge that at all down through recognizing those breaths but giving the full breath an AC to simv where the patient will determine the size of their breath all the way down to pressure support where the patient's not going to get any mandatory breaths and everything's going to be based on their own work of breathing like I said it's sort of this progression from the most amount of support and the most effort and the most coverage taking over of our patients work of breathing down to the least amount all right and with that said I do want to thank you guys so much for watching if you found this lesson helpful please leave us a like on the video down below don't forget to subscribe in order to continue to get the latest in our critical care education also don't forget to check out ICU advantage on social media as well as I just recently started a patreon page so if you'd like to show support beyond youtube head on there I do have additional content that you won't find just on YouTube finally make sure and check out this awesome video right here and as always you guys have a great day and I'll see in the next video