I’ve wondered if that sort of dramatic cooling is more of an optimal path to cryonic preservation than the current method of waiting for “natural” death and then immediate perfusion. E.g. since it’s an official medical treatment, get cooled significantly “to prevent organ damage” and kept in that state until some measure of clinical death occurs, at which point it may be more likely to avoid ischemia.
I looked into cold-water drownings for similar reasons but it appears to me that what actually happens is just a preservation of oxygen in the brain and heart and lungs by the mammalian diving reflex and not necessarily any reduction in risk from ischemia during subsequent cryonic suspension. But being pre-cooled may still have some advantages.
Cooling to a few degrees below normal body temperature for a few days after ishchemia does help keep down reperfusion injury and after-the-fact inflammatory brain damage and is indeed now the standard of care at some heart centers around the US now...
Maybe a naive question, but you’ve got me curious: why is it the standard of care at some heart centers, rather than most or none? Is it a matter of cost, or are the benefits you mentioned not well-established, or are heart centers slow to change their standard of care? Or is it some fourth thing I didn’t think of?
It was recommended as potentially useful all the way back in the 2005 American Heart Association guidelines for CPR, actually, and there’s been spotty literature even further back.
It isn’t so much about preserving function during hypoxia (that damage is already done by the time they get to the hospital) as preventing the subsequent damage that happens both immediately after and over several days after restoration of bloodflow. This is due to reperfusion injury as cells poison themselves due to metabolisms disrupted by the hypoxia, and slower issues caused by the immune system reacting via inflammation against very slight brain damage and thus greatly exascerbating it (a useful response to physical damage in peripheral tissue but problematic if you manage to restart someone’s heart).
I suspect the reasons for slow adoption consist of it having a focus that is very different than the ususal ‘get the blood flowing again’ aspect, where the bloodflow and proper immune function is actually the problem, and the fact that you need the equipment procedures and institutional coordination to integrate another step of care for a day or more after the acute treatment. I don’t think its so much a question of cost as setting up all the procedures and conditionals and institutional experience to do it reliably and automatically.
Course that leaves institutional inertia or laziness as additional prime obstacles.
When a friend of the family had a heart attack resulting in temporary cardiac arrest recently this aspect of treatment consisted of keeping them in a chemically induced coma for several days after the incident and cooling them to somewhere around ~34 C (I’m estimating based on what I heard), then slowly warming them and withdrawing the drugs.
I’ve wondered if that sort of dramatic cooling is more of an optimal path to cryonic preservation than the current method of waiting for “natural” death and then immediate perfusion. E.g. since it’s an official medical treatment, get cooled significantly “to prevent organ damage” and kept in that state until some measure of clinical death occurs, at which point it may be more likely to avoid ischemia.
I looked into cold-water drownings for similar reasons but it appears to me that what actually happens is just a preservation of oxygen in the brain and heart and lungs by the mammalian diving reflex and not necessarily any reduction in risk from ischemia during subsequent cryonic suspension. But being pre-cooled may still have some advantages.
Cooling to a few degrees below normal body temperature for a few days after ishchemia does help keep down reperfusion injury and after-the-fact inflammatory brain damage and is indeed now the standard of care at some heart centers around the US now...
Maybe a naive question, but you’ve got me curious: why is it the standard of care at some heart centers, rather than most or none? Is it a matter of cost, or are the benefits you mentioned not well-established, or are heart centers slow to change their standard of care? Or is it some fourth thing I didn’t think of?
It was recommended as potentially useful all the way back in the 2005 American Heart Association guidelines for CPR, actually, and there’s been spotty literature even further back.
It isn’t so much about preserving function during hypoxia (that damage is already done by the time they get to the hospital) as preventing the subsequent damage that happens both immediately after and over several days after restoration of bloodflow. This is due to reperfusion injury as cells poison themselves due to metabolisms disrupted by the hypoxia, and slower issues caused by the immune system reacting via inflammation against very slight brain damage and thus greatly exascerbating it (a useful response to physical damage in peripheral tissue but problematic if you manage to restart someone’s heart).
I suspect the reasons for slow adoption consist of it having a focus that is very different than the ususal ‘get the blood flowing again’ aspect, where the bloodflow and proper immune function is actually the problem, and the fact that you need the equipment procedures and institutional coordination to integrate another step of care for a day or more after the acute treatment. I don’t think its so much a question of cost as setting up all the procedures and conditionals and institutional experience to do it reliably and automatically.
Course that leaves institutional inertia or laziness as additional prime obstacles.
See http://emedicine.medscape.com/article/812407-overview
When a friend of the family had a heart attack resulting in temporary cardiac arrest recently this aspect of treatment consisted of keeping them in a chemically induced coma for several days after the incident and cooling them to somewhere around ~34 C (I’m estimating based on what I heard), then slowly warming them and withdrawing the drugs.