3 ms·

To be fair, have we REALLY tried this with people?

thaumasiotes 5y ago
Some people are documented as surviving in freezing temperatures for extended periods, yes. This is what you would expect from freezing. It preserves things. The difficulty with freezing is getting back up to normal temperatures safely. (And the creation of ice crystals, which can be very damaging.)
TremendousJudge 5y ago
I think it was tried with larger mammals and it didn't work, which is why the research for humans was dropped. The hope that at some point in the future it may be possible is the entire point of cryonics. It works with severed body parts though.
- SemanticStrengh 5y ago
  Cryogenics is not about freezing humans, it is about vitrifying them, huge difference.
Someone 5y ago
Yes. https://en.wikipedia.org/wiki/Emergency_Preservation_and_Resuscitation https://en.wikipedia.org/wiki/Emergency_Preservation_and_Res...: Emergency Preservation and Resuscitation (EPR) is an experimental medical procedure where an emergency department patient is cooled into suspended animation for an hour to prevent incipient death from ischemia, such as the blood loss following a shooting or stabbing. That page doesn’t say this is a net win or worked well at all, but it’s a difficult line of research. Not only are the first patients almost dead at the start of the process (as is always the case with high-risk of death experimental procedures), but there also is no way to know when a patient will show up. https://en.wikipedia.org/wiki/Deep_hypothermic_circulatory_arrest https://en.wikipedia.org/wiki/Deep_hypothermic_circulatory_a... is easier in this respect: Deep hypothermic circulatory arrest (DHCA) is a surgical technique that induces deep medical hypothermia. It involves cooling the body to temperatures between 20 °C (68 °F) to 25 °C (77 °F), and stopping blood circulation and brain function for up to one hour. I think that’s a proven winner for some patients, but only at relatively high temperatures (“Profound hypothermia (< 14 °C) usually isn't used clinically. It is a subject of research in animals and human clinical trials”)
xenadu02 5y ago
Besides the research discussed in the other comments we have now many documented cases of people falling into extremely cold water in the winter, being pulled out after an hour, and recovering. The warming has to be done properly though, if you just pull them out and heat them up immediately they'll die. If you just pull them out and let them warm up very slowly in a warm room they'll die. You have to heat them up as evenly as you can at a certain rate. When you consider that oxygen deprivation is the primary cause of cell death it makes sense. Cooling down the cells greatly reduces their metabolism and thus oxygen requirements. But cooling the heart down before the brain just makes the brain run out of oxygen first. The more oxygen-dependent the organ the more critical it is that organ be cooled first. Conversely you can't warm up those organs before the heart and lungs or they'll survive that long time of cooling only to die during warming due to lack of oxygen.

Some people are documented as surviving in freezing temperatures for extended periods, yes. This is what you would expect from freezing. It preserves things. The difficulty with freezing is getting back up to normal temperatures safely. (And the creation of ice crystals, which can be very damaging.)

TremendousJudge 5y ago

I think it was tried with larger mammals and it didn't work, which is why the research for humans was dropped. The hope that at some point in the future it may be possible is the entire point of cryonics. It works with severed body parts though.

SemanticStrengh 5y ago
Cryogenics is not about freezing humans, it is about vitrifying them, huge difference.

Someone 5y ago

Yes. https://en.wikipedia.org/wiki/Emergency_Preservation_and_Resuscitation https://en.wikipedia.org/wiki/Emergency_Preservation_and_Res...: Emergency Preservation and Resuscitation (EPR) is an experimental medical procedure where an emergency department patient is cooled into suspended animation for an hour to prevent incipient death from ischemia, such as the blood loss following a shooting or stabbing. That page doesn’t say this is a net win or worked well at all, but it’s a difficult line of research. Not only are the first patients almost dead at the start of the process (as is always the case with high-risk of death experimental procedures), but there also is no way to know when a patient will show up. https://en.wikipedia.org/wiki/Deep_hypothermic_circulatory_arrest https://en.wikipedia.org/wiki/Deep_hypothermic_circulatory_a... is easier in this respect: Deep hypothermic circulatory arrest (DHCA) is a surgical technique that induces deep medical hypothermia. It involves cooling the body to temperatures between 20 °C (68 °F) to 25 °C (77 °F), and stopping blood circulation and brain function for up to one hour. I think that’s a proven winner for some patients, but only at relatively high temperatures (“Profound hypothermia (< 14 °C) usually isn't used clinically. It is a subject of research in animals and human clinical trials”)

xenadu02 5y ago

Besides the research discussed in the other comments we have now many documented cases of people falling into extremely cold water in the winter, being pulled out after an hour, and recovering. The warming has to be done properly though, if you just pull them out and heat them up immediately they'll die. If you just pull them out and let them warm up very slowly in a warm room they'll die. You have to heat them up as evenly as you can at a certain rate. When you consider that oxygen deprivation is the primary cause of cell death it makes sense. Cooling down the cells greatly reduces their metabolism and thus oxygen requirements. But cooling the heart down before the brain just makes the brain run out of oxygen first. The more oxygen-dependent the organ the more critical it is that organ be cooled first. Conversely you can't warm up those organs before the heart and lungs or they'll survive that long time of cooling only to die during warming due to lack of oxygen.