- I'm pulmonologist Dr. Ravi Kalhan.
Let's answer some questions from Twitter.
This is "Lung Support."
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@jwaizen asks, "If you vape, what your lungs look like.
Quick."
Normally a lung looks like this.
There's a black, which is air
inside the lung, and it looks really clear.
So if you vape
and you are unlucky and get vaping-associated lung injury,
inflammation happens and the air sacs fill up with stuff.
So this white stuff
in this X-ray really is the injury caused by vaping.
So this means there's fluid inside the air sacs.
You can't move oxygen and carbon dioxide through fluid.
They're gases.
It makes it hard to breathe
because the air can't move in and out of your lungs
and exchange the oxygen for carbon dioxide.
@gvybi asks, "How do lungs know
what's oxygen and what's carbon dioxide?"
So the lungs don't know what's oxygen and carbon dioxide.
The air comes in through the windpipe,
gets spread out throughout the lung in a bunch of air sacs.
Each air sac has a blood vessel going by it,
so the gas moves from inside the air sacs in the lung
into the blood where it attaches to hemoglobin
that's job is to carry oxygen.
It's really avid for oxygen.
And then the carbon dioxide, which is higher
in the blood than it is
in the air that's inside the lung, diffuses out.
@haris_a1 asks, "Can lungs be transplanted?"
They sure can.
Lung transplants are done mostly for chronic lung diseases
like pulmonary fibrosis, cystic fibrosis,
or COPD, chronic obstructive pulmonary disease.
To get a lung transplant, you have to go on a bypass machine
and then they actually remove a lung,
cutting off the windpipe and reattaching the windpipe,
and put in a new set of lungs.
But you've gotta be pretty, pretty, pretty sick
to get a lung transplant.
@NeimanMarcusEsq asks, "I wonder what bad lungs sound like?
I'm in the doctor's office with good sounding lungs
so I wanna know how bad lungs sound."
When you go to the doctor, they put on their stethoscope
and they, you know, very doctorly, start listening
in the back, side to side, bottom.
When we say lungs sound good,
that means we can hear air moving in and out of the lungs
without making any extra noises.
One of the most common things we hear is wheezing.
It sounds like this.
[muffled wheezing]
That whistling noise
on the way out means that there's resistance
to air moving through the windpipes.
We hear this sound, wheezing, pretty commonly with asthma,
sometimes with COPD.
Because of narrowing of the windpipes, people can wheeze.
Another thing we listen for is crackles.
They sound like this.
[crackling]
Crackles occur when there's stuff in the air sacs.
So if there's fluid
in the air sacs, that creates a crackling noise
when it inflates.
That can be created by heart failure,
blood backing up into the lungs
from the heart 'cause the heart isn't pumping well.
It can be created by pneumonia
when fluid fills up areas of the lung,
and those are usually what we call fine crackles.
There also can be something called coarse crackles.
[coarse crackling]
Coarse crackles occur when there's pulmonary fibrosis,
or scarring in the lungs.
@yoseiyume asks, "Honestly WTF is COPD?
Like what."
C O P D is the most common lung disease.
It occurs mostly in smokers
and it sometimes gets called emphysema.
The lung is normally rubbery and elastic.
It's like made up of tons of balloons,
and if you take a balloon and you blow air into it...
[balloon hissing]
And when you take the air and let go, so air fills the lung,
it comes out super easily and fast.
With emphysema, the lung loses its elasticity,
so it gets like this grocery bag.
Air can go into it, and then someone has to breathe in again
'cause you gotta keep breathing, right?
So more air goes in and then it just stays there,
and then more air goes in and it just stays there.
Imagine taking a breath in and then taking another breath in
and then taking another breath in without air coming out
fully after each breath, and then getting up
and trying to like go up a flight of stairs.
It's pretty uncomfortable to move around
with air stuck in your lungs.
@artsetsufree asks, "How much snot can your lungs hold?"
The lung capacity, like the amount
of volume in someone's lungs, can be anywhere
from three to five liters.
Mucus is produced by the cells that line the windpipes.
If someone has allergies, right,
and they inhale a bunch of pollen,
their nose starts running and dripping
and their lungs can produce stuff and they start coughing,
and to protect against that reaction, it creates fluid
or a film along the lining of the lungs so that the exposure
to that stuff goes down.
@bless_bottle asks, "Does anyone have studies
of #cannabis inhalation effect on the lungs?
Trying to gauge long-term damage,
how it compares to smoking cigarettes
and whether vaping really reduces risk."
It's been known for some time
that smoking marijuana causes less injury
to the lungs than smoking tobacco cigarettes.
