When possible it is advisable for cryonics patient in a terminal (pre-deanimation) condition to supplement with antioxidants and other agents to reduce the effects of ischemic and other injuries. Magnesium oxide would be given to prevent low magnesium levels, as often occurs in enterically fed patients and which can worsen brain ischemic injury. Mixed tocopherols means both alpha and gamma forms of Vitamin E, because gamma-tocopherol removes the peroxynitrite radical, whereas alpha-tocopherol does not. Vitamin E and fish oils can reduce clotting, but should not be given for a patient likely to be receiving surgery because bleeding can be increased. Curcumin (curry powder) and melatonin could also be given. Vitamin C should not be used because it can become strongly pro-oxidant in ischemic brain tissue.
(For more detailed scientific justification of pre-treatment protocol, see Pre-Treatment for Cryonics Patients.)
Initial Cool-down and Transport
If possible CI Members should arrange to have a team of cryonicists standing by their bedside when they are in a terminal condition. Such a team can initiate rapid cooldown with a portible ice bath and ACDC Thumper.
The patient should be pronounced dead as soon as possible after clinical death (which usually means after cessation of heartbeat and breathing). As soon as possible after that, the patient should be cooled--especially the head--by application of ice. A slurry of ice water can cool much faster than ice cubes, so inflatable basin for giving shampoos, such as the EZ-Shampoo Basin should be used when it is not too messy or inconvenient to do so. The best scenario is for the patient to die at home under hospice care, with trained personnel -- morticians or Cryonics Institute (CI) volunteers --on hand. (No guarantee is made that CI volunteers can be found.) Arranging for deanimation in Michigan near the CI Facility eliminates transportation delays and involvement of a remote funeral director.
If not contraindicated by local rules or regulations, an anticoagulant should be legally injected--usually heparin, 30,000 units for a patient of average size.
During transportation, if feasible and not contraindicated, CPS (CardioPulmonary Support -- CPR-like compressions, not literally "CPR" because the objective is not "Resuscitation") should be given manually or by machine (thumper), to keep oxygenated blood circulating, minimizing deterioration, and to help cool the patient, and to help distribute the heparin.
Patients living outside of the Michigan area will be packed in ice in an airtight container by a funeral director local to the patient and shipped to the Detroit airport in that container. A Michigan funeral director will take possession of the patient at the Detroit airport and transport the patient to a funeral facility near the CI facility (northeast of Detroit).
Washout and Perfusion
At the premises of the Michigan funeral director the patient's blood is washed out with washout solution and a mixture of CryoProtectant Agents (CPAs, "anti-freeze" substances that prevent ice formation) is used to replace the patient's body water. Blood vessels are cannulated for these perfusions. (Perfusion means the pumping of fluids through blood vessels.)
The blood washout solution used is based on the organ preservation solution RPS-2 (Renal Preservation Solution), which also acts as the carrier solution used in vitrification. We use a special light-weight pump with new sterile tubing for each occasion.
After the blood is washed out, the cryoprotectant mixture is introduced. It has also been stored at refrigerator temperature. This is made by adding the cryoprotectant to the washout solution. The cryoprotectant used by CI is called CI-VM-1, a Vitrification Mixture developed by CI's in-house cryobiologist Dr. Yuri Pichugin. Vitrification solutions can completely eliminate ice formation. (For more on vitrification solutions see Vitrification in Cryonics.) The perfusion with vitrification solution is done at increasing concentrations, until a target concentration of 70% CI-VM-1 is reached. The 70% CI-VM-1 has been stored in a freezer, so it is below freezer temperature.
As we have done with all perfusions since our 69th patient, we perfuse through both the vertebral and the carotid arteries. The carotids alone do not perfuse the whole brain for about 15% of people and for about 50% of stroke victims, which is why perfusion through the vertebrals as well as through the carotids is done.
On the right side of the body the vertebral artery comes off the subclavian artery immediately distal to the bifurcation that forms the common carotid and the subclavian. Thus, ligating the subclavian just distal to the vertebral on the right side and cannulating proximal to the bifurcation provides a means of perfusing only into the vertebral and common carotid. The left side of the body is more complicated, however, because the common carotid arises as an independent branch from the aorta and the vertebral arises from the subclavian, which is also an independent branch from the aorta.
Our funeral director
gains access to the blood vessels by incisions just below the clavicle.
