How can you tell if you are hypoxic?

[blueface]

Is there a certailn feeling you get after a deep dive or long breath hold that is recognizable?

I once did a 22 meter dive and it lasted 2:14 seconds. I was on the bottom waiting on a mangrove snapper that ended up swimming away. I started up to the surface and a jack came in so I dropped back down (stupid I know) and waited a bit and realized that I needed to get up.
After surfacing I exhaled and had tunnel vision and then lost vision for a second. I felt tingling and then a powerful head rush like I stood up too fast. It was very frightening. I could hear my partner talking to me. He said, "Are you alright?" and I responded, " I'm fine but I can't see." and then the rush.
Needless to say I went back to the boat and spent the next few trips in less than 10 meters.

If someone could explain what I experienced I would appreciate it. This happened several years ago and I am surprised that I didn't post something earlier. Maybe I was just tooo ashamed.

Thanks!

Skip

 

[BennyB]

Hi Skip,

I would say what you had was a blackout. During a blackout it's not uncommon for your sight to be the first thing to go and the last thing to come back, so when you say that you heard everything, and you said "i'm fine but I can't see", plus all the other symptoms you describe sound like a textbook blackout, or at least so close to it that you were on the borderline of a blackout.

A couple of things - when you surface take a big inhale, hold it for for a flash second then release it passively, ie. don't forcefully exhale. This is called a recovery breath. A full forced exhale when you surface will change the pressure and increase the chances of blacking out.

Second thing - don't let a bloody fish dictate your dive patterns!!!! If you see a fish when you're returning to the surface then that's way too late to be thinking about that fish, you need to surface, recover, breath up and dive again giving yourself ample time for each part. As they say, no fish is worth dying for.

Glad to hear you had a buddy there with you - remember a buddy is not someone you dive with, it's someone committed to make sure you're safe in the water.

Very glad you're still here and sharing your experiences with us. It can be a bit intimidating and shameful, but we all learn from it. Thanks!

Cheers,
Ben

 

[blueface]

Thanks for responding! Jupiter-No, I didn't samba (according to my partner) nor did I loose control of my body as far as I could tell. I remember touching my mask to see if something was covering my face.

BennyB-yes I agree with you on all points. Having an attentive partner is great. He was less than arms length away when I surfaced. That's how we dive. There are just too many deaths. There were two in November last year!

I don't remember if I felt contractions or air hunger.

Skip

 

[bite ya]

Blueface, you dont need to feel contractions or any urge to breath to have a black out. I can say that from experience. When it happens it happens without warning. Again well done for having that all important safety!

 

[Lazuli]

I've never had an SWBO, but I've had a syncope. Both seem to be hypoxic events. I cannot imagine thare is that much warning, certainly not enough to reason "Oh gosh, I'm in deep sh##t, better breathe NOW!" A syncope often switches you off - instantly and without warning, like the flicking of a switch in real time. On dry land you are out before you even hit the floor. SWBOs (or other BOs) seem to have something in common with syncopes - you may remember seeing stars or a bright light, but thats only if you wake up to tell the tale. Grim but true.

 

[Bill]

'If someone could explain what I experienced I would appreciate it'

One of the problems is time distortion. Your memory is erased from about seven seconds before black out until you wake up. This is 'stored' as a zero time interval. Often memory says everything was going well, then a short pleasant dream and opening your eyes to see concerned faces asking if you're OK, with ten seconds or more missing.

Sounds like you came very close.

 

[azapa]

I had my first very short samba/BO three weeks ago at a static comp. It was very safe and everyone was fine. The video is a treat!

Completely coincide with Bill in that I lost about 5 seconds of memory.

I removed my nose clip fine on exiting my airways, but "forgot" to breath. My colleagues took 30 seconds to convince me to breath again, easy to analyze because as I said, the whole thing is on video. I had over ventilated before the hold and new it was a 50/50 risk. I'm glad it happened and in such safe surroundings.

In a spearing scenario, on the way up on a long dive, you will get leg burn. Did that happen to you? Or do you always have burn?

I would say that if you always have leg burn you are always a little too close. The big problem in that as we advance as freedivers all the bodies very well placed and timed signals can be pushed aside, especially when there are fish around or PB's to beat.

Take care.

 

[efattah]

Blueface,

I have experienced what you did, many times, and you were certainly right on the edge of disaster. That's the important thing to realize.

I have had full blackouts as well as the momentary type you describe -- the dividing line is very thin.

 

[trux]

The problem is that many freedivers mistake hypoxic signs with hypercapnic, or with the effects of diving response. That's why it is quite useful training separate hypercapnic and hypoxic tables, which will teach you better understanding the body signals.

So for example urge to breath, lungs burn, or diaphragmatic contractions are primarily driven hypercapnically (by the level of CO2), and they tell you nothing about your oxygen levels. They depend on the level of previous effort, on the ventilation, on the surface time, diet, and some other factors.

Finger or extremities tingling, blood rush, heat waves can be signs of hypoxia in medical conditions, but when freediving, they are rather signs of the Diving Response working correctly, and actually tell you that you are in the oxygen saving mode, which means you can in fact hold longer than without it.

