Talk:Decompression sickness

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[edit] Headline text

I added the modifier 'pressure' to altitude since that is the correct term when physiological effects are addressed (the term 'altitude' alone is too vague - it may mean the cabin altitude or the actual altitude above sea level) [[User:Crum375|Crum375]] 23:40, 5 May 2006 (UTC)

[edit] Altitude-induced decompression sickness

Does anybody know if these are truly identical and need to be merged or should be kept as separate articles? Tidy, tidy, tidy. MeltBanana 13:42, 23 Sep 2004 (UTC)

The conditions themselves (decompresion sickness) are the same. Dissolved gas bubbles out of the blood and/or tissues due to a decrease of pressure. Likewise the treatment is the same, returning to the higher pressure environment (either by landing, or barometic chamber).
The actual causes themselves are very different, one's caused by flying too high, and the other is caused by diving too long. I'm also of two minds about combing the articles — pilots are unlikely to worry much about diving DCS, and vice-versa.
I'll read through both articles careful. If there's significant overlap, then I think we should merge. If there's little overlap, then it would be reasonable for them to remain separate. --PJF (talk) 10:29, 28 Nov 2004 (UTC)
While both articles are significantly different in content, I do think they would be better merged, with separate sections on diving DCS and flying DCS. The parts that relate to both (eg, symptoms, causes, etc) can be merged together. The altitude-induced DCS article discusses the symptoms of DCS much better than this one. --PJF (talk) 12:27, 28 Nov 2004 (UTC)

[edit] DCI = DCS + Air embolism

Some people distinguish between DCI and DCS, see http://www.hyperchamber.com/decompression_illness/

--Mark.murphy 13:27, 04 Dec 2004 (UTC)

Thanks for the edits, there's been a few times where wikipedians have confused DCI and DCS, and there was even an attempt to merge them a little while ago (see Talk:Decompression illness).
I'm currently unsure as the best way to arrange all these articles. Since the treatment for DCS and embolisms are the same, it would seem redundant to have treatment listed three times (once for Decompression sickness, once for Decompression illness, once for air embolism). It may be worth putting all the treatment under Decompression illness to avoid re-work, or to have a separate article that's transcluded into all DCS/DCI/Air embolism.
Comments and ideas would definitely be appreciated here. --PJF (talk) 23:41, 4 Dec 2004 (UTC)
Often DCI stands for Decompression Illness. Michagal 16:45, 13 August 2006 (UTC)

[edit] Disclaimer

We are dangerously close to giving medical advice in this article. Someone ought to slap one of those "Wikipedia does not give medical advice" disclaimers on the article. Anyone recall the template? --Dante Alighieri | Talk 23:08, Jun 6, 2005 (UTC)

[edit] Suggest adding additional info on relationship of O2 to DCS

Since all US manned space missions before the shuttle used pure O2 at about 5 psi (still used in space suits), an obvious question is how this affects DCS and why. Also divers through equipment failure or error can breath pure O2, and if not killed by oxygen toxicity, if they make a sudden emergency ascent, does O2 gas evolution cause DCS. If not, why not. Joema 00:03, 24 December 2005 (UTC)

Here are some reasons why equilibrating nitrogen might be more of a problem than equilibrating oxygen.

  • Nitrogen diffuses in water at half the rate of oxygen.
  • Nitrogen does not have proteins that bind and transport it like hemoglobin and myoglobin do for oxygen.
  • Nitrogen is not metabolized, unlike oxygen.

These suggest that blood oxygen will come to equilibrium faster with air than nitrogen when the pressure changes, perhaps so rapidly that it is unlikely to produce bubbles.

--AJim 18:08, 29 March 2007 (UTC)

Having just become NITROX certified (because I was on a week-long dive trip and most divers were using NITROX, which didn't exist when I learned diving) and finding the theory given to me wholly unconvincing to someone with a Physics degree, I had a similar question as Joema. I checked the wikipedia NITROX page and found the same theory regurgitated without any reflection. I think it would be worthwhile for someone to research this and add it to this page (with a reference from the NITROX page).

Of AJim's three reasons I find the first one credible, but not the other two. The chemical binding of oxygen to hemoglobin should be a process independent of the physical solution of oxygen gas in the water component of blood, unless the bound oxygen is in an equilibrium with the dissolved oxygen, and the rate of transfer is small compared to the exchange of bound oxygen in lungs and muscles. Without further information I consider this unlikely. For the same reason, the fact that oxygen is metabolized seems irrelevant.

