Dangers of dry apnea

[trux]

Well, we (hopefully) all know how dangerous diving alone is, what the risks are, and that we never should dive alone. Unfortunately, most of us dive sometimes alone anyway. Reasonable and experienced freedivers do not make performances and records-breaking attempts in such situations, but diving alone still costs tens of lives yearly. However, I do not want to discuss this topic - it is often discussed here and elsewhere, the problems are well known, and it is unlikely that the situation changes any soon.

Instead of it I am looking for information about risks of dry apnea training. Generally it is considered as a safe practice, and I guess that practically everyone who does it, does it alone. The problem is, that since people consider it a safe practice (unlike at wet apnea training alone), they do not hesitate to go to (or over) their limits.

I wonder now what happens in such case, when one experiences blackout during dry apnea training? Does he recover without external help? Are there other risks associated with dry apnea that are not acute when training wet? Did anyone of you experience a BO during dry apnea training? Are there any articles, medical research documents, AIDA rules speaking about dry apnea training and associated problematic? If so, please post links and/or your comments.

Thanks,

 

[naiad]

There are some threads on this...
[ame="http://forums.deeperblue.net/showthread.php?t=52899"]Risks doing dry statics alone?[/ame]
[ame="http://forums.deeperblue.net/showthread.php?t=25316"]Are dry statics considered dangerous?[/ame]

I have experienced blackouts during dry apnea training and recovered without external help. (I'm still posting here, so my training can't be too bad ) It has only happened very few times considering that I have done hundreds of dry statics alone, including many max attempts.

I don't recommend solo training because I can't be certain of the risks.

Lucia

 

[SEDATE]

I have experienced blackouts during dry apnea training and recovered without external help.

I don't recommend solo training because I can't be certain of the risks.
Lucia

Lucia
This is good thread..
you remember breath up cylce or you remember HV cylce before big hold.?
i do 3 times slow hiperventilation just before big hold and pay attantion to leave enough CO2 cancelling doing full exale before big hold, For ''3 HV'' i beg ''full exale'' to my body..
cos' i know it is a trigger i respect it, not sure but the sensor( reseptors on face) are not working at home very well but it works in water very well i mean maybe 10-15 HV may one BO not sure.. i only heard that tom sieatas had BO while holding breath in basin.. i am just beginner my PB 5:50 ..i want to know what waiting for me..i love holding breath, i can't resist it, very sedative..i like it! who discovered it i thank to him/her

 

[trux]

There are some threads on this...
http://forums.deeperblue.net/showthread.php?t=52899
http://forums.deeperblue.net/showthread.php?t=25316

Excellent! Thanks, Lucia. I was sure it had to be discussed already here, but I've been looking for similar threads before posting, without success. Apparently I did not search deep enough. I am going to read these threads now.

 

[TNdiver]

I would always do it laying down either in bed or on the floor, that way if something happens you cant fall. But also, realisticly, i highly doubt many people if any can hold their breath to the point of blacking out with out TONS!!!!!!! of training to increase CO2 tollerance. I have read that some people here (efattah i think is one of them) can hold to the point of BO at will, but i dont think that is anywhere near possible for the normal person. If im wrong there someone please correct me. Anyway, it seems to be generally accepted here that dry statics, in a possition that prevents falling injuries, is more or less safe. I say more or less, because i know a guy who fell out of bed during the night broke his neck and was paralized, so nothing it completely safe, but i dont see any real chance of anything bad happening with dry training.

 

[efattah]

After many dry blackouts, I would recommend that if you plan to push a dry breath-hold to the limit, then do not use a nose clip or mask. I sometimes use a nose clip for dry static (to simulate wet static), but I think that this is a bit dangerous if pushing to BO.

After blacking out, your body will try to breathe through your nose (primarily). If it is unable to breathe through the nose, then I think that recovery is not 100% certain.

 

[naiad]

I would always do it laying down either in bed or on the floor, that way if something happens you cant fall. But also, realisticly, i highly doubt many people if any can hold their breath to the point of blacking out with out TONS!!!!!!! of training to increase CO2 tollerance. I have read that some people here (efattah i think is one of them) can hold to the point of BO at will, but i dont think that is anywhere near possible for the normal person. If im wrong there someone please correct me.

I certainly can hold my breath to the point of blacking out, and it has happened during dry statics a few times. Of course I try to stop before that happens.

I almost always do dry statics on the bed, so there's no risk of impact with a hard surface.

I don't use a mask or nose clip for dry statics.

 

[BennyB]

For me, the biggest danger of dry apnea is boredom. I can't stand them at all, everytime I try and do them I usually bail out at 2 min, because in that 2 min i've found a thousand good reasons not to do it.

I've recently discovered apnea walking, which is interesting in it's own right. Didn't think much of the concept originally but now that I walk home from work 3 days a week it's growing on me - why wait 2 minutes in bed for contractions when you can get them in 10 quick paces!

 

[TNdiver]

I wasn't trying to take anything away from anyone else, Eric was just the only person i could think of off the top of my head that i had read about. If anyone took offence i apologize for the misunderstanding. I'm sure there are many people here that can, i just meant that I didn't thing a beginner would be likely to be able to go that far.

 

[trux]

Even beginner can go easily so far. It is sufficient that you hyperventilate and you can black out without even feeling any discomfort and without feeling it coming. Many people do not even realize that they hyperventilate, so it is not so unprobable.

And if you are packing, you can black out at the beginning of the apnea due to the packing (not a hypoxic BO).

