X-Message-Number: 1906 From: R. Ettinger Subject: Replies From Ettinger Robert Ettinger sent to me a reply to the CryoNet postings that I sent to him. (Since then, several more people have posted messages that I need to forward to Ettinger.) He also included a detailed reply to Mike Darwin's feedback (which was posted as message #1787) and gave the OK to forward his messages as I wish. I have appended his replies below. Kevin Q. Brown ----- March 2, 1993 Dear Mr. Brown: Thanks very much for the Cryonet copies. Enclosed are my second letter, which you may or may not have seen, and my response to Mike Darwin. Following are my responses to some of the comments you sent me. You may use all this as you wish. On the matter of convection (Steve Harris) : No doubt there will be some convection, of a nature very hard to calculate. But remember my first stratagem in the first (Feb. 12) letter: we use buffers of insulation around the patients where appropriate, to damp temperature changes; and also an inside wrapping or pod of highly thermally conducting material, that tends to equalize temperatures all around the patient's surface. What the net result will be can only, I think, be determined by experiment, which is what we (Cryonics Institute) plan to do, as time allows--using a cylindrical cryostat, which might allow neuro storage by this system. (CI does not do neuros, and at present does not store them, but we still want the information.) On the matter of stable top temperature (Brian Wowk) : There is insulation at the top. Nitrogen loading is through an insulated access tube reaching through the insulation at the top and extending almost to the bottom. This may be adequate: again, only trials will tell for sure. On the desirability of mass storage (page 2 only of a letter, no name given): My second letter, Feb. 21, describes a system that could handle a fair number of patients per cryostat. On Steve Harris' suggestion of patient in foam block between air and liquid nitrogen: This is similar, in part, to my letter of Feb. 21. On the cracking of foam insulation near liquid nitrogen: We avoid this, in our liquid nitrogen cool-down boxes, by not using continuous or poured foam, but layers of 2-inch foam slabs, with glass wool padding and caulking--Andy Zawacki's idea. If cracks occur (which we have not observed) they don't propagate more than 2 inches outward. Long life-- Bob Ettinger ----- Feb. 26, 1993 Michael Darwin Cryovita taboratories 1220 E. Washington St.,#24 Colton CA 92324 Dear Mike-- Thanks for the information and comments. Enclosed is a copy of some further ideas on storage near GT, which - if I haven't made some blunder - might improve space utilization. Your ideas sound 0.K., lthough I'm not too comfortable with the idea of using something like ethyl chloride. There are doubtless many workable approaches, varying in cost for a given level of reliability. But -- although we (CI) intend to proceed with trials of the float version in a cylindrical cryostat -- some fundamentals remain unclear to me. For one thing, if the patient must be kept very close to a particular temperature, and if that temperature varies with concentration of glycerol (and other factors) it becomes very tough. Even if you have a good way of estimating the average glycerine concentration in the body (brain), the local concentratioa within the body will surely vary considerably, and some regions will be at the wrong temperature. Even more basic is the question of estimating the bottom-line change in the patient's chances. Knowledgeable people think the reduction in cracking is *significant* near GT; but even if it is 95%, there will still remain 5% cracking, which could well require full-fledged nanotech for repair. If nanotech is (probably) both necessary and sufficient for either procedure, then it becomes very hard to justify the more expensive procedure, except for those rich enough to be willing to pay a high premium for a marginal and possibly meaningless improvement. Similar remarks apply to the whole question of improvements in the hypothermic phase (except as these relate to improvements in cryoprotectant uptake). We know that several people have fully recovered after drowning in cold water, even after being under water for 45 minutes or more. In other words, with prompt topical cooling, they made complete recovery with no prior medication or treatment of any kind. This appears to prove that - within the limits of these examples, including the fact that they were initially healthy people and the cooling was only moderate -- any treatment prior to or coincident with death can have only marginal importance. As far as I know, in almost all cases the hypothermic damage is small, probably trivial, compared with the cryothermic damage. (This tends to be borne out, among other things, by Suda's experiments, comparing his first and second series.) Nevertheless, we tend to think that our people should have the benefit of all available options and be allowed to use their own judgment. Hence Cryonics Institute hopes to provide anything that appears to have a substantial potential for benefit, if it is practically feasible for us. This includes Trans Time's services and yours. As you know, we already have an agreement with Trans Time; if Cryovita develops a proposal, or if Alcor does, for that matter -- we will consider it. Long life-- Bob Ettinger ----- Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=1906