What is Asthma and Its Types:

 What is Asthma and Its Types:

Welcome to our health blog. We are going to talk about asthma and specifically the causes the pathophysiology diagnosis and treatment of this very common disease. I want to kind of show you what's going on at the bronchial level.

You remember if you look at our pulmonary function test discussion we looked at a flow volume loop and what happens when you blow out air very quickly? Your forced expiratory volume or flow rate goes up very quickly and then comes down and then you take a inhalation in and thus obstruction that occurs in asthma and in COPD occurs. In this area here which is the small airways and as that obstruction gets worse, you see a decrement in the flow rates especially later on in blowing out. The point here I want to make is that these are the small airways so this is where asthma is occurring. It’s obstruction of these small airways not the large ones but the small ones.

You've got the airway and this is a very simplified version of what it is that's going on you've got this lumen of the airway that's here and as you may know it is lined with smooth muscle when that smooth muscle contracts this lumen gets smaller. So there's two major things that are occurring in asthma or obstruction of these small airways is you've got some sort of an inflammatory process for whatever reason that's going on here. This inflammation stimulates certain cascades that occur and it causes smooth muscle constriction and as a result the inflammation causes the lumen to get smaller and smaller and smaller until finally there's wheezing. There's obstruction and the primary problem is that you can't get air out of these small airways and that is why in an asthma attack, you will see that this flow volume loop comes down and the flow rates in these small airways is almost non-existent. That's when you run into asthma attacks, now the severity of this contraction is going to give you the severity of asthma attack.

I want to emphasize that in asthma, what we have, is reversible airway inflammation that is opposed to air reversible which we would see in COPD where this airway inflammation has occurred. This constriction has occurred in COPD. It’s kind of irreversible in asthma, we can actually reverse it back to almost completely normal. This inflammation and constriction can sometimes be mediated by IgE. So sometimes you will see elevated IgE levels and that fits into the pathophysiology and the treatment. What is IgE? It’s an immunoglobulin specifically it's an immunoglobulin E and that's important because immunoglobulin E affects a cascade that releases histamine which causes swelling which is going to make the area in that Bronco even smaller IgE uses the basophils and mast cells. These release histamine. There are ways of preventing these cells from releasing histamine and that is sodium chromo gleich 8. You'll see, for instance, medications like Chrome illan sodium criminal glycated is used to stabilize these mast cells and basophils and prevent histamine. So sometimes we actually use that in the treatment of asthma. We've got a situation where you have inflammation which causes constriction of the smooth muscles in the bronchioles.

So we've got nerves that affect this smooth Muscle. Two types of nerves specifically and they have receptors. The first one, I want to talk about is the beta receptor. So you have a nerve that come down and releases compound which hits this beta receptor and this causes relaxation. There's another receptor which is the muscarinic receptor that causes constriction. So in both asthma and COPD as it turns out we want this muscle to be relaxed that's the goal we want relaxation and so what we're going to actually end up doing is activating this receptor and blocking this receptor.

What you see is pharmacologically? We're going to be using anti muscarinic s' and we're going to be using beta agonists that's how we get to the treatment. Now the other thing that we're going to see pharmacologically and we'll talk about this is inflammation.

Inflammation is going to cause constriction because of inflammation. So what we're also going to use is anti-inflammatories? What I've just shown you here are the three cornerstones of asthma treatment? Some of them are going to be used first because they're much more effective than others and you could probably guess which one is going to be most effective because inflammation is starting everything off. The anti-inflammatories are gonna be number one the beta agonists are gonna be number two and the anti muscular necks are gonna be number three. We'll get into the pharmacology of that let's talk about the pathophysiology about perhaps clinically where this inflammation may be coming from things that can trigger problems in our airways based on a number of things.

First of all because of the stuff that we breathe in so that's a trigger the air that we breathe. What else could trigger asthma, what else could be causing it well? There’s a tube that sits right next to the trachea which goes down to the stomach called the esophagus. Sometimes stuff in the stomach can reflux up and irritate the airway that continues up. So another thing that can cause this is gastro-esophageal reflux disease that can sometimes cause symptoms of asthma.

Now if we go up here we have the nasal passageway. Sometimes you can have allergies that drip down and cause irritation in there so then post nasal drip can cause asthmatic symptoms. Whenever you see a patient with asthma or you're asked about on a test, you should think about these things as causing asthma. What we call coffee variants asthma post nasal drip and gastro esophageal reflux disease? Some of the other things that can contribute to all of these things about down feather pillows pets in the bedroom these are places that you spend a good six seven eight hours a day and could affect some of the treatment symptoms. So these are some of the things that by getting rid of we might improve asthma. There’s also environmental things and things from work for instance from your occupation. There's something called isocyanates or cotton dust wood dust solvents. All of these things can by breathing the men set off asthma exacerbation.

There's one other thing that I should make you aware that they might ask you on a test. They love to ask things that are uncommon in asthma that could be very unique or make you think of something. There's something called samplers triad where you see number one aspirin sensitivity, number two asthma and number three nasal polyps. Now when these people take aspirin or any type of NSAID what can happen. These medications inhibit cyclooxygenase and as a result. They're going to have increasing compounds that are going to set off asthma exacerbations. The key here is that within hours of taking aspirin, they're going to start to feel flushed and they're going to go into an asthma exacerbation. These patients who are typically sensitive to aspirin or NSAID products are also going to have nasal polyps. They need to stop using aspirin and NSAID products and find an alternative these patients. By the way, we'll talk about treatment also respond very well to leukotrienes antagonists.

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