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Current time:0:00Total duration:7:27

Video transcript

so somebody's short of breath and we want to find out could they have emphysema the first thing we might get is a chest x-ray and let's just look at what a normal chest x-ray might look like here you see the shape of the lungs like that and this muscle down here is the diaphragm it helps us breathe by moving down and a person with emphysema their x-ray their picture is going to look more like this look at how hyper-inflated these lungs are it looked like puffed out bags right so here let's write hyper-inflated and that's one of the first signs of emphysema oh really obstructive disease because of the air is stuck back here because these Airways have collapses and are no longer elastic so the air stuck back here makes the lung take on this kind of shape and look at how it's pressing down on the diaphragm so it's no longer this nice curve now it's kind of flat if this makes it harder to breathe because they have less room to go down the chest cavity is so full and round it's hard for them to make it a little bigger to take more of a breath so look here in their neck do you see how the angle here is different from a normal person's neck that's because they're using extra muscles to help themselves breathe extra muscles to further expand that tries to breathe in and out here they might be using their ab muscles try to force some of that air out because the natural recoil the lungs is gone so this is our extra it's a good entry point into working something up because it's cheap it's easy and all the person has to do is just stand there now next this person might be doing some lung function tests and important one for this one will be forced expiratory test here's how it works so you have a person I like to give my stick figures a little bit of hair thick it makes them look a little better so we have mister Bob here because I can't breathe it's hard for me to breathe out so we give him a mouthpiece to put in his mouth it's connected to this tube which is done connected to a machine in a nutshell and we have mr. Bob take the biggest breath you can possibly take fill up that chest all the way hold it for a second and then suddenly and forcefully blow it out as fast as much as you could I've actually done this test when they thought I might have had asthma turns out I didn't but this test is miserable because they're trying to get you to get all the air out in here so even when you think you have no more left they tell you to keep going keep going it just feels like you're going to die it's terrible but it's important for them to do that because we're looking for two values number one we want the full vital capacity what that means is just all the air that he could possibly breathe out from the top of the breath to when you can't get any more out that's the fvc and then we also want the fev1 which stands for forced expiratory volume one and that's because believe it or not even though you were struggling that entire time to get more air out most of the air came out in the first second this is like so have candles here like on a cake you're blowing out a candle it goes out in the first second right if it doesn't go out and you just keep blowing without taking a new breath in nothing's going to happen so to normal lung about 80% of the air comes out in the first second so fev1 over FBC should be around 80 percent but in emphysema actually in all obstructive diseases this ratio changes so first the full vital capacity definitely goes down in obstructive disease you can get less air out of the lungs so that absolute rate absolute difference between the top of the breath and the bottom it really Inc decreases but more importantly the fev1 here goes down much more that's because that first second of getting most of the air out really relies on the recoil of the lungs it says that's gone the fev1 here takes a much bigger hit you know let's let's just put some numbers to this whole thing so that we can see it better let's say that bought what was his name Bob mr. Bob no let's say his full vital capacity was five liters so he usually should be able to get four of it out in a normal functioning lung but here because he has info Xena let's say his full vital capacity goes down to four but this fev1 is going to go down even more it goes from four to let's say two two or four that's 50% so we went from 80% to 80% so do you see how even though both went down this ratio goes down even further and that's diagnostic for obstructive disease so in emphysema the ratio between fev1 and fvc is going to be less than about 75 to 80% and actually how much it goes down can tell us how severe mr. Bob's diseases now emphysema is usually related to smoking or working in an environment with a lot of irritants but if mr. Bob here doesn't smoke and doesn't work in that kind of environment we want to know why does he have emphysema a possible blood test we could do is measure his alpha 1-antitrypsin level because the other reason somebody would have emphysema without smoking or being exposed to irritants is to have an F one antitrypsin deficiency I really quickly we have elastin giving the elastic quality of the lung being destroyed it in vizima because it's usually cleaved by let's change the color here it lasts days I like to use red because it's like the culprit in this disease that's going crazy eating up all day last in and usually this elastase is kept under check by alpha 1-antitrypsin this compound made in the liver stuff say last days so alpha 1-antitrypsin usually allows there to be more elastin in this relationship so some people can have a deficiency of alpha 1-antitrypsin and that's how they get emphysema so if we really want to find out why and we can't explain otherwise we can look for the alpha 1-antitrypsin level in mr. Bob over here in terms of other blood tests there's something we can do called a blood gas I'm going to put it in parenthesis here because it's not going to be a most routinely done thing because first of all it's more expensive than just a regular blood test and it's painful you're getting blood from the artery instead of the vein which is more sensitive so we really only do this if somebody's in the hospital for a bad case of exacerbated emphysema but blood gas will allow us to find out exactly how much oxygen and carbon dioxide is in the blood but usually if this person is still doing okay and we don't need to get the blood gas right away you get what's called a complete blood count this from the vein so it's pretty routine it's not as painful and here we don't get to directly see how much oxygen carbon dioxide is there but there is a compound we can test for it's called the bicarb bicarbonate and this basically would increase if the body is having too much co2 to balance how acidic it is and the emphysema mother is usually increased co2 because it's not getting breathed out so this is easier to do that on both gas but it still we usually don't routinely do it unless this person's in the hospital not doing well these tests can tell us more of a snapshot of how this person is breathing and doing at the moment but for our diagnostic purposes the x-ray the pulmonary function tests and even the alpha-1 antitrypsin will be more valuable