What is emphysema?

Voiceover: It's such a mouthful to say chronic obstructive pulmonary disease, so since there's an acronym for everything we just call this COPD. Chronic means it develops and happens over a long, long period of time. Pulmonary disease means it happens in the lungs. But obstructive is really the key word here, and we'll come back to this in just a second to describe exactly what's obstructed here. But first let's draw some airways. You have your trachea, that's where air enters the airway. To me the whole thing looks kind of like an upside down tree where you have these branches that keep branching off. There's 20 or 30 branches, I can't draw them all, but you can imagine it just keeps getting smaller and smaller, just like branches on a real tree. As they get to the end of a unit here, let me draw it where there's more space, we encounter something that kind of looks like this, it's kind of like a cluster of little bubbles. We call this the alveoli cluster. Alveoli is plural for alveolus. It's a Latin thing to make the plural into an -i at the end. All of these are alveoli. In fact, aside from the cluster at the end they happen around on the stem near the end of the cluster as well, kind of on the tree branch. To get into the nitty-gritty, this is where emphysema happens. Let's just blow up that end unit there and get a better look. You have your terminal branch here. The way I'm drawing this kind of looks like little clusters of tents. You'll see in just a second why I'm drawing it in particular like this. I'm trying to get across the idea that there are walls separating each alveolus from each other. The walls have alveoli and at end you have your cluster. This is what the whole thing looks like at the top of the breath when it's filled with air. I'm really tempted to compare this to a balloon that's blowing up, but we have to keep in mind that the comparison between lungs and balloons only exist during expiration. In a second we'll see what happens during expiration but first, just to be clear, let me explain why it's only expiration that's like a balloon. When you have a balloon, this is your regular balloon and you have air going in, usually there's positive pressure out here putting air in. Either you're blowing into it or it's hooked up to a machine or something and that's how air gets in. But in the lungs during inspiration, nothing is blowing into your mouth forcing the air in. The air comes in by a negative pressure inside. The way that happens is because our chest wall, it's kind of like a box outside the balloon. It expands with muscles, and as they expand it takes the walls of the balloon with it, and that negative pressure is how air goes in. But we're really not concerned with inspiration right now because obstructive diseases are expiratory. Regardless of how the air got in there we can start thinking of it exactly like a balloon at the top of a breath now. When you let a balloon go the air just rushes right out, it's the same thing in your lungs. As soon as you relax the walls of this airway pushes the air out, because the wonderful protein that we call elastin that makes up the structure of these walls. Whoever named this really thought it through because elastin describes the fact that it's elastic, like a rubber band. As soon as the lungs relax these walls snap back to their regular size, kind of like this. Not very much air inside at all, because the recoil strength of these walls pushes the air out. Now in COPD what happens is this elastin gets destroyed. I just said that elastin gives the elastic quality of the walls, so when that's gone, the elastic quality of these partitionings that hold their structure, that give their recoil strength, that's all gone as well. Instead of looking like a perky balloon animal with all these shapes, I think of a lung that has COPD, or this same structure, same unit of the lung that has COPD, kind of looks like this amorphous blob because the walls have lost their structure, they've lost their recoil strength, so they don't hold their original shape. It's kind of floppy, kind of like a plastic bag instead of a balloon. When you have a plastic bag and you let it go air does not rush out, there's no recoil strength making the walls snap back. It kind of just stays here and nothing happens. That's the first step, and to make matters worse in emphysema, what happens is here in the stem of the airway this area actually collapses and forms a physical obstruction to the air coming out. The reason that happens, I kind of like to think of it as what happens when you have an open door in your house and it's a windy day or breezy. As the wind goes through this open airway sometimes the door just shuts with it, and you hear this loud, it suddenly pulls the door shut. It's kind of the same thing, that as air is trying to get out here it pulls the walls with it. Usually there's elastin and structure to the walls so this remains open, but here without all that the walls just want to go with the air, such that it collapses here. Now you have all these air