all engineers in this video we're going to talk about compliance so first off how we Define compliance well we have a mathematical definition of compliance and I'm just going to give you a kind of like a a a simple term of compliance let's write compliance right down here so what is compliance compliance is defined as the change and volume in this Cas we're talking about the lungs or the chest wall right so compliance could be for again it could be for the actual lungs or it could be for the chess wall and we'll talk about both of these so compliance is equal to the change in volume of the lungs over the change in the pressure okay but simply when we talk about compliance compliance is a measure of stretchability or distensibility in other words if I want to stretch something something and it stretches very easily you know like a rubber band or something like that stretches very easily okay something like that is very compliant our lungs are naturally very compliant but at the same time they have the opposite of that they have just the right amount of elasticity so in order for us to talk about compliance we have to compare compliance to another term which is referred to as elasticity because compliance is the it's another way of of explaining is it's the ease at which you stretch something it's how easy it is is to stretch it where elasticity is the resistance to the stretch it wants to recoil assume the smallest SI possible so elasticity and again there is the elasticity of the same thing the lungs as well as the chess wall but this situation is opposite it's dependent upon the change in pressure over the change in volume and we'll explain what we mean by these formulas here let's do that before we go into all of these examples in which compliance can actually vary in certain scenarios so if we talk about compliance first let's see how we can compare the situation with volume okay change in volume to compliance and the change in pressure to compliance all right so first things first how would we say that volume is affecting compliance it's simple they're directly proportional so we can say from this formula that the change in volume is directly proportional to the compliance whether it be the compliance of the lungs or whether it be the compliance of the chest wall whereas if we increase pressure what happens to the compliance it decreases so the change in pressure is inversely proportional to the compliance in other words if we increase the pressure it decreases the compliance if we decrease the pressure it increases the compliance and we'll talk about what this pressure is because technically if if I were to rewrite this this pressure here if we're talking about the lungs actually we'll talk about in a little bit because if it's in the lungs it's the transpulmonary if it's across the chest wall it's trans thoracic we'll write that down now let's write that down here so if it's for the lungs it's transpulmonary we'll actually go and show examples of this but if it's the chest wall it's the trans thoracic pressure if you remember TTP we denoted it same thing for this for the lungs the pre change in pressure is the transpulmonary pressure the TP and the chest wall which is going to be TTP okay now elasticity look at the relationship here any increase in the pressure any change in the Inc any change in the pressure upon which it's increasing is directly proportional to the elasticity so in other words if you increase the change in the pressure you increase the actual elasticity whereas if you change the volume if I try to stretch something I'm increasing the volume what does that do to the elasticity it DEC increases it so these are inversely proportional so I just really wanted to make sure that we differentiate the term compliance from elasticity because they are not the same term they're not of the same thing they're exactly opposites okay now what I want to do is I want to talk about what is affecting compliance in the lungs so what's actually maintaining this normal compliance within the lungs and then what we'll do after that so what's the first thing I want us to do first thing I want us to do in this video is talk about what things are affecting compliance normally so what affects compliance normally that's the first thing I want to do okay then the second thing that I want to do is I want to go ahead and relate these changes and volumes and changes and pressures with real life examples to compliance so then we're going to compare Delta V which is the change in volume and then Delta P which is the change in pressure to compliance and then we'll throw in there some clinical comp correlations with that okay so let's go ahead and start that so first thing what is affecting compliance normally okay there's three main things that are affecting compliance I want you to remember these so three main things affecting compliance here look at this here three main things affecting compliance first first thing is elasticity of the lungs this is one thing that is actually affecting compliance the elasticity of the lungs second thing that's affecting compliance is the surface tension we've talked about this a couple times it's that tension that's developed in the alvioli of the lungs right between the air and the water interface it's trying to shrink the alveoli trying to make the alveoli collapse and the third thing that's affecting compliance is is the elasticity of the chest wall okay so let's explain what each one of these things is actually trying to do so let's first start off with the elasticity of the lungs now our lungs are they can stretch but they naturally want to snap back but there's just the right amount so in our lungs you know there's different types of tissues within our lungs but in general our lungs are generally very compliant they're very compliant but they also have just the right amount of elasticity so they're very compliant but they have just the right amount of elasticity just the right amount so what do I mean by this the lungs can actually