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. 


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