Questions on breathing

[lozadora]

Some really basic questions but I'd like to understand the "science" behind the answers. Knowing why I need to do something is important...

1) I understand that if you were hold to breath ascending it could lead to lung over expansion, air embolism etc. BUT if I am taking a photo underwater at say 12m and want to hold my position as steady as possible at that exact depth -- what is wrong with holding my breath for 10-15 seconds as long as I can guarantee I don't move?

2) When ascending I understand that you should not hold your breath, as above. It also makes sense to me that for the same reasons you shouldn't inhale if you ascend rapidly. If I am ascending very slowly though I need to inhale (otherwise I run out of air!) - so my question is should I be just inhaling a little bit and then very slowly exhale, or can I breath as normal as long as my ascent is slow. How slow is slow enough to be able to take a normal breath without risking over expansion?

Thanks!!

 

[TMHeimer]

1. UW photographers apparently do this all the time to eliminate bubbles. Students are trained to never hold your breath because this is the easiest and safest thing to remember. They are also trained to blow a steady small stream of bubbles any time the reg. is out of the mouth. This insures that the airway ("glottis" specifically, I believe) is always open, allowing air to leave the lungs. If one is familiar enough with how everything works in the airways you would be able to just keep the airway open without blowing bubbles or exhaling. But some people have trouble even controlling mouth vs. nose breathing. So better safe than sorry.

2. I have never breathed any differently than normal while ascending. But I always ascend slowly as taught. If you had to do an emergency buoyant ascent it would make sense to not take deep breaths as you say, assuming you can think of that at the time.

 

[boulderjohn]

1. Photographers stop breathing while taking the shot frequently, not only for the sake of buoyancy but to avoid blowing bubbles. There is a difference between stopping breathing (wth the airway still open) and holding your breath, with a stopped glottis. If you are absolutely certain you are not ascending, you are pretty safe.

2. First think about the physics of breathing. You enlarge you lung volume by increasing chest size, either by expanding your chest or lowering your diaphragm. This sucks air into your lungs. Next, think about the physics of why we don't hold our breath while ascending. It is because if the lungs are completely full, the expanding air must come out to prevent a lung over expansion injury. That means that if the lungs aren't full, then you won't have a lung overexpansion injury, even if you do hold your breath briefly.

Now put those two together. If your lungs are full, you can't inhale. If you open your airway to inhale with full lungs, air will come out, not in. If you feel a need to inhale and are able to inhale, then your lungs aren't full, and it is safe to do so.

As long as you are breathing you are OK. It is perfectly safe to inhale while ascending.

 

[TMHeimer]

Thanks John. Do you know if breath holding with airway open while taking the photo is advised/taught in the UW Photog course?

 

[boulderjohn]

Thanks John. Do you know if breath holding with airway open while taking the photo is advised/taught in the UW Photog course?

I don't teach that course. I tried my hand at photography for a while, before I realized how badly I sucked, and the books I read all recommended it.

 

[spectrum]

Iozadora,

In order to keep imitial training simplistic the matra is a cut and dried "don't hold you breath, keep breathing message. The reality is the more subltle act of maintaining an open airway.

1) Yes you can stop breathing, that is pause your diaphram and do not move air. In this utuation your airway is open. Even if you accidentally begin to rise the expanding air will just vent through your exhaust valve.

2) Pretty much the same principle. Go ahead and breathe on ascent. Any extra pressure will just blow off thugh the exhaust valve. If you find yourself ascending fast go for short inhales and long exhales but Boyle's law will pretty much take care of that for you.

Pete

 

[Instructor_Tom]

as you get further in your diving and take up something like diving steel tanks, doubles, or side mount you will learn that diving with heavey gear causes inertia that makes it easier to maintain your buoyancy level even while breathing normally.

I recently completed my PADI side mount class and found it to be one of the easiest configurations I have dove to date for maintaining steady trim in the water. I highly recommend it...


Sent from my iPad using Tapatalk HD

 

[TSandM]

Continuing to breathe normally while ascending works just fine. If the air in your lungs is expanding, you will stop inhaling when you feel as though your lungs are full. The only time it's dangerous is when you close your glottis while ascending.

 

[Rhodesaz]

In time, you will also learn to "inhale & hold" to ascend or "exhale & hold" to descend while you're diving. Of course, you never hold for very long, 2-5 seconds at the most normally. My LDS never taught me this trick. For the first 25 or so dives I used my inflator to ascend or descend. Obviously, I went through a lot of air until I learned.

 

[elmer fudd]

In time, you will also learn to "inhale & hold" to ascend or "exhale & hold" to descend while you're diving. Of course, you never hold for very long, 2-5 seconds at the most normally. My LDS never taught me this trick. For the first 25 or so dives I used my inflator to ascend or descend. Obviously, I went through a lot of air until I learned.

This is a particularly handy trick to use for ascending those last ten or so feet when you surface. Simply take a deep breath and make yourself just a tiny bit positive when you are ready to ascend. Then control the speed of your ascent by exhaling.