pass out from light headedness

[speargrub]

Hey all , just wanting to get a bit of feed back on something i experience from time to time. Ive been spearfishing for a little while (8 months or so) and have just started doing some apnea training with CO2 and O2 charts. After a while of slow breathing relaxing i have been anle to hold my breath for around 2:45 (just for reference). The issue is if i hyperventilate a bit before holding my breath, say about 3 breaths in and out when i do hold i get very light headed and my vision starts to go slightly. In the past and occasionally still i will get up to fast feel the lightheadedness come over me and then pass out for a few seconds and have a little fit on the ground. I have talked to people about this once or twice and i know that i experience this more often than others. So the question is do other people reading this get the same about to pass out feeling after just a few deep in out hyperventilating style breaths? and would anyone know a reason why i experience full black out some times (this happens very rarely, maybe only a few times a year on average). cheers

 

[Antoine]

There are HEAPS of threads about hyperventilation, vasoconstriction and the light-headedness which results so if you ant to know more have a quick look around and you'll have no problem finding information

I'll give you an overview. When you do breath-ups, also known as hyperventilation, you are increasing the O2 levels and decreasing the CO2 levels in your bloodstream.
This occurs when deep-breathing and purging when air which is richer-than-normal in oxygen is circulated in the lungs. Normal outside air is approx. 21% oxygen. Normally, in your lungs, due to rebreathing 'dirty' air which has not been properly exhaled, oxygen content is as low as 16%. When deep-breathing, more 'fresh air' is circulated in the lungs and therefore oxygen levels can reach as high as 20%. The alveoli absorb these unusually high levels of oxygen into the bloodstream. Simultaneously, when you purge(deep exhale) you get rid of a maximum amount of CO2 thus significantly lowering the CO2 levels in your bloodstream.

Okay, that was easy physics. Now comes the chemistry! When dissolved in water in the blood, CO2 makes carbonic acid - a weak acid. During hyperventilation, since the CO2 levels decrease significantly in a short period of time, the CO2 dissolved in your bloodstream reduces relatively quickly as well. This in turn decreases the amount of carbonic acid in the bloodstream and thus increases it pH as it becomes more alkaline.

Take a moment to wipe the sweat off your brow!

Now for the biology! The bloodvessels in your brain actually react to a change in pH. Since a high pH translates to low CO2, the vessels constrict in a phenomenon known as vascoconstriction, to restrict the bloodflow. This becomes logical when considering the converse. A low pH means high CO2 so the vessles expand to let more blood flow around the brain to compensate for the fact that the blood has too much CO2 dissolved in it.

Okay. well done if you've readup till here! Since the vessels have narrowed, less blood in flowing around the brain and that gives you that dizzy feeling.

This light-headedness differs for each person. Just about everyone feels it to different degrees after hyperventilating. After three minutes of deep-breathing, most people will no longer be able to stand, read, or even comprehend people speaking. It can feel very strange and wears off only after discontinuation of the hyperventilation. Some people are very sensitive to a raise in pH of the bloodstream, as you seem to be, and therefore can pass out after only a few deep breaths. This is not abnormal and usually improves the more you hyperventilate(not recommended!!!). Black-outs aren't theoretically very dangerous if all your airways are open and you are lying on soft ground. However, although I myself have passed out a couple of times hyperventilating and I have seen other people passing out doing so, I have never experienced or seen anyone having a fit during a blackout.
The fact that you say you feel the light-headedness come over you when you get up makes me think you may have low blood-pressure. I won't explain why coz i'll go on another rant!

REMEMBER. Hyperventilation is dangerous and gives you a false feeling of security when doing apnea. It is very easy to black out during hyperventilation and also have a shallow-water black out during a dive. Also, contractions will come more suddenly and much harder after having hyperventilated.

Sorry about the rant but I hope this helps!

GO New South Welshmen! Btw, where do you dive?

 

[Simos]

You need to check it out with a doctor - what you are describing is not normal (taking 3 breaths and then getting light-headed and having a fit on the ground) and I don't think is necessarily related to hyperventilation (which you shouldn't do anyway).

Get a check up on things like blood pressure etc.

Also, if you are packing or filling your lungs to the max, try to take in a bit less air to avoid putting pressure on your heart and obstructing circulation...

 

[speargrub]

Thanks Antoine, that was a great little read really interesting and informative, i had no idea blood pH would have anything to do with it. Its great to gain an understanding of something down to a base level like you have just explained. I had also considered low blood pressure as a cause however when ever i have been to the hospital and had my blood pressure taken ( not something i do a whole lot) i have never been told that i have low blood pressure. And thanks for the info Simos, yeah as far as the fits go i think what it is, is losing and regaining consciousness inermittently very quickly and my muscles trying to take up the same position as they were in (thats what it feel like), i can feel it coming on and only occasionally will lose consciousness and then only for a few seconds (like i said though this is a pretty uncommon thing to happen). Perhaps i will go see a GP. And i live in Ballina Northcoast NSW. Cheersguys

 

[Antoine]

No probs man I do think you should get it checked though, coz as much as I love chem and bio I can't explain that very early onset of dizzyness.

 

[BennyB]

Were you standing, seated with inclined (eg couch) or lying down?

Were you packing?

Hyperventilation is very different from person to person. I can crazily blow my air our for 2 or 3 minutes and barely have a single symptom, yet if I blow up a couple of balloons i'm a space cadet. Other people can take 3 or 4 breaths and start getting light-headed.

