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We're gonna talk about asthma and um the immunology behind it and then kind of move on to a bit of restrictive lung disease. So, like different types of restrictive lung disease are present a bit about their management and investigation as well. Um So let's um start. Um Was my eating large skin me come in? OK. So, OK. Um So today's OK. So today, so the timeline is gonna be like this. So we're gonna talk, we're gonna start start off by talking about um asthma what it is. Um it investigations and diagnosis, how to manage asthma. Um And then after we're done with that, the second half of the lecture is gonna talk about restrictive lung disease, as I said, so the different kind of intrinsic and extrinsic lung disorders and then different types of restrictive lung diseases, which um some of them listed. So, interstitial lung diseases, um Idiopathic pulmonary fibrosis, hypersensitivity, pneumonitis. Um So we'll touch on that a bit later. We'll la later down on, on the lecture. Um So we move on um our next slide. So we're talking about asthma. So, so some of the key kind of um features of asthma is your, I mean, I'm sure you guys already know, but like a wheeze with, um, a dry cough and dyspnea or just shortness of breath. So those are kind of like three key features of asthma. Um, and the important thing to note about asthma is it's, it's reversible after, for obstruction. So you can actually reverse the obstruction with certain medications. So it's not irreversible. Um And that's, that's the key differentiating feature in terms of asthma, that's reversible afro obstruction. Ok. Um And asthma obviously has a airway inflammation, which is what causes kind of the, the, the wheeze and the and the shortness of breath. So, and airway inflammation is, is caused by um two types of cells. So east nipples and type two lymphocytes. So these, these two cells are key in terms of causing your airway inflammation. So that's important to know as well. Ok. Um in terms of character symptoms, so what the symptoms are, what type of they, they, they, they persistent symptoms. Um and it's like episodes of it, it's usually precipitated by things like exertion temperature changes. So like cold temperatures, um and allergen exposures can also kind of precipitate your um asthma exacerbations. So, so that, so there are certain examples of what can actually worsen your asthma, right? Ok. So this is kind of a your general overview of what asthma is. Ok. So moving on in terms of the pathophysiology, I guess. So, what asthma is is, it's so asthmatic airways usually have relaxed mood muscle, ok? And the wall is inflamed and thickened, right? So the wall is generally, as I said, inflamed due to these nipples and type two lymphocytes, but usually the smooth muscle is quite relaxed. Ok. But during an asthma attack and as I touched you on the slide before going back, as I said, it can be precipitated by things like exertion causes allergen exposures, right? So, um during, when, when, when a person is exposed to certain things, it can cause an asthma attack and during the asthma attack, the smooth muscles are not relaxed anymore and they're tightened so they can track quite a bit. Ok? Um And the thickened airway um is caused by inflammation as I touched on before. Um and the wheezing has, is caused due to the narrow airway too. That's what causes that wheezing sound. OK? That you can hear. Um because the airway is quite narrow, right? Um So just as as, as you can see on the right hand side of the slide, I've written down your fe B1 over FBC ratio. So, um in terms of adults who have asthma, if it's less than 0.7 usually asthma and in Children is less than 0.8. So that's something to note. Um just those two numbers less than 0.7 less than 0.8 in terms of adults and Children, right? Ok. So moving on, let's talk about, OK, this is a nice kind of flow chart talking about how asthma actually comes about, right. So we as I mean, in terms of allergy specific, so we can have, we have allergies and allergy allergic diseases which um along with genetic sus susceptibility um and environmental exposures, which are things like allergies, infections, pollution can cause your reversible, a obstruction and a inflammation, right? So this is just like a nice flow chart um which shows how it comes about. But basically all these factors play a part. So, so allergies, your genetic susceptibility um and your environmental exposures all play a part in causing this kind of airway inflammation and um uh and the reversible afl obstruction, right. So, um so that's just that diagram. OK. So moving on to a bit about to talk a bit about the immunology involved in um in asthma. OK. So this is um an eye flow chart showing how exactly um