Does "shallow water blackout" really exist?

[snorklebum]

Frankly, I don't think so. But it's so accepted...lots of people seem to think that just BEING in shallow water is dangerous, or that you can only black out in shallows. Well, I've never experienced anything close to that, and neither has anybody I have ever known or talked to.
My biggest reason for thinking that this is just another PADI/NAUI myth is Underwater Hockey. When you spend thousands of hours around hundreds of people who dive repeatedly in pools--exerting to the max, pushing the limits of their breathhold, going down with shortened recovery periods, driven by competitive spirit--and NEVER see anybody pass out you have to wonder.
For those who haven't noticed, NAUI WAUI and such have a history of inventing problems and creating weird rituals, probably to protect themselves from any conceivable lawsuit.
But really, does this thing actually exist? Have YOU ever blacked out? How about it?

 

[Cliff Etzel]

You don't know what you are talking about

:naughty You evidently are lacking in your knowledge of diving physiology, where SWB is thoroughly documented, proven in controlled environments and is a measurable physiological response.

Since it appears that you haven't done any research before posting your question, please read the following information at these websites:

http://www.gulftel.com/~scubadoc/Freedive.htm

http://www.freedive.net/chapters/SWB3.html

http://www.mtsinai.org/pulmonary/books/scuba/gaspress.htm

I may come across as sounding irritated - and as a matter of fact I am. To post a conspiritorial question like this undermines the necessity of safe diving practices by planting a rediculous idea like this.

This forum is designed for intelligent discussion.

Please keep it as such...

 

[snorklebum]

Yes, you sound pretty irritable. No, I don´t think my question shows a lack of intelligence, as you were rude enough to suggest. I honestly ask why there is so much discussed (and generally second hand) about something I have never experienced nor had reported first hand from actual diving people. Again, the lack of such reports in Underwater Hockey makes me wonder.
I am leaving the question open to those less opinionated and self-righteous. Have you ever blacked out?
I am shocked that the editor of an open forum would be so snotty to somebody trying to get open information fromtheir forum. Maybe you are having a bad day.
Also, maybe you are a suba guy. Maybe there is something about tank air that causes such problems. Maybe its a psychological thing that comes from belieiveing all you hear in all those PADI courses. I don´t know. That´s why I am in here asking questions. If there is something wrong with that, you should say so up front, not flame people for curiosity.

 

[snorklebum]

By the way, upon looking into the links you posted I notice a lot of the following (apart from the fact that they are repetitive and seem to repeat a single source of information):
1--They seem to be talking about scuba and closed-circuit divers, not free divers.
2--They make a lot of use or implication of "interpreted as", in other words they are assuming that dead people died for certain reasons, then posing explanations.
3--Many of their tips are unrealistic. Should ocean spearfishers have a buddy standing by on the surface?
When you come up from 65 feet, should you try to avoid the last 15 feet before the surface?
4--You are at more risk in a swimming pool than in the OCEAN????

Im not sure what is going on here, but I have spend a lot of time diving repeatedly in water from a few feet down to 60 feet, doing it repeatedly, hyperventilating, spending all day out there, exerting strenuously while down (driving for the goal, chasing fish, fighting out of caves, etc.) and have not seen this phenomenon in myself of anybody else. It is not reported in the itnernational Underwater Hockey community. Forgive my questioning as to whether I am really at risk from this thing. And wondering what the explanation is. Im hoping some freedivers interested in training here will have some answers for me. Thanks.

 

[Cliff Etzel]

Freedivers who have experienced SWB

Here are a couple of the top freedivers who have experienced SWB:

Tanya Streeter (She told me about it occuring while in New Zealand while filming with a production company for National Geographic in a recent interview I did with her)

Pipin Ferraras (Had this documented in the new IMAX film Oceanmen on a recent unlimited deep dive attempt)

I am sure that others in the top echelons of the sport have had this occur as well.

They may not want to divulge this event occuring but it is a reality of the sport.

