CESA from 100 feet?

[String]

picking on ya...

I bet the DIR crowd have that photo somewhere as what not to do

I cant really leave any of the kit except camera behind on a dive and have nowhere to stow the stuff properly so its clipped to d-rings. The pockets have long since broken (but too small for anything to fit in anyway).

 

[jepuskar]

Gary,

I read your disclaimer and I also read that it possibly may be ok to hold your breath between 600 and 400 feet. The reason I even commented on it was because I was hoping you would come back and say something like holding your breath while ascending is never a good idea, but hypothetically..........etc etc

It's just not the type of thing I think should be out here for people to read, thats all.

 

[Doc Harry]

Its CO2 level that causes the breathing reflex not oxygen lack. This is why issues such as shallow water blackout are a problem for free diving and snorkellers if they purge their lungs too much before diving.

Actually, there is both a hypoxic drive and a hypercarbic drive to breathe.

The hypercarbic drive is definitely dominant in most people, as mentioned previously.

hypoxic = low oxygen
hypercarbic = high carbon dioxide

--

 

[Gary D.]

Gary,

I read your disclaimer and I also read that it possibly may be ok to hold your breath between 600 and 400 feet. The reason I even commented on it was because I was hoping you would come back and say something like holding your breath while ascending is never a good idea, but hypothetically..........etc etc

It's just not the type of thing I think should be out here for people to read, thats all.

Your right about breath holding but thats why I went so deep. A rec diver trying for 600' would have a bigger problem and most likely wouldn't have a chance to worry about holding their breath. Deep divers outside of the rec world will, or at least should know better.

I just used an example that was more realistic than balloons.

Gary D.

 

[Schizlor]

Actually, there is both a hypoxic drive and a hypercarbic drive to breathe.

The hypercarbic drive is definitely dominant in most people, as mentioned previously.

hypoxic = low oxygen
hypercarbic = high carbon dioxide

That is true, but for all intents and purposes the hypoxic factor in breathing-reflex can be thrown out, because it is possible for someone in a hypocarbic state to lose consciousness due to hypoxia without ever feeling the urge to breathe. Since your brain will go "lights out" due to lack of oxygen before low O2 levels in the blood trigger the urge to breathe, in a practical sense the hypoxic influence on the breathing reflex is negligible.

Now, I'm not a doctor (and I just noticed, you are) but I'd infer the same effect comes into play when doing a CESA (which I have never done) Whereby the fact you do not feel the burning need to breath even on a 1-2 min ascent, has little to do with the O2 remaining in the volume of gas in your lungs, and everything to do with the off-gassing of CO2 via exhalation on ascent as it is continuously discharged from the blood into the lungs.

Does that jive?

 

[Doc Intrepid]

************* MOD POST **************

New guys - check dates of threads.

This one, for example, was last posted to in July, 2005.

So Schiz - you're getting involved real late in a conversation that occurred about four years ago.

Try not to bring Dead Threads back to life!!

We'll all thank you for it...

(And oh by the way - welcome to ScubaBoard!)

Doc