what's up future respiratory therapist so I got an email about a question I don't know who has a practice TMC or if it was just a test question but it was about a VQ ratio and I'm gonna give you an example of the question at the end of this video so so hang tight with me but to answer this question I'm gonna break it down to another level and I've done a video over this in the past I don't know if it was really all-inclusive I'm gonna try to make this one a little more all-inclusive so you get a better picture okay so the title of this video is shot versus dead space and ultimately how does that affect your VQ ratio because that's really what we're talking about here okay you have to understand that as a respiratory therapist every patient you take care of has some sort of VQ mismatch if something is not right in there pulmonary anatomy and their pulmonary circulation otherwise they're healthy individuals like us right and they're walking around there's no problem but that's not the patients were taken care of the patients were taken care of them usually need our assistance because we are addressing patients with Shutts or dead space problems and that affects your VQ ratio so I'm going to try to give you some practical information here to address and to recognize shut versus dead space but also how are you gonna answer your VQ ratio questions on your on your finals on your tests and on your TMC exams okay so here we go I'm gonna draw a line right here and we're gonna break it down like this okay so shut vs. dead space now most students I ask and I say what is the shut most of the time they can answer that question and what that answer is as well as shut is when perfusion is greater than ventilation and that's correct then I take it a step further and say okay give me an example of a disease process or give me an anatomical alteration that would cause a shunt and the answer I get if I get one is atelectasis now with that Alexis we realized that we have alveoli that are collapsed and when they collapse they are no longer being ventilated but there is still blood flow passing through these collapsed alveoli which puts perfusion perfusion in excess of ventilation the other thing I get is consolidation so consolidation is another good example you have alveoli that are filled with with consolidated fluid and mucus there's no air coming in and out of those alveoli because they're occupied by fluid or this consolidated material so they still have blood flow which puts perfusion greater than ventilation and then the last one is pulmonary edema which is kind of the same thing when you're talking about shut versus dead space when you think consolidation and you think consolidated material in an alveoli that's impairing air movement in and out same thing with pulmonary edema you get this fluid leaking into the alveoli the alveolar now filled with fluid and there's no air coming in and out of the alveoli and that makes perfusion greater the ventilation because those alveoli are still being perfused there's still blood flow passing through those alveoli so that makes sense now when you think about this when you think about Alexis you're thinking about any disease process that causes atelectasis post-op surgery shallow breathing patients pneumothorax that that causes air in the pleural space which collapses the all the alveolar tissue and causes a shot pleural effusion compresses out and causes a shot they causes add lectins and that would cause a shot now consolidation you're talking about pneumonia and pulmonary edema several things but one of the big ones is CHF okay so when we take this down to disease processes you realize when we say consolidation a lot of times we're talking pneumonia when we're talking about pulmonary edema fluid leaking from the pulmonary capillaries into the alveoli a big example of that is congestive heart failure with CHF along with other things okay now what these look like from a an illustration standpoint is if we talk about atelectasis you have alveoli that look like that they are collapsed right but you have blood flow passing by those alec tannic regions if thou viola with pneumonia or pulmonary edema is filled with fluid then you have alveoli that look like this and you see blood flow passing through these consolidated or fluid filled alveoli and there's no gas exchange happening because perfusion is happening passing out vo live where there's no ventilation happening and so that is what you get when you're talking about a shut now when we talk about dead space we talk about ventilation greater than perfusion so what does this look like and what are we talking about we're talking about any disruption in blood flow through the pulmonary capillaries so the big one here is pulmonary embolism you can also have COPD this is when we're talking about dead space problems these are two of the more common dead space diseases now when we give you graphical illustrations of this you'll see with pulmonary embolism is you have a normal alveoli but when you look at blood flow you see that you have a collide and there's no blood flow passing by that alveoli so you have ventilation of this alveoli but the gas coming in and out of it is not participating with gas exchange this creates a dead space problem when you're talking about COPD you're talking about a big hyper inflated alveoli and you have blood flow coming past it but you have to understand that the center of this hyper inflated enlarged alveoli this gas here does not participate with gas exchange even though it's being ventilated so this is why COPD can present and presents with a dead space problem okay COPD is not a shot problem you have ventilation and excess of perfusion okay now I'm going to erase all this because I'm going to bring this back to VQ ratio discussion because that is the area VQ ratio is the area that I sucked at when I was a student I don't know if I ever got a question right related to VQ ratio and my purpose here today is to tell you how to answer these questions correctly and Brit and open your mind to something here okay I'm going to show you something that you're going to go that makes perfect sense so if you understand shut vs. dead space then you're on a good path to understanding VQ ratio okay so I'm gonna erase all of this and now we're gonna put a line up here this is V Q and like I've said before you have to understand that VQ ratio is a line of movement increased decreased it's not at one single number but we can but we have a starting point that's what's important so when you think about ventilation over perfusion what we have here is we know ventilation let's just go with five we know it's five to seven but let's just go with five because I'm gonna make the math easy for you when we talk about perfusion we know cardiac output normal is four to eight liters per minute and I'm just going to go with five and that gives us a VQ ratio of 1 so 5 over 5 equals 1 now what would cause this ratio to increase or decrease that's the question now remember when you said shut you said perfusion in excess of ventilation these are alec tannic regions consolidated regions fluid filled out the older regions so that in those areas is going to decrease the ventilation so we're just gonna say 2.5 so your ventilation in those affected areas is 2.5 and cardiac output is 5 this takes your VQ ratio to 0.5 which is a decreased VQ ratio that makes sense