X-Message-Number: 3599 Subject: SCI.CRYONICS Re: Flash freeze of Humans From: (Edgar W. Swank) Date: Wed, 04 Jan 95 23:22:42 PST In Message: #3552 (Robert D Grahame) writes, In article <CryoNet Message: #3543> Jan Coetzee write: >If so, then if it was possible to flash freeze a living human and then >flash thaw him he should have not suffered damage from it. Possibly... But the thermal conductivity of a human is extremely low (compared to a metal). Even if you dunked a naked brain straight into a vat of liquid helium only a thin layer on the outside would be flash-frozen. The rest would freeze in a normal manner, and the un-even contractions from that process would probably crack the fragile flash-frozen layer in to the bargain. If you could somehow pump a similar coolant *through* the brain quickly, then you might be on to something, but to do that you'd have to get the liquid out of the blood vessels first, which sounds like a non-starter. Perhaps not. I can think of two ways to evacuate liquid from the circulatory system to be replaced by cold gas, which can be pumped through and acheive quick (if not "flash") and uniform cooling. First: look for a "transition" fluid, more volatile then the initial water/glycerin based cryoprotectant, but which is miscible with it, and non-toxic at near 0 C. Use this fluid to "wash out" the initial cryoprotectant. Second: Use a partial-vacuum chamber to encourage either the transition fluid or (at a higher temp) the initial cryoprotectant to vaporize. The vapor can then be washed out by circulating another gas, like helium, or any non-toxic gas with BP less then N2. -- (Edgar W. Swank) SPECTROX SYSTEMS +1.408.252.1005 Cupertino, Ca Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=3599