The Case for Field Cryoprotection

The last major technological innovation at Alcor was vitrification (cryopreservation without ice formation). Viability assays of brain slices and electron micrographs of brains cryopreserved with vitrification solutions show substantial improvements over the older cryopreservation protocols. But this was almost 20 years ago and it is time for another technological innovation that will improve patient care. I want to suggest that the strongest candidate for such an innovation is to introduce field cryoprotection for all Alcor members.

Field cryoprotection aims to close the gap in outcome between patients that are pronounced legally dead in the Scottsdale area (where Alcor is located) and patients that are pronounced legally dead in other US states by conducting the cryoprotective portion of Alcor’s procedure prior to transport to Alcor.

Currently the procedure would be to deploy a standby team to the patient’s bedside, start rapid cooling and cardiopulmonary support, replace the blood with an organ preservation solution, and then ship the patient to Alcor for cryoprotection and long term care. Those organ preservation solutions have been designed to counter the adverse effects of cold ischemia but are from for perfect. After about 6 hours of cold ischemia, the brain is rendered non-viable (no EEG can be recovered). Electron micrographs of mammalian brains show that the fine ultrastructure of the brain degrades in a time-dependent manner and blood vessels start to leak. As a general rule, when a patient is shipped to Alcor by air transport the blood brain barrier of the patient has been compromised, which can lead to swelling of the brain during cryoprotection. In whole body patients, substantial abdominal swelling during cryoprotective perfusion occurs, despite remote blood washout.

The good news is that preventing these outcomes does not require novel scientific breakthroughs but a simple commitment to eliminate shipment of patients on water ice in favor of doing field cryoprotection and subzero cooling in the field instead. This procedure is named “field cryoprotection.”

The reason why we call it “field cryoprotection” instead of “field cryopreservation” (or “field vitrification”) is because the patient is not cooled all the way down to liquid nitrogen temperature. While this is theoretically possible (and desirable), the logistics of this procedure are too demanding at this point. So instead of cooling the patient to liquid nitrogen temperature (-196° Celsius) the patient is shipped to Alcor on dry ice (-78.5° Celsius) where further cooldown begins. Research supports this is a safe temperature for shipping patients, provided stabilization and cryoprotection procedures are done timely and competently. From the patient’s perspective the advantages include minimization of cold ischemia, preservation of integrity of the vessels and blood brain barrier, and, under good conditions, cryoprotection can start when the brain is still in a viable state.

One of the most remarkable aspects of making field cryoprotection the default option for all eligible patients is that it does not just improve patient care but reduces cost as well. Right now, for non-local cases Alcor needs to deploy a team consisting of surgeons and technicians twice. Once at the patient’s bebside and later again at Alcor for cryoprotective perfusion. Field cryoprotection would eliminate this double employment in favor of one single deployment at the patient’s location. As a consequence, remote stabilization costs will go up but Alcor HQ costs will be basically eliminated except for a small cooling expense. This should allow for a non-trivial
decrease in costs per case, which can be passed on to the member in the form of lower cryopreservation costs or can be used to eliminate or decrease future increases.

During the last couple of years Steve Graber and Hugh Hixon have collaborated to improve neuro field cryoprotection technologies and the gap between conducting cryoprotection in Scottsdale or “on the road” has increasingly been closed.

Field cryoprotection procedures are currently only available to neuro members (or for whole body members who agree to neuro-cryoprotection only) but various approaches are currently being discussed to extend this technology to whole body members, too.

Field cryoprotection constitutes the next big step in cryonics. Currently only overseas members can benefit from this procedure but the time has come to cautiously extend this procedure to more members.  Eliminating water ice shipment in favor of field cryoprotection will be need to be incremental and closely evaluated but the patient care and cost advantages are evident.

Originally published as a column in Cryonics magazine, November -December, 2017