X-Message-Number: 20702 Date: Mon, 23 Dec 2002 23:49:06 -0800 (PST) From: Michael Hartl <> Subject: Stepdad's argument Toby Christensen wrote: > My stepdad's argument, succinctly > Is this: > > That after 7 minutes without oxygen a person is > brain-dead and that the idea that someone will > develop the technology to revive brain dead people > one day is mysticism. Hi Toby, Your stepdad's argument is important and deserves a detailed rebuttal. Steven Harris is probably the best person for that, but I can give you the short version. Most "damage" done by oxygen deprivation to the brain is in fact only *potential* damage. The body reacts to brain trauma through an autoimmune cascade, the strength of which depends on the level of trauma. The damage can largely be prevented through cooling, which is why we ice sprained ankles. The current record for resuscitation without damage in canines is 15 minutes at flatline, but only with subsequent cooling to minimize damage. Without cooling, even 5 minutes can be fatal. The key point for cryonics is that the most of the damage from oxygen deprivation is realized only after the autoimmune response begins, after circulation is restored in the patient. If a patient is rapidly cooled, this damage can be minimized upon re-warming (and in fact cooling heart attack victims will likely become standard emergency medical practice soon), but in cryonics the patient is not re-warmed: he is cooled right down to liquid nitrogen temperatures without the autoimmune cascade ever having a chance to do its damage. By the time technology can reverse the damage from the suspension, the question will be moot: suppressing the autoimmune reaction is trivial compared to the cellular repair needed for a successful resuscitation. I suspect that the damage is realized late enough that the upper limit on time spent at flatline is quite high, maybe even on the order of hours, as long as the patient is cooled all the way down to cryogenic temperatures after that point so that little or no autoimmune damage occurs. This is speculation, though, and determining exactly when oxygen deprivation damage is realized -- and how severe it is -- is an important research problem. In any case, if cool-down happens soon after the pronouncement of legal death, the damage due to oxygen deprivation is minimal, and the prospect for eventual revival is excellent. Cheers, Michael -- Michael Hartl http://www.michaelhartl.com/ __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=20702