Talk:Hypoxia (medical)

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[edit] Suggested merger with Oxygen depletion

I was surprised to see that these two pages are separate - it seems to me that they describe essentially the same condition, just in different organisms. I reckon it'd make sense for them to be merged.

—The preceding unsigned comment was added by Napalm Llama (talk • contribs). 22:27, 14 June 2006
  • Strong Disagree - oxygen depletion, as it is currently written, is mostly to do with reduced oxygenation of waterways/supplies and whilst an important topic, is nonetheless quite separate from [[Hypoxia {medical]]. That said, I think Oxygen depletion is a little unclear as a title and perhaps a rename is appropriate, e.g. to Waterway oxygen depletion or Oxygen depletion of waterways. David Ruben Talk 22:32, 14 June 2006 (UTC)
  • Do not merge, for exactly reasons stated above. Oxygen depletion might be renamed Hypoxia (environmental)? and establish a new page Hypoxia (disambiguation) to handle disambiguation of the following and probably other articles:

Hypoxia (medical)

Hypoxia (environmental) Renamed from (oxygen depletion)

Hypoxaemia

Anoxia

Anoxic

Hypoxic

Anoxic sea water

Oxygen minimum zone

Hypoxic hypoxia (does this exist? Seems to have some inbuilt redundancy here.)

Others similar?

And reroute existing or create new redirects on anoxic, anoxic, hypoxic, hypoxaemia, hypoxaemic, hypoxia. Happy to do this if there is consensus. Ex nihil 23:19, 26 June 2006 (UTC)

    • Well, there wasn't a lot of traffic on this discussion so I went ahead and did it pretty much as above. Try hypoxia now. I hope you all like it because there are an awful lot of links to unpick if not. I think it works a lot better, hope you do too. Ex nihil 07:37, 30 June 2006 (UTC)
    • Removed the mergefrom|hypoxia (environmental) as its now 18 July 2006 and no comment. Ex nihil 08:18, 18 July 2006 (UTC)

[edit] Suggestion merge Hypoxaemia with this page

THIS MERGE HAS NOW BEEN DONE

What's the difference between this and Hypoxia (medical)? User:Jmeppley 03:30, 14 November 2005 (UTC)

I am a medical student and can say that the distinction between hypoxia and hypoxemia is a very important one (at least in my education and clinical exposure). These terms are not synonomous to most physicians. As someone has mentioned, hypoxemia can lead to diffuse tissue hypoxia; however, there can be many different underlying pathologic mechanisms in any given case of hypoxia. If these two pages are to be merged, it is important that this distinction be made absolutely clear. In fact, merging these pages may be a bad idea. —The preceding unsigned comment was added by 69.230.18.96 (talk • contribs).

By what percentage must the pO2 decrease before the term 'hypoxia' can be applied? -Russell

pO2 of <10 is regarded as hypoxia on room air. But why are you asking? JFW | T@lk 20:34, 28 December 2005 (UTC)

The discussion then moved over to the Doctor's Mess. So I have copied that over to here: David Ruben Talk 03:39, 17 January 2006 (UTC)

I'm not a clinician, and not familiar with typical use of these terms so I was unsure if I should put a merge tag on these articles. If merging the two is not advisable, hypoxemia could do with some cleanup. --Uthbrian (talk) 10:31, 15 January 2006 (UTC)

The terms are synonymous in most concepts. The extreme nitpickers among us would distinguish the two as follows: Hypoxia is a general deficiency of oxygen in the body. Hypoxemia is a deficiency of oxygen in the blood. You dont get one without the other and in clinical care people use the term hypoxia to mean both. So the articles should be merged with a one sentence explanation of the difference. alteripse 13:39, 15 January 2006 (UTC)
I've put a request for merge tag. Andrew73 14:56, 15 January 2006 (UTC)

Can I be a bit of a nit-picker? I agree that the terms are synonymous to some extent. I do not have a medical dictionary at hand, and I would be grateful if someone could check this, but in think there is an important distinction which is clinically relevant. Hypoxaemia is a generalised lack of oxygen in the blood, which can be caused by number of pathologies, as listed on the relevant page. Hypoxia, in my book, is more about a regional lack of oxygen. As such, hypoxia can happily exist without hypoxaemia. Some examples, and why they are relevant:

  • Tumour hypoxia. This is a major cause of tumour resistance to radiotherapy, and also to chemotherapy. It is caused by tumour growth oustripping blood supply. The result is necrotic tumour, and hypoxic, but viable tumour cells. There is a specialised branch of cancer research looking at this, using such esoteric devices as eppendorf electrodes. The hypoxic sensitising drug tirapazamine is one of a family of pharmaceuticals that have been developed to exploit this.
  • Infectious abscesses, empyema. Generally termed hypoxic rather than hypoxaemic. Low oxygen tension allows growth of anaerobic bacteria. Antibiotic penetration is poor due to poor local perfusion.
  • Ischaemic limbs, digits etc. Are these hypoxic or hypoxaemic? Need to ask a vascular surgeon.
  • Cerebral hypoxia. As in Ischaemic stroke, hanging, strangulation.
  • Myocardial infarction. Locally hypoxic myocardium dies with the well known sequelae.