People smoke fewer joints historically
than they do cigarettes in a day.
It's also true
that marijuana itself is what we call a bronchodilator,
so it relaxes the muscle in the windpipes and opens them up
a little bit so people temporarily can breathe easier
if they get cannabis in their lungs.
Now, the problem is vape juice
doesn't just have pure cannabis in it.
It has all sorts of other things
and you heat it up and it causes long-term problems
because all the other stuff gets in the lungs
and causes damage to the wind pipes and air sac.
@cattlegoth asks, "I've been thinking about alveoli
too much lately.
I just want to know what they feel like.
Are they soft like roe
or is there firmness like a ripe berry?"
I think maybe the best way to think
about the lung is like a sponge.
Not really firm like a raspberry.
So the lung has a main branch, that's this Y here,
and then it branches into millions of tiny branches.
At the end of each branch
is a tiny air sac called an alviolus.
Then the whole thing is surrounded
by like a Saran Wrap called the pleura.
which holds the whole thing together.
@jinxeptor asks, "Why is cold air so hard on lungs?"
Well, cold air triggers reactions in things, right?
It's hard on skin, it makes your eyes water.
You breathe in, cold air hits your windpipes,
can really irritate them.
In people with asthma, it can cause an asthma flare-up.
It can cause wheezing and real trouble breathing.
So what should people do about that?
Well, breathing through your nose is better than breathing
through your mouth.
When you breathe through your nose,
the air gets warmed up and humidified
before it goes into the lungs.
Or when it's really cold,
people, especially with asthma, but probably
everybody who gets sensitive to cold air,
should wear a scarf
or a mask or something that allows the air to get warmed
before they breathe in.
@emilycblz asks, "How do I train my lungs to not asthma?"
You can't really train your lungs to not have asthma.
You can avoid the things that trigger your asthma.
So if you're allergic to cats, get rid of your cat.
So when asthma's acting up, there's inflammation
inside the windpipes, and when there's inflammation
inside the windpipes, they get narrowed and filled up
with mucus and phlegm so air can't move in and out,
and then the muscles around the windpipe actually spasm
and squeeze the windpipe shut.
So the best way to deal
with asthma is to use an inhaled antiinflammatory medicine.
A lot of people have asthma.
10% to 15% of people in the United States have asthma.
Their inhaler may have a bronchodilator,
something called albuterol
or rescue medicine that opens up their windpipes.
Most people with asthma who have significant symptoms
should be on an antiinflammatory inhaler,
an inhaled corticosteroid which lowers the inflammation,
so they don't need this rescue bronchodilator.
@AlexanderMcCoy 4 asks, "Is there any truth
to the urban legend that smokers do better than non-smokers
in high altitude rucks, because their lungs are used to it?"
There is no truth to that.
Smokers do not do better at altitude.
In fact, lots do worse because they might have COPD
or other things that impair their oxygen in their lungs.
There's lower oxygen pressure at higher altitudes,
which means there's less oxygen available
to transfer to the lungs.
One of the adaptations that the body makes
after it's been at high altitude is to make more hemoglobin.
The oxygen-carrying capacity of the blood goes up.
Athletes sometimes train
at high altitude to improve their hemoglobin
so that they are capable of carrying more oxygen
when they are at sea level.
@yoyo_yelena asks, "Curious, what does covid do to lungs?
Does it fill them with fluid?
The x-rays look horrible but I have no clue what they mean."
When covid was causing the pandemic
and people were dying everywhere, it caused pneumonia.
So this is what covid can look like in the lung.
This one has worse pneumonia on the left side
and not as bad on the right side.
This area right here, this white stuff,
it's filled up, socked in, we call it consolidation.
It has bacteria, immune cells, white blood cells,
things that are trying to fight an infection.
I betcha this person got really sick,
had a low blood oxygen level,
and was having a really hard time breathing.
Why some people with covid caught a runny nose
and other people got pneumonia and died, we don't know.
Some people are just more vulnerable,
like if you have diabetes, if you smoke cigarettes or vape,
you're probably more vulnerable to infections.
@watrcoolr asks, "How does a pulse oximeter
measure the blood oxygen levels
without actually taking blood?"
So this pulse oximeter you can wear
on your finger shoots infrared light from one side
and has a sensor on the other,
and you've gotta put it on a part of thin skin.
That's why we put it on our finger or our earlobe.
Hemoglobin, when it has oxygen attached
to it, has a certain configuration, and when it doesn't
have oxygen attached to it,
it has a different configuration.
That influences how much light gets absorbed.
And then the sensor in the pulse oximeter
can then calculate how much blood oxygen there is based
on that confirmation of hemoglobin.
