Okay. Let’s talk about differential diagnosis,
shall we? Chronic Obstructive Asthma. So,
atopic asthma. So, what we’ll do here
and as you proceed into subsequent
topics of asthma and so forth, you want to keep
in mind that those three circles that I’ve
showed with the overview of asthma, chronic
bronchitis and emphysema. Often times, you’ll
have an overlap. So, chronic obstructive asthma.
Atopic asthma, what does that mean to you?
It’s extrinsic asthma. And what does that
mean to you? That means this individual got
exposed to something in the outside world.
Let it be through occupation, maybe through
habits, maybe through in the park, whatever
it may be. You’ve heard of pollen, you’ve
heard of industrial exposure, maybe in inner
cities, there might be cockroaches and so
forth. Atopic asthma since childhood
plus heavy smokers in their 20s and 30s could
present with a combination of COPD plus asthma.
Usually, this would be chronic bronchitis
plus asthma. What do you need to do? What
needs to be distinguished for the purpose
of clinical management?
So, chronic bronchitis, you are absolutely
relying upon the definition. You find this
definition even in a patient that has asthma
and they’re smoking. Please understand that
you’ve given yourself chronic bronchitis a
type of COPD. 3 months, 3 and 2.
3 months of productive cough over 2 successive
years and normal pulmonary function test not
considered COPD. Fantastic! Isn’t that crazy?
So, which you must find is that definition,
but what’s a pulmonary function test? How
important is that? Very. What is this? FEV1
over FVC. And so therefore, if you find this
to be normal, at this juncture, by definition,
your current day practice, you cannot call this
COPD. You must find that ratio being normal,
or excuse me, you must find that ratio
being decreased. If you find it normal, then
you cannot medically and clinically consider
it to be COPD. Keep that in mind. I’m giving
you more information based
on the foundation that we
are setting up.
Continuing our discussion of COPD differential
diagnosis. Now, we’ll take a look at central
airway obstruction and upper airway obstruction.
CAO, UAO respectively. What are these
structures? Tracheal, how many do you have?
Please say one. Okay. You have one trachea.
Therefore, you call this central airway type
of obstruction. And we have vocal cord, this
would be considered upper airway obstruction.
Know them both. The last time we talked about
vocal cord obstruction was dealing with the
healthcare workers. And so therefore, you
have vocal cord type of obstruction taking
Now, this is where it gets a little tricky,
but stick with me, you’ll be fine. Do not
typically respond to bronchodilators, because
where are you? The trachea and the vocal cord.
Now, if it was the bronchi, the bronchiole,
we have smooth muscle and therefore, by giving
a beta-2 agonist, there’s every possibility
that you might be improving such obstruction.
However, here, you’re paying attention to
some of that flow volume spirometries that
we’ve been looking at.
Now, let’s walk through this one more time.
Let’s talk about fixed obstruction and we’ll
talk about what’s known as your.. well,
you tell me. Is this a vocal cord or your
trachea? Would you then call this an extrathoracic
or intrathoracic type of pathology? Good.
Extrathoracic. Okay, great. Now, what does
that mean? Let’s walk through these.
Say that you’re having obstruction in the
upper airway, okay? Maybe it’s a tumour,
head and neck tumour. Maybe it’s, you know,
something like your central airway obstruction
with trachea. First off, think about the trachea
and how big the diameter of that tube is.
It’s big. And so therefore, first, let
me walk you through this. That means in order
for you to find any changes in your flow volume
type of spirometry, you became that tiny before
you start seeing changes on your flow volume
loop. That’s a little too late, isn’t
it? I’ve been meaning to say, your disease
process was taking place for a long period
of time before you found the changes on
your flow volume loop. Is that clear?
So, but, just to make sure that we’re okay,
if you get a clinical vignette and you find
the following fixed obstruction, what does
that mean? Close your eyes, think about a
flow volume loop. What’s the top half known
as? That is all exhalation. What is the bottom
half? That is all inspiration, isn’t it?
Now, normally speaking, you should have expiration
or exhalation peak flow and down you go. But
what happens in fixed? You can’t rise too
high. Why? Because there’s a upper airway
type of obstruction. In addition, not only
can you not get air out properly, what about
inspiration? Inspiration, you should be
inspiring until you get to total lung capacity,
but even that has been curtailed. So that
fixed obstruction to you should indicate,
there’s an issue in the upper airways.
Now, we will go one step further as well.
Because this is an extrathoracic issue, you’re
going to have more problems with inspiration.
If you have not followed me, I need you to
go back if you’re not clear about this.
Go back to the review of where we discussed
in great detail, our pulmonary function test
and we walked through each one of these. Now
at this point, I assume that
you know them and you’re quite familiar.
Because this is extrathoracic, with upper
airway obstruction, it may also present not
so much with the problem with exhalation,
but more so with the problem with inspiration.
That will be shortened or curtailed. Keep
those two in mind when you’re dealing with
central airway obstruction or upper airway
Now, as I was saying earlier, if
you find changes in your flow spirometry or volume
loop, then please understand, you’re pretty
late in your pathology. Okay, so,therefore,
it is going to be extremely specific, but
you know, in terms of when you see it, you
could be late in your disease. Just keep that
in mind and that’s pretty big.
Let’s continue. Other differential diagnosis
for COPD include pneumonia, bacterial pneumonia.
We’ll have focal infiltrate on imaging,
more likely to have a fever, higher, positive
sputum culture. So this would be
pretty straightforward in terms
of you being able to diagnose your pneumonia,
but then it may mimic COPD type of patients,
meaning to say dyspnea and so forth.
Now, here’s a quick little review of everything
we've looked at that. Here’s your fixed obstruction.
Take a look at exhalation on top, inspiration
on the bottom. You’re moving clockwise.
Clear? Clockwise. Both exhalation and inspiration
have been compromised. Quickly, extrathoracic.
This is going to be two major issues.
This one and I want you to take a look at
intrathoracic. Is it once again, reviewed?
With extrathoracic, you’re referring to
your vocal cord, you’re looking at a mass
in the upper airway. What is the bottom half?
Good. Inspiration. That has been compromised.