Talk:Freediving blackout

message: * Original author comment.  I have now developed more detailed treatment of Deep Water Blackout and have split this off as new article in its own right. Consequently cut it out of here and interlinked.  Better this way. Ex nihil 01:53, 31 January 2006 (UTC)
replies: text: Well, you include diagrams that you admit have created yourself, and you make numerous specific assertions and recomendations without reference for them.  That's why I"m calling it OR.  I shouldn't have to read all the external links just to know if anything you're saying is accurate or not, and if something was common knowledge, why have I never heard it before?  Also, the advice section, as written, goes against WP:NOT.  We're not an instruction manual, so it needs to be written as facts, not advice. Night Gyr 16:29, 28 February 2006 (UTC)
thread_title:  Edits 

message: The information below is categorically false. A brown-out in freediving is a colloquial term for fecal incontinence. Otherwise known as pooping your pants. A common occurrence when a freediver blacks out. 
I can find no medical reference for this term, and I am not sure what precisely is meant.  Near-blackout?  Confusion?  Dizzyness?  Any of the above?  208.20.251.27 21:51, 7 June 2006 (UTC
Ex nihil 01:28, 9 June 2006 (UTC)
thread_title:  Brown-out? 

message: This article states that there is no O2 detection in the body.  There is in fact O2 detection, and the strongest breathing drive in a person is the O2 level.  I'm an EMT-Paramedic student and part of my hospital OR clinical rounds required me to know this for people on ventilators.  The CO2 drive to breath triggers first, at approximately 40-45% CO2 level.  Severe COPD patients have gone so long with high CO2 levels that their CO2 drive diminishes, sometimes completely, and in that case the drive to breath is triggered by the O2 level in the blood, at approximately 60% O2.  This is dangerous, as anything below 85% is severe hypoxia.  
Hyperventilation blows off the CO2 level too fast, and the person is unconscious long before their O2 drive kicks in (a person can maintain an O2 saturation in the 90's% for several minutes after they stop breathing, then it falls fairly fast).
Also, I don't know if its universal or not, but both SSI and NAUI SCUBA books stress very highly the importance of not "skip breathing" or not hyperventilating then holding your breath while underwater.
If I can get ahold of the books the Anesthesiologists had me reading this up on, I'll put in some sources.
*  That is interesting, 'though I suspect that you have hit upon an exceptional case with your COPD patients. If it is true that they can detect low O2 then is this ability available to anyone else?  And if so where in the body is it detected?  Not in the carotid sinus.  My background in this is flying.  In training we were put into a hypobaric chamber and taken up to 20,000' breathing O2 via mask.  One of us was on air from groundlevel up but we didn't know which one, we had to guess.  Nobody did of course, we had to wait until the person flaked out.  Then we were given tasks while our O2 was changed to air. Undetectable.  The point of the exercise being to drum into us that if we have a slow depressurisation and we haven't been watching the cabin altitude, unconsciousness is the first symptom and that there is no way to detect low O2.  All those sumariners gasping in the sunken sub are gasping because of CO2 buildup, they may or may not have enough O2.  This was reinforced when caving in wet limestone.  The limestone breaks down to CO2 so we pant.  We can tolerate this provided that we know there is still O2 in the air, sometimes there isn't.  With no way to tell, panting away, we had to use expensive instruments to tell us we could continue safely.  A rather cheap and dodgy way is to carry a candle and check it's still burning well.  Having said all that, however, I have always been puzzled why, when climbing at high altitude we pant heavily.  In theory the low ppCO2 should suppress panting and the only symptom should be that our muscles don't work, which they don't, and we have brownouts, which I haven't personally, yet here we are gasping, that must indicate that our bodies know something, somehow.  Workers in sewers and ship holds have similar training on the undetectability of anoxic conditions.  I would love to see this all spelled out, maybe in another article, let us know if you get it sorted but in the meantime I think what is written should stand. Ex nihil 06:05, 5 August 2006 (UTC)
thread_title:  The breathing drive 

