Alcor agreed to accept Matheryn as a patient, and enrolled her as a member. The initial plan was to fly Einz to the United States while she was still alive, so Alcor’s team could perform the procedure domestically. That procedure is complex and highly invasive; the BBC calls it “intense.”
It involves moving the patient onto an ice bed, coating her in freezing materials, artificially restarting the heart with a “heart-lung-resuscitator,” administering over a dozen different medications, draining the blood and replacing it with medical grade antifreeze, opening the chest cavity to attach the major blood vessels to a machine that flushes out all remaining blood, then slowly lowering the body’s temperature, at a rate of 1˚ Celsius every hour. (After two weeks, the body reaches deep cryofreeze at -196˚ C.) Alcor had selected a well-equipped pediatrics hospital in California for the job.
—Brian Merchant, writing for Vice about two-year-old Matheryn Naovaratpong, the younger person to ever be cryonically frozen.