A normal blood oxygen level is like 95% or higher.
It's dangerous if it's below 90%.
That's when I think we should really pay attention.
@ireojima asks, "I'm sorry,
but how is mouth to mouth even real?
Like how am I not just exhaling carbon dioxide
into your lungs instantly killing you?
Scientists explain this."
So it's not mainly carbon dioxide.
What we breathe in, remember, is mostly nitrogen.
The atmosphere is mostly made up of nitrogen.
It's about 21% oxygen,
and then some small portion of carbon dioxide.
So when you breathe out there's a little more carbon dioxide
than what's in the air, but it's not 100% carbon dioxide.
It's still more like the air we breathe in
than anything else.
@paisleymoths asks, "Like do lungs have muscles?
Can I train myself to be like able
to hold my breath longer than anyone?"
The diaphragm is outside the lung.
It goes downward, the lung opens up.
So those muscles can be trained
and you can make those muscles stronger
and breathe more efficiently to some extent.
But the lungs themselves don't have muscles
that generate breathing.
One of the reasons people who train can hold
their breath longer is they're in better shape,
so all their muscles in their body demand less oxygen
and produce less carbon dioxide so their lungs
don't have to do as much work to keep those muscles fueled.
Sometimes people who have operations
or are in the hospital get a gadget
called an incentive spirometer where you're told
to breathe in and make these balls go up.
The reason for that is people who are lying
in bed don't breathe deeply, and then if that happens, areas
of the lung can end up without air in them
called atelectasis, and we wanna prevent that
'cause areas of the lung
without air in them are prone to developing pneumonia.
And one of the ways we prevent that is forcing people
to breathe deeply using one of these machines.
@bphesq asks, "Which is worse for your lungs,
vaping or smoking?
#AskingForSeveralFriends."
Smoking we've known forever to be bad,
and vaping is newer and we don't know how bad,
but I'm a lung doctor so I think inhaling anything
but air is bad for your lungs.
The lungs can recover from some injuries.
The things that are caused by the environment
like smoking cigarettes causing COPD or emphysema
or pulmonary fibrosis, which is scarring in the lungs,
those things don't heal.
We have treatments that stop them from getting worse,
but we don't have a way to just fix it
and make it act like you were never exposed to that problem
and the lung never got damaged in the first place.
@iwasrightonce asks, "Why TF do lungs
have an uneven number of lobes?
What's up with that?"
Well, the reason is is that the left lung
has to make space for the heart
because the heart sits in the left side of the chest.
There are three lobes on the right, upper, middle, lower,
and two lobes on the left.
@deepak_rajgor asks, "Does lung cancer happen
only because of smoking?"
Lung cancer's most common cause is smoking,
but there are a lot
of people who don't smoke who get lung cancer.
There's one exposure that's well known to cause lung cancer,
and that's radon exposure.
Around the country, people's basements
can have a lot of radon,
and home tests are available to test for radon.
And radon is clearly associated
with lung cancer when it's present in someone's house.
A lot of young women seem to get lung cancer
who didn't smoke.
We have no idea why that is.
They get a type
of lung cancer that's often called an adenocarcinoma.
Maybe they had secondhand smoke exposure in the home,
maybe there's a genetic factor, but it's pretty scary
that non-smokers still get lung cancer
at a pretty significant rate.
@farazmunshi asks, "How long before AI can label lung cancer
better than a certified radiologist?"
The automated tools on CAT scans are coming soon
and will be really helpful.
One of the things where I think they'll be super helpful
are the things we can't see.
You know, a CAT scan's a picture
and it has various densities of images
and we can't see every density on a CAT scan,
but there might be parts
of the lung that are starting to have abnormalities
that we can't see visually that a machine could detect.
And in that sense, AI would be huge, right?
And figure out whether that person
needs some enhanced surveillance or things to keep an eye on
to see whether they get cancer.
@estoyArTo_ asks, "How TF do lungs collapse?
Like do they just get tired or something?"
They don't get tired.
Usually they get injured and it causes the lung to collapse
and causes what we call a pneumothorax.
Getting stabbed or shot or having something go
through the chest wall can puncture the lung.
So there's two sets of pleura.
There's a layer of Saran Wrap
that's holding all those alveoli together,
and then there's a layer against the chest wall,
and there's a space between the lungs and the ribcage.
If you pop the balloon, poke a hole in the Saran Wrap,
air can escape from inside the lung to outside of the lung.
That builds pressure and the lung can collapse.
It doesn't have enough pressure
inside the lung to stay open, so it deflates.
So those are all the questions for today.
Lots of good ones.
Thanks for watching "Lung Support."
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