message: There have been several attempts to delete this image.  If you feel the image is inappropriate please discuss it here first.  Let me explain why it was created:
It was created originally to illustrate shallow water blackout and it was later appropriated by others for drowning, which is fine.  The purpose was to illustrate how such drownings really appear.  The traditional image of drowning involves the splashing, waving and shouting that one has come to expect from the movies; in reality victims usually go silently and without visible struggle to attract attention and in pools are discovered exactly like in this picture.   The pool that hosted the picture actually had a shallow water blackout incident two years before this staged picture and the photograph shows exactly how it was discovered.  The person in the picture and myself have an interest in explaining shallow water blackout, the picture is unpleasant, perhaps even shocking but it is very accurate; if you are unfortunate enough to discover a drowning in a pool this is how you will find it and this is what you should look for, the pool lifesavers look for this. The picture was also taken to contrast it with the mechanism for deep water blackout, see the partner image in that article.  The picture is not added to be macabre, it is there to illustrate and explain.  If you do have reason to object to it please disuss the matter first before deleting it. Ex nihil 12:24, 7 August 2006 (UTC)
replies: text: For some reason I remember when you added that picture o_O you posted it on the misc help desk or something. Anyway I think the image isn't overly "shocking" and that the moribund girl is even appropriate to the somewhat ghastly topic of the article, and of course the water looks very cool =) In fact, call me weird but I think I have this photo in My Pictures o_o Very good article by the way- esp the diagrams. It's definately on its way for featured! --Froth 21:04, 29 August 2006 (UTC)
replies: text: I think the picture is certainly a good one. However, consider the audience of this page. They might, perhaps, have known someone who recently suffered from a shallow water blackout and died. They may wish to find out more about the phenomonon. However, they find this picture and it could have a damaging effect on them.
Then again, if they're looking up this article in the first place, they should probably expect to find some shocking information. Psychade 15:09, 11 September 2006 (UTC)

text: I don't have an ongoing interest in the article - just happened by while learning about increasing your lung capacity, but the picture struck me as odd and at first I honestly thought it was a really poor-taste act of vandalism.  The picture could be useful in illustrating the lack of any kind of panic or struggle (although a dead body looks lifeless whether the cause was panic in the water or blacking out) but the caption "Victims go quietly, often unnoticed." sounds a bit too much like a horror movie tagline.  Reworking the caption and locating the block "below the fold" where the article mentions that there is little warning before the victim blacks out may make the illustration more useful and appear less intended for shock value.  Jzerocsk 15:19, 5 January 2007 (UTC)
replies: text:  Jzerocsk, actually the caption was a quote from a child safety advertising campaign either by the Autralian RSLSA or my the Northern Territory Childsafe.  Anyway it's changed now. Ex nihil 02:14, 3 February 2007 (UTC)
replies: text: The image has been reversed by me and the old image is orphaned. This may not completely help, but the old view is now ready to be deleted, with the new version completed. Catherine Woods 00:39, 3 February 2007 (UTC)
replies: text:  This image is not specific for freediving related problems. user : ozokurt  —Preceding unsigned comment added by 86.108.132.136 (talk) 11:58, 14 January 2011 (UTC)
replies: text: Not sure what your point is here, can you expand? Ex nihil (talk) 03:20, 15 January 2011 (UTC)
thread_title:  Deletion of Image:SWB3 temp.jpg 

message: There is a lot of material in common with deep water blackout, particular with the explanation about hyperventilation. Why not just combine the two into one article? Stevage 05:38, 5 March 2007 (UTC)
replies: text: Well, to be honest, the two articles as they stand confused me quite a lot. Merging two articles doesn't mean that they are synonymous - it simply means that they are best explained as a pair. In this case, something is obviously badly structured: there is a section on "deep water blackout" in the SWB article, and a section called "DWB vs SWB" in the DWB article. That's an awful lot of repetition. Perhaps you want to create one article called "Underwater blackout" which contains the general material and brief discussion of the difference of the two types, and then have separate articles which purely concentrate on the phenomena specific to each type? Stevage 11:30, 6 March 2007 (UTC)
thread_title:  Repetition 

message: I've been meaning to rewrite this section for months because it had become rather confusing.  I have removed all the repetitions that had crept in.  The item about Type II Respiritory Failure, while of interest, is an aside and disturbed the flow of the principal explanation so I have placed it at the end of the section.  I have also added a comment about asymptomatic hypocapnia as an unsafe condition to dive. Ex nihil (talk) 01:15, 30 July 2008 (UTC)
thread_title:  Role of hyperventilation 