 

[hydro]

Hi Snorklebum,
Regardless of the fact that it hasn't happened to you -although you seem to have been pushing your luck a bit- doesn't mean it doesn't exist. If you keep pushing, it will happen and you will not need any second hand explanation for it. Just make sure you have someone there with you when it happens.
I notice two points of possible confusion in what you are saying. The first one is that shallow water black out happens when you swimm/dive in shallow water. SWB happens in shallow water after long and DEEP dives and has to do more with the decompression of the lung than the mere lack of oxygen after a long dive.
It also, appears that you base your judgement mostly on underwater hockey which is quite different from diving in terms of depth and pressure variability issues.
I have never been a scuba diver but I know SWB is very much a reality among us freedivers. Apart from personal experience, I have many friends who survived it and unfortunately, some who didn't. I understand your disbelief, I was diving for a decade before I heard about it myself. But I can also, sense that it can sound almost insulting to people who have lost friends and/or relatives because of SWB.
There is nothing unrealistic about diving in pairs. It is being practiced widely and has proved to be safer. If you ask, me it is more fun too.
Some looking around will give you plenty of information on the physiology and stats of SWB.

Dive to live
Hydro

 

[Erik]

SWB

?Como estas, snorkelbum? I understand your paranoia about the mass-marketing of scuba agencies,(Put Another Dollar In, Not Another Underwater Idiot, etc) but I assure you that blackout exists, both SWB ( on ascent from a breath hold) and Surface blackout, which is quite common among static competitions and training(at the surface). I have experienced SWB once, after I had reached the surface. I have experienced blackouts during breath hold attempts at the surface. They are not the worst experience, when you have someone there to hold your face out of the water. I admit that I dive solo a lot, but I am extremely careful, know my limitations, and accept the risk.
Underwater Hockey people might not be too willing to talk about close calls, etc, as it could bring the lawyers running, especially in the very litigious USA. Also, underwater hockey players are not really pushing their limits, compared to a performance fdiving attempt. Certainly they are working hard, but I've never heard of a player continuing to dive after 60 involuntary contractions of the diaphragm. The players that I've met couldn't hold their breath for 2 minutes. I am not belittling hockey players, so please don't take that the wrong way, it's just a different aspect of the sport, with different goals.
If you look at the Freediver.net list (subscribe), then you will hear lots of stories of blackout, some solo, some with buddies, and some tragic. Keep diving, don't bother with the tanks, and take care,
Erik Young

 

[Stephan Whelan]

Okay

Snorklebum,

Welcome to the Deeper Blue forums!

Firstly let me say that we do appreciate your candor in your feelings. I was wondering when someone who naturally challenges assumptions would come along into the forums and stir things up - and unfortunate side effect is your going to hit a few nerves along the way! These forums are just one example of the ease and speed people can reply, sometime before they have had time to examine what your really saying (and hence the term "flame war" came into being on the Internet!)

Anyway, to the matter at hand.

Let me first qualify that I am not a Freediver. I am an experienced Scuba Instructor, and have a strong interest in Freediving (so I hope that doesn't exclude me from putting my point of view across!)

OK - Shallow Water Blackout does exist, in the sense that there is a medical condition that can occur if the lungs suddenly expand (due to a pressure differential) and "suck" oxygen from the blood.

Does it exist for Freedivers - I believe so, enough cases have been documented on various internet resources and "major" stars such as Pipin and Tanya, that I think a court of law would most probably accept that it had enough proof.

Why does it strike more experienced freedivers? Well, novices tend to stick well within their limits...only once they have gained a certain confidence will they start pushing the envelope and thus causing potential hazards to themselves. Why does it happen more often in the pool than open water...well, most people feel more comfortable in 2 metres of water than 30 metres, this comfort probably induces a sense of safety, that may not necessarily be there, hence people push themselves too hard and cause SWB.

Anyway, again I thank you for your comments and questions...let's see how we can learn more from each other!

 

[Tom Lightfoot]

Hello Snorkelbum,

As a freediver and long-time underwater hockey player I just had to register and reply to this one.

Your confusion about shallow water blackout probably comes from the fact that it's a bit of a misnomer. It isn't shallow water that's the problem; it's the transition from deeper water to shallow water that is the most problematic. If underwater hockey were played in 30ft of water instead of 4-10ft, you would see a much higher incidence of SWB.

