lung expansion???

[Scuba]

Thank you Dr. Paul Thomas for your thoroughly detailed explanation.

I also read the explanation for arterial gas embolism on the other thread and I am trying to understand their differences compared to pneumothoraces ( burst lung ).

A few more questions if I may.

Is it necessary for one to occur before the other? Sequence? Simultaneouly?

Is a diver with lung health below normal predisposed to one over the other? With arterial and/or heart health below normal? Other?

Which of these two conditions AGE and pneumothoraces is the most likely to occur to a diver?

Which is most dangerous?

Better recovery rates?

Peter

 

[Zept]

Originally posted by mtdivegirl
But, the human body is an amazing thing and the theory is that your body would force the air out of your lungs no matter what you tried to do.

The human body is pretty cool, but nothing in several million years of evolution has prepared it for sudden pressure changes while breathing compressed air. Scuba diving is highly unnatural.

Lungs are spongy and stretchy. Stretch them too much and they tear, like any other tissue. Have you ever pulled a muscle while lifting something? Your body isn't smart enough to go, 'Gee, that's heavy, I'm really feeling the strain, I think I'll just relax that muscle before it gets damaged.' Likewise, your body isn't clever enough to relax your throat muscles when the pressure builds up in your lungs. Instead, the lining of the lung tears, with the (rather nasty) consequences described by Dr Thomas.

Zept

 

[DiveTub]

Once saw a young lady run out of Air in 10m I guess thats about 30feet of water, she paniked and bolted to the surface holding her breath.

Sure enough that night she was lying in the Recommpression chamber with an air embolism.

Never Hold Your Breath !!!!

Try this, take a condom or balloon to depth and inflate it with your Ocy, tie it closed and let it go. when you get ot the surface you will soon see hoe your lungs would look if YOU held your breath

 

[mtdivegirl]

I am still not advocating holding your breath, I am just trying to get to the core of this curiosity...just consider it academic.
Your body can only expand to a point understood. But, if you are conscious and your lungs are expanding how can you hold your breath against the pressure? Your air way is not blocked your mouth is open against your regulator in theory air can escape.
I realize that the concept is don't hold your breath bad things can happen..i get it..im not arguing the validity that certain things can happen. I just want to understand the physiological responses to a breath being held in the lungs without the knee jerk response of "your lungs will over expand." I would think you would have to try really hard to hold your breath against the pressure..and why would you?

 

[The Iceni]

Originally posted by Scuba
I am trying to understand their differences compared to pneumothoraces ( burst lung ).

Is it necessary for one to occur before the other? Sequence? Simultaneouly?

Is a diver with lung health below normal predisposed to one over the other? With arterial and/or heart health below normal? Other?

Which of these two conditions AGE and pneumothoraces is the most likely to occur to a diver?

Which is most dangerous?

Peter

Hi again Peter,

You have done remarkably well if you have understood even half of the my two latest posts. Burst lung and AGE are completely different conditions.

1) AGE; A gas bubble obstructing an artery from whatevervsource.

2) Pneumothorax, damage to the integrity of the lung (or chest wall) allowing air to get btween the lung and chest wall. Often the tear acts as a one-way falp valve allowing the pressure within the pleural cavity to increase with each breath causing a tension pneumothorax. If the ambient pressure decreases the tension increases in any case.

As I think I made clear earlier, an arterial gas embolism is almost an inevetable consequence of a severe tension pneumothorax but is not only caused by a pneumothorax and a pneumothorax doesnot always cause an AGE but, sadly, these are often post- mortem diagnoses.

I would think you would have to try really hard to hold your breath against the pressure..and why would you?

Not at all Peter, it take very little effort to close the glottis (Straining at stool, obsteric patients pushing out their babies) and since it is the chest wall - and not the lungs - that have the sensory innervation, you will have little or no perception of the increasing size of the lungs themselves. The body is not equipped for this alien environment and does not appreciate that, when diving, lung size and chest volume are not always the same - the chest tells the diver it is half inflated so everything is OK - not so!

As for lung health. Asthmatics and all patients with COPD are at risk of pneumothorax because there is chronic outflow obstruction. This also creates bullae, which are greatly enlarged alveolar sacs, effectively large holes in the lung with considerably weakened walls. The vast majority of burst lungs are cause by these bullae "popping".

As an aside, have a think about what happens to free divers when they descend and ascend this will help to explain it all.

 

[Dr Deco]

Dear Readers:

There you have replies from several readers. Burst lung is not a physiological curiosity. It most certainly can occur and has killed many people. This is why we have the prime directive in diving NEVER HOLD YOU BREATH.

Dr Deco :doctor:

 

[mtdivegirl]

I meant no offense and I was not implying that this was something I was planning on trying to conduct an expirement with, I think I made that plainly clear in my original posts. My question was the result of a number of conversations with academic scientists (not mds) who had mentioned that the human body would be incapable of holding a breath while surfacing from pressure. Therefore it is most certainly an academic curiosity on my part.
Your knee jerk response "it can happen, dont hold you breath" was exactly what I was trying to avoid. If you have nothing additional and useful to contribute to a dialogue why even post? It is my understanding that this thread is for questions regarding DCS...since lung over expansion is lumped with dcs I posted my question here.

 

[Scuba]

the human body would be incapable of holding a breath while surfacing from pressure

mtdivegirl, if I may comment from a laymans perpective.

I agree this issue has not been addressed directly in terms of providing an exact scientific answer. What the doctors have asserted to, from my understanding of it, is that holding a breath to the extent the human body is capable of - is sufficient to cause a burst lung.

Imagine a balloon with a relief valve, as it ascends from a high pressure environment to a lower pressure environment, it releases some gas, but the environmental pressure drop could be drastic enough to the point where the valve is unable to maintain the balloon surface within its operating limits, resulting in a balloon surface failure.

The question still remains: Is there any amount of gas leakage through the body's airways from breath holding while surfacing from X number of fsw before the lungs burst?

An interesting question indeed that maybe someone can answer. Then again from this much to be studied field with so many complex variables involved, I would'nt be surprised if there is no research on this subject.

Peter

 

[Zept]

Originally posted by mtdivegirl
My question was the result of a number of conversations with academic scientists (not mds) who had mentioned that the human body would be incapable of holding a breath while surfacing from pressure.

You are freaking me out, mtdivegirl! I have visions of you lying on a dive boat, coughing up blood, going, 'Okay, I was wrong about the breath-holding thing.' I know you've said your curiousity is academic, but you seem very devoted to your point of view.

Dr Paul Thomas has explained how lung overexpansion injuries occur. Here's another explanation from DAN. Several people have reported witnessing incidents. What more do you want?!

Zept

 

[mtdivegirl]

Zept..you need not worry about me...im one of the more cautious breed of humans on this planet. Honestly, it was purely an academic question planted in my head by academic type folk who were incapable of explaining their position to me..and when i went to find info on it in my available text or with my instructor the answer was "dont hold your breath..you can cause lung over expansion"... i get it..i get it..from a diving point of view never hold my breath..and i wont..im not holding to any one opinion over another i was merely looking for a deeper answer than "dont hold your breath".
I agree that the first doc to post on the subject totally covered the subject but i was still curious.. so i asked some more..
but I was disappointed when the touted Dr. Deco posted a simple "dont hold your breath" response.