X-Message-Number: 1998 From: whscad1!kqb (Kevin Q Brown +1 201 386 7344) Subject: CRYONICS Ettinger replies concerning -136 C storage Robert Ettinger sent to me his replies to the Feb. 28 - March 12 CryoNet postings concerning approx. -136 C storage and I have appended them below. Kevin Q. Brown ----- CRYONICS INSTITUTE 24443 Roanoke, Oak Park, Michigan 48237 Telephone (313) 548-9549 or (313) 547-2316 March 15, 1993 > Subject: Not-so-cold storage From: Robert Ettinger To: Correspondents Kevin Brown has kindly sent me a summary of CryoNet comments, Feb. 28 - March 12. Let me Let me try to summarize part of this summary and comment. (No offense to those not mentioned; I am citing / commenting mainly where I have a further comment that might be useful.) Brian Wowk reiterated the concern of Steve Harris and others about convection in the flotation approach. I note again that convection will occur, and also that stratum temperature (aside from convection) depends not only on distance above the liquid nitrogen but also on the total height of the column; but appropriate use of conducting and insulating sheaths may damp the effects sufficiently. We won't know until we try it, which Cryonics Institute intends to do. (Mr. Wowk has also mentioned the use of a conductive sheath to suppress temperature variations over the patient's surface.) Brian Wowk comments on my observation that, since people have recovered fully after drowning in cold water with more than 45 minutes immersion, this tends to prove (within the limits of the examples) that -- if someone is cooled quickly after clinical death -- any other treatment can have only marginal importance. (1) He thinks, in the drowing cases, the heart may have kept beating a considerable time, and that blood oxygen can keep things going (most systems functioning?) for ten minutes or more without breathing. (2) He thinks cooling, after drowning in cold water, would be more than the "moderate" amount I mentioned. (3) He concludes that, unless a cryonics patient gets prompt and effective cooling, and cardiopulmonary support, he will be in much worse shape after 45 minutes than a cold-water drowning victim. My comment: (1) Even if true, the prompt cooling is still the main consideration. (And, contrary to Mr. Wowk's comment, all cryonics organizations do provide prompt cooling and cardiopulmonary support, when feasible -- not necessarily with equal efficiency.) (2) I said "moderate" cooling in the drowning cases as a conservative estimate that tended to reduce the power of my argument. lf there was more cooling, all the better for the argument -- more evidence that the degree and rate of cooling are primary factors, as compared with medication. (3) Agreed. But if prompt cooling is the main factor, then, for patients at a distance, it is much more important to try to get local (mortuary or other) people to provide it than to rely on traveling teams from a cryonics organization; and in such cases the matter of cardiopulmonary support may be secondary, and that of medications tertiary at most. Rich Schroeppel suggests that storage at -50 C might be adequate, based on assumptions about enzymatic and other activity. (One of his assumptions is refuted by Brian Wowk.) Comment: As far as I know, no really definitive work has been done on long term damage in these temperature ranges. We know that some tissues suffer considerable long term -- even relatively short term -- damage in dry ice, but whether deterioration continues indefinitely or is self-limiting isn't clear to me. Several people have been talking about room-sized storage with conventional (non-vacuum) insulation. Brian Wowk offers calculations involving an "optimum" 2 meters of foam insulation, with a room 5m x 5m x 3m. However, unless I have misread him somehow, he has overlooked a crucial point. He says the thermal conductivity of good foam insulation is 0.02 watt/m/degC; this is not true. The coefficient (0.02 watt/m/degC in this case) is not a constant, but varies with distance. The relation is linear (Newton's law of heat transfer) only for fairly thin walls. For thick walls, or at least walls that are thick relative to the overall dimensions, the temperature gradient is much steeper near the inside than near the outside, which means that increasing thickness rapidly loses effectiveness. I haven't done the calculation for Mr. Wowk's case, but the boiloff will be much larger than he says. Charles Platt thinks nanotech could repair big fractures more easily than cellular damage (which also occurs), hence there is little point to the higher temperature storage. But others -- some very well informed -- think the opposite, that cellular damage would be easier to fix, because the connections could be more easily inferred. Ralph Merkle seems to agree with me that nanotech is likely to be both necessary and sufficient to repair damage caused by current procedures, and also by the not-so-cold storage, hence the latter is likely to be of marginal importance at best. But because opinions differ, and we want to make all feasible options available, CI still plans to investigate further. Mike Darwin says the typical cryonics patient is not comparable to a cold water drowning victim, and that his studies show the former suffers serious injury during ischemia and reperfusion, and that "...some of this injury results in immediate and serious destruction of ultrastructure. Other injury is secondary to loss of capillary integrity, leukocyte plugging of capillaries, and other problems which compromise subsequent cryoprotective perfusion." Comment: The first part of that quotation does not seem convincing, in light of the extensive experience with recovery or partial recovery of animals and tissues under very adverse circumstances. As to the second part, we seem to get pretty good cryoprotectant uptake with relatively simple procedures. Mike Darwin offers to provide uniformly glycerolized animals -- dogs or pigs -- in dry ice, for Cryonics Institute to test further cooling and not-so-cold storage. We thank him and his associates for this, but we will not any time soon be prepared to handle specimens that large; but we could use the heads. Our first step is to prepare the cryostat; we expect to have the HSSV-1 reconfigured in a week or two. We will then measure temperatures at various heights and radii above the liquid nitrogen, with various depths of liquid; and we will test the efficacy of temperature change damping using sheaths of conductors and insulators. If these results are encouraging, we will prepare a flotation device and make further tests. After that we may be ready for further work, consisting of or leading up to the kinds of experiments Mike suggests. At that point, if everyone is in agreement, we will undertake a cooperative effort; or if there isn't agreement, we will do whatever we judge to be warranted. A couple of people agreed that glycerine concentration can vary over parts of the body, and therefore the ideal storage temperature could vary from point to point, but they said we need only worry about the brain. Nobody connected with ny suggestion that cryoprotectant concentration will probably also vary from region to region, tissue to tissue, of the brain itself. I still don't know how much of this kind of variation actually occurs; in fact, I don't even know what methods Alcor or Cryovita uses to assess local concentrations. Nobody seems to have commented on my letter of Feb. 21 on the idea of radial strata without a gas region, so I assume no one has found any fatal defect. When CI buys and moves into a new building, we will work on this too, if the whole not-so-cold idea still seems worth pursuing. On the topic of different kinds of insulation, I remind people that one of these days someone is going to renew the production of rigid open-cell foam, which will allow moderate- vacuum insulation with rectangular geometry without internal bracing -- a big improvement over both the MVE type units and ours. Also, there is already commercially available, or according to reports very soon will be, mass-produced vacuum insulation modules (intended for kitchen refrigerators as a substantial advance over the present foam). I've misplaced the reference, but it will certainly surface again soon. ----- Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=1998