Treating the Dead 246
FlyByPC writes "According to a NewsWeek article, oxygen deprivation doesn't kill patients as much as the resumption of oxygen does. This discovery could bring about new ways of resuscitating people whose hearts have stopped."
Not completely new (Score:3, Informative)
Still some pretty nice work and may lead to quite a few lives being saved.
Re:Makes a little bit of sense. . . (Score:2, Informative)
The idea is to minimize the amount of time you're not pumping the heart, as all the blood in the world doesn't do any good if it's stagnant.
Re:What about the brain though. (Score:2, Informative)
Tagged "oldnews" (Score:1, Informative)
Make it simpler.... (Score:4, Informative)
I forget the actual numbers, but the idea was really to simplify the procedure [americanheart.org]. It's more important to get blood flowing through the heart than do the breaths, so this way inexperienced people spend less time fumbling around with the breaths and more time pumping.
More information: (Score:2, Informative)
Re:Makes a little bit of sense. . . (Score:3, Informative)
It came from research that shows that compressions are what get oxygen to the blood and the breathing was merely interrupting the far more important compressions.
The goal there is still to get oxygen to cells more rapidly.
Stew
Re:Makes a little bit of sense. . . (Score:5, Informative)
Re:This makes sense in a lot of ways. (Score:2, Informative)
As an occasional EMT, this story reminds me of one of our favorite maxims - they're not dead until they're warm and dead. Children have been known to survive near-drownings in frigid water (won't bother trying to recall a specific length of time). Perhaps this work will lead to a field technique of cooling patients enroute to a hospital.
Re:Makes a little bit of sense. . . (Score:5, Informative)
First off, a public service announcement. The current guidelines (which are actually backed up by some pretty good science) are a ratio of 30:2 compressions to breaths. Another important thing to note is that the rate of compressions is 100/min. This is faster than you think and believe it or not is incredibly difficult to do. For the tempo, think "Another One Bites the Dust" (and pardon my irony).
Ok, now on to the reasoning behind the change. ("Well, I could explain it better, but I'd need charts, and graphs, and an easel.") Essentially, the flow of blood through the arteries and into the myocardium requires the creation and maintenance of a pressure head. Research has shown that it takes about 5-7 compressions to create that pressure head, and every time you stop pumping, you lose that pressure. Now only when this pressure head exists is oxygen being delivered to the myocardium, thus any time you stop pumping, you're creating a period of time in which oxygen is not being delivered. And apparently 30:2 was the best ratio for oxygenating blood in the lungs and delivering blood to the heart.
Here's the official guidelines and all the studies behind them in all their linky goodness. http://circ.ahajournals.org/content/vol112/24_supp l/ [ahajournals.org]
Wikipedia's entry on reperfusion injury (Score:2, Informative)
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).
Re:Makes a little bit of sense. . . (Score:2, Informative)
During a cardiac arrest, metabolism is very slow, and the amount of oxygen in the lungs is not depleted very rapidly. Therefore emphasis has changed to improving the oxygen delivery by increasing the blood flow, by increasing the number of compressions relative to rescue breaths.
Re:Makes a little bit of sense. . . (Score:3, Informative)
Ah, yes. That was one of the other changes to simplify resuscitation - don't bother checking for a heartbeat, start resuscitating right away. If the patient doesn't need it, he'll protest soon enough.