Cryo with magnetics added

persufflation

That was a mild pain to google, so I'm leaving what I dug up here so others don't have to duplicate the effort.

Persufflation is perfusion with gaseous oxygen. Perfusion is when fluid going to an organ passes through the lymphatic system or blood vessels to get there.

If I'm reading this correctly, there's no thermodynamic reason to pump the organ full of oxygen gas, but only a biological one. Cells need less oxygen when they're on ice for an organ transplant, but they still consume O2. If this isn't being delivered via blood flow, another source is needed.

I take it that the persufflation is to help with recovering kidneys from liquid nitrogen temperatures, and not in getting there without damage?

Precisely. Normally, vitreous H2O (glass phase of ice) is produced through 1 of 2 methods:

1. Pouring liquid H2O on a highly conductive heatsink which is cooled to liquid nitrogen temperatures (Ie, a block or sheet of copper in contact with LN)

2. Taking a block of ice and compressing it at low temperatures.

The first method only works for thin sheets of ice, or creates a thin vitreous layer on the outside of a larger water-filled object. The second method allows one of the normal phases of ice to form, and then converts it to vitreous ice.

However, if we could supercool large volumes of water low enough without spontaneous crystallization, it might be possible to choose which phase of ice forms by deliberately nucleating with that. If turning off the magnetic field doesn’t cause freezing fast enough to vitrify, maybe a sufficiently sharp ultrasonic pulse could disrupt the metastable liquid state fast enough? Similarly, I’d be curious whether a thermoacoustic heat pump could remove heat fast enough to vitrify the water without completely shredding everything nearby.

On a related note, I wonder if it would be possible to suppress the less dense phases of ice (which expand more, and therefore cause more damage) just by increasing the ambient pressure during freezing? Method #2 is a crystalline solid to vitreous solid phase change, but there's no reason the same thing wouldn't work for a liquid to vitreous solid phase change. It looks like it's done at 5,000-1,600 atmospheres of pressure, but that might just be to speed up the rate of transition.

The depth diving record is the equivalent to 701 meters, which works out to 68 atmospheres of pressure. However, most of the effects have to do with respiration, such as the lung's ability to remove CO2 as it builds up in the blood. Nitrogen narcosis has effects on judgment a bit like alcohol, but this might not matter for cryonics. If it does, we could always use a liquid or gas like helium, which has effectively zero lipid solubility.

Is the reason this isn’t done cost, or something else? From a material science perspective, pressure seems like the obvious solution to fight expansion during crystallization. Working with nature is much easier than messing with thermodynamically unfavorable solutions.