expand with ease okay they can expand with ease we have to utilize some skeleton muscle to assist in that process but they can easily expand but they also want to recoil let's say for example though that I Chang the elasticity so right now the compliance with of the lung so the compliance of the lung is pretty much equal to the elasticity okay they're in just a nice interplay there nice interplay let's say that I changed the situation up let's say I actually make the lung more elastic how can I make the more L more elastic well I prevent it from wanting to stretch okay that's how I do it I prevent it from wanting to stretch how do we know that because we did the formula we said that what in the formula in the formula we said that if you actually decrease the volume in other words you you just don't allow for the lung to stretch as much it'll actually do what if you decrease the volume it'll increase the elasticity right or vice versa increase if you want to increase the elasticity you actually do what decrease the volume so it's not going to want to stretch in this situation let's say that I have I you know the person unfortunately has what's called uh pulmonary fibros is right so they have pulmonary fibrosis in other words let's say here is actually um over here let's say over here you have this person's lung right they have just the right amount of elastic tissue but now I'm going to do this in like this brownish color this brownish color is to represent fibrous tissue so let's say that if someone's getting older or they have certain type of situation they're developing a lot of fibrous tissue and a lot of fibrous tissue is developing all around the lungs as this starts developing a lot of fibrous tissue what's the whole point of this well fibrous tissue is not distensible it doesn't like to be stretched so if you actually have a lot of fibrous tissue deposits here instead of normal healthy lung tissue so a lot of scar tissue fibrous tissue is really scar tissue so let's say this is a lot of scar tissue which is the pulmonary fibrosis that we said here a lot of scar tissue formation it's not distensible so if it doesn't want to stretch what happens to the compliance the compliance decreases but the elasticity increases okay so if there is ponary fibrosis a lot of scar tissue formation okay that fibrous tissue accumulation it's not going to want to stretch so what happens to the elasticity now the elasticity goes up and the compliance decreases so let's write that here we'll do with color coordinator right so in this situation compliance is actually going to what decrease and then what happens to the elasticity the elasticity increases and what's the overall effect on the lungs the lungs will not want to expand or they'll want to recoil constantly so they're going to have a hard time being able to be inflated this is an example of some type of restrictive pulmonary disorder where they have a low Force vital capacity let's take the opposite now let's say that we actually make the long super compliant okay now we take the opposite let's say that I break down a lot of that elastic tissue there so let's say that we use the example here of uh you know there's a disease called osma so there's a disease here called osma and osma is a disease you know in the alvioli they have a lot of um this pink tissue here a lot of these actual they're very you know normal alviola have a large surface area normal healthy alviola have a large surface area so that's one really important thing about alveola is they have a large surface area but with osma those neutrophils start reling a lot a lot of elastase enzymes and anti-alpha 1 antirion ISM preventing it and what starts happening they start breaking down a lot of that elastic tissue as you start breaking down a lot of that elastic tissue what's going to happen to the lungs well now they're not going to have as much elasticity if they don't have as much elasticity then what does that mean well if their elasticity is decreasing what do we say elasticity okay let's go back to the formula we said that this is inversely proportional so elasticity decreases what happens to the volume it increases huh well I thought if volume increases compliance increases it does you see how it's not that bad if we use the formulas they can help us to really understand this so in this situation in actually empyema a chronic obstructive pulmonary disorder the lungs are very floppy so they're they're not very compliant so in other words you can take a lot of air in it's easy for these individuals to take a lot of air in generally but the problem is is what does elasticity lungs allow for expiration passively right so because of that when the lungs collapse they help to be able to push the air out passively without having to put a lot of work into it but in these individuals they're not very actually elastic they're very compliant and so their elasticity is very less so they have very little elasticity so the lungs aren't going to snap back as well and so they're going to have a hard time being able to get air out so they have a low forced expiratory volume so in this situation we take the opposite so what happens to their compliance their compliance goes up and their elasticity goes down not too bad so now that we've done elasticity of the lungs let's do the elasticity of the chest walls just stick with this concept here okay and after we do surface tension I'm going to talk about pressure too how pressure affects these things okay so let's do this one in purple let's do this one in purple so let's say we talk about the chess wall okay chess wall again same thing chess wall is generally very compliant and what do we say about the lungs lungs generally have an inward recoil right they want to they want to snap again we said it like this right if we showed the arrow it always wants to snap in like this whereas the chest wall wants to have a outward recoil right it likes to be stretched outwards that's what helps to keep this int plural pressure nice and