Cryonics 101

Conveying the core ideas

Photo by Mo on Unsplash

Cryonics and biostasis are complex topics. When presenting the idea to someone unfamiliar with it, it is easy to get lost in the complexities. Here are two excerpts from my book-in-progress that aims to convey the core ideas.

It’s 1960. You are working in an office or factory. You weren’t feeling great this morning and now you’re short of breath. “I’m sure it’ll go away,” you think. “I can’t afford to stop work and see a doc.” As you stand up to go talk to a colleague you feel a painful tightness in your chest. The room spins, you black out, and collapse to the ground.

Several people see you fall and run over, calling your name and asking if you’re okay. You are unconscious and can’t hear them. After milling around in consternation, one proactive person kneels beside you and puts two fingers on your carotid artery. “He doesn’t have a pulse!” he cries. “What should we do?” Everyone looks distressed or uncomfortable. No one has an idea. Then someone says, “I guess we should call the coroner. He’s gone.”

Most cases of cardiac arrest happen outside of a hospital but today you might get lucky. Starting in the 1960s the lifesaving potential of cardiopulmonary resuscitation (CPR) started to become recognized and adopted. If a bystander sees you collapse and knows CPR, you have a far better chance of surviving than you would in 1960 or earlier. CPR administered immediately following sudden cardiac arrest can double or even triple a victim’s chance of survival. CPR may get the person breathing and their heart beating again or it may buy time for medical professionals to arrive and take over. Unfortunately, less than half of stricken people will receive bystander CPR.

Consider the 1960 version of you a few minutes after cardiac arrest. Are you dead? Your heart has stopped and you’re not breathing. You have no consciousness. Back then, you would indeed be considered dead. Your critical life functions failed and no one knew how to restart them. You could immediately be prepared for burial or cremation. Everyone at that time would say you were dead. Would they be right or wrong, and why?

From today’s perspective, you are only clinically dead. In the words of Miracle Max (no relation) from The Princess Bride, “It just so happens that your friend here is only MOSTLY dead. There’s a big difference between mostly dead and all dead