Like you, I haven't seen an SWB in underwater hockey in almost 18 years of playing. (Although I've come pretty close myself a few times) The reason for this ironically is that you're working so hard. The heavy exertion raises your CO2 level and thus the urge to breathe. Dive times are typically on the order of 10 seconds and very rarely over 30 seconds. Between the short dive times and the heavy breathing at the surface, your O2 level never gets dangerously low, even at the end of a big breakaway.

Freediving for depth, distance or time is much more dangerous because the diver will allow his or her blood gasses to vary much more widely. Being more relaxed, CO2 and the urge to breathe start off and remain much lower. A competitive freediver will also fight the urge to breathe much longer than an underwater hockey player and allow O2 levels to go much lower.

You also expressed doubt that freediving in a pool could be more dangerous than the open ocean. It's true, at least statistically. A pool seems save so people are more inclined to test their limits there than in the ocean. I've blacked out and had a few sambas in the pool but never in the ocean. (knock wood) Fortunately I had the undivided attention of at least two people each time it happened.

Dive safe and dive with a buddy.

Tom

 

[Cliff Etzel]

Re: Okay

Originally posted by Stephan Whelan
Snorklebum,

Welcome to the Deeper Blue forums!

Firstly let me say that we do appreciate your candor in your feelings. I was wondering when someone who naturally challenges assumptions would come along into the forums and stir things up - and unfortunate side effect is your going to hit a few nerves along the way! These forums are just one example of the ease and speed people can reply, sometime before they have had time to examine what your really saying (and hence the term "flame war" came into being on the Internet!)

Anyway, to the matter at hand.

Let me first qualify that I am not a Freediver. I am an experienced Scuba Instructor, and have a strong interest in Freediving (so I hope that doesn't exclude me from putting my point of view across!)

OK - Shallow Water Blackout does exist, in the sense that there is a medical condition that can occur if the lungs suddenly expand (due to a pressure differential) and "suck" oxygen from the blood.

Does it exist for Freedivers - I believe so, enough cases have been documented on various internet resources and "major" stars such as Pipin and Tanya, that I think a court of law would most probably accept that it had enough proof.

Why does it strike more experienced freedivers? Well, novices tend to stick well within their limits...only once they have gained a certain confidence will they start pushing the envelope and thus causing potential hazards to themselves. Why does it happen more often in the pool than open water...well, most people feel more comfortable in 2 metres of water than 30 metres, this comfort probably induces a sense of safety, that may not necessarily be there, hence people push themselves too hard and cause SWB.

Anyway, again I thank you for your comments and questions...let's see how we can learn more from each other!

I should publically apologize for my less than professional responses to this thread. I just find it disconcerting that this issue would be raised in light of the fact that SWB is a well known problem we as freedivers have to contend with in the backs of our minds as we dive.

I am not usually one who flames someone publically in such a forum, and my response was probably taken as such.

SWB has taken many lives and I feel very passionate about the topic.

 

[Cliff Etzel]

A response from a medical doctor on SWB

Eliot Light M.D. is a member of the 2001 U.S. Freediving Team that will be competing at the World Freediving Championships in Ibiza, Spain this October - I posted the question to members of the freedivelist and he responded with this - and I quote per his email to me:

Hi Cliff:

SWB absolutely exists.

I have experienced it on four occasions. Twice at the surface (after
surfacing) and once at around 5 feet.
It is preceeded by a sense of mild exhaustion then comfort. It has been in
controlled settings where I was testing the limits of constant ballast
freediving for competition-level training.

The other episode was during a static apnea (on video during Kirk Krack's
Clinic!)


Upon "awakening" there is absolutely no memory of anything except the last
comfortable feeling, and then suddenly seeing concerned faces looking
closely at me.

My first words were: what? what's the matter. I'm fine.

Hope this helps

Eliot

 

[Erik]

Originally posted by Tom Lightfoot
Hello Snorkelbum,

As a freediver and long-time underwater hockey player I just had to register and reply to this one.