the a the immunology behind the asthma, right? So, first of course, we start off with the antigen. OK. This can be an allergy antigen or anything. OK. And the antigen is then presented to um the M EC class two receptors which is present on antigen presenting cells. OK. So ABC. So the ABC, so androgen presenting cell binds to the antigen, OK, using your MC class two receptor, right? What this does is once the antigen is bind bound to the antigen presenting. So it then activates your T helper cells. OK? And a specific th zero, right? And once, once um the th zero is activated, the T the T cells zero goes on to activate th one and th H two. OK? And in our case, we're, we're gonna look a bit more specific in T two, get T two cells, right? So T two cells, as you can see in the diagram, then go on to produce interleukin 45 and 13. OK? And these are quite important. OK? In terms of why asthma is so severe. OK. So il four interleukin four goes on to produce um IgE. OK. So it helps produce your IgE antibodies. OK. Um So that's the il four again and interleukin five helps with esop a inflammation. OK? It helps produce esoph which then causes you inflammation, right? That's, that's the role of interleukin five again. Now interleukin 13 then finally helps with mucin production. OK? So you can have mucus and then that will also cause you am production and, and that's what Il 13 does. OK. So this is quite important to remember because this can count on my exams, right? So um it's quite important to know what each interleukins role is what it does. So, Il four is IgE Il five and Il 13 is a mu secretion. OK? Um I would uh that, that's quite important. No. OK. But that's just the basics of the immunology of asthma. OK. So now that we've talked about immunology behind asthma, let's uh move on to talking about the tests involved. OK. So for allergic sensitization, OK, we can carry out blood tests, right? So, um basically we can look at specific IgE antibodies to the allergens of interest. Ok. We can just carry a blood test to check for IgE antibodies um um to the allergens of interest. That's, it's quite a straightforward one. OK. Just basically looking for IgE antibodies in the blood, right? Um That's a test for allergic sensitize sensitization. Ok. Now, for esoph, OK, we can look at the blood ese Neil count. Ok. So when the blood il count, when stable, if it's greater than 300 cells, right? It's going to be classified as abnormal. So anything greater than 300 is abnormal right? Now, in a patient with suspected um or confirmed asthma. Ok. You can do something called an induced sputum will count. Ok. And when, if I induced sputum E will count is greater than 3% right? Or equal to 3% greater than, or equal to 3%. It's abnormal. OK. So these are two key numbers in the slide. OK. So a blood count is stable if it's greater than 300 is abnormal and an induced an induced sputum ph count if it's greater than equal to three thou 3%. Sorry, it's abnormal. Ok. So those are two key numbers to note from the slide, right? Ok. So Now, let's talk about the investigations. Ok. For actually diagnosing asthma, right? So, the first step is you want to perform a spirometry in Children and young people, uh, with any, with any symptoms of asthma. Right? Now, if, and if this parametric shows an obstruction, you would consider a bronchodilator reversibility test. Ok. All right. But the first test you in form is, et if that's obstructive or shows an obstruction, then you consider a bronchodilator reversibility test. Ok. No, if the child is unable to perform any objective tests, right, you want to treat based on just kind of observing and clinical judgment. Ok. So the child can't do any other tests like a spirometry or a bronchodil possibility test, then you can, you can, you can treat and you can assume they have asthma based on just clinical judgment and observation again, just, just, just the symptoms they have basically right and, and what the symptoms are. So, and obviously, you wouldn't just leave it at that. You would try doing the test again every 6 to 12 months to see if the child can actually do it right. OK. So if no, but if the diagnostic uncertainty remains, so say the child is able to do the spirometry and your bronchodilator reversibility test, right? But the diagnostic uncertainty remains. Ok, then you consider something called a fraction of exhaled nitric oxide, right? Um And in terms of fraction and that's a test that basically check for levels of, of exhale nitric oxide. If it's great on a certain, at a certain number, you can kind of diagnose asthma and we come on the numbers not on this side, we come on that a bit a bit later on. OK. Um And now if you diagnostic uncertainty, so you're still concerned about asthma after your fraction of exhale.