Slits (incisions) are made in the arteries for the insertion of the cannulation tubes
(blunt needle-like cannulas) required for perfusion. The vessels are clamped below
the incisions. The cannula on the left side of the drawing (right side of the patient)
perfuses both the vertebral and the carotid. The right side of the drawing (left side of
the patient) illustrates that the carotid and vertebral are independently
cannulated and perfused. Jugular veins are cannulated on both sides for drainage
and for sampling of the effluent.
|Tubing for perfusion||Blunt needle-like cannulae|
Perfusion pressure is maintained at 120 mmHg (normal physiological perfusion pressure) throughout the perfusion, while flow rates declined with the increasingly viscous perfusate. The only exception to this is the first introduction of 70% CI−VM−1 (Vitrification Mixture one) vitrification solution (which is more viscous than the 30% ethylene glycol which precedes it, at least partially because it is at a lower temperature). In introducing CI−VM−1 the first 0.2-0.3 liters are introduced at about 70-90 mmHg with a flow rate of about 0.36 liters/minute. Otherwise, perfusion data for the head (brain) can be presented in tablular form, beginning with the blood washout with m−RPS−2 (modified Renal Perfusion Solution two) carrier solution and ending with 70% CI−VM−1 -- with 120 mmHg perfusion pressure.
The objective is to perfuse the brain until the refractive index of the jugular vein effluent and/or the burr hole samples at least matches the refractive index of 60% CI−VM−1. The refractive index of 65% CI−VM−1 is 1.422 and the refractive index of 60% CI−VM−1 is 1.416. A 60% CI−VM−1 solution is deemed adequate for stable vitrification. (A perfect vacuum has a refractive index of 1.000 and water has a refractive index of 1.333 at 20ºC.)
m−RPS−2 = modified Renal Perfusion Solution two (washout/carrier solution)
EG = Ethylene Glycol
CI−VM−1 = Vitrification Mixture one
RBHRI = Right Burr Hole Refractive Index
LBHRI = Left Burr Hole Refractive Index
RJVRI = Right Jugular Vein Refractive Index
LJVRI = Left Jugular Vein Refractive Index
Between steps 3 and 4 two burr holes are drilled in the patient's skull, one on the left hemisphere and one on the right hemisphere. Because the brain shrinks away from the skull when perfused with vitrification mixture, there is no danger of injuring the brain with a burr hole. A refractometer is used to measure the refractive index of the fluids in the burr holes and in the effluent until they all matched the refractive index of CI-VM-1. This occurs at the end of Step 7, at which time perfusion is ended.
Perfusion is halted based on the refractive index of the left jugular vein. All refractive indexes are above that of 65% CI−VM−1. Thermocouple temperature probes are placed deep in the chest, in the nasopharynx (proxy for brain core temperature) and under the skin of the skull near a burr hole.
After CI's 77th patient it was decided to never perfuse the body, but this proved to be too unpopular with CI Members. Perfusion of the body of the 77th patient with 80% ethylene glycol had achieved little other than loading the abdomen with cryoprotectant. Worse, the core temperature of the brain rose more than the surface temperature of the head in the 77th patient -- indicating flow of fluid from the body into the head and brain. The potentially destructive effect of body fluids entering a perfused brain osmotically (which caused us to elevate the head of the operating table for this patient) is all the more a threat as a result of the pressure generated in perfusing the body with cryoprotectant. Glycerol perfusion of the body seems to be safer for the brain, and CI Members now can choose to have body perfusion, although head-only perfusion is the default. The head must be perfused first because perfusing the body first with glycerol adversely affects blood vessels. Body perfusion with glycerol after having perfused the brain results in longer brain exposure to cryoprotectant toxicity and ischemic damage — and glycerol cannot only reduce rather than eliminate ice formation in the body. Until some solution to these problem is found, it is much better to straight-freeze the body. A straight-freeze of the body does not mean that information is lost, there should still be plenty of information in the body which future nanotechnology and molecular repair technologies could utilize in reconstruction, rejuvenation and reanimation.
The patient is slid from the operating table to a stretcher that contained her backboard and sleeping bag. The head is then placed in the head enclosure box and surrounded with pellets of dry ice. On the suggestion of Dr. Pichugin silicone oil rather than n−propyl alcohol is used as the the fluid added to the dry ice. This works as well and does not create the toxic stench that had been generated with the n−propyl alcohol in previous cases.
