Lung overexpansion

[socc]

Hi guys,

Probably a silly question but I was wondering. Can you get a lung overexpansion on the surface ? For example when you take a very very deep breath up to the point you cannot inhale more air and push it too the limits. I am asking just from curiosity.

Thanks,

Socc

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A ScubaBoard Staff Message...

This thread was moved to the Diving Medicine forum at the request of participants because as the discussion continued (around post 11) it moved to an area that called for the attention of participants with medical training. I am putting this information in the first post so that physicians looking in on the thread will be alerted to the change in topic to come.

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[HungoverDiver]

If you had your nose plugged and a regulator into your mouth, your lips forcibly sealed around the reg and continually purged, I imagine you could get lung over-expansion. However, I think the seal of your lips on the reg would break before you'd get lung damage. But why someone would be in that situation eludes me...



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[tbone1004]

sort of. Your lungs work on a vacuum so you can't get an over expansion injury just from breathing unless you have ridiculously strong lungs and can breathe off of a snorkel at about 5ft down. Very very few read less than 0.01% of people are capable of doing this and it would require a full breath of air then ascending with the epiglottis closed.

Same on a scuba regulator, because it is a demand valve, it can only give you as much air as you ask for and you can't ask for any more than you can fit. If you seal your mouth on the mouthpiece and hold the purge button, you can almost start an expansion injury, but the exhaust valve will usually blow first. If the regs didn't have an exhaust valve you could get an expansion injury at the surface which is why the MTV-100 is preferred for emergency O2, it has a stop so you can't overexpand the lungs.

I guess you could also technically get one if you were hanging vertically on a snorkel, but it would be very very difficult. Your lungs aren't very strong, so it doesn't take much....

Hope that made sense....

 

[HungoverDiver]

If you seal your mouth on the mouthpiece and hold the purge button, you can almost start an expansion injury, but the exhaust valve will usually blow first.

I hadn't considered the exhaust valve. Do you think that would fail first or seal of the lips on the reg?


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[RJP]

Hi guys,

Probably a silly question but I was wondering. Can you get a lung overexpansion on the surface ? For example when you take a very very deep breath up to the point you cannot inhale more air and push it too the limits. I am asking just from curiosity.

Thanks,

Socc

I would think you'd need to wrap your lips around a tank valve and crank it on.

Even purging a reg in your mouth - unless you had the exhaust T blocked - wouldn't do much of anything anything unless you really sucked hard on it at the moment you really laid on the purge.

 

[socc]

I hadn't considered the exhaust valve. Do you think that would fail first or seal of the lips on the reg?


Sent from my iPhone using Tapatalk

I would think you'd need to wrap your lips around a tank valve and crank it on.

Even purging a reg in your mouth - unless you had the exhaust T blocked - wouldn't do much of anything anything unless you really sucked hard on it at the moment you really laid on the purge.

If you had your nose plugged and a regulator into your mouth, your lips forcibly sealed around the reg and continually purged, I imagine you could get lung over-expansion. However, I think the seal of your lips on the reg would break before you'd get lung damage. But why someone would be in that situation eludes me...



Sent from my iPhone using Tapatalk

sort of. Your lungs work on a vacuum so you can't get an over expansion injury just from breathing unless you have ridiculously strong lungs and can breathe off of a snorkel at about 5ft down. Very very few read less than 0.01% of people are capable of doing this and it would require a full breath of air then ascending with the epiglottis closed.

Same on a scuba regulator, because it is a demand valve, it can only give you as much air as you ask for and you can't ask for any more than you can fit. If you seal your mouth on the mouthpiece and hold the purge button, you can almost start an expansion injury, but the exhaust valve will usually blow first. If the regs didn't have an exhaust valve you could get an expansion injury at the surface which is why the MTV-100 is preferred for emergency O2, it has a stop so you can't overexpand the lungs.

I guess you could also technically get one if you were hanging vertically on a snorkel, but it would be very very difficult. Your lungs aren't very strong, so it doesn't take much....

Hope that made sense....

Thanks you for your replies guys.

So I guess the answer is no. Your chest muscles are not nearly strong enough from what I understand to create such a big pressure to your lungs when inhaling to cause over expansion. Only if using a device that can blow so much air with pressure into your lungs (from example pressing the purge valve on reg and having the exhaust valve blocked) injury might happen, and still most of the times even this will not do an over expansion injury.

The reason I was wondering is that they say that even very small changes in depth can cause over expansion injury so I was wondering if that small fraction of pressure can be mimicked somehow by our body such as inhaling extremely deeply and hard - if you understand what I mean.

 

[boulderjohn]

Same on a scuba regulator, because it is a demand valve, it can only give you as much air as you ask for and you can't ask for any more than you can fit.

In a related way, that is why even though you can get an injury from holding your breath while ascending, you can inhale safely while ascending. If your lungs are full and you hold your breath, the expanding air can damage the lungs because the air has nowhere to go. In contrast, if your lungs are full, you cannot inhale. If you try to inhale during an ascent with full lungs, your airway will be open as the air expands, and the air will escape.

 

[Rick Murchison]

Do a google search on "spontaneous pneumothorax" & you'll find lots of ways to do it. Most require some preexisting disposition to it, but is it possible? Absolutely.

Rick

 

[boulderjohn]

The reason I was wondering is that they say that even very small changes in depth can cause over expansion injury so I was wondering if that small fraction of pressure can be mimicked somehow by our body such as inhaling extremely deeply and hard - if you understand what I mean.

See my post above for the explanation.

 

[tbone1004]

the depth changes are only relevant for pressure differential, you can die from an over expansion in 3ft of water, but it has to be the first three feet of water which has a .1ata pressure differential. At 100ft, that's a rise of 12ft, and is also really only an issue if you are taking FULL breaths, like to the point that it hurts. Obviously don't hold your breath, but closing your epiglottis is what kills you. It can take much more pressure than your lungs can. As long as it is open your lungs will vent as you ascent, but on a "normal" breath you have a long way to go before it is full enough to cause damage