negative well on this say this situation there's a nice interplay between the chest wall elasticity right and the chest wall compliance so there's just it's like you know we said again compliance of the chest wall is just enough that there's not any type of situation where there's one overcoming the other it's just the right amount in Norm normal healthy individuals where there there this this nice dynamic dynamic and we need to make sure that we say this because it's not always perfect there's this kind of pull pull pull one side but it's always trying to keep it in equilibrium so there's a dynamic interplay between these two to maintain the natural compliance and elasticity but again let's understand this in pathological conditions or just in different types of physiological situations let's say that this person their chest wall I let's say that they have ankle loing spondilitis you know there's a it's a situation it's an inflammatory arthritis and in that inflammatory arthritis they have like kind of like a hunched over posture right so in this situation which is called ankal loing spondilitis ankal loing spondilitis or you know there's another one it's called um kyphosis kyphosis when they have that hunched over posture too their their chest cavi is kind of like bent over like that so they have kyphosis so an individual we can even have what's called kyphosis or even scoliosis too and even scoliosis if you guys remember scoliosis so kyphosis I like to remember like this let's say here's the K here's the guys put the guy's head like this put his feet right here and here's his arms like that he's actually having a hunched over posture so he has a hunched over posture whereas scoliosis they have a abnormally s-shaped spine right and again here's the guy here's his arms whatever you know just a little funny diagram there so kyos is to have a hunched over posture so does ankal loing spondilitis and scoliosis you know what else can happen in these individuals let's say that there's another person no abnormality you just get older you know when we get older we get a little bit more decrepit our cartilage within the actual ribs and stuff like that it starts to get really really aifi and it doesn't want to allow for stretching so if that happens this can also affect the actual stretching desire of the chest wall so in certain situations in which as we get older like the aify you aify aify the actual uh cartilage the actual cartilage around the ribs cartilage of ribs and so it doesn't allow for it to allow for that expansion okay so anyway we got this one anking spondilitis kyphosis scoliosis or even oifc of the the cartilage of the ribs what would that do to the compliance okay if you're in this hunched over position and you're stuck like this are you I'm going to have a hard time bringing air in so imagine me trying to do that it's it's hard doing it right here but then if I hunch back over you know into normal position I can take a decent amount of air in so because of that they're going to these people are going to have a really hard time bringing air in so their compliance is going to decrease because their chest wall is not very good at being able to have that nice distensibility so because of that the compliance of their chest wall decreases okay so these people have a decrease compliance of the chest wall and in the opposite of that because of them maybe having some oifc of the cartilage or the ribs or these type of situations they're stuck in that position they don't they they have a hard time being able to go they they're back to that normal position they're kind of stuck in that position so because of that if you think about it it's not necessarily that their elasticity is actually increasing it's really more that their chest wall just doesn't have the ability to expand we can say in a way that their elasticity is increasing but we're not going to do that here because more of the situation here is that the compliance of their chest wall is actually de increasing so it doesn't want to actually stretch out and expand to allow for the lungs to fill with air and you can imagine if there was some type of situation in which the chest wall was very very flexible right if the chest wall was very very flexible for whatever reason if the chest wall was very very actually flexible and it can actually expand out a lot then what does that mean that means that the compliance goes up and if the compliance of the chest wall goes up what does that mean that means we can actually inhale more air so it's that simple right so not very very confusing next one let's do surface tension so surface tension and then we're going to talk about pressure so we're going to go a little bit more into these formulas right after this so now let's talk about surface tension let's do this one in this nice blue color here okay so the next one is surface tension first off what is surface tension we'll talk about this in more detail in another video but surface tension is basically whenever you take like an alveoli let's say here's an alveoli and you have this liquid you have this actual water layer there's a nice little water layer here that's interacting with the air sometimes what can happen is there can be a lot of tension developed between the air and the water interface and what this does it tries to actually shrink the whole purpose of is it tries to shrink the alvioli and when it tries to shrink the alveoli it tries to collapse the alveol it wants to get to be as small as possible well if you think about that if alveoli are the basic like functional unit and structural unit of our lungs our lungs are made up of many of these so if all of these alveoli start shrinking what's going to happen to the lungs they're all going to want to start trying to be as small as possible if they become very very small what is that going to do then that's going to be a lot of lot of resistance against me trying to bring air in you know there's a situation that this can happen in infants when they don't produce