Some definite info from an expert would be appreciated.

Heiser (talk) 01:39, 12 January 2008 (UTC)

Oxygen can supersaturate tissue and "contribute" to decompression sickness (DCS). Dr. K. W. Donald made observations at the Royal Navy Physiology Lab where they exposed goats to 64% Oxygen and 36% Nitrogen at 5.54 ATA and rapidly decompressed them. The animals suffered "grave" DCS that resolved "rapidly without recompression". They were unable to show symptoms of DCS with 100% Oxygen. They concluded that "providing a certain degree of supersaturation (oxygen) when nitrogen is present, the initial risk of dangerous bubble formation can be greatly influenced by increased tensions of oxygen in the body". from: Donald KW. "Oxygen Bends" J Appl Physiol. 1955 May;7(6):639-44. PMID: 14381341. -Gene Hobbs (talk) 19:35, 18 March 2008 (UTC)

Kenneth Donald's work often involved exposures to oxygen levels far beyond what is now likely to be a realistic scenario when diving ("Oxygen and the Diver" is well worth a read). It is difficult to envisage a diver being exposed to the nitrox he used in the goat experiments quoted above. Even so, it is notable that Donald was unable to induce DCS using 100% oxygen. I might conclude that the goats exposed to a partial pressure of 2 bar of nitrogen (equivalent to 15 metres on air), when rapidly decompressed, experienced DCS due to nitrogen bubbles forming.

With regards to AJim's assertion that oxygen in solution will either be taken up by haemoglobin or metabolised, it is necessary to remember that the pressure in the arterial system is considerably higher than in the venous. This leads to the observed result that on decompression, bubbles form first within the venous system. Unless the partial pressure of oxygen is extremely high, the haemoglobin in venous blood is not fully bound. Both nitrogen and oxygen are pretty insoluble in water - a tiny amount volume/volume is in solution in equilibrium. Thus any dissolved oxygen which might form bubbles (as the pressure drops) can reasonably be expected to be picked up by the unbound haemoglobin within the venous system - haemoglobin has a huge affinity for oxygen. Similarly, tissues surrounding veins are likely to be able to metabolise excess oxygen - from what I understand, that is a very fast process.

Taken together, I have little reason to doubt "that blood oxygen will come to equilibrium faster with air than nitrogen when the pressure changes, perhaps so rapidly that it is unlikely to produce bubbles". I suppose a scenario could be constructed where the oxygen partial pressure is so high and the decompression so rapid that oxygen bubbles could form within the arterial system and then be able to exist for a prolonged period. But I doubt whether that could translate into a possible scenario within the current bounds of diving - a very deep dive using a rebreather which malfunctions and somehow puts 100% oxygen into the loop long enough to come into equilibrium in the body, followed by rocket ascent to the surface? I still think you would succumb to oxtox or have sufficient nitrogen or helium in your system to cause DCS without worrying about the possibility of oxygen bubbles :) All this is just my very humble opinion, of course - is it enough to answer Joema's original question? --RexxS (talk) 00:52, 22 March 2008 (UTC)

[edit] "Bends" refering only to non-neurological symptoms?

Since when does the term "the bends" refer only to type I DCS? I think this article should be changed to classify DCS/DCI into type I and II instead, and "the bends" should be described as a colloquial term for all DCI. -- David Scarlett(Talk) 01:36, 20 July 2006 (UTC)

There are 2 separate points:

  1. The "bends" was originally DCS in joints but is now slang for DCS generally. DCS in joints is only Type I DCS. The "bends" should only be mentioned in connection with slang and DCS in joints.
  2. Types I and II DCS should be explained. They may be a good abbreviations for professionals who use them often but the abscence of meaning in those terms make them difficult to remember and a barrier to communication for infrequent users, so I don't think it would be useful to structure the symptoms around Type I and Type II.

