Whole-Body Field Cryoprotection in Cryonics

History, Procedures, and Future Directions

Introduction

Field cryoprotection (FCP) is a procedure in cryonics in which the patient is perfused with a cryoprotectant at the location of the patient’s death, typically a cryonics emergency vehicle or cooperating funeral home, followed by dry ice transport. By conducting stabilization procedures (cooling, cardiopulmonary support, and medications administration) plus cryoprotection at the location of the patient, practically all cryonics procedures are done in the field instead of the cryonics facility.

FCP blends two procedures that historically have been done at different locations (stabilization and cryoprotection), reducing ischemic damage to the brain and improving cryoprotection. Everything else being the same, FCP also reduces cost because it entails one instead of two deployments. The “only” thing left to do for the cryonics organization is to carefully cool the body down from dry ice temperature (-78C) to liquid nitrogen temperature (-196C) for long term storage.

Field cryoprotection vs field cryopreservation

Field cryoprotection needs to be distinguished from field cryopreservation. Field cryoprotection protects the patient from freezing damage during long term storage in liquid nitrogen by replacing the blood with a vitrification solution. Field cryopreservation would go one step further and would entail that the patient is also cooled and transported at cryogenic temperatures to the cryonics facility. While possible in theory, such a procedure is currently considered too complex and risky for whole-body patients. For all practical purposes, the ischemic clock stops ticking when the patient is cooled to dry ice temperature for transport.

A short pre-history of whole-body field cryoprotection

The defining difference between field cryoprotection and facility cryoprotection is not procedural but regional. For example, it is possible that one cryonics organization’s FCP procedure is identical to another organization’s in-house facility procedure. What sets FCP apart is the location of the procedure. A cryonics organization in, let’s say, California, that sends out its team to do the cryoprotection procedure in Maine, is conducting field cryoprotection.

In June 1990 Alcor patient A-1239 received a field cryoprotection with the cryoprotectant glycerol in Australia prior to shipment on dry ice to Alcor in the USA. On October 23, 2004, the cryonics company Suspended Animation conducted a whole-body field cryoprotection with glycerol for the American Cryonics Society prior to shipping the patient on dry ice to the Cryonics Institute for long-term care.

In the past, both major cryonics organizations in the US (Alcor and the Cryonics Institute) have permitted some type of field cryoprotection in cases where long transport times otherwise would have produced a “straight freeze” (cryopreservation without protecting against ice formation). Such procedures were often performed after extensive ischemic delays and usually only cryoprotect the head through the neck vessels (allowing the rest of the body to freeze).

True universal whole-body field cryoprotection was pioneered by the German / Swiss cryonics organization Tomorrow Biostasis (founded in 2019). Tomorrow Biostasis uses open heart surgical technique, pump-based perfusion, cryoprotection with VM-1, and dry ice transport to its facility, followed by CT scanning and cryogenic cooling. A similar procedure was introduced by the US-based SST organization Suspended Animation for Cryonics Institute members in April 2025.

Scientific considerations

The state-of-the-art procedure for whole-body patients for a long time was remote blood washout with an organ preservation solution and transport on water ice. In most cases, remote blood washout with an organ preservation (such as MHP-2) is clearly superior than funeral director transport of the patient without blood removal.

The procedure of blood washout itself produces faster cooling than ice bath cooling by circulating a cold fluid through the body of the patient. Aside from removing the patient’s blood, and thus opportunities for blood clotting and red cell aggregation, the organ preservation solution itself provides metabolic support and protection against the adverse effects of cold ischemia. Research at Alcor and Advanced Neural Biosciences has shown that whole-body blood substitution with MHP-2 preserves viability of the brain for several hours and perfusability of the brain up until 48 hours after washout.

Despite these advantages, further research at Advanced Neural Biosciences, and observations at the major cryonics organizations, revealed that extensive cold ischemia still produces damage to the fine structure of the brain and compromise of blood vessels. Breakdown of the blood-brain-barrier, and swelling of the brain and the rest of the body, are routine observations after remote blood washout protocols. These observations bolstered the case for eliminating cold transport altogether and doing cryoprotection on-site.

