X-Message-Number: 5313 Date: Fri, 1 Dec 1995 07:56:11 -0800 (PST) From: Doug Skrecky <> Subject: avoiding devitrification Apologies in advance if the following is a repeat of a previous discussion on cryonet. After talking with a long term cryonicist I was told that he had never heard of using the cardiovascular system as a heat exchanger during rapid warming of frozen tissue, as a strategy to avoid devitrification. In case this idea has never been put forward before I would like to ammend the following article so as to explicitly incorporate this. As before the following article may be reprinted in any cryonics oriented newsletter or magasine, whose editor wishes to do so: A VITRIFICATION PROPOSAL By Doug Skrecky Any attempt to vitrify with relatively low and non-toxic concentrations of cryoprotectant would require cooling rates in excess of that acheivable by immersing the entire body in any coolant. I would like to here outline a possible way out of this impass. The cardiovascular system has an internal area over 300 times that of the external bodily surfaces. Using the cardiovascular system as a heat exchanger would allow cooling rates considerably in excess of that achievable by whole body immersion. Coolant circulating through veins, arteries and capillaries would have to have a freezing point lower than the annealed glass transition of glycerol (-100 C) if glycerol is selected for the cryoprotectant, as well as a boiling point of at least 0 C. The coolant must also be nontoxic - which seemingly eliminates simple solvents such as ethanol (freezes -130 C) from consideration. However freon 11 or trichlorofluoromethane freezes at -111 C, boils at +23.7 C, is chemically fairly inert, nonflamable and insoluable in water. After perfusion with freon 11 cooled to 0 C, we could rapidly inject freon cooled to -100 C, thereby achieving very high cooling rates and hopefully vitrifying the body. After cooling to -100 C we might pump the freon out of the cardiovascular system and begin slow cooling to liquid nitrogen temperatures to avoid tissue cracking. After the storage period is up the above process might be reversed to provide warming rapid enough to avoid devitrification. Warming rates considerably in excess of that available with microwaves should be possible. Again to avoid cracking first slowly warm the body from liquid nitrogen temperatures to -100 C. Pump freon 11 cooled to -100 C into the cardiovascular system and circulate as a safety check. Then rapidly inject freon heated to +20 C. After the body has thawed replace the freon with the University of Wisconsin solution. Keep temperature below the boiling point of freon till replacement is complete and then transplant the patient into a new life. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=5313