right so if if perfusion exceeds ventilation when we do the math we see that it decreases the VQ ratio now the exact opposite is true also if we start at 5 over 5 but we have an area where perfusion becomes blocked okay so such as pulmonary embolism if this decreases the 2.5 then 5 divided by 2.5 is 2 that's an increase in VQ ratio okay now I told you COPD right well COPD doesn't cause a disruption in blood flow so blood flow stays the same but ventilation increases still 10 over 5 do the math equals 2 you still get an increase in your VQ ratio so what we know here is that dead space causes an increase in BQ shut causes a decrease in VQ that's the key now if you understand the diseases if everything I've said so far makes sense then you should easily be able to answer these questions I'm about to ask you so I'm going to erase all of this and we're going to do some practice questions now they eat I'm going to start with the question I got in the email which was probably from a practice TMC exam or something along those lines and it basically said you have a patient who had a VQ scan and the VQ scan in the right upper lobe showed decreased ventilation and normal perfusion so I'm just gonna stop there this isn't a right upper lobe so they give you this information patient has a VQ scan in the right upper lobe it shows decreased ventilation but normal perfusion so and the question was what could be this patient's VQ ratio now option 81.5 option B 1.2 option c 1.0 and option D was 0.8 now it this is the point 0.8 now if you understand VQ ratio and you understand that normal is 1 and you understand that I shut is it decreased is a decrease in VQ ratio and that's perfusion greater than the ventilation and you understand that dead space is a ventilation and excess of perfusion then this question becomes much simpler if you understand how those two affect your VQ ratio obviously right so first of all we know that normal BQ ratio is one so it's not C okay if it was if it was one then right upper level ventilation would be normal right upper lobe perfusion would be normal but that's not what we have we have a right upper lobe perfusion that exceeds right upper lobe ventilation so if you go back to your numbers and you go five over five five over five but now you say perfusion is normal but it exceeds ventilation and you change this to four and you do the math you're gonna get 0.8 now these are arbitrary numbers the question didn't give you numbers these are numbers that I put in okay just to show you how the VQ scale works remember perfusion and excessive ventilation is a shunt it causes your VQ ratio to go down so if you know normal is one then it can't be one it's not 1.2 or 1.5 because that's an increase it's gotta be D 0.8 now here's the thing about this question look at this guy's if you know normal and you can eliminate normal right off the bat then you have to choose between three answers one of them is decreased two of them are increased well with the information you have which is nothing more than right upper lobe shows decreased ventilation right upper lobe shows normal perfusion you don't have numbers that calculate anything by both of these are increased this is decreased this has to be the answer because this is the oddball you have a normal option it's not normal how do you choose between these two you can't so it has to be the 0.8 and that was the cur dancer okay let me give you another example this is another example kind of the same type of thing related to the cue ratio what effect would a PE pulmonary embolism have on your VQ ratio a/b c/d a is none B is increased C is drastically decrease and D is minimally decrease well again you ask yourself okay okay they do the same question at me but in a different way but pulmonary embolism equals ventilation greater than perfusion every disease process is going to have an effect on your VQ ratio so it's not done so does it cause it to decrease or does it cause it to increase the drastically and the minimally they don't matter they're distractors the answer here is ventilation and excess of perfusion equals to normal as 1 2 is greater than 1 so it has to be increased so your VQ ratio for a pulmonary embolism has got to increase okay one morning imma let you guys go which of the following will cause an increase in your v/q ratio and the answer here is a pneumonia B atelectasis C COPD D pulmonary edema now if you want to try this pause this video come back I'm about to explain it okay just like the other two I forgot to tell you to pause the videos previously but pause this video see if you get the right answer now the question here is which of the following will cause an increase in your VQ ratio what causes my VQ ratio to go up ventilation in excess of perfusion so which of these disease processes leads to ventilation being an excess of perfusion well it's not pneumonia because that leads to a decrease of ventilation of those areas and an increase in perfusion so you have perfusion greater than ventilation and like this is the same thing perfusion in excess of ventilation that's not it COPD and I don't know I don't really know I don't I don't know what about pulmonary edema oh wait my alveoli are filled with fluid leaking from the pulmonary capillaries so that would be a decrease in ventilation with an increase of perfusion so that's not it that would be a shot that would cause a decrease in a VQ ratio so it can't be that so the answer must be copd and that's the correct answer now I can easily put pulmonary embolism here I didn't because it have been too easy but it's simply and very easily and most likely on your TMC will be pulmonary embolism so I'm just going to put PT right here now another way you can answer this question if you have no idea what's going on is look at them and go okay pneumonia is consolidation that's going to cause my lungs to become filled with fluid Alexis collapsed alveoli you still have perfusion so that's still there pulmonary edema I'll be whole I filled with fluid still perfusion active but no ventilation or decreased ventilation COPD or pulmonary embolism this is the only one who presents with a situation where you might have the ventilation in excess of perfusion and that's the right answer and a lot of times you can look at this if you think of at Alexis pneumonia and pulmonary edema if they're all shunts if you go well I don't know but I know this is a shunt and I know this is a shot and I know this is the shot and I know pulmonary embolus with COPD is dead space then whatever they're asking you it has to be this one it has to be the oddball because the rest of these three would cause the decrease in your VQ ratio does that make sense I hope so if it doesn't put a question up and I'll address it I'll answer your question and I'll try to simplify it even further for you I hope this videos make sense hope all you guys are enjoying your final semester your second semester your your your second whatever semester you're in if you're in a bachelors program and you're in your your whatever fourth semester whatever it might be I hope you're having fun I hope you're having a lot of fun and I hope you're learning send me your questions send me your requests hit the subscribe button and turn on all your notifications so that you know when this video goes live you know respiratory codes put out another video appreciate you guys for watching best wishes