Name: Diffusing capacity of the lung for carbon monoxide (DLCO) | NCLEX-RN | Khan Academy
Uploaded: 2019-02-02T08:19:11.000Z
Duration: 10 min 3 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Voiceover: There's a test that can tell us

how well diffusion is going in the lungs.

and then CO, standing for carbon monoxide,

it's the same scary gas
that we're afraid of

of being in our homes
because it can poison us.

We'll get to in just a
second why we use this gas.

from a high concentration
to a low concentration,

let's think of it as a gas
moving across a barrier

which is the end of the
airway in the lungs.

This is where gas
exchange will take place.

That is covered by this
layer of blood vessels.

because usually, its job, this whole area,

is to have one gas diffuse from
the airspace into the blood

and another one from the
blood to the airspace.

and this one going from
blood into the lungs

This test is able to
answer that question of

how well can the lungs move
a gas into the bloodstream?

To do this test, we have our patient here.

and it's also connected
to his nose up here,

Theoretically, that could
go also down the airway.

To isolate all the numbers
and data we're getting,

so he can only breathe through his mouth.

and I can't draw what the
machine really looks like,

In the first one where
he's breathing from,

He takes a big breath as
much as he can breathe in,

and then when he can't
breathe in any more,

he holds it for a second,
for just a split second,

and then he blows it all
out as much as he can go,

keep going, keep going
until he has no air left.

Now the computer is able to
calculate two things for us.

One is how much carbon
monoxide he breathed in

We care about these two
numbers because essentially,

how much you took in minus
how much came back out

equal however much went
into his bloodstream.

That's the amount that
was diffused across.

If we come back and look
at this drawing here,

A certain amount, if it
crosses in the bloodstream

and then all that's still
left in the airspace,

so there is nowhere
else for the gas to go.

It either went in the
bloodstream or it came back out.

Therefore, our equation
here gives us an estimate

instead of the two gases that
usually are in the lungs,

and its job is usually to
carry these gases in our blood.

which, for our purposes,
is a waste product.

it exchanges the carbon
dioxide for oxygen.

Back here, when we talked
about these two gases

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Diffusing capacity of the lung for carbon monoxide (DLCO) | NCLEX-RN | Khan Academy

chronic

assume

scenario

constant