Minimum depth change required for an AGE?

[tbone1004]

With a freediver technique call lung packing or buccal pumping, you can inflate your lungs to the maximum volume.

The easy way to achieve the same is to go ~86cm below the surface (body horizontal) and breathe in completely from your scuba regulator . If you hold your breath and surface, your lungs likely won't be damaged.

For AGE, you'll have to go deeper. The 1.2m mentioned in the article that Simon referred to, is probably enough for most people.

yeah, don't do that. I've seen that depth cause AGE, and it sounds like @Duke Dive Medicine has as well. Someone who has trained their lungs to deal with it probably wouldn't have any issue, but you have to build up to that kind of pressure. Don't do it.

 

[Miyaru]

@Miyaru I'm going to respectfully disagree with you here. 86 cm is about 2.8 feet, enough of a depth change to result in pulmonary barotrauma on a full breath.

You are absolutely right, the mentioned depth probably would be valid for a healthy individual without any restrictions in lung flexibility.

yeah, don't do that. I've seen that depth cause AGE, and it sounds like @Duke Dive Medicine has as well. Someone who has trained their lungs to deal with it probably wouldn't have any issue, but you have to build up to that kind of pressure. Don't do it.

It's a bit sarcastic the way I put it, but I think we can agree that the last meter to the surface is the most dangerous part. The nice way would be Disclaimer: don't ever try this, not even in your shallow pool.

 

[Akimbo]

While on this subject, I have been looking for a historic reference to the "discovery" of lung barotrauma in diving. I couldn't find any reference in the 1916 US Navy Diving Manual even though ear and reverse/squeeze barotrauma was discussed. I can understand how AGE would be pretty rare in heavy gear but there must have been a bunch of breathe holding divers working from open-bottom bells that blew their lungs out before someone connected the dots.

Any reference to early documentation would be appreciated.

 

[Subcooled]

there must have been a bunch of breathe holding divers working from open-bottom bells that blew their lungs

Probably, but has it ever been recorded?

Open-bottom bells have been used for quite a long time. Aristotle, Problemata XXXII:5 (400 BCE): "for they enable the divers to respire equally well by letting down a cauldron; for this does not fill with water, but retains the air, for it is forced down straight into the water; since, if it inclines at all from an upright position, the water flows in". In the same chapter we find explanations of a number of things: Why is it that the ear-drums of divers burst in the sea? Why do divers tie sponges round their ears? Why do sponge-divers slit their ears and nostrils? Clearly they were experiencing ear barotrauma. It is not that difficult to conjecture a burst lung or two then! These were, in essence, freedivers equipped with a breath or two of compressed air. And they did not have a clue about compressed air - or the concept of pressure for that matter. Or, at least, Aristotle did not.

 

[Akimbo]

Probably, but has it ever been recorded?

Not that I have been able to find but you would think that somebody would have written about random divers surfacing with blood froth in their mouths and dying shortly thereafter. Image what the divers thought after seeing their mates die soon after an open bottom bell was lowered to the site.

They probably noticed that their chest got smaller at depth and returned to normal at the surface and also noticed that the bell got much heavier and the water level rose as it was lowered deeper. I can't help but think that the problem was rediscovered many times before it became universal knowledge.

 

[Dr Simon Mitchell]

Probably, but has it ever been recorded?

Hello,

Here is an example of effectively the same thing (paper free to download):

Fatal air embolism in a breath-hold diver

Some of you who have a strong interest in diving physiology and medicine should consider becoming associate members of SPUMS or EUBS so you get DHM journal with no embargos.

Simon M

 

[Akimbo]

Hello,

Here is an example of effectively the same thing (paper free to download):...

I think @Subcooled was responding to my speculation that the earliest pulmonary barotrauma was "probably" from ancient freedivers using open bottom bells.

While on this subject, I have been looking for a historic reference to the "discovery" of lung barotrauma in diving. I couldn't find any reference in the 1916 US Navy Diving Manual even though ear and reverse/squeeze barotrauma was discussed. I can understand how AGE would be pretty rare in heavy gear but there must have been a bunch of breathe holding divers working from open-bottom bells that blew their lungs out before someone connected the dots.

Any reference to early documentation would be appreciated.

The earliest documentation I have been able to find was between the late 1920s and early 1930s when submarine escape towers were being considered. There must have been some pure Oxygen rebreather divers that blew their lungs out earlier than that, let alone divers using home-brew Miller-Dunn style open bottom diving helmets. I can't imagine how many divers were lost before somebody figured out the relationship between Boyle's Law and the accidents.