I Can't Believe You Missed ThisMarch 12 2010 at 12:45 AM
|Steve Harris (Login StevenHarris)|
Response to Can't Believe I Missed This...
Harris: "If there are any signs of awareness later, such as eyelid movement or even shivering (not a sign of awareness but certainly a sign of CNS activity), another equal dose is held in reserve."
Maxim: Did Harris just write that, in the event a cryonics patient shows signs of life, the cryonics team is going to give them another dose of propofol? Shivering means the muscles are receiving signals from the hypothalamus and, as far as I know, legally dead people do not shiver. In fact, when people are subjected to hypothermia, they usually stop shivering even before they lose consciousness.
COMMENT: There haven't been any close studies of what "legally dead" people do, since being "legally dead" is not a fully-scientifically-defined state. What would be the point of looking at something that is semi-arbitrary? At any time you're in cardiopulmonary arrest with no blood pressure (that's the biology), your doctor is free to assign you, on a purely social basis, to the social status of "legally dead." Whether this actually happens, and when, will depend on your advance directives, the wishes of your family, and other social intangibles. If you wanted to be resuscitated, perhaps an attempt will be made to do that, instead. It may even succeed. But if you have a terminal disease or for some reason don't want resuscitation, no attempt will be made. In that case you may well be classed as "legally dead" upon cardiac arrest, perhaps before your brain becomes non-resuscitatable, and certainly before your organs become unusable and your cells unculturable.
The resuscitation literature contains accounts of persons in cardiac arrest showing awareness (and other brain stem functions like pupillary response) while undergoing chest compressions. That's the biology. Whether such a person has been assigned the status of "legally dead" beforehand, is not relevant biologically, but it is a paradox legally. Only in cryonics is it likely that chest compressions would be done on a person in cardiac arrest who had previously been pronounced "dead," instead of to a person in cardiac arrest who had not yet been pronounced "dead." It is thus in cryonics that there is a theoretical possibility that a person in cardiac arrest who has been classed as legally dead might become aware of chest compression. We all hope this never happens, and part of the purpose of propofol is be sure that it does not.
The only other choice would be to deliberately wait 10 or 15 minutes (perhaps more?) to be absolutely sure that there is enough natural brain damage from lack of oxygen to keep the person in coma, after chest compressions start. Is that what you're suggesting? Propofol seems a better idea to me; as it doesn't prevent cardiac resuscitation, but only prevents awareness. In no way can it be said to keep people legally dead-- the worst that can be said is that it keeps them unconscious after the consensus decision that they should stay legally dead, with no attempt at resuscitation, has already been made.
As for shivering, there is no perfect correlation between when it can or cannot occur. I assume that like pupillary response and other brain functions, shivering has a chance of happening in anyone who is conscious. Humans may certainly shiver while unconscious and even while hypothermic (there is no set rule). So can dogs.
Maxim: Since Harris and Platt's posts, I have verified that the dose of propofol in the SA standby kits was 200mg, rather than 20mg, but each kit held only one 200mg bottle, with nothing in reserve. Is the reserve dose Harris comments on a new thing? Since when?
Good question. We ourselves carry backup doses of many "small volume" medications, since just an extra dose of the meds with no extra syringe or other equipment requires very little extra room in the kit, and then one has a backup if a vial is accidently broken. I thought Alcor and SAI did this. If not, I'll formally suggest it.