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There is a potentially fatal "apneist" technique, believed by some of its practioners to amount to a safe hyperoxygenation of the blood. In fact what allows them to hold their breaths longer is that they have reduced their blood CO2 to abnormally low levels, delaying the time when the buildup of CO2 forces breathing, by a time roughly equal to the time in which produces the amount of the initial CO2 deficit. The danger, as i understand it, is that a sufficient CO2 deficit can hold off the impulse to breathe so long that loss of consciousness occurs first, producing a high likelihood of drowning when the technique is for underwater activities.

IMO, the discussion of ==Apneic oxygenation== is sufficiently hard for lay readers that it might be seen as an endorsement of the technique i am refering to.

And in any case, should the danger of the CO2 deficit technique i refer to perhaps be part of this article? --Jerzy 02:17, 2004 Feb 21 (UTC)

--- Earlier in the article it was mentioned that some people have learned to increase their period of voluntary apnea up to 7 minutes, and it notes that trained free divers hold their breath for a long time. This seems to have introduced the subject of prolonged apnea while diving. However, there is no discussion of how these effects are achieved. Since the article holds out the hope that an increase can be achieved, it seems relevant to point out an obvious (but wrong) path that should not be followed. I have observed a diving instructor warning students on this. If the warning is not clear enough, perhaps it can be improved.

The paragraph on the voluntary hyperventilation technique confusingly contradicts itself. —Preceding unsigned comment added by Justin Stafford (talkcontribs) 18:04, 4 June 2010 (UTC)

Many thanks for this -- I was one of those who'd thought taking a few extra breaths before diving was a good idea.UrsusMaximus (talk) 18:03, 27 November 2010 (UTC)

Do we really need to do wiki links for things like 'gas'? Someone reading this article is scarcely likely to wonder what 'gas' means, nor to care. If you follow it to the conclusion half the words in the article would be links, and it would be a mess.

Someone removed most of the legitimate links which are necessary. Have reverted to bring them back. If you think the greater number of them are not necessary, you shouod explain why, not just remove them almost all.Dieter Simon 23:36, 27 May 2006 (UTC)

I'm not at all a medical professional, but I do have a question someone might be able to answer: is there any risk to breathing primarily through your mouth as opposed to your nose? I've heard it said that so-called "mouth breathers" have a harder time being energetic than the people who breathe through their noses. Jaerune 19:48, 27 September 2006 (UTC)

Changing the keyword to apnoea[edit]

Please do not change "apnea" to "apnoea". This article was obviously created with the American spelling, or at some time changed to the American spelling. All occasions show the American spelling, it is not on to suddenly change some words to the British spelling. We must respect this. Have changed the article to wwhat it was before. Dieter Simon 21:30, 16 October 2006 (UTC)

I agree at present but if the so called "Americans" start defining it differently, then there should be a page with the present meaning one way or the other.

What about Respiratory arrest ?[edit]

not much difference, I would say... -- 22:15, 23 October 2006 (UTC)

Does one lead to the other??? Alec - U.K. 20:23, 30 October 2006 (UTC)

"Especially fresh water"?[edit]

"If a person loses consciousness underwater, especially in fresh water, there is a considerable danger that they will die by drowning."

This is just a personal curiosity - but why is this the case? My only guess is that it has to do with the buoyancy of humans in salt water.

It has to do with osmotic effects. When permeable tissues, e.g. red cells and lungs, are exposed to a non-isotonic solution, water will flow from the region of higher water concentration (fresher solution) to the lower. Consider what happens if you place some blood in fresh water versus in salt water. In salt water the red cells in the blood will lose water and shrivel. In fresh water the red cells will swell until they burst. It is simply much easier to receive irreversible damage to your body in fresh water. --AJim (talk) 18:13, 18 March 2009 (UTC)
I am adding a link to the drowning article discussion of secondary drowning. They make the point that hypoxia is usually what kills you, but I thing it is clear that fresh water will do more damage, and the point is that death is more likely to ensue in a fresh water drowning. --AJim (talk) 16:52, 24 March 2009 (UTC)
However, a detailed drowning discussion plays down the role of osmotic effects. The author agrees that salinity can matter, but not most of the time. --AJim (talk) 17:04, 24 March 2009 (UTC)

'Citation Needed' Indeed![edit]

Please explain why a simple factual statement along the lines of 'the damage to alveoli caused by smoking reduces gas exchange efficiency' requires a 'citation required' tag. If no one can provide a concrete reason, this bogus tag is going. I didn't write any of the original article btw, just incensed at what seems blatent pro-smoking anti-factual trolling. I also happen to be a smoker, but I'm not an idiot. Blitterbug (talk) 09:58, 25 August 2009 (UTC)


This section seems to contradict itself. If the effect is false, how can the effect be attributed to anything? (talk) 13:08, 11 May 2011 (UTC)

More or less Citation needed[edit]

Sorry, but I don't see why the statement of the fact, that an untrained person usually cannot voluntarily hold her breath for more than one or two minutes needs a 'citation needed' tag. I would consider this public knowledge.

On the other hand, IMHO the fact, that a healthy adult breathing pure oxygen stores enough of it in her body that it would be sufficient for about an hour, is very interesting and I wonder where this claim comes from. So I allowed myself to add a 'citation needed' tag at this point. (Sorry, if I did something wrong, but usually I only read wikipedia and only edit once in a leap year.) (talk) 13:52, 2 August 2011 (UTC)

The tag in question hasn't been justified and I have therefore removed it. If you have reliably sourced evidence to verify that statement, by all means, add it in - but don't contradict common knowledge just because it isn't explicitly documented.-- (talk) 02:11, 11 October 2011 (UTC)