message: Rather confusing advice.  Is this suggesting that the free dive end when the urge to breathe occurs?  There is often an urge to breathe immediately (eg within 10 seconds) after diving, and of course every successful diver ignores this initial urge.  Or does it mean that one shouldn't hang around at the surface after diving without clearing snorkel?  Or does it mean something else, like don't dive too long, in a rather ambiguous and unhelpful way?  In general I find the tone of this article unhelpful for anyone interested in free diving (not SCUBA) in its various forms, as it comes across as too rigid to be of any practical use, and will most likely be ignored entirely. 76.170.86.78 (talk) 17:14, 5 July 2009 (UTC)
thread_title:  Immediately seek access to air 

message: This article seems more focused on convincing people not to hyperventilate before diving rather than shallow water blackouts themselves.  —Preceding unsigned comment added by 75.135.171.24 (talk) 11:15, 24 August 2009 (UTC)
replies: text: I have the same impression.  —Preceding unsigned comment added by 92.140.44.197 (talk) 18:27, 12 December 2009 (UTC)
replies: text: Better now. • • • Peter (Southwood) (talk): 15:54, 29 January 2017 (UTC)
replies: text: I thought the article was supposed to be about freediving blackouts, not underwater blackouts. Tommy has a great username (talk) 23:56, 8 March 2021 (UTC)
thread_title:  Are we getting off track? 

message: *Never pre-ventilate using blended gas mixtures such as Nitrox, Trimix or Heliair that might purge carbon dioxide in a bid to extend the dive. 
Leaving aside the fact that WP articles are not supposed to be "how to" lists (IAR if it's a really good tip, though), I don't UNDERSTAND the basis of this one.
Trimix and Heliair are usually hypoxic. The reason not to use these is obvious and has nothing to do with purging carbon dioxide! As for nitrox, it actually might be a good way to safely extend breath-hold time and decrease chance of shallow water black out, if you DON'T hyperventilate with it, but merely pre-breathe as you would air. The difference in CO2 content of air vs. gas mix is negligable (thus irrelevent). And the higher O2 content in nitrox would help to prevent low O2 at the same CO2 levels acheived naturally, by obvious mechanisms. Extention of breathhold by pre-breathing pure O2 is well-known to work, and in fact has given us all our shallow water absolute records (of course this would probably be dangerous for free-diving, but nobody really knows; one breath is NOT the same as continuous breathing ox-tox-wise).  In any case, I think the main danger of pre-breathing nitrox to do breath-hold diving, is you might get used to it. If you develop a set of new set of "safety" comfort parameters on nitrox and THEN try this on air, it might get you THEN. But this needs explaining. SBHarris 03:07, 24 September 2009 (UTC)
replies: text:  I agree for the saturation, but if you increase the partial pressure, by increasing the concentration I think saturation means also more oxygen.  —Preceding unsigned comment added by 86.212.38.48 (talk) 01:13, 22 December 2009 (UTC)
replies: text: If you fill your lungs with pure oxygen then there is a lot more oxygen available for transfer into the blood during the dive. If you managed to completely flush your lungs and circulation of inert gases (can be done by oxygen prebreathing for a long enough time), there would be oxygen available in the lungs at the ambient pressure, less pCO2 and water vapour, for the whole dive. Hypoxia would become almost impossible short of complete lung collapse, and it seems unlikely that hyperventilation induced hypocapnia could delay CO2 break point long enough for that to happen. There would be a risk of CNS oxygen toxicity for a deep dive.  • • • Peter (Southwood) (talk): 16:02, 29 January 2017 (UTC)
thread_title:  An odd suggestion 

message: I quote: 
: Note that the body can actually detect low levels of oxygen but that this is not normal. Persistently elevated levels of carbon dioxide in the blood, hypercapnia (the opposite to hypocapnia), tend to desensitise the body to CO2, in which case the body may come to rely on the oxygen level in the blood to maintain respiratory drive.
As far as I know (based on my academic education on this subject matter some time ago) there is no respiratory drive connected to oxygen. There are not even oxygen sensors in the body for this purpose. For this reason, to write that the body can detect low levels of oxygen is rather misleading. Correct is, that low levels of oxygen lead to symptoms, in particular fainting as the lead symptom, which makes it hard to be 'detected' by the very same body. Additionally, low oxygen levels leads to a slight euphoria (and are probably anxiolytic) and decelerate the thinking process which gives the individual an even harder time to detect/reflect the situation properly (even when knowing properly about these facts). There is also not much time left between any possible symptoms and fainting (given breath is held). Summarizing, in my opinion it would be closer to reality to say that the body cannot detect low levels of oxygen. Given that the word 'detect' seems to lack meaning in this context, I would rather remove the phrase. Any comments?  —Preceding unsigned comment added by 92.140.44.197 (talk) 19:07, 12 December 2009 (UTC)
thread_title:  Can the body detect low levels of oxygen?  

