0:00

That brings us here to interstitial lung abnormality

0:03

and progressive pulmonary fibrosis.

0:06

These are two interrelated ideas.

0:09

They're not actual diagnoses, they're more like ideas.

0:11

And I know that might be confusing.

0:13

We'll go into it in just a bit.

0:16

So let's talk about interstitial lung abnormalities.

0:20

So what the heck are interstitial lung abnormalities?

0:23

There's, there's a definition here, so I'll just,

0:25

here's a definition, bottom line,

0:27

but again, it's more of an idea.

0:29

So I talked about this before.

0:32

It's these cases of mild reticulation,

0:34

usually in the lung basis, usually in the lung periphery,

0:39

where you're not sure if it's just from a previous one-time

0:43

event, like a bad aspiration

0:45

or bad infection causing some reticulation

0:48

or if it's the earliest finding of a progressive subtype

0:52

of pulmonary fibrosis.

0:54

So it's that dichotic decision point.

0:56

'cause on one hand,

0:57

if it's just scarring, you don't do anything.

0:59

A patient just lives their life.

1:00

They have plenty of lung parenchyma for them to, to be able

1:03

to ventilate normally and they're gonna be fine.

1:05

If it's early fibrosis, you wanna treat that patient.

1:10

And we have antifibrotic medications

1:12

and we know that antifibrotics can slow the progression

1:14

of pulmonary fibrosis

1:16

and obviously they wanna see,

1:17

they wanna maybe be put on a pulmonary rehab

1:19

and just followed closely to decrease their risk factors

1:22

for pulmonary fibrosis progression.

1:24

So it, it sounds so simple,

1:26

but at this point I think it's like the holy grail

1:29

of interstitial lung disease is, is there a way

1:31

to differentiate these two groups?

1:33

And at this point there isn't when it's very mild like this.

1:37

The way interstitial lung abnormal body is defined in this

1:40

guideline that was actually just recently published this

1:43

year, is that you wanna have non-dependent lung

1:46

abnormalities, which can be comprised

1:48

of ground glass opacity, reticulation,

1:50

architectural distortion, traction,

1:52

bronchi have even honeycombing involving at least 5%

1:56

of a lung zone if it starts approaching 5%

1:59

of the total lung.

2:00

So lung zone, right? It's like superior, mid inferior.

2:04

So 5% of a third of a lung zone, right?

2:07

So it's like a one third of,

2:08

of 5%, whatever the heck that is.

2:10

So less than 2%, more than 1% of the total lung.

2:14

You get these interstitial changes

2:16

or glast abnormality, we start

2:18

to think about interstitial lung abnormality.

2:20

If it's greater than that, then we start to actually think,

2:23

oh this might be a real interstitial lung disease.

2:25

This patient needs a, a more aggressive workup

2:28

and more maybe aggressive follow up.

2:30

But bottom line, this is how ILAs are defined.

2:33

But even with these definitions, they're

2:35

so worded in such a way

2:36

where there's not a lot of specificity.

2:39

I think just to remember these interstitial lung

2:41

abnormalities, it's an idea, it's not a diagnosis.

2:44

And you kind of know when you're coming across a case

2:46

of ILA, even

2:48

before you think about the definition itself, it used to be

2:52

that we only considered low risk patients

2:55

to have interstitial lung

2:56

abnormality and high risk

2:57

patients. We didn't. We just said,

2:58

Well high risk patients, you have ILD.

3:00

But now either in low

3:01

or high risk patients, we understand

3:03

that interstitial lung abnormalities exist.

3:05

So cases where it's just mild scarring

3:07

or it's early interstitial lung disease,

3:10

interstitial lung abnormality,

3:12

in most cases we bilateral with some exception.

3:15

So if you're very, very high risk for development

3:17

of interstitial lung disease, maybe, I dunno,

3:19

some genetic abnormality

3:20

or connective tissue disease,

3:21

maybe even a unilateral interstitial changes will

3:24

make you invoke this.

3:25

But most cases can be bilateral. What's not ILA?

3:29

Things that we know don't progress to pulmonary fibrosis.

3:32

So dependent lung alais, some osteophyte fibrosis,

3:35

if it's a focal

3:36

or unilateral abnormality, it's just like scar.

3:38

We're not gonna call that interstitial lung abnormality.

3:41

Uh, things like central lo nodularity or

3:43

or non emphysema cyst, we're not like a,

3:46

like those post-infectious

3:47

or post-inflammatory pneumatic seal.

3:49

So not diffuse cystic lung disease, like one or two cysts.

3:51

They don't progress into fibrosis.

3:53

So we're not gonna call it ILA findings

3:55

of acute things like heart failure or aspiration.

3:58

Obviously these are not ILAs.

4:00

We also wanna differentiate ILA interstitial lung

4:03

abnormality from early interstitial lung disease.

4:05

So the patient's symptomatic, if the patient is abnormal,

4:08

pulmonary function testing has clear fibrosis greater than

4:12

5% of a total lung volume.

4:14

So not just like one to 2% of the total lung volume, right?

4:18

So 5% of a lung zone,

4:20

but there's more of this abnormality

4:23

relative to the total lung volume.

4:24

We start thinking about ILD

4:26

or if we see obviously progression

4:28

or a defined fibrotic ILD pattern on ct.

4:31

So U-I-P-N-S-I-P fibrotic,

4:34

hp certainly we're not gonna call it ILA

4:36

'cause now our suspicion

4:37

that this is early pulmonary fibrosis is quite high

4:40

and we're gonna treat it that way.