Mark.murphy 19:01, 20 July 2006 (UTC)

[edit] US specific remarks

  • Upon landing seek medical assistance from an FAA medical officer. And if you're not in the US should you travel there to find an FAA medical officer or should you consult a medical officer of your own aviation authority? I'll change "FAA" to "aviation authority".
  • These sections look to me like they came from an official publication. If that's a US government one which is not copyright then I imagine that's OK but perhaps it would be useful to cite the source. EdDavies 21:54, 16 September 2006 (UTC)
  • Much of this article appears to have been plagiarized from FAA publication AM-400-95/2 JSB73 10:03, 28 January 2007 (UTC)
  • When was it allegedly plagiarized? It has been edited more than 50 times. Is "FAA publication AM-400-95/2" on the internet, and if so where, or where to get a copy to check? Anthony Appleyard 14:12, 28 January 2007 (UTC)
    • It appears to have happened in the edit of 11:38, 29 November 2004 as a result of the merge with altitude induced decompression sickness. The publication does not appear to be online from an official government source, however a google search turns up a document purporting to be the same publication (http://www.2pi.com/les/flying/faa_400altitude.html) while a more general search turns up a current FAA document that looks like a recent revision of the earlier pamphlet (http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/DCS.pdf) I don't believe this is copyright infringement, simply copying without correctly crediting the source. JSB73 05:09, 29 January 2007 (UTC)

[edit] Wikipedia:Avoid trivia sections in articles

Thanks in advance. El_C 17:31, 14 April 2007 (UTC)

I support the removal of the trivia section. Non-encyclopedic and half of it was POV anyways. Leuko 17:34, 14 April 2007 (UTC)
You: agree with everything I say [O...kay]; you: disagree with everything I say ["Sorry, English not so nice"]; and you: get morally outraged at everything I say ["That's permanent marker, you know!"]. Wow, you guys are good! El_C 17:54, 14 April 2007 (UTC)

[edit] Time?

  • How long after the activity does it take for dcs to prove fatal?

[edit] Decompression tables external link

  • I added a link to [1] http://www.divetables.org (a site that lists all the various deco tables) I was given a spam warning! - this was certainly not my intent - do you think that this is reasonable or was I out of line in listing this page? 01:52, 6 September 2007 User:24.36.27.164
  • I have restored this link. It has useful pointers to several decompression tables (as well as matter that could be treated as advertisement). Anthony Appleyard 05:26, 6 September 2007 (UTC)
  • Thanks Anthony - I also added the link in the Dive tables category - probably the best place for it - I think it is still relevant here too tho' —Preceding unsigned comment added by 24.36.27.164 (talk) 05:43, 6 September 2007 (UTC) I was going to put it on the main Scuba section too - as a diver myself I found the central repository for tables useful but I will wait for your input on that - cheers
  • I have removed this link because
  1. It was spammed into a number (11+) WP articles all from the same anon IP.
  2. It contains an objectionable amount of advertising per WP:EL - more than 75% of the page are ads, referral links, etc. Obviously, the link was added to drive traffic to the site.
  3. A free non-commercial government source exists, which is what I've replaced this link with.
I really don't feel that the commercial site offers any advantages over the non-commercial site to outweigh the WP:SPAM concerns. Anyone disagree? Leuko 06:27, 6 September 2007 (UTC)
Not me. Deleting content is almost always not good, if the content adds at all to the encyclopedia. SPAM is not good (and this certainly WAS spam from the way it was added), but it's very hard to say this definitively for single additions, as some spamoid stuff comes with extras that we need. With net-sites you tend to do what you do with all media-- you try to find the link to the site which minimizes advertising to information ratio. If it can't be zero'd, you pick next-best, for the time being. If you've found a non-comercial site which is as good, then use that, as you've done, and then that's an improvement. I'm only for deleting a commercial link if no link can be found to replace its info. In some cases, I think a link with ads is an improvement even over a (bare) cite to a library work, but of course you should include both.

And after a bit of thought, I will add something else that not every editor will agree with, but which I think conforms with overall policy: you should in some cases try to forget the source of material and ask only whether or not it improves the encyclopedia. In some cases the motives of the content-adder may be less than pure. But people with bad motives can still add useful content. If they do, keep it. Try to separate the intent of spam from its effect. It might be entirely appropriate to warn a spammer, but keep what they've put up! Fortunately, in this case we don't have to choose betwee content and advertisement, because an alternative was found. But that doesn't always happen. SBHarris 02:35, 22 March 2008 (UTC)