Emergency ascents

[novadiver]

If you have already exhaled there isn't going to much air expanding in your lungs for the first part of the ascent... so you don't have to worry about exhaling what you don't have.

As you begin ascending the gas in your lungs (since you can't really exhale it all) will expand... and as others have said, keeping your airway open as opposed to *exhaling* will take care of the expanding air.

The reason you should keep your regulator in your mouth is that at some point during the ascent the ambient pressure may be reduced to the point that you will ge able to get one more breath off of the regulator... maybe even more than one.

Been there done that.

Text book assent. nice.

 

[tracker]

Was reading about OOA incident in the acidents forum which required emergency ascent from 70 fsw :11: . I cannot imagine ascending even 40-50 feet after exhaling and finding no more air to be had, considering must keep exhaling to keep airway open and prevent barotrauma. How can this be safely practiced? Any tips on this scary possibility.

My first week of diving I ran out at 60 ft. 'cause I had to chase by buddy to 140 ft. I put my hand straight up (to push boats out of the way, lol) and made a slow ascent blowing bubbles all the way. Naui instructor taught that and it worked rather well. Stay relaxed.

 

[wpscortland]

Thanks to all for the great info!

 

[Vengro]

It seems like the question was answered, but now I'm confused. What's the difference between exhaling all the way up and simply keeping your airways open? How can you tell if your airways are open or not?

 

[Uncle Pug]

Hmmmmm.....

 

[jbd]

It seems like the question was answered, but now I'm confused. What's the difference between exhaling all the way up and simply keeping your airways open? How can you tell if your airways are open or not?

Exhaling is an "active" endeavor i.e. you are "forcing" air out. With a relaxed but open airway you simply do nothing. The air comes out on its own.

Charlie99 has some good advice in doing this first thing first dive, quick descent to minimize N2 loading. Go slowly. No need to race to the surface.

Start with shallow depths 15 to 20 feet and follow the other procedures as given by reefraff and Charlie99. Training and practice are good things but make sure its done as safely as it can be done.

 

[Vengro]

When I was taught about the emergency ascent, my instructor told us to follow our bubbles up, and never go faster than the bubbles, which actually did help. I guess I'd have to try it myself to understand. It seems hard from my perspective to imagine it, because either the air is going out, or I'm not breathing and it feels like I'm holding my breath, which is never a good thing while scuba diving.

Thanks for the answer, though.

 

[Uncle Pug]

Vengro:
1) Don't ascend at the same rate as your bubbles... as they grow in size because of reduced pressure they speed up.

2) Place you hands crossed flat on your sternum, take a deep breath and with your mouth still open compress your chest sharply. Did a huff of air come out of your mouth?

Now close your airway after taking the deep breath (you can leave your mouth open... just *hold* your breath) and repeat the chest compression. Did a huff of air come out of you mouth?

The difference is between holding your breath and holding your lungs at full inhalation with your airway still open.

 

[ScubaDadMiami]

As noted by SeanQ the air that is in your lungs will expand as you ascend. One of the the problems with the way this skill is taught, is that people are taught to blow bubbles i.e. exhale. They are taught this when they are asked to swim the length of the pool or some other set distance while the instructor watches to see that there are bubbles coming frmo their regulator. The only way bubbles will come out, when you are not ascending, is to exhale. This is the wrong concept.

When doing one of these ascents you do not need to exhale. You simply need to let the expanding air out. All that is needed is a relaxed, open airway and the air will flow out on its own. If you are asending quickly you will almost feel like you are choking on the escaping air. The ascent shouldn't be this quick though.

This is the answer.

 

[ScubaDadMiami]

It seems like the question was answered, but now I'm confused. What's the difference between exhaling all the way up and simply keeping your airways open? How can you tell if your airways are open or not?

Let's talk about how this feels in comparison with some other feelings you already know about:

First, when you do a breath hold dive, you inhale, close off the airway and then descend, etc. To check the feeling of closing off the airway, while not diving--like right now--after taking the breath, if you tighten your abodomen and rib cage muscles like when you are straining to lift something, you can feel air being forced against the closed off airway but it will not escape. You can actually feel like your throat is closed off and you can feel the pressure trying to force the air against it.

Next step in the progression: if you are blowing up a balloon, you take a breath, constrict those same muscles and exhert yourself to push against the force of the balloon, filling it. You have now done as before but you have not closed off the airway.

Next step: Take a nice deep breath, again while not diving--this is just to get the correct feeling of what it is like to do this properly. This time, after filling your lungs, do no push the air out; just let your lungs do what they might without pushing the air out. You will notice that a fair amount of gas is exhaled out of your lungs without forcing it out.

One last exercise: do the same thing again: fill your lungs. Then, relax them and let them drain on their own. Once this stops on its own, then start pushing the exhalation a bit (like blowing up the balloon) just to get the feeling of where the natural expulsion of gas stops and your controlled exhalation starts. This serves no diving purpose other than to get in touch with your feeling of when you are pushing and when you are not. You do not actually do this when diving during an emergency swimming ascent.

Now, you know all of the feeling of doing it right versus when you are forcing (even gently) gas out of your lungs. Just like the exercise you did where you took a deep breath and then relaxed, letting the gas escape on its own without pushing, that is how you want to be during the ESA. This way, you keep any potential oxygen for exchange to your body in your lungs during the ascent but do not get a lung overexpansion injury.

Last, go out and practice in about 30 feet of water with an instructor and under the instructor's guidance. You will really feel the gas expanding and leaving your lungs during the last ten feet or so during the ascent. Once you feel it actually happening, you will get it. It is a balance between ascent speed control, so that you can make it to the surface, and allowing the existing gas to expand so that you don't feel like you are running out of breath.