Talk:Oxygen toxicity
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Could any experts add some information about the mechanism of the intoxication? Or at least add something like "The mechanisms behind this is poorly understood"?--218.191.131.92 12:13, 29 May 2005 (UTC)
At normal pressure, breathing 100% Oxygen for more than an hour starts to cause chest pain and changes are seen in the Type 2 pneumocytes that line the alveoli. These are the cells that secrete surfactant and keep the alveoli open despite the tendency of Laplace’s law to close very small spaces. So the knock on effect is to get atelectasis,alveolar oedema and sometimes massive lung collapse. Over time the cells can accommodate their defences and if the need to breathe 100% is arrived at over a few days it is less toxic.
In ICU doctors like to get people down to 60% as soon as possible to avoid toxicity (having given 100% to preserve life) 100% can only be given via anaesthetic circuits not facemasks that entrain air. We frequently give 100% for tens of minutes at the start and finish of anaesthetics with no ill effect. All cells are subject to oxidative stress via oxygen radicals. Mechanisms such as Super oxide dismutase (SOD) and Glutathione mop up these radicals. High partial pressures drive the production of 02 radicals and toxicity results from this - cell membrane damage etc. The lungs are first in line to receive the damage Dissolved Nitrogen coming out of solution on decompression causes the 'bends'. Bubbles forming in the pulmonary circulation cause intractable coughing - 'the chokes' Oxygen in high concentration causes a number of different effects. At more than 2 bar the main problem is seizure activity. Hence the fact that you can't overcome the Bends by just breathing pure oxygen. The gas still needs to be diluted with something inert to avoid excess partial pressure -hence the use of Helium on deep dives that still need prolonged staged compression/decompression cycles.
Could anyone, even a non-expert, add to the "article" what Oxygen toxicity *is* ? The "article" says almost nothing about Oxygen toxicity beyond what is already conveyed by its title, but is especially notable for omitting a description of the symptoms. This makes the so-called article quite bizarre.71.224.204.167 03:33, 19 March 2006 (UTC)
