Welcome to another MedCram lecture. We're going to talk about emphysema today,
otherwise known as C.O.P.D. It seems as all these diseases have abbreviations
in medicine. This one is "chronic obstructive pulmonary
disease." What is C.O.P.D.? It's a common preventable and treatable lung
disease and the typical symptoms that you'll see in patients with emphysema C.O.P.D. is shortness of breath, and you'll also see
cough, and if it's wet you'll have sputum as well. These are very nonspecific symptoms, but they're
very typical of what you see in C.O.P.D. How important of a disease is this? Couple of statistics that you should know
is it's the third most common cause of death in the US; pretty significant. There's a number 2 and there's a number 1
above it and that's heart disease and cancer and sometimes these, depending on how you
survey, will flip spots. There's also number 4 and number 5. The key here is that this is the only cause
of death in the United States out of these 5 that have actually gone up from about 2007
to 2010 all the others have gone down in frequency except for this one.
This is a pretty significant disease that
we've got to be concerned about. In addition to all of this, it's also the
second leading cause of disability. Okay, so the bottom line here is that this
is a very important disease to know about. In case of course, you're wondering how much
of this costs the US healthcare system in the United States every year, the answer is
about 50 B with a billion; 50 billion with a B. That's quite a lot of money
As I mentioned, C.O.P.D or emphysema is a disease that affects the lungs. Specifically, if you were to take a look your
lungs, you of course know that your lungs have 2 sides and that there's a major airway
call the trachea and it branches off into the right and left main-stem bronchus.
From there it just goes down to smaller and
smaller branches, without getting into too much anatomy. If we were to take these very small bronchioles
or respiratory bronchioles they would eventually end in a grape like cluster called a alveolus. This essentially increases the surface area. This is what a normal respiratory bronchioles
would look like. If you were to take all these alveoli in the
entire lung and spread it out it would be about the size of a tennis court. It's pretty big. These bronchioles of course allow the air
that you breathe in to go down and cause gas exchange. Now C.O.P.D. affects 2 main areas. It affects this bronchus, the small bronchial
and it also affects the alveolus in a bad way. What happens, is because the elastic fibers
are destroyed, we'll get into that later, is that that airway becomes very collapsible
and essentially it becomes very small, and that's where the obstruction in C.O.P.D. comes
from. Furthermore, you're also going to get destruction
of the alveoli and you lose a lot of surface area, so instead of having a nice tennis court
you end up with maybe a badminton court or even a table tennis court here that you're
working with.
The surface area becomes much smaller and
all these changes happen throughout the lung, but mostly in the upper regions of the lung. As a result of that it's hard to get the air
out. There's an obstruction, that's the key point
there is that air cannot get out of the lungs. That's why it's called chronic obstructive
pulmonary disease. In addition to that because these alveoli
are all destroyed and become areas of large balloons if you will, the long actually increases
in size and as a result of that you get these patients with large lungs but they're full
of air and they can't get the air out and that's basically C.O.P.D.. The way that we diagnose C.O.P.D. is based on this obstruction. We set them down in front of a spirometer,
that's basically a machine where you breathe into it and it measures how much you breathe
out. We asked them to basically breathe out after
taking a deep breath in, breathe out as much air as they possibly can and we measure it.
This represents how much air they can blow
out given enough time to blow it out, so we give them 6 to 10 seconds to blow it out enough
time that they need to blow everything that they possibly can out in the lung. We call that, by the way, the forced vital
capacity. Otherwise known as the FVC. That's how much air they can blow out completely. We said that C.O.P.D. is an obstructive lung disease so what we're
really looking for is how fast can they get that air out, because if there's an obstruction
that's going to impede their ability to get that air out as fast as they possibly can. The next thing that we do is that we have
them do the same maneuver, but we measure how much comes out in 1 second, so there's
kind of a timed proportion to this.
How much can you blown out given an infinite
amount of time? And how much can you blow out in just 1 second? There's a little bit of a velocity factor
involved there. What we do is, we call that by the way, the
forced expiratory volume in 1 second. This is otherwise known as the FEV1. Then we do a very simple calculation, we measure
and we see. We take this number, the forced expiratory
volume and we divide it by the forced vital capacity number and we come up with a fraction. This is known as the FEV1 divided by the FVC
ratio. The definition that's come up in the literature
is that .70, 0.70 is the cutoff. If the FEV1 divided by the FVC ratio is less
than .70 that means that you could get less than 70% of the air that you could normally
get out, given an infinite amount of time, out in the first second. That means you've got obstructive lung disease. If you can get more than .7 out that means
you don't have obstructive lung disease. The question here is, can you get out at least
70% of the air that you could normally blowout in the first second, and if the answer is
yes then you don't have obstructive lung disease.
If the answer is no and it's less than .7,
then you have obstructive lung disease. Of course, the lower this number is, the FEV1,
the worse your C.O.P.D. is going to be. Let's review. C.O.P.D. is 1) common, it costs a lot; 2) it's the
third leading cause of death and is the only 1 of the 5 that are actually increasing in
frequency; 3) causes difficulty with breathing out, that's obstruction; 4) reduces the cross-sectional
surface area, causes drops in oxygen; 5) you diagnose it by spirometry, and then finally
6) the diagnosis is the FEV1 divided by the FVC is less than .7
Thank you for joining us.