Not only is Tom a freediver, he is a great freediver, is a member of Team Canada, and is a nice guy to boot! Too nice to brag about his abilities. See you in a couple of weeks Tom.
Cheers,
Erik Young

 

[snorklebum]

Wow. Thanks for all the response. This is exactly the kind of resource I had hoped this forum would be.
I think there is some confusion of terms. (Not as bad as what is "diving" or "freediving", though). I read warnings not to hold breath in swimming pools and it doesn't jibe with what I see in UWH (or in the current Static and Dynamic records, either--exercises in nothing but holding breath in pools). I read people saying that shallow water is more dangerous than deep water. I doubt it.
What many of these posts are making clear to me is that this SWB thing (at least as applies to freedivers --by which I mean diving without tanks) seems to be something pretty specific: seems to mostly apply to people coming up from great depths into shallow water and getting vamped by pressure differential. That makes sense.
Saying don't dive in pools or don't hyperventilate before a dive doesn't make sense. I appreciate those who have shared their experiences of blacking out and hope I don/t join the club.
The next question, I guess, would be how to avoid it or what to do about it, but there seems to be a new thread on first aid for it. Thanks again, people.

 

[Stephan Whelan]

Hyperventilation

Snorklebum,

Glad you got the response you wanted.

I do have to disagree with you when you say you don't agree with warnings against hyperventilation...this can be very dangerous if done too much and cause SWB as much as pressure differentials.

The reason being that hyperventilation reduces the level of CO2 in the body, thus fooling the body into thinking that it doesn't need to breath (as the body knows when to breathe when the CO2 level rises above a certain level). If (by hyperventilation) you lower your CO2 levels too much, the body doesn't know that it needs to breathe when you O2 levels drop too low - and you become unconcious - hence SWB.

I'm not saying "don't" do it, i'm just pointing out that you have to be careful with hyperventilation as it can cause SWB.

 

[Erik]

Hypervent

During my breathe-ups, I breath at 4 to 6 breaths a minute, then do 5 to 10 big, fast breaths to clear out any excess CO2. Those 10 breaths fall into the category of hyperventilation. Pipin's method of breathe-up is around 16 breaths a minute for the entire breathe-up, which is certainly hyperventilation. He teaches this, and people use it.
I have experimented with both types, and found that Pipin's method delays the onset of the urge to breath, but does not really increase my botttom time, or my static time. With the slow breathing method ( ala Kirk Krack), I believe that I have a more realistic awareness of what is happening in my body, as my urge to breath comes at a normal time, and it's up to me how long I choose to resist, based on my capabilities and the environment that I'm in (deep, shallow, cold, dark, spearfishing, solo or buddy,etc).
Many of the world champion breath holders, who consistently hold over 6 minutes, use the slow method. It keeps your heart rate down, and doesn't seem to extend breath-holds. Certainly a beginner who is not adapted and does not have the body-awareness will benefit from hyperventilation, since it will trick him into longer breath holds.
Cheers y ciao,
Erik Young

 

[snorklebum]

Thanks for this interesting response. And thanks for info based on personal, not second-hand experience, rather than hearsay.
I don't want to go on unduly about this, but I think its pertinent to building a body of information for divers. The previous post says hypervent is bad, but based on what? There are differences between levels of credibility of personal anecdotes, documented research, and rumor (wives tales) and I think it's important to differentiate them.
For instance, a previous poster says that he assumes that top level divers suffer blackout but aren't telling about it. This is NOT much help. A poster in another thread passes out dire warnings on swimming pool blackout because he read an article about it.
I'm seeing some reports and rationale about dangers to guys coming up from long, deep dives and blacking out because of pressure weirdness...but absolutely nothing to justify the idea that hyperventilation of pool diving is dangerous, much less the sort of vague horror of shallow water.
Your post is interesting and I will try your techniques. Thanks

 

[Cliff Etzel]

Originally posted by snorklebum
says hypervent is bad, but based on what? There are differences between levels of credibility of personal anecdotes, documented research, and rumor (wives tales) and I think it's important to differentiate them.
For instance, a previous poster says that he assumes that top level divers suffer blackout but aren't telling about it. This is NOT much help. A poster in another thread passes out dire warnings on swimming pool blackout because he read an article about it.
I'm seeing some reports and rationale about dangers to guys coming up from long, deep dives and blacking out because of pressure weirdness...but absolutely nothing to justify the idea that hyperventilation of pool diving is dangerous, much less the sort of vague horror of shallow water.
Your post is interesting and I will try your techniques. Thanks

By hyperventilating, you do not increase the amount of oxygen in your system, you actually reduce the amount of CO2 - which is the substance in your system that causes the urge to breath. By decreasing the amount of CO2, you are fooling your body into not wanting to breath for a longer period of time - but when the body finally realizes that it needs oxygen, it is usually too late. You black out.