Sorry to be a pedant. Very happy to be contradicted. Jellytussle 04:44, 16 January 2006 (UTC)

Oh I can identify with pedantry or I wouldn't be here, but we more commonly say a person is hypoxic than hypoxemic, don't we, and mean the same thing? But I admit, you have identified a couple more contexts in which the terms are not equivalent. Do you think they should be kept as two separate articles? I will also admit I havent even looked at the contents. alteripse 05:11, 16 January 2006 (UTC)

Yeah, I say someone is hypoxic when technically they are hypoxaemic. Can we have a page entitled "Hypoxia and Hypoxaemia" which clearly explains the differences and common points (and explains the slack jargon) and then points to the relevant detailed syndromes? Or perhaps Hypoxia, with sections on generalised hypoxia (AKA hypoxaemia) and regionalhypoxia. Hmm. I seem to have argued myself into agreeing with the merge idea. Jellytussle 05:21, 16 January 2006 (UTC)

Hypoxemia is when blood oxygen is low. Hypoxia is when tissue oxygen is low. Hypoxic is a term meaning less oxygen than should be there. I'd vote to put stuff under hypoxia, with hypoxemia being when blood is hypoxic. Kd4ttc 02:08, 17 January 2006 (UTC)

  • Merge Never heard the term Hypoxaemia used in the UK during my time in hospital or as a GP since, always Hypoxia. However, on it own this is always taken to mean 'the patient as a whole is hypoxic'. Whilst I agree that the term hypoxia can be qualified with regional locations (as per good examples above), a patient who has hypoxaemia will have tissues that are hypoxic and so the same discussion then ensues as to the resulting effects. I would suggest merging into Hypoxia, with a small inclusion as to the terms hypoxia vs hypoxaemia, then the causes of both generalised lack oxygen (hypoxaemia) as opposed to localised restriction. The current Hypoxia (medical) article already has in its introduction the body as a whole (generalized hypoxia) or region of the body (tissue hypoxia), but this is developed no further - so merge the two with separate sections/sub-sections as required. David Ruben Talk 03:26, 17 January 2006 (UTC)
  • Merge - while technically different terms as abundantly explained above, the clinical use overlaps and IMO does not warrant separate articles. We could have similar discussions regarding acidosis and acidemia, hypercarbia and hypercapnia, dehydration and volume depletion. There is considerable overlap in the uses of all these terms and the distinctions can be adequately explained in the article of the more commonly used term. --DocJohnny 07:03, 18 January 2006 (UTC)

For the sake of people learning about pulmonary function, such as myself, I think they should be kept separate. If I was to write that they are essentially the same thing on an exam, I would really be penalized. There are small differences and it is important not to confuse people that need to know the differences.—The preceding unsigned comment was added by cdlangen (talk • contribs).

  • I don't doubt that in the context of an exam it is important to demonstrate a full understanding of each of the terms :-) But in the context of an encyclopaedia (rather than dictionary definitions) the discussion about them is best held in a single article (else a full discussion in each will duplicate much of the information). Also, wikipedia is not a medical/physiology textbook, but rather meant to inform lay people from the level of clueless to reasonably competent - and this discussion on nuances of meaning will be above all but the most well-informed. Wikipedia can manage this well with a redirect and then the article indicating the specific meaning of associated terms. David Ruben Talk 05:43, 17 March 2006 (UTC)
  • Merge but not redirect. I think hypoxemia should have a one or two-liner explaining that this means a decrease in oxygen content in the blood and to refer to hypoxia if one was looking for tissue hypoxia or general hypoxia as a whole. While layperson may care less about the distinction, and while wiki is not a medical textbook, accuracy is still important and a distinction should be made (since we all know by now that one can have tissue hypoxia without having hypoxemia, ie infarcts). Andrewr47 02:51, 8 April 2006 (UTC)

Merge if I'm allowed to vote! Keeping the two as separate pages involves duplicating 95% of the information for a 5% distinction which could as easily be made on the one page, IMHO. Nmg20 11:16, 9 May 2006 (UTC)

Merge done - with a 7 to 1 (if my counting is correct) vote, consensus over this open vote of the last 4 months is in favour of merging. However I had no idea what the following meant, or where therefore to incorporate it.:

Standard existing shunts include the thebesian vessels which empty into the left ventricle and the bronchial circulation which supply the bronchi with oxygen.

