Holding your breath on ascent...

[pjones]

I understand that under no circumstances should anyone hold their breath while ascending however it seems that there are a few posts floating around that suggest that for whatever reason this still happens. I'm not trying to blame or shake my head at these people rather my intent is to further understand what happens.

When I try to to simulate a breath hold on ascent while on dry land (by breathing in as deep as I can) I can feel my lungs expand and my chest area feels tight. I'm not about to try this under water so I was wondering if anybody knew if you would feel the same sensation if this ever happened while diving. I can only imagine that you would feel pain as your lungs over expand. Anybody have any insight on this matter? Experience or hear-say?

These are the things that keep me awake at night...

 

[FF-EMT Diver]

Yes you would feel a tight squeeze and then you'd feel your lung perforate and the inability to breathe.

 

[Jax]

I can't find it, but I'd swear someone cited a source that said words to the effect of - breath holding over as small an ascent as 10' was enough to cause pulmonary edema . . . In other words, damage could be done before you would feel anything.

This one cites pulmonary edema and hemoptysis in healthy breath-hold divers to 3 to 6 m.
http://jap.physiology.org/cgi/content/full/104/4/912

 

[NIT-LVR]

It si my understanding on this topic that this type of injury can occur quite painlessly.Probable causes could be rapid ascents resulting in overexpansion between breaths,lung blockages due to congestion or poor diver fitness,bottom line poor breathing habits underwater,and an already underlying lung defect/issue.My instructors years ago told me that in the right circumstances 3 feet could create a perforation into the pleural space.The diaphragm...being an extremely strong muscle coupled with the lung walls(already obviously semi permeable) creates a recipe for disaster.Regardless of who we are,during even normal breathing there is a split second point between inhalation and exhalation wherein the airway kind of "shuts".If you were ascending at an incredible rate could it be enough???I do not wanna find out.Intersting topic...indeed.

 

[TSandM]

The one diver I have been near who had an overexpansion injury felt a dull ache in his chest, but no sudden or sharp pain.

 

[Thalassamania]

I can't find it, but I'd swear someone cited a source that said words to the effect of - breath holding over as small an ascent as 10' was enough to cause pulmonary edema . . . In other words, damage could be done before you would feel anything.

This one cites pulmonary edema and hemoptysis in healthy breath-hold divers to 3 to 6 m.
Pulmonary edema and hemoptysis after breath-hold diving at residual volume -- Lindholm et al. 104 (4): 912 -- Journal of Applied Physiology

4 feet to the surface is enough to do it.

 

[AlexKilpatrick]

One of the things I always wondered is how your lungs actually seal this way? Clearly they do, but I don't understand the mechanism in your throat. When I hold my breath, it feels more like something is closing up so that I can't intake any more air.

What I picture for lung overexpansion is trying to hold a balloon shut by just pinching the neck with my fingers. If I were to squeeze the balloon, some air would leak out between my fingers.

I don't see how your lungs can really be shut if the pressure from the inside increases. It seems like it would just push air out through your throat.

(Don't worry, I am not planning on testing my theory)

 

[Thalassamania]

Epiglottis.

 

[Bob DBF]

The rubber in the balloon is stronger than your lung tissue and the muscle in your throat is strong enough to keep anything from getting into (or out of) your lungs.

Bob

 

[Doubler]

It also depends on the depth at which the breath holding takes place. Holding ones breath between 100 and 90 feet will not have the same impact as between 20 and 10 feet. IMO