Let me quote a few sources who have experienced it or seen it first hand:

Eliot S. Light M.D. - member of the U.S. Freediving Team participating at the Worlds in Ibiza in October:

SWB absolutely exists.

I have experienced it on four occasions. Twice at the surface (after surfacing) and once at around 5 feet. It is preceeded by a sense of mild exhaustion then comfort. It has been in controlled settings where I was testing the limits of constant ballast freediving for competition-level training.

The other episode was during a static apnea (on video during Kirk Krack's Clinic!)


Upon "awakening" there is absolutely no memory of anything except the last comfortable feeling, and then suddenly seeing concerned faces looking closely at me.

My first words were: what? what's the matter. I'm fine.

Hope this helps

Eliot

Joe Burke - New Zealand Freediver

I went for 100 metres in the pool one day.I told the lifeguard I was about to push it and I wanted him walking along side me. When I hit 90 metres I was still kicking but I couldn't feel my legs. I was in the shallow end of the pool and I tried to stand up but couldn't pull my head out of the water. My limbs were shaking and I could hear the lifeguard yelling Joe are you ok. I felt like I was in a frame. I did get my head out of the water by myself but if I had been in the deep end of the pool without anyone watching I would have drown

Lost in New Zealand - Joe Burke


Sean Meehan - Freediver

Hi Cliff,

I have witnessed it personally , in the same pool, five feet away from a dive buddy, as well as a samba. I have also lost my best friend/ dive buddy to it in 1998 in a pool in Hawaii. I can attest that it exists, to that level. I myself have not yet experienced SWB or a blackout.

Hope that helps
Sean

 

[snorklebum]

After reveiwing this great response, I'd like to revise my question. Which would now be, has anybody ever blacked out in a pool or while repeatedly diving at depths of less than 30-40 feet? This is what we keep hearing dire warnings about, but I haven't really seen any actual reports of it, just vague allusions. Perhaps this is something that is only of concern when coming up from great depth?

 

[cjborgert]

Not that we need to hear additional confirmation, but a few years ago, a freediving instructor died at Florida Pool at the University of Florida with several people present. I don't have all the specifics straight (I've heard he was either teaching a class and demonstrating his static apnea abilitites, or training and the life guard did not recognize the possibility of SWB), but I can tell you that this was not only a tragedy for a young man, but also for the reputation of freediving in this area of Florida. I've even had cave divers tell me that freediving is a crazy thing to do!

 

[Tom Lightfoot]

Yes, for the last time, really!!

Snorkelbum,

Yes, indeed it is possible to blackout in shallow water or even lying on the surface doing static. As I stated on my first post on this thread, I blacked out after surfacing from a dynamic apnea run. My max depth was no more than 5 feet. I have had a few sambas as well doing the same thing.

In competitions and in helping with classes here in Vancouver, I have also witnessed a fair number of blackouts, both in static and dynamic. You don't have to go deep to get a blackout, you just have to hold your breath too long. I know at least one guy who blacked out without ever having the urge to breathe.

The reason for this frequency of blackouts is that in the relative security of an enclosed pool and in the presence of full safety, people will tend to push themselves much further than they would ever consider in the open ocean. Even when there's a lifeguard in the chair watching kids horse around on the other side of the pool, freedivers will feel secure enough to push their limits.

The point I really want to drive home here is that once you get good enough at freediving, it is relatively easy to black yourself out coming up from any depth, even zero. Never doubt that. Several people on this forum know this from personal experience. Some of us (including me) know people who have died.

The bottom line is that if you are intending to come anywhere close to testing your limits, make sure you have the undivided attention of at least one or two trained people. Lifeguards don't count.

Tom