I left the physiology bits right at the bottom of the article as more specific than most readers might need, and the causes/classification system is very much an introduction to other more specialised articles here in wikipedia. David Ruben Talk 14:25, 9 May 2006 (UTC)

[edit] High Altitude Sickness

Ref the changes to the section on high altitude sickness, HAPE and HACE my understanding is that these are not caused by hypoxic conditions but by the low partial pressure of carbon dioxide in the blood leading to acidosis. High altitude can certainly leave you breathless, or even unconscious but the headaches, insomnia, cerebral and pulmonary oedema and the nasty stuff that actually kills you in the end is low CO2 rather than low O2 and the medicines, the diuretics etc are aimed at normalising blood pH. This was certainly the mountain medicine textbook view when I was into that sort of climbing in the 70's, I doubt that has changed much. Can someone who knows sort this out? Ex nihil 23:00, 24 July 2006 (UTC)

Thanks for asking for my input - I don't have direct knowledge of mechanism of HAPE & HACE - would need to read-up/search about it, but my lack of specialist knowledge also means that I can point out where I might expect to see information spread across wikipedia - whilst precise pathophysiology of HAPE/HACE needs clarification/confirmation in respective articles true, this article also needs mention them at least to compare & contrast with features of generalised hypoxia. It is this latter point that travellers to high altitude places (and mountaineers) need be aware of.
So even if pCO2 is the immediate mechanism of HAPE/HACE, one has to ask why this occurs at altitude. Given that inhalled atmospheric pCO2 is neglible small (compared to blood and expired pCO2) at sea level, it is thus little changed at altitude. So this would seem to leave 2 possibiliies for these conditions if via altered pCO2:
  1. Reduced atmospheric pO2 (i.e. hypoxia) that causes other effects that eventually leads to a change to pCO2 causing these conditions. If so then hypoxia is indirectly the cause of the conditions and there is a clear link of topics. Obvious question then is do patients at sea level with either severe COPD who drop their pO2 or acid-base derangement ever get HAPE/HACE like conditions ?
  2. Overall reduced atmospheric pressure? But given that the easiest external cause of reduced atmospheric pressure is same as that for reduced O2 - namely to assend to a higher altitude (aircraft or space craft decompression are artificial infrequent examples of this), then the two even if separate, remain linked by common cause (i.e. altitude).
As a GP, the issue that I must be aware of is to advise any patient planning a high altitude trip of the distinction between just low pO2 hypoxia symptoms and those of more serious altitude sickness. So my tuppence worth of opinion is try to clarify pathophysiology, but continue to mention HAPE/HACE here too. David Ruben Talk 00:25, 25 July 2006 (UTC)
Hi, I think I can help clarify the pathophysiology a bit. The primary physiological insult on ascent to high altitude is hypoxia, caused by a decline in atmospheric pressure. The immediate physiological response to hypoxia is hyperventilation. For a constant metabolic rate (which may be safely assumed), arterial partial pressure of carbon dioxide (PaCO2) is entirely determined by ventilation. If you breathe faster, you "blow off" more CO2 so your PaCO2 falls. This is why PaCO2 is lower at altitude. This causes a respiratory alkalosis. It is also correct that over 3-5 days renal compensation normalises pH by removing HCO3-. This process is rather neatly mathematically modeled at the website that I have referenced in the hypoxia (medical) article.
However, none of this has been shown to have direct relevance to the pathogenesis of HAPE, which is believed to arise from a combination of pulmonary arterial hypertension because of hypoxic pulmonary vasoconstriction, and non-inflammatory alteration in capillary permeability, possibly a consequence of the paradoxical excess of reactive oxygen species (free radicals). A few references to the relevant published work are already present on the HAPE page. Fibrosis 02:11, 10 August 2006 (UTC)

[edit] Anoxia / Hypoxia

As someone who was looking for clarification of the term in a botanical sense, there are some interesting comments as to whether the different versions of Anoxia should be merged or not. Why can't the terms be used as Anoxia (Botanical) and Anoxia (Medical)?

my vote would be to merge, hypoxia (environmental), Hypoxic zone, Anoxic sea water and Oxygen minimum zone under hypoxia (environmental) and reirect from these terms and anoxia (environmental). I don't see it as hard but I can't see myself with time just now. Ex nihil 03:39, 2 October 2006 (UTC)
Keep 'Hypoxia (medical)' rather than 'Anoxia (medical)'. Reduced oxygenation is far commoner (and involving more medical attention, investigation and treatment) than total absence (COPD reduces oxygen through lungs into blood whilat a total absence of oxygen entering the blood stream = death, ect per specific localised body tissue). In medical usage (thats use by doctors and how it actually relates to patients), hypoxia is the term most used rather than anoxia. David Ruben Talk 15:37, 3 October 2006 (UTC)

[edit] Sleep apnea and Hypopnea

I've just added these two closely related/overlapping disorders to the shortlist of causes of hypoxia. I was surprised they weren't already on the list, given how common they are (and surely are a major cause of hypoxia). I had a quick look at the history entries -- didn't spot any reference to either term, but that's not conclusive. So I'm wondering, does anybody know if one or both was/were previously mentioned but removed from the article? In any event, I can see from the history & talk pages that a lot of work has gone into this relatively short article -- my thanks to everybody who's had a hand in it. Cgingold 15:51, 16 November 2006 (UTC)

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