Now that we’ve looked at the overview, of
obstructive lung disease and the different
overlaps of asthma, chronic bronchitis and
emphysema, we dive into the particulars of
emphysema. Now, what you must focus upon would
be the definition that we are seeing here
and the fact that it does technically come
under COPD, which if you were to take a look
at those overlapping diagnosis of circles
that I showed you, then this would be the
green shaded area.
So, what is emphysema? Defined by abnormal,
permanent enlargement of the airspace in distal
to the terminal bronchioles. So, where are
you? You’re getting closer to your alveoli.
You’re thinking about your alveolar
ducts and you’re thinking about the alveoli.
That is accompanied by destruction of the
airspace walls without obvious fibrosis and
that’s a big point. Because if fibrosis
was to take place then you wouldn’t be referring
to obstructive lung disease, would you? No.
You would then be referring to restrictive
Now, before we move on, think about
the anatomy of your respiratory tree. Distal
to the terminal bronchioles, you are thinking
about the respiratory bronchioles, you are
thinking about the alveolar duct and alveoli
and those structures are supported by parenchyma.
There are septae that are involved, keep that
in mind, as we go through various steps of
emphysema and there will be a little bit of
a difference between the damage that’s taking
place to the ducts versus the damage that
will be taking place permanently to the alveoli.
Let us begin.
So, to begin with, I want you to take a look
at the cartoon and where we are. On the very
left, move down the divisions and generations
of your trachea through the bronchi, through
the bronchiole, eventually through the terminal
bronchioles of entry into the respiratory
and, on or in the middle you have your normal
bronchiole and alveoli. The reason you can
say that is because the septae there are dividing
each alveoli, kind of looks like, well, a
cluster of grapes, doesn’t it? Whereas if
there is emphysema, just as a theme here,
it’s a fact that there is a destruction
that’s taking place of the parenchyma. So,
you can only imagine here that you are losing
your surface area. If you lose your
surface area, this means that you do not have
effective gas exchange. And hence, your DLCO,
your diffusion capacity of carbon monoxide,
in fact, is decreased. It’s not because
of decreased compliance, in fact, in emphysema,
what happens to your compliance, do you remember?
It increases, but it doesn’t mean that your
lungs are more effective as being a breathing
apparatus, it’s a fact that now you lost
your surface area. Now, this is in general.
Obviously, there’s a lot more detail to