Diagnosis, history of
course being the predominant theme. Is your
patient exposed to whatever that we just walked
through and we’re looking for wheezing that’s
episodic and coughing. That’s the hallmark.
Now, if you find this to be at night we talked
about how that the patient that is untreated
and that’s rather dangerous because
you're always worried about this immediate type
of reaction called status asthmaticus. Chest
x-ray typically normal but could show hyperinflation
but especially during a flare but the point
is, hyperinflation, remember this is COPD right
comes under the category. And obstructive by
that we mean that you’re having a hard time
getting your air out. Once again what I wish
to show you at a later on discussion is the
current day practice of asthma, chronic bronchitis
and emphysema all sharing similar symptoms
ultimately with your patient but keep in mind
that it is an obstructive type of issue. Now,
your pulmonary function test because we’re
talking about this being obstructive, you
can predict as to what you can find with laboratory.
Your FEV1/FVC ratio by definition has to be
decreased, right? Okay, so if this obstructive
you tell me as to what the TLC should be.
An increase in TLC, an increase in residual
volume. I’ll tell you when we have transitioned
into restrictive lung disease topics. The
reason I bring that up is, now as you move
through this, I want you to compare and contrast
always. In restrictive you’ll have a decrease
in total lung capacity and you have a decrease
in residual volume and FEV1/FVC ratio will
never be decreased in restrictive. Now the
obstructive pattern usually reverses after?
Now you keep this in mind, very important for
you to pay attention. The bronchodilator
here, often times this type of obstructive disease
is reversible. So, what was that receptor
again that brings about bronchodilation? Good,
Beta2 receptors. After doing this the pulmonary
function test may be normal when the patient
is not experiencing such a flare.
Patient will have a positive methacholine
challenge, what does that even mean? Well,
if Beta2 receptors then cause bronchodilation,
well, what if you gave something that was
a parasympathetic analogue? If it was a
parasympathetic analogue, what does that then
do to your bronchi? Bronchoconstriction.
So, understand the concept that you already
have spoken and discussed earlier. The patients
will have a positive methacholine challenge. So,
if your patient definitely has asthma they’re
going to have a severe decrease in FEV1.
This is nearly 100 percent
sensitive, but not necessarily specific. So
with the methacholine challenge if it comes
back to be negative, your patient most likely
does not or is not experiencing asthma. Sensitivity,
100% big time important.
Let’s go ahead and take a look at this loop spirometry
in the setting of bronchodilation. Take a
look at the drug here in parenthesis. A Beta2
agonist such as your? Good, albuterol. You’ve
heard of short-acting bronchodilators? So
here, let’s take a look at the loop spirometry
and I’m not going to go through detailed.
You’re good here being able to identify
your patient with an obstructive disease.
Take a look at the red. The red is the disease
isn’t it? How can you tell? You tell me
about the scalloped portion of your expiration.
Isn’t that, therefore, diagnostic of obstructive?
Yes. So now, you’re given a bronchodilator.
Take a look at before in red, upon administration
of a bronchodilator what happened with breathing?
It got a lot better upon exhalation hence
you find a increase in peak flow, is that
Whereas if you were to give metacholine or
methacholine, what does that mean to you?
Well, that's a parasympathetic analogue.
So therefore, what would you then find? You’d
find a patient who has a really hard time
breathing out or exhalation in that one second.
So, look for that FEV1 to drop like crazy,
what will then happen to your ratio? Good,
decrease. Remember in asthma one of the few
conditions in which if they’re not having
a flare, loop spirometry will actually
be normal. It’s only doing those attacks
episodically in which if you’re able to
catch your patient during such a time you’d
obviously find the obstructive type of pattern
here, which is scalloped. Now ultimately, the normal
is going to be the dashed line. So, that’s
what’s predicted, but understand please,
that even with treatment, you’re never going
to get back to normal levels.
Whenever you have a disease process
for the most, remember when we did acid-base
disturbances? And even with compensation,
are you ever going to achieve full compensation?
Never. When you’ve broken a bone and you’re
worried about tensile strength, are you ever
going to get to 100%? Never. Same concept
here. Sure you’ll find improvement but never
back to normal.