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What is chronic bronchitis?

Created by Amy Fan.

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Video transcript

- [Voiceover] There are actually two diseases that fall under the umbrella of chronic obstructive pulmonary disease, which we just call COPD as an acronym. The first one of these is emphysema. This is a disease that has to do with airway collapse due to change in the structure of the walls. What I'm going to talk about today is the other category called chronic bronchitis. Chronic bronchitis. Now, both of these are obstructive meaning air is stuck in the lungs, and it can't get out. In our case, in chronic bronchitis, the culprit here is too much mucus. So, that's going to be the theme of the day. Remember that, too much mucus. Just a quick Latin lesson here, so, chronic over a long, long period of time, bronc refers to the lungs, and anytime you see itis in a medical context, it means inflammation of that area. So, we have constant irritation of the lungs. Speaking of which, let's draw some lungs. So, we have the trachea here branching off into the left and right main bronchi. It's just keeps branching off into smaller and smaller segments. That's the basic pattern in the organization of the lungs. I can't draw all the levels here. I just wanted to give you an idea. They go like that. Now, of course, on this side it's the same thing I'm just not going to draw that right now. Keep in mind that along with the lungs we have the blood supply line very close to it. This is where the gas exchange happens back-and-fourth from the blood into the lungs. Of course, what's going into the lungs is our oxygen, and what's coming back out is carbon dioxide. In a nut shell, that's what the lungs do. So, keep in mind this gas exchange. So, chronic bronchitis is what happens when the airway becomes all gunky with too much mucus. Now, mucus in there is a normal thing. You and I, when we get sick, you cough up the phlegm. That's basically what it is. It's the body's defense mechanism against any irritants that are bothering our lungs. As you can see, when this space gets all gunked up like that, the air going back-and-forth between the lungs and the blood supply is hard to get across. In addition, it's just going to be hard to move air through. See, the oxygen is getting in here, and the walls just become narrower. It's harder to move through the mush. That's where all the problems come from. So, when I talk about irritation, it can come from things like being a smoker. Smoking every day irritates the lungs, or if you live in a very polluted place, pollution can do that as well. What goes with that is smog from our cars. Or, this person can have an allergy, and the allergens constantly irritating the lungs can lead to this as well. So, chronic bronchitis is the lungs response. It is not specify one kind of irritant. If we have a guy here with chronic bronchitis, I'm going to give him some hair, because I just think it makes all my stick figures look a little better. Here we go. He has a big fro. Let's call him Robert or Bob. Give him some eyes, and then I'm going to draw his mouth in blue here is referring to an infamous nickname that people with chronic bronchitis have. Their called blue bloaters. You'll see this in every text book. It's kind of confusing. Why are they blue? So, let's break this down one word at a time. Blue is talking about the fact that their blue opposed to red. If we come back here to the oxygen, we think of blood with oxygen in it looks a little bit brighter and more red then blood without oxygen. So, the lungs job is to deliver this oxygen to our blood supply. Without this gunk in here, since they get not as much air and not as much oxygen across, this person's going to look little bit bluish to the tint. This shows up in the lips, it can show up in the whites of the eyes, it can show up in the person nail beds, depending on their complexion, sometimes it can show up in their skin. So, blue reefers to the fact that they have lower oxygen. Instead of having a percentage of oxygen in the high 90s like people usually do, high 90s to a hundred, they might have lower 90s, 80s, depending on the severity. The second word here bloater reefers to their shape. So, if you can image ... what was his name? Bob can't take a good breath in, can't get enough oxygen, that he's going to take bigger and deeper breaths to try and compensate for that, right, which artificially increases his chest volume. Since this is a chronic disease, that over years and years, the diameter of his chest actually increases. He literally just looks bloated. In addition, we have carbon dioxide back in the lungs here that are trapped. This is when we talked about obstruction in the beginning. So, it's obstructed in the lungs and can't get out as effectively. That further leads to the expansion of his chest diameter. So, he's just going to look bloated and kind of hypoxic. Let's write that word again, which just means lower oxygen, not enough oxygenation. So, blue bloater is someone with lower oxygen, who is literally bloated from trying to get more air in and can't get all the air out. Now, the second component they'll have is a very nagging cough. Now, this cough is actually part of the diagnosing criteria. So, chronic bronchitis is actually diagnosed through this story. So, they have to have a cough for three months out of the year for two years in a row. This has to be consecutive. This cough has to be productive, so, there has to be mucus, phlegm, that their coughing up. That pretty much diagnosis chronic bronchitis, so this cough has to be present. What makes this cough happen is, if we go back to our lungs here, embedded in the green part ... I don't know if you can this, but in the tissue of the walls of the lungs there is smooth muscle. In response to all this irritation going on, the smooth muscle spasm, and that's how you get the cough. It's a reflex. We can't help it. It's our body's natural way of getting rid of irritants. When it goes overboard, we have chronic bronchitis. Now, another component I wanted to mention is that even though chronic bronchitis is a chronic disease, you can have acute flare-ups or acute episodes where it suddenly gets a lot worse. This can happen when our patient has a cold, they can have the flu, by the way, this is why it's important for people with this disease to get flu shots. It can just even happen from it being winter and the air being cold, because cold air also irritates the lungs in causing spasm of the airways, and can make the cough worse. The acute flares can happen when there's a double-whammy to the irritation to the lungs. So, the mucus goes even more overboard, and sometimes one section of the lung can be just clogged off, one little branch, because there's so much mucus here. Now, it's a rule in the body that anytime you have a complete obstruction like that, the bacteria will build-up behind it. Anytime you have bacteria build-up, you can have infection. In the lungs, we call this pneumonia. So, pneumonia can be bacteria, or it can be viral. In this case, if it's a blockage of the mucus is very likely to be bacterial. Once you have infection on top of obstruction, it makes it even harder to clear the infection. So, now Bob is in real deep trouble. Part of the treatment is to not only prevent acute flares but to treat them aggressively. So, going back to the beginning like I said, the theme of our day is mucus production. As you can see, a person with chronic bronchitis will have a nagging cough, they'll be hypoxic with not enough oxygen in their blood, and they'll be bloated from trying to take deep breath and not being able to breath out all the extra air.