 

[naiad]

TNdiver, I didn't take offence, I just wanted to say that it can happen.

 

[TNdiver]

I had completely forgot about packing black out. Also kinda assumed that most people looking into dangers would have found atleast one or two of the hyperventilation posts... I guess we really shouldnt assume anything though. Anyway, thanks for setting that straight. I guess i did need corrected.

 

[Panos Lianos]

And if you are packing, you can black out at the beginning of the apnea due to the packing (not a hypoxic BO).

Sorry for being a little off-topic.

A packing black out is still a hypoxic black out. Think about it: Your heart can't push blood to the brain, the O2 in the blood that is already in the brain gets used up, brain detects hypoxia, black out.

So the main reason for the blackout is still Hypoxia detection, even though your lungs are full of O2. It's a kinda like having a car with a full gas tank, but having the gas line blocked so no fuel can reach the engine.

 

[trux]

A packing black out is still a hypoxic black out.

I am afraid this is oversimplified and possibly not quite exact. The limited blood circulation due to the pressed heart is possibly only one of factors at packing blackouts. According to many, the packing blackout is actually hypocapnic blackout (similarly as after over-hyperventilating), it means due to extremely low partial pressure of CO2. I am no medical expert to be able to tell that it is exact, but at least I wouldn't claim that packing BO is a purely hypoxic one. If you want to know more about "hypocapnic blackout", just enter the expression into Google, and you'll see that is is beeing associated with hyperventilation and packing. As I wrote, I am no medical expert, so maybe it is just an urban legend, and Panos is right, but so far I did not see any discussion denying the hypocapnic blackout theory.

 

[naiad]

But isn't a hypocapnic blackout actually a hypoxic blackout? Hypocapnia reduces blood flow to the brain, and makes it harder to use the O2 in the blood, so it still essentially a hypoxic blackout.

 

[trux]

Yes, the final mechanism may be as described, but it is more complex, therefore I do not think it is correct not to differntiate between hypocapnic and hypoxic blackouts at all. There are differencies, and that was certainly the reason for having the two terms.

 

[DiverTodd]

I experienced the interesting side effects of packing on Friday, at work....

I was a bit bored, covering register duty, so I decided to do a few packing stretches. I was having trouble getting the hang of packing, so I would practice it. I did a full inhale, sipped in more to the max, then pulled in around 5 packs, and started an intercostals stretching exercise, arms together over the head, then leaning to each side. As soon as I leaned, I felt the burning, pulling sensation of my VERY full lungs in my upper chest. HOWEVER...I was also overcome by a VERY powerful, light-headed, dizzy sensation, and I could feel myself starting to black out. I IMMEDIATELY blew out all my air and grabbed the register to stabilize myself. I guess I learned two things; 1. I've figured out packing, and 2. NEVER DO IT while standing at a register at work!

Todd

 

[SnuFPunK]

HOWEVER...I was also overcome by a VERY powerful, light-headed, dizzy sensation, and I could feel myself starting to black out. I IMMEDIATELY blew out all my air and grabbed the register to stabilize myself. I guess I learned two things; 1. I've figured out packing, and 2. NEVER DO IT while standing at a register at work!

I remember experiencing this when packing, sometimes this overwhelming lightheaded dizziness just seems overwhelming, I would usually try and stand it for about 15 seconds (count from 1000 to 1015) If it doesnt begin to fade away after that time then exhale.

~ Snuffs

 

[BennyB]

Packing blackout is not that uncommon. I won't try and explain the nuts and bolts of it as i'll more than likely get it wrong, but I can tell you that I am way more prone to blackout in an upright position rather than a lying down position.

My first packing blackout was at a hospital while doing some lung packing testing. I was lying up in bed and remember overpacking and feeling too much pressure, then "coming back" with a cardiologist and a scientist peering down on me asking if I was ok.

Second one was at the pool. Sitting cross legged, pack pack pack..... no more vision, could still hear fine, CRACK!!! head hurts, vision comes back, and my dive buddy wanders past, looks at me on my side and says "dude - you ok?" Apparently one second I was there, the next I was keeling over backwards.

My advice - don't pack standing up, sitting upright (without having support like a wall to lean on), or moving about. If you decide to anyway, wear a helmet.

Cheers,
Ben

 

[bubestube]

But isn't a hypocapnic blackout actually a hypoxic blackout? Hypocapnia reduces blood flow to the brain, and makes it harder to use the O2 in the blood, so it still essentially a hypoxic blackout.

Yes, the black out is caused due to brain tissue becoming hypoxic. However, what has caused the hypoxia there is a different story (essentially it is restricted blood flow to the brain tissue, caused by hypocapnic brain vessel constriction (hyperventilation) and/or restricted pulmonary circulation (due to high pressures in the lung if packing was involved) or, if combined (packing with hyperventilation) a bit from both).

efattah has summarized it nicely (http://forums.deeperblue.net/showthread.php?mode=hybrid&t=41422):

- Blackout. All blackouts are caused by brain energy failure, which is normally preceded by lack of oxygen. The lack of oxygen can be caused by:
1. Holding your breath too long
2. Too low CO2 = too much vasoconstriction = too little blood flow to the brain
3. Too much packing = crushed arteries = too little blood flow to the brain
4. Combination of 2 & 3 = classically called a 'hypocapnic blackout', although it is more a combo of somewhat low CO2, and somewhat excessive packing, although neither enough of each to cause blackout on its own

bube