enough of a a protein lipid complex called surfact and we'll talk about it's called infant respiratory distress syndrome and what happens is because of that there's so much surface tension that it takes so much effort so much work to bring in as much air as possible to inflate the avoli so because of that if you imagine if the surface tension is increasing excessively in some type of situation like we gave an example uh infant resp respiratory distress syndrome where they don't make a protein lipid complex called surfactant what would this do to the compliance it would decrease the actual compliance what would that mean for this individual they would have a really really hard time bringing air in they would it would increase the workload of breathing so what would it do what would this decrease compliance do this would decrease the I'm sorry not decrease the workload this would increase the workload of the breathing process so this would incre increase the work of breathing that's why these uh babies or infants that have this situation you usually have to put them on a mechanical ventilator because they can't breathe on their own they have a hard time being able to inflate the alveoli and even when they expire the alveoli collapse and it takes so much effort to reinl them so it's a terrible situation but let's take the normal situation so let's say that this is the extreme what if you produce a protein called surfactant you know there's a protein lipid complex that that our type two Alvar cells produce and the whole purpose is that they try to decrease this surface tension and when they try to decrease the surface tension that tries to decrease the desire of this alveoli to collapse and when it prevents this actual recoil it allows for the alveoli to it then in instead of wanting to recoil to allow for it to expand so if we decrease the surface tension and how could we do that how can we decrease the surface tension we give you know you have this person producing normal amounts of surfactant which is this protein lipid complex and what that does is that decreases the surface tension so if that's the case then let's say I redraw this alveoli and again I put here this is the liquid right here and it's interacting with the air so there's this air water interface and what's happening is that you're trying to be able to decrease the surface tension so what's going to happen now if you decrease the surf surface tension between the air water water interface here's the air here's the water right you're going to allow for this alveoli to more likely be want to expand and if the alveoli will want to expand and not recoil what does that mean for the lungs well again this is the basic structal and functional unit so if this wants to expand all of the lung would want to expand and if the lungs wants to expand what does that mean for compliance that means the compliance is increasing right and so so compliance for this situation could compliance should increase and what does that mean for the workload it decreases the actual work of breathing man it's a beautiful thing okay but now these are the three main things that affects compliance okay these are the things I really want you to remember but if you really want to be good at compliance you really want to be able to remember other things that really is important I want you to remember two other situations that is neuromuscular problems okay so I want you to remember this neuromuscular problem and this is actually this is going to be the main thing we'll just specifically talk about this one one more uh thing that I want to talk about neuromuscular problems let's say uh that you have a situation where the diaphragm is injured if the diaphragm by some terrible situation is injured and it's damaged and it can't contract will it be able to contribute to the inspiration process no if the diaphragm is damaged will the lungs be able to expand no so what does that Doe to the compliance it decreases compliance let's say by some situation you paralyze your external intercostal muscles if you paralyze the external intercostal muscles what does that mean for that that means that they can't lift the ribs outward like the bucket handle movement that means that they can't pull the sternum outward like this like the pump handle movement what does that mean for the actual expansion of the lungs it decreases so what does that mean for compliance it decreases but that's the muscles directly you know there's another terrible condition remember this was the vrg and it was sending down these axons into the actual anterior gray Horn of the spinal cord you know there's a a disease that damages some of these neurons right here that come out and Supply these muscles okay look this condition which can actually destroy these actual neurons right here these anterior um specifically in the vental grey horn of the spinal cord they call it ALS alss which stands for a myotropic lateral sorosis right in that situation in which someone has ALS it destroys these neurons if these neurons are destroyed will they be able to send action potentials out to the diaphragm no so the action potentials out to the diaphragm are decreased will the muscle be able to contract no if it can't contract what will that do to the actual compliance it'll decrease the compliance same thing here if you damage these actual vent gray horn right the the sematic motor neurons there the cell bodies they're not going to be able to send muscles Ste the ACT send impulses to the external intercostals if that's the case these muscles can't contract and they can't Elevate the ribs and pull the actual Stern them out and that would also decrease compliance last thing I want to talk about is oh one last one more thing before we finish this right here one more thing that can also affect compliance before we go in here and explain these pressures and volumes a little bit more is this situation here let's say that someone has mucus so they don't actually have like you know let's say that we have