Cheers,
Ben

 

[Antoine]

What I find weird is the fact that the light-headedness comes over you as you gets up, logically meaning that as you get up, blood is draining away from your head - that doesn't sound normal.

 

[Simos]

What I find weird is the fact that the light-headedness comes over you as you gets up, logically meaning that as you get up, blood is draining away from your head - that doesn't sound normal.

That's usually a common sign for low blood pressure. Especially at the end of a hold when the blood pressure drops, if you stand up immediately (you shouldn't) you risk passing out. Hence why you shouldn't stand up right away and also, especially if you have low blood pressure, hook breaths should help.

 

[FreeRestriction]

Im pretty certain standing up too fast can make people light headed. You hear people say it all the time "woah i stood up too fast". But they dont pass out typically. Perhaps low blood pressure makes you pass out but i dont think getting light headed when standing up means low blood pressure by itself.

 

[Simos]

Im pretty certain standing up too fast can make people light headed. You hear people say it all the time "woah i stood up too fast". But they dont pass out typically. Perhaps low blood pressure makes you pass out but i dont think getting light headed when standing up means low blood pressure by itself.

Getting light-headed or dizzy means typically that your brain is not getting enough oxygen - obviously the next step is to pass out.

In a 'normal' situations, as far as I know, your body tries to compensate in other ways (e.g. higher heart rate etc) to maintain the supply to the brain and keep the BP high to avoid light-headedness. Also in most 'normal' situations, even if there is some temporary light-headedness and drop in BP, it is usually not enough to make you pass out and your body recovers.

After apnea, the blood pressure drops and if you combine this with standing up right away (mostly in pools) then you can get into shaky ground. Your body is already oxygen starved so it's not as easy to recover so combined with the low BP it can result to a BO.

I've seen this happen in practice so it's not some far fetched scenario that never happens...

 

[Antoine]

I have occasionally felt as though I was going to pass out standing up too fast after having been lying down on the beach in the sun - probably a combination of heat-stroke and bloody draining away fro the head whilst standing up.

Usually, quickly ducking back down does the trick(and getting out of the sun). I have never actually BO though.

 

[wjohnson100]

Breathe up does not necessarily mean hyperventilation. As an example, my breathe up for my first warmup hold is 3 minutes of normal breathing, followed by 3 about 50% purge breaths in about 15 seconds, no packs, and then the hold. The 3 purge breaths may or may not be excessive hyperventilation, but the 3 minutes of normal breathing is for sure not hyperventilation. I have done up to a 5 minute static on that breathe up. My normal first warmup hold is 4 minutes on that breathe up, but lately thinking of increasing it to 4:30. My point being that I don't do any particularly special breathing for this other than the purge breaths. Interestingly, I do no full exhales at all in this process, only relaxed exhalations to Functional Residual Capacity, even on the final breath.

You, however are standing during a period of cerebral vasoconstriction caused by hyperventillation, so you are passing out - no big news there. First thing you should not be doing is standing up after hyperventilating. Second is to not hyperventilate.

 

[Simos]

Breathe up does not necessarily mean hyperventilation. As an example, my breathe up for my first warmup hold is 3 minutes of normal breathing, followed by 3 about 50% purge breaths in about 15 seconds, no packs, and then the hold. The 3 purge breaths may or may not be excessive hyperventilation, but the 3 minutes of normal breathing is for sure not hyperventilation. I have done up to a 5 minute static on that breathe up. My normal first warmup hold is 4 minutes on that breathe up, but lately thinking of increasing it to 4:30. My point being that I don't do any particularly special breathing for this other than the purge breaths. Interestingly, I do no full exhales at all in this process, only relaxed exhalations to Functional Residual Capacity, even on the final breath.

You, however are standing during a period of cerebral vasoconstriction caused by hyperventillation, so you are passing out - no big news there. First thing you should not be doing is standing up after hyperventilating. Second is to not hyperventilate.

Makes sense of course but on the other hand, as you said, 3 purge breaths are not necessarily a huge amount of hyperventilation.

Empirically, I find it a bit odd to pass out as a result of this - I've been doing 3 purge breaths since I started freediving (and at times more) and I never had this issue, even remotely.

Also many others have been doing 3 purge breaths and again I've never seen any issues like this at the beginning of the hold.

Anyway I guess it varies from person to person and also 'purge breaths' can be anything from normal breaths but a bit faster to super deep breaths.

Also, very importantly, the three purge breaths are often... not three lol

 

[wjohnson100]

One thing you will find in your training is that the response to various things, in this case purge breaths, varies not just from person to person, but also in you from one time to another. At one point in my training I was having a similar problem. During my statics, I kept feeling like I had not gotten a full breath. I videoed most of my big holds, so I watched the videos to see if there was anything I was doing. I saw that I was exhaling slightly at about the 30 second point in many of my holds. I wasn't doing that intentionally, so I must have been blacking out, however briefly. These exhalations did not stop my breath holds. I kept going, not even knowing what happened. Once I knew I was blacking out and when. I had to reduce my breathe up to prevent its recurrence. Eventually the problem went away, and I have not had it since.

In your case, there are things you can do, such as reducing the number of purge breaths and slowing your breathing before the purge breaths.

 

[speargrub]

Thanks for all the feedback everybody. Sounds like what i get is just a normal thing but perhaps a bit more extreme than most (which is the way if always thought about it). I reckon there must be some underlying reason for it so i think i will try to sort the issue out by process of elimination, starting with going to get my blood pressure checked, and chating to a gp then going on from there.Cheers