Blood cyanosis (getting bluish) is also not a good way to guess your state - in fact people with high hemoglobin will get bluish very early in the breath-hold, while anemic people can easily black out without the slightest sign of cyanosis.

Leg burn means your muscles work in anaerobic mode, and produce lactic acid. That's usually also the consequence of a profound diving response (namely the vasoconstriction). It does not mean the brain tissue is hypoxic and that you are close to BO - quite in contrary, it may mean the muscles won't consume the oxygen the brain so desperately needs.

So what are the real hypoxic signs, do you ask? Fading or tunnel vision, and other cognitive disturbances, problems of logic and short term memory, poor judgment, decreased motor control, or sometimes euphoria. However, sometimes when you feel the symptoms, it may be already too late (especially because when hypoxic you have poor judgment anyway), so diving in safe conditions under the watchful eyes of experienced and trained buddies is the only way to handle it properly.

 

[blueface]

Thanks for all the responses guys! I am so greatful.

I usually don't get much lactic in the legs and I dive totally different now than at the time of the above incident. I was too negative (over-weighted) and I had to work hard to get up to the surface. Now getting up is a breeze. I've been practicing duck dives and beign more efficiant getting down to the static phase and it's working. I can go to 20m on a full breath with no weight at all and be very comfortable. I add weight only to compensate for the buoyancy of the wet suit.

Thanks!

Skip

 

[sgnips]

I removed my nose clip fine on exiting my airways, but "forgot" to breath.

one of the most important things is LEARNING TO BREATH after the hold: i always try to breath in the right way (something like the one explained above by BennyB) even after a 10 seconds hold
i'm used to this and i'm almost sure i will do the same if ever i come out from a hard dive

 

[blueface]

'If someone could explain what I experienced I would appreciate it'

One of the problems is time distortion. Your memory is erased from about seven seconds before black out until you wake up. This is 'stored' as a zero time interval. Often memory says everything was going well, then a short pleasant dream and opening your eyes to see concerned faces asking if you're OK, with ten seconds or more missing.

Sounds like you came very close.

Wow Bill! That sounds so scary. I had no pleasant dream or a loss of memory or time gap. I just lost sight and big head rush like I have not felt before. I know that it was the closest I've ever been to a blackout. One could argue that it was a blackout I guess.

Whatever happened was my fault and I have to live with it and be thankful that I survived and learned from it.

Thanks!

Skip

 

[waxlips]

i blacked out before and dreamt weird stuff. like being in an avatar sequel or acting silly(in my dream) pretending to be a scary monster and my dream dad saying to quit acting so stupid. they are fun so sometimes in bed i just hold my breath until i fall asleep and have amazing lucid dreams that night. i should tell the lucid dream site about this technique(i am a member of ld4all) but this is no ad so don't go there unless you really want to. it has very little to do with most of this site's content(unless you dream of freediving).

 

[blueface]

i blacked out before and dreamt weird stuff. like being in an avatar sequel or acting silly(in my dream) pretending to be a scary monster and my dream dad saying to quit acting so stupid. they are fun so sometimes in bed i just hold my breath until i fall asleep and have amazing lucid dreams that night. i should tell the lucid dream site about this technique(i am a member of ld4all) but this is no ad so don't go there unless you really want to. it has very little to do with most of this site's content(unless you dream of freediving).

Can you really induce a lucid dream by blacking out? That would be interesting. I just hope it's not one about Saint Peter welcoming you. LOL!

 

[waxlips]

yes u can but what i do is making me start to forget things while i'm awake such as my mom's name one day...that was terrifying. i don't do it as much anymore since that happened.(i remembered it again its kim but that day it just would not come to me).

 

[nostres]

yes u can but what i do is making me start to forget things while i'm awake such as my mom's name one day...that was terrifying. i don't do it as much anymore since that happened.(i remembered it again its kim but that day it just would not come to me).

I wouldn't worry about my mom's name, I always call her "MOM" anyway But if I forgot my wife's name I'd be in deep trouble...

 

[Siku]

i blacked out before and dreamt weird stuff... sometimes in bed i just hold my breath until i fall asleep and have amazing lucid dreams that night.

Careful! If you are deliberately inducing black out you could be cognitively conditioning yourself to black out in response to certain signals (e.g breath hold) way before hypoxia forces black out.

I've heard that a certain diver can't dive ropes in competitions anymore because, after many blackouts in just this situation, his body has been trained to black out immediately! (And a VERY high level free diver too. Don't want to name as it's just here say).

 

[azapa]

Siku. Thats is half true, not proven. I know many divers who black out very frequently but seem to have no problems at world level efforts.

To be honest I was quite pleased with my blackout. I was always worried about what it would be like, but once I had one in safe conditions (great safety), the fear went.

 

[Siku]

I'm not saying he blacked out frequently, undermining competitive efforts. I'm saying he blacked out at competitions leading to cognitive programming that made it more likely he would black out IN THE SAME SITUATION, i.e. with similar stimulus.

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[Simos]

his body has been trained to black out immediately

Immediately? Sounds more like a packing blackout to me

Obviously I've heard the same thing too Tom but not to THAT extend i.e. black out immediately. Doesn't make much sense to me but of course that doesn't mean it can't happen! If it can happen to that extend, it sounds like it's more like some internal system/mechanism gets screwed rather than classic conditioning...