a situation here where they have a lot of mucus building up here if you have a lot of mucus building up inside of these actual bronchi or bronchials or whatever maybe due to chronic bronchitis or cystic fibrosis whatever it might be what happens to the air can the air get in no all this air is prevented from getting into the alveoli if you can't get air into the alvioli what happens to the AL alveoli they become underventilated if they're underventilated will the alvioli be able to expand as well as the lungs be able to expand no so if there's a lot of mucus buildup what could that do a lot of mucus buildup could also decrease the compliance of the lungs all right so what if I actually what if I poke a hole what if I poke a hole through the chest wall and into the parietal plura and I open up the actual plural cavity to the atmosphere let's say that I do that let's say that somehow I got stabbed it went through the skin and you know went through the actual muscle tissue and through this connective tissue structures and it penetrated and punctured a hole and it opened up this space here look look at this all that's open so now what was the actual pressure in here what was this pressure you guys remember this pressure in the plural cavity it was called the int plural pressure you know the int plural pressure is normally uh closes uh you know to about -4 millimeter mercury and then what did we say the intrapulmonary pressure was the intrapulmonary pressure was a proximately during this process right it's about 0o millimeter of mercury and then we said that the pressure in the atmosphere was approximately about 760 millimeter mercury right because again these two there's no change between this one and this one is actually a 4 mm Mercury difference so I could even rewrite this one as 760 M MMG or 756 MMG but nonetheless look at this look what happens the atmospheric pressure is 760 how could I write this one remember I said we could write it as 756 so let me write that as 756 756 millimet of mercury look at the pressure radient difference 760 mm Mercury to 756 what does the diffusion principle say things like to go from areas of high pressure to areas of low pressure so where will the air start flowing the air will start flowing very very viciously and vigorously into the actual plural cavity as it starts accumulating within the plural cavity what starts happening air starts accumulating as air starts accumulating into the plural cavity oh what is that call what is that call whenever air accumulates in the plal cavity you know it's called numo thorax it's called a numo thorax what do you call it whenever there's some type of infection you know there's actually the capillaries here you have the pulmonary capillaries and the pulmonary capillaries are actually supplying the alveoli let's say by some situation there's some type of infection or damage and some of the blood from this actually leaks out here what is that called what is that situation called that situation right there is called a hemothorax anyway nonetheless a any type of situation in which air or blood or different types of fluid is actually accumulating inside of this actual plural cavity what do you think it's going to do to the int plural pressure it's going to increase the int plural pressure so as more air accumulates the air is going to keep flowing in and flowing in and flowing into this actual plural cavity until the intop plural pressure equalizes with the atmospheric pressure what is the atmospheric pressure 760 so what would the int plural pressure become the int plural pressure pressure will eventually have keep receiving air until it equals atmospheric pressure which is 760 mm Mercury what is that in this terms -4 will go up to 0 millimet Mercury which is 760 right now look at this when the intal pressure the pressure inside of this plural cavity equalizes with the actual intrapulmonary pressure even by some chance it becomes even greater like plus one it's going to start pushing on the actual lungs and as it starts pushing and pushing and pushing and pushing on the lungs creating this actual Force what is it going to try to do it's going to try to collapse the lungs what would that do to the compliance it would decrease the compliance right so it's going to try to collapse lung what ises that called whenever you collapse the lung what is lung collapse called whether it be numo thorax or hemothorax or other different types of situations any type of plural affusion that's accumulating out there this could introduce what's called atal lactases right so ATA lactases okay so now if this is a lung collapse right what is the lung trying to doing it's trying to shrink if it's trying to shrink what does that mean for elasticity it's trying to actually snap back right so in a way you can think about if it's trying to be very elastic if it's trying to be very elastic it wants to snap back and become very very small what does that Doe to the volume of the lung well the volume of the lung will start decreasing if the volume of the lung starts decreasing what does that mean for compliance if volume decreases compliance decreases it's not that bad right all right so in this video we talked a lot about compliance and elasticity and we basically focused on what what affects compliance normally right we talked about elasticity the lungs elas to chest wall surface tension neuromuscular problems we compiled a whole bunch of different types of uh disorders or different types of physiological conditions that can affect it and then we even applied we compared this whole ch CH in volume change in pressure to compliance along all of these examples right and then we even threw in there a little pathological condition called numo thorax and hemothorax to compare it with adal lactases all right all right Engineers I hope all of this stuff made sense I hope you guys did enjoy it if you did please hit the like button comment down in the comment section and please subscribe all right Ninja nerds as always until next time