How to identify pre blackout and safely avoid them

[ryan65]

Hi
I am pretty new in this , I have read alot on the net and even took lessons but still cannot say that I fully understand this.
What I would like to know is - is there any way to assure (or at least almost assure) that there will be no blackout. My teacher said that usually one can hold after diaphragm contractions almost twice as much as the time before they began, i.e if they begin at 2 min I can hold almost 4 minutes more however that seems like pushing it too far.
I understand that there arent always signs before blackout , that is why I am asking.

Is there any threshold that can can be considered SAFE once the contractions begin assuming I am not really trying to stretch to my fullest limits. I am just trying to learn what my limits are are without actually blacking out.
for example if they started after 2 minutes would it be fairly SAFE to hold another 2 minutes , assuming I can ?

Of course I AM NOT HYPERVENTILATING.
Thanks

 

[cdavis]

Given than there is so much variability among divers and within different situations for the same diver, assuring no blackout is pretty hard. There has been some discussion of limiting dives to 1 minute. For the vast majority of full lung divers, that should do it, but its a pretty severe limit. After that, have a good, attentive buddy. Most BOs occur after exceeding the divers obvious limits, but not all. I participated in one where the diver was apparently no where near his limits, not even close, little or no urge to breathe, nothing untoward. Scared the pants off all of us.

 

[ryan65]

Given than there is so much variability among divers and within different situations for the same diver, assuring no blackout is pretty hard. There has been some discussion of limiting dives to 1 minute. For the vast majority of full lung divers, that should do it, but its a pretty severe limit. After that, have a good, attentive buddy. Most BOs occur after exceeding the divers obvious limits, but not all. I participated in one where the diver was apparently no where near his limits, not even close, little or no urge to breathe, nothing untoward. Scared the pants off all of us.

Hey
Thanks for the reply. Pretty interesting what you mentioned at the end.
1 minute really sounds very very severe.
What about oxygen levels . if I use an oximeter in dry land , what saturation level is considered pretty safe ? I read about people reaching 40% but that sounds pretty borderline.
Thanks.

 

[esom]

Hi Connor, i recall this early BO case being documented in a thread - can you post a link please? Thx

 

[cdavis]

here is the link. One addition, Unirdna doesn't get much for contractions, seems to have a very high tolerance for co2.

http://forums.deeperblue.com/threads/bahamas-return-2009.83173/

 

[ryan65]

here is the link. One addition, Unirdna doesn't get much for contractions, seems to have a very high tolerance for co2.

http://forums.deeperblue.com/threads/bahamas-return-2009.83173/

That sure is scary.

 

[charlie.]

the best thing to do is just listen to what your body's telling if anything feels weird (tingling in your lip arms etc) get to the surface and always dive with a buddy.

 

[giddyuptiger]

In sta get my first contraction around 2 min of a 7 min breathhold. In dyn/dnf can first contraction around 45 secs into a 3:15-3:30 swim. Some variables to take into account that you're not addressing. How high is your heart rate at the time, how many breathholds had you done before hand, how long was your breathup, how relaxed are you. Cold/warm? You could go on and on. The most important thing is to be relaxed and take a long breathup. Then look for the signs, but honestly Co2 signs are much more obvious than hypoxic.

 

[Bussard]

Earlier this year I thought I had begun to learn what my pre-blackout signs where and how to avoid a BO, mostly learning to identify the sensations of full on Hypoxia.

That was stupid of me, as there are too many variables to take into account before each dive. How you breathe, how tired you are etc.. One evening on a routine training dynamic that wasn't usually difficult for me, I blacked out with no warning, full on BO followed by violent samba. No signs, no warning. That doesn't mean you can't sometimes feel it coming, you just can't rely on always knowing in advance.

 

[MarcinB]

Three out of four my blackouts occurred without a slightest warning. In one case there where obvious signs of hypoxia, nevertheless, I still blacked out because my mind was too dazed to be able to realize these signs as a warning. From my experience it seems that a no-warning blackout is more likely to occur after hyperventilation. Nevertheless, even if you feel that BO is coming it may not help you because you may not be able to think clearly enough to make the right decision on time.

 

[Apneaddict]

Earlier this year I thought I had begun to learn what my pre-blackout signs where and how to avoid a BO, mostly learning to identify the sensations of full on Hypoxia.

That was stupid of me, as there are too many variables to take into account before each dive. How you breathe, how tired you are etc.. One evening on a routine training dynamic that wasn't usually difficult for me, I blacked out with no warning, full on BO followed by violent samba. No signs, no warning. That doesn't mean you can't sometimes feel it coming, you just can't rely on always knowing in advance.

How far was the dynamic?

What % of your PB was this training distance?

 

[Bussard]

How far was the dynamic?

What % of your PB was this training distance?

I Bo'd seconds after turning at 100m, normally I can cranked out a good 15-20m more and still come up with a clear head.

 

[HLanger1955]

In statics I feel strong contractions after 2.30 or 3.00, and can go on another 2 min. I'm well aware when it is enough. In dynamics it is more difficult to guess where the limits are. I don't get strong contractions even pushing hard..I stop when feeling dizziness. Probably I' BO after some more seconds. Fortunately I didn't BO yet

 

[growingupninja]

Hey
Thanks for the reply. Pretty interesting what you mentioned at the end.
1 minute really sounds very very severe.
What about oxygen levels . if I use an oximeter in dry land , what saturation level is considered pretty safe ? I read about people reaching 40% but that sounds pretty borderline.
Thanks.

To be conscious with O2 at 40% could be possible with training but you would be rather useless--ie, dim/no vision, lack of coordination, judgement, probably unable to remember anything later, no feeling in arms and legs, etc. When I used to train alone dry dynamic tables with a pulse oxy meter I typically stopped any holds once my device read in the mid fifties, and for me, anything below 80% is very difficult and I am getting plenty of hardwired LOW O2 signals by then. 95% - 99% are fairly normal ranges. Very fit people frequently have a resting pulse oxy reading at the low end of normal, although when their respiration increases it should rise to 98%-99%. If you walked into a hospital and registered under 90%, they would immediately put you on oxygen and start running tests.

 

[Apneaddict]

I Bo'd seconds after turning at 100m, normally I can cranked out a good 15-20m more and still come up with a clear head.

Doesn't surprise me at all. I've seen well trained individuals black out unexpectedly / spontaneously at 75% of their routine max figures.

It depends by day, hydration, food, tension, heart rate, etc.

 

[Bussard]

Doesn't surprise me at all. I've seen well trained individuals black out unexpectedly / spontaneously at 75% of their routine max figures.

It depends by day, hydration, food, tension, heart rate, etc.

Yep, some blackouts are more telegraphed, but it's the ones that sneak up on you that you can't do much about, except have safety in place.

 

[Bussard]

the best thing to do is just listen to what your body's telling if anything feels weird (tingling in your lip arms etc) get to the surface and always dive with a buddy.

Those sound more like signs of dive response, which is a weird but good thing (prevents a BO)

 

[FjordDiver]

the best thing to do is just listen to what your body's telling if anything feels weird (tingling in your lip arms etc) get to the surface and always dive with a buddy.

I was wondering if anyone else experiences this? If I push it my legs tingle like they are going to sleep. I take it as a sign of low oxygen and surface immediately (usually it happens while surfacing).

On another thought. Why dont we just wear blood oxygen sensors? I have used small clips that you put on a finger and it registers blood pressure, heart beat and 02 levels

 

[FjordDiver]

I used the device in medical care, it wasnt waterproof

 

[cdavis]

My hands tingle when I am getting a good dive reflex. I take it as a good sign, not a sign of hypoxia