Pulmonary Barotrauma

[rapscallion]

I've wondered for awhile how our lungs work related to air in our alveoli and the effect of breath holding. At neutral buoyancy we gently rise and fall as we inhale and exhale air into our lungs. Though I never hold my breath, I do at times breathe v e r y slowly and find myself keeping my diaphragm flexed with a partially full breath for a few seconds.

My question is best asked by describing a similar experiment. If you took a bellows down to depth, and expanded the bellows drawing air at ambient pressure and then held the bellows open while ascending, the expanding air would escape through the intake nozzle without causing damage to the bellows. Now, if the bellows was capped after being filled, obviously we would see an overexpansion.

So the true question is, do our lungs behave as the bellows experiment? Is there danger of pulmonary barotrauma when your breath is held by your diaphragm with the airway open?

Obviously I'm not going to experiment on myself to find out.


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[DocVikingo]

Is there danger of pulmonary barotrauma when your breath is held by your diaphragm with the airway open?

Hi rapscallion,

Given a healthy pulmonary system, an ascent rate that is at all reasonable & a completely open airway, a lung over-expansion injury related solely to simply holding the "diaphragm flexed with a partially full breath for a few seconds" appears extremely unlikely. A note of caution is that the retention of breath without any closure of the glottis may take some practice.

Regards,

DocVikingo

This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual, and should not be construed as such.

 

[vcanabal]

DocVikingo is right. The glottis is like the cap on your bellows.

When people "hold their breath" they are closing the glottis. Leaving it open is probably better described as "not breathing" rather than "holding your breath"

Perhaps easier said than done


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[rapscallion]

Thanks for the responses. That was my assumption as well. When we do the CESA exercise we are exhaling slightly, which I'm guessing has more to do with keeping the glottis open than actually forcing the expanding air from our lungs.


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[TSandM]

When I did my CESA in open water, I was amazed to discover I had to exhale actively on the way up, because just a passive, open glottis didn't feel like enough.