Now, usual interstitial pneumonia, what are
we looking at? It’s idiopathic remember
that’s the clinical diagnosis that you’ve
taken out of this. Leading to what? Fibrosis
of the lung parenchyma. What happens?
Your DLCO is then going to decrease and what
happens to your A-a gradient? Rule of thumb,
definition that we walked through already,
increased. Good, pulmonary. The fibrosis increase
the distance over which the oxygen has to
be properly transported from one side of the
membrane to the other and that is then impaired.
What’s the test that you’re doing here
please? Good, your DLCO. We talked about
hypoxia and if this occurs over a long period
of time what are you going to found with your
nails, fingers? Digital clubbing, right?
Cyanosis, yeah of course but that you know,
that occurs even acutely. Chronically,
you see clubbing. So therefore, the nails
are then going to become thickened. The fibrosis
also decreases the compliance., what does that
mean? It’s becoming stiffer, so therefore
restriction of entry. And usual interstitial
pneumonitis is a disease of older patients as
you can expect because of increased
Now, consider diffuse lung disease differentials.
Make sure it’s not associated with connective
tissue disease and that’s important so whenever
there is the issue with fibrosis in the parenchyma
rule out any drugs or maybe occupational exposure,
and we’ll talk about more of this later
on when we start addressing what’s known
as hypersensitivity pneumonitis, is that clear?
So, usual interstitial pneumonitis, sure you’ll
have your fibrosis but with this fibrosis
well, as you’ve said the clinical pattern
here is going to be your idiopathic pulmonary
fibrosis and then your pathologic pattern
would be usual interstitial type of pneumonitis.
Go back to that table and take a look at the
two categories. Clinical pattern, pathologic
pattern. Clinical pattern, pathologic pattern.
Do not be confused between the two.
Now, consider the diffuse lung disease differentials,
what are these? Well, you may require lung
biopsy. Keep in mind that the pathology of
usual interstitial pneumonitis which is the
fibrosis is the final common pathway of severe
lung disease, isn’t it? so often times when
you find this fibrosis apart from just automatically
giving it a label of idiopathic, was there
an underlying issue, was there recurrent bout
of whatever lung disease resulting in fibrosis?
UIP, IPF will go hand in hand. Now, 80% or greater
would be of sporadic. Familial, smaller
percentage. The mucin gene that you want
to know, MUC at least be able to identify
that and there’s also telomerase plus surfactant
mutations as well seen mostly in older