Talk:Reperfusion injury

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[edit] General Discussion

Reperfusion injuries are a new topic of concern in the EMS comunity because we are the first to treat any ischemia in most cases. The large question I have been trying to figure out is if High flow O2 on these patients puts them at higher risk for these reperfusion injuries. The source is mainly due to reintroduccing O2 to the ischemic tissue, so is high flow O2 going to make a large impact on the out come of these patients? Some medics put all patients with signs and symptoms of an ischemic event on high flow o2 regardless, others of us use low flow on patients with signs of adequate perfusion. This really raises the nessecity of the use of O2 on patients who appear to have adequate perfusion and good SPo2. _________________________________________________________________________________________ —Preceding unsigned comment added by 65.25.13.218 (talk) 20:57, 6 June 2008 (UTC)

Reperfusion injuries can't occur unless there was a loss of perfusion that is restored. This is usually particular for cases where an artery is clamped or damaged (surgery, partial amputation, tourniquet). It could also include the blockage of a vessel where the blockage is removed, but unless you are using thrombolytics in the field, this probably won't be an issue. As for high flow oxygen, nothing is really getting "reperfused" by placing a patient on oxygen, as it would generally require a surgical fix or reattachment of vessels to replace blood flow, which is accomplished at definitive care. These injuries are, however, one of the reasons why a tourniquet is not removed until definitive care and the time of placement is recorded. Because of this, reperfusion injury doesn't raise much of a question for the use of high-flow oxygen on patients. Other factors might, but this wouldn't. If it is a concern you have, be sure to talk with your medical director. Schu1321 (talk) 22:08, 6 June 2008 (UTC)


I came to the Wikipedia article on reperfusion injury for a quick refresher on the enzymes involved and this sentence threw me for a loop: "The enzyme xanthine dehydrogenase is converted to xanthine oxidase as a result of the higher availability of oxygen." I think that it is actually the influx of calcium that happens during ischemia that activates a protease which converts xanthine dehydrogenase to xanthine oxidase. It doesn't make sense for the oxidase to be formed with availability of oxygen because then that would happen in the normal condition.

I just wrote to a friend about this concept. Here is what I wrote:

The general concept [of reperfusion injury] is that the actual damage from the ischemia to the brain does not actually occur until oxygen is reintroduced. Ischemia causes an influx of calcium into the ischemic tissue which activates a protease that converts xanthine dehydrogenase to xanthine oxidase. Both these enzymes eventually lead to the production of uric acid, the purine catabolic product. Hypoxanthine is the ultimate breakdown product of ATP metabolism (ATP to ADP to AMP to IMP to hypoxanthine). When oxygen is reintroduced (as after an ischemic condition such as a stroke), the xanthine oxidase goes to work on the large amounts of hypoxanthine that accumulated. (The dehydrogenase is what normally is used in vivo and does not produce reactive oxygen species.) Superoxide and hydrogen peroxide are formed in large amounts and cause the tissue damage. The clinical implications of reperfusion injury are addressed in Lancet 344:934-936 (1994).

(Neutrophils, as already mentioned in the article, also contribute to the oxidative stress of reperfusion.)

A fix would be as easy as just correcting the sentence that talks about the "higher availability of oxygen," though my paragraph may be clearer.

If someone wants to go ahead and edit this article with this information please feel free to do so.

Thanks!

Sklettke 03:35, 19 February 2007 (UTC)

[edit] Reoxygenation injury

Is reoxygenation injury the same thing as reperfusion injury, or is there a subtle difference between the two? Is the latter a special case of the former? -- Karada 14:52, 16 May 2007 (UTC)

[edit] Proposed Merger of Reperfusion to here

To the extent that the external link on the Reperfusion page is of value (debatable), it should be moved here and the word "Reperfusion" should be redirected here, in my opinion. --Ben Best 19:30, 18 October 2007 (UTC)

Agree. The Reperfusion "article" is nothing more than a definition, and the word already exists on Wiktionary, so moving the link and redirecting makes sense. Captain Infinity 22:33, 18 October 2007 (UTC)
The deed has been done. --Ben Best 07:12, 29 October 2007 (UTC)