Logistical and Technological Challenges

One historically compelling argument against true whole-body FCP was that the sheer amount of cryoprotectant necessary to do the procedure (between 150 and 200 liters in total) is not a practical volume for air deployment. In the United States, Biostasis Technologies worked with Suspended Animation and other partners to pre-position complete sets of cryoprotectant solutions in strategic locations across the country. This approach is more feasible for CI’s VM-1 than for Alcor’s M22 given the much lower cost of the VM-1 vitrification solution. Another advantage of the low cost of VM-1 is that FCP can be conducted “open circuit” without the need for more advanced re-circulation technologies (using a mixing reservoir and stir bar). Suspended Animation also deploys a network of perfusionists and surgeons to the location of the patient to start surgery and use mainstream cardiopulmonary bypass techniques for the washout and cryoprotection part.

Perfusing a patient with full concentration cryoprotectant necessitates immediately cooling the patient below freezing temperature to mitigate cryoprotectant toxicity. In current whole-body FCP procedures this typically entails dry ice cooling and transport.

Whole-body FCP protocol

There is not one, universally agreed upon, optimal whole-body field cryoprotection procedure, but the following summary captures both the FCP procedures practiced by Tomorrow Biostasis and Suspended Animation.

After pronouncement of legal death, mechanical chest compressions and ventilations are started to restore blood flow to the brain, the patient is placed in a portable ice bath for rapid cooling, and medications are administered to prevent blood clotting and to further limit cell damage. When a core body temperature of about 20C is reached mechanical chest compressions are stopped, surgeons open the chest, cannulae are placed into the heart to start, and blood washout with a cold solution is started.

When the patient’s temperature drops below 5C the lowest concentration of VM-1 is perfused, followed by progressively higher concentrations. The highest concentration is perfused until a venous concentration (as measured by refractive index readings) is reached that is necessary for vitrification. After termination of cryoprotection, the surgeons close the incisions and ensure temperature probes remain in place for monitoring cool down to dry ice temperature.

After the patient is cooled to dry ice temperature, the dry ice is replenished again and the patient is prepared for ground or air transport to the facility, depending on distance and other logistical considerations. Upon arrival at the cryonics facility, the patient is further cooled to liquid nitrogen temperatures for long term care.

The future of field cryoprotection

Universal whole-body field cryoprotection practiced by organizations such as Tomorrow Biostasis and Suspended Animation (available to Cryonics Institute members) constitutes a paradigm change in cryonics but there are still technical concerns and further improvements possible.

One concern is dry ice cooling and transport. Vitrification solutions usually have a “critical cooling rate” to prevent ice formation. If a patient is stored for too long at dry ice temperature without further cooling, ice can still form over time. Tomorrow Biostasis and Suspended Animation, however, use a hyper-stable formulation of VM-1 that cannot freeze, even if held at dry ice temperature for several weeks.

Other future modifications that are possible include incorporating a type of software-controlled inline mixing that permits a gradual, linear, type of cryoprotection concentration increase. Whether the typical (ischemic) cryonics patient benefits from such modifications, however, is currently an open question.

In theory, it is possible to cool the patient at location to cryogenic temperatures but whether such a technically and logistically complex procedure produces meaningful benefits in care or cost is doubtful, too.

Transport at cryogenic temperatures (or at least below glass transition temperature of the vitrification solution) is possible for brain-only patients by utilizing a so called vapor shipper (or “dry shipper”). These shippers can be charged to "absorb” the liquid nitrogen and allow samples or tissues to be stored and shipped in the vapor phase. Because these shipping containers do not include actual liquid nitrogen, they can be used for safe ground- and air transport of brains. Currently, the only cryonics organization that offers isolated brain cryopreservation is Tomorrow Biostasis.

Navigating field cryoprotection claims

When a cryonics organization (or service provider) claims to offer field cryoprotection, it is important to ask a number of pertinent questions. Is the whole-body being perfused with a cryoprotectant - or only a part of the body (like the head)? What is the surgical protocol? If only the neck vessels are used for perfusion, what is the surgical protocol, and does this protocol work well for patients with impaired brain circulation? What is the vitrification agent composition, and is there a risk of freezing during prolonged dry ice storage and transport? What about temperature control of the patient and the vitrification solutions during the cryoprotection procedure? What kind of dry ice shipper and transport protocol is being used? Are CT scans (or microscopy of tissue samples) used to evaluate the quality of care? A credible cryonics service provider should have given careful consideration to these questions and have the technical expertise to conduct field cryoprotection and transport.