The head is placed in the box while the neck is cradled on the edge of the
cutout in the side of the box and the body
remains attached. The body lies outside of the head-cooling box. A slider in the
notch for the neck makes a complete seal around the neck so that the head-cooling
box can be filled with dry ice and silicone oil.
|Head-Cooling Box||Outside View with Mannequin||Inside View with Mannequin|
(Much as a slurry of water ice and ice water in a portable ice bath greatly accelerates cooling of a cryonics patient's body, a slurry of dry ice and n-propyl alcohol in a head-cooling box accelerates cooling of a cryonics patient's head. As a proof in principle I cooled two golf-ball sized spheres of hamburger in two cottage cheese containers filled with dry ice. Without n-propyl alcohol a hamburger sphere cooled from 7.7ºC to −56.9ºC in 32 minutes, but the container with dry ice in n-propyl alcohol slurry cooled from 7.7ºC to −56.9ºC in 7.25 minutes -- more than four times faster. Although n-propyl alcohol is more expensive than isopropyl alcohol, it has a wider range of liquid state temperatures: −127ºC to +97.2ºC versus −86ºC to to +82.4ºC for isopropyl alcohol. Insofar as the sublimation temperature of dry ice is about −79ºC n-propyl alcohol may be overkill, and we may try using isopropyl alcohol in the future.)
Further Cool-Down and Storage
|Patient Arrival at CI Facility|
After washout and perfusion, the patient is packed in dry ice and transported from the funeral home to the CI facility (a few miles distant). At the CI facility the patient is placed in a sleeping bag, tagged, and cooled down further, taking several hours to cool down to -120ºC and another four or five days to cool to liquid nitrogen temperature. The cooling is done by CI's computer-controlled cooing box. (For details see Computer-Controlled Cooling Boxes at CI.)
In order to reduce the amount of water vapor entering the cooling box as well as to increase thermal efficiency, a long copper pipe was placed on the vent hole. The copper pipe runs along 3 sides of the cooling box and has a copper valve at the end which can vent the nitrogen gas without much air (and water vapor) entering the cooling box. Brackets were placed at the top of the cooling box to hold foam board insulation and covered that with batten insulation.
The vent pipe works fine until the ambient temperature in the cooling
box reached cryogenic temperatures (below −100ºC) when the
seal on the foam board breaks causing the liquid nitrogen gas to shoot
out the top rather than through the copper pipe. Nonetheless, the insulation
provides some lasting improvement because the ambient temperature in the
cooling box bottoms-out at −193ºC or even −194.6ºC
rather than at −191ºC -- as was seen for patients cooled before
the pipe and extra insulation. Also, when we removed the patients from
the cooling box, frost visible is no
longer present on the sleeping bags or on the faces of the patients.
|Pipe Around Cooling Box||End of Pipe||Insulation Seal|
|First 23 Hours||Full 170 Hours|
The thermocouple in the skin above the burr hole is used as the controlling thermocouple by our LabVIEW computer control system. Cooling of vitrified tissue should be as rapid as possible to glass transition temperature (Tg), but should not go much below that temperature.
The cooling strategy is to cool the surface of the brain as rapidly as possible to Tg and then wait until the temperature in the center of the brain approaches Tg. Once the center of the brain is close to Tg the surface is warmed slightly in the hope that the entire brain could be of uniform temperature in a highly viscous "liquid" state just above Tg. This is not "annealing", because annealing involves warming a solid to just below melting temperature as a means to relieve thermal stress in a solid. By remaining just above Tg for the entire brain and cooling very slowly through Tg we believe we achieve the greatest temperature uniformity and the least thermal stress, while relying on the very high viscosity to prevent devitrification.
Cooling must be done quickly above solidification temperature (Tg) to prevent ice formation which might occur in areas which are poorly perfused. Below solidification temperature cooling must be done very slowly to minimize cracking due to thermal stress.
At the end of cooling, the patient is fully is transferred to a cryostat (long term storage unit), which is done quickly, the sleeping bag saturated with nitrogen, with no appreciable warm-up during transfer. Liquid nitrogen is poured from a bucket onto the sleeping bag near the patient's head during transfer.
Each patient has a rope tied to their backboard which allows for movement, placement and even removal, if a move should be necessary. These ropes are separated when adding a new patient, and then tied together again to be fished-out when need again (as when adding another new patient). The ropes on the other patients already in that cryostat are tied to the sides in such a way to assist in the placement of a patient in the remaining "hole" between the other patients.
|Cooling Box in Operation||Patient Removal after Cooling||Patient Tied to Backboard|
|Patient's Plywood Support Board|
|Holes on Boards||Foot End of Patient Board|
|Patient Lifted for CryoStat Insertion||Other Cryostat Patients Tied||Cryostat "Hole" for the Patient|
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