behind it that cannot get out. Not only are the walls not pushing it out but now you have a closed door. These things combined together is what gives you obstructed disease. COPD technically refers to two different diseases. There's emphysema, which is what we're talking about today, with elastin destruction, and there's chronic bronchitis. Anything -itis just means inflammation or irritation to an area, the airway is irritated. Depending on how this person got the disease a lot of times these two variations of COPD can exist together in one person, but today we're just talking about emphysema in terms of elastin destruction. Okay, so where were we. We talked about how there's all this extra air in here that cannot escape your lungs. You might think, "So what? I work all day to "get air into my lungs, that's the whole point," and you would be half correct. If we imagine that there's a blood supply here, I mean the blood supply in the airways go together because they need to form an exchange system. Oxygen is usually in the lungs that we pulled from the air, so oxygen goes into our blood stream making it red. Then the other half of the deal is that we have carbon dioxide that the blood brings to the lung to get rid of. These are made by our tissues after they've used up the oxygen. It's kind of like a waste product. This needs to go back into the lungs and out through our mouth, and this exchange is really the complete job of our lungs. With obstructed disease you can do half of it. You can put oxygen in but if you can't get carbon dioxide out it's just as big of a problem as not getting oxygen because half of our exchange is not working. There's the root of all the problems in emphysema. We have about 2.5 million of these alveoli in our lungs. Let's imagine that all of them have lost their elastin and they look like floppy bags. What would emphysema actually look like? If you have your regular lungs that usually look like this, which I hope that your lungs don't look like this but I'm sorry, I can't draw any better right now. That's what they usually look like, and if they're filled all the way up and air can't get out it reminds me of big pillow cases. Day in and day out they're over-inflated and they can't go back down. As this person has emphysema for a long, long time - remember it's chronic - the ribcage and the tissue out of the chest actually changes shape because the lungs are pushing on it all the time. I don't know if you can tell what I'm drawing at all here but what I'm trying to draw is a barrel. People who have COPD are often described as having a barrel chest, which means they're almost as far from front to back as they are from left to right. With this shape changing this person is very uncomfortable to have to carry around such a huge, round chest and have air not being able to get out. I need to give him some hair. I feel like that's the only way my stick people can look like real people. He's unhappy because his chest is like a barrel sitting there, he can't deflate it. There's a special way that people with emphysema often breath that have earned them the infamous nickname of being a pink puffer. There are two things that this name is trying to describe. Pink is because they don't lack oxygen, so pink instead of blue. Remember I said that the oxygen getting into the lungs is not a problem, our problem is in exhaling. They're pink because they don't really lack oxygen in their blood. Puffers describes the fact that they have pursed lips. Pursed lips, kind of like if you imagine putting your mouth around a straw, and they breathe through this smaller opening. The reason for this goes back to this mechanical obstruction we talked about earlier with the door slamming shut. Let's draw the door again. It's like this. Usually when we breathe out it's like the door is hinged on something, it's not going to close. The air rushing out, it's pretty fast, there's a lot of air because the walls are pushing it out. Imagine this is the amount of air that goes through. In emphysema with the door unhinged and just flopping around in the wind it is less likely to snap closed like that if there's less air going through and it's going slower. That's why people have figured out that when you have COPD if you purse your lips and you breath slower it keeps this airway open for just a little longer, and every second you can keep that door open is a tiny bit more air out. Let's just put that down in writing here. We have the pursed lips, that's the first thing. Now we have this slowing down of the speed of the air going through, because the pursed lips are trying to control it. But the rate of their breathing actually goes up, just because since they're breathing not so efficiently they compensate by breathing more times per minute. This also contributes to the fact that they look like they're puffing and huffing to other people. In a nutshell if I were to describe what I think of emphysema as being in my head it would be these dilated lungs, a big barrel chest, and this person breathing with pursed lips and they're puffing.