message: A distinction is made between shallow water and deep water blackouts than can be misleading.
When a person is only just below the surface (<50 cm) and near blackout, the small increase in lung volume on surfacing may be enough to lower the partial pressure of oxygen in the lungs and cause blackout. If the person takes in air before blacking out, then this may be enough to return consciousness, seconds later.
The effects of depth are much greater near the surface - the change in partial pressure of oxygen surfacing from 2 m is much greater than moving from 52 to 50 m. It's simple physics (pressure = depth x density).
I experienced this nearly 50 years ago in a school underwater swimming competition, having swum nearly 100 m underwater.  — Preceding unsigned comment added by Deeuubee (talk • contribs) 00:06, 19 December 2011 (UTC)
replies: text: The absolute change in partial pressure is the same for a 2m change in depth no matter where the 2m is, as long as it is under water of the same density under the same gravity. It is the absolute value of oxygen partial pressure that controls the ability to sustain consciousness. The effects of a given depth change on volume are greater near the surface. The simple physics is: Change in pressure = change in depth x density x gravitational acceleration (δP = δh x ρ x g) • • • Peter (Southwood) (talk): 16:22, 29 January 2017 (UTC)
thread_title:  Shallow Water vs Deep Water blackouts 

message: (for WikiProject Scuba diving - no guarantees it will be good for WP Medicine)
The article is suitably referenced, with inline citations. It has reliable sources, and any important or controversial material which is likely to be challenged is cited. Any format of inline citation is acceptable: the use of <ref> tags and citation templates such as  is optional.Several requested citations still missing. Some quite important. All outsting citation requests are either not very importan, well known, or otherwise not controversial. It will take a bit of time to find the references, but I know I have seen most of them somewhere in the existing sources. 
The article reasonably covers the topic, and does not contain obvious omissions or inaccuracies. It contains a large proportion of the material necessary for , although some sections may need expansion, and some less important topics may be missing.Looks OK to me. 
The article has a defined structure. Content should be organized into groups of related material, including a lead section and all the sections that can reasonably be included in an article of its kind.Looks OK, though some content missing. 
The article is reasonably well-written. The prose contains no major grammatical errors and flows sensibly, but it does not need to be "brilliant". The Manual of Style does not need to be followed rigorously.Looks OK to me. The part on avoiding blackout could be written more how it is done than how to do it. Also might be worth clarifying what happens to the breathing once the victim passes out.  
The article contains supporting materials where appropriate. Illustrations are encouraged, though not required. Diagrams and an infobox etc. should be included where they are relevant and useful to the content.Looks OK to me. 
Needs citations where challenged, and could be improved by expansion/clarification in some places. • • • Peter (Southwood) (talk): 18:48, 13 January 2017 (UTC)
replies: text: Improved. Acceptably clear, and lacking only a few citations, almost all of which are uncontroversial. Promoting to B-class. • • • Peter (Southwood) (talk): 15:51, 29 January 2017 (UTC)
thread_title:  B-class review 

message: I suggest a merge with Shallow water blackout and a rename to Freediving blackout with redirects and disambiguation where applicable.
There appear to be several aspects of blackout associated with freediving, with a significant amount of overlap in when they are likely to occur, and in causative factors, mechanism etc. There are also a wide range of alternative names. The only thing they all have in common, is their association with apnea diving, which suggests that they may be logically combined in one article. At present, the size of the combined article appears likely to be within the preferred range. The existing separate articles are both fairly small, and no articles appear to exist for the other types of blackout.
Redirects would probably include: Shallow water blackout, Deep water blackout, Blackout of ascent, Apnea blackout, Surface blackout, Hypoxic blackout and possibly others.
I have been looking for reliable sources and have so far found the following, some of which may be more reliable than others: (remove from this list when used in the article)
* 
Comments and discussion please. • • • Peter (Southwood) (talk): 07:20, 17 January 2017 (UTC)
thread_title:  Merge and rename? 

message: Both articles were created by the same editor  Ex nihil at the same time, so I imagine there was a good reason to keep them separate then. Would be useful to get their input. CV9933 (talk) 15:07, 24 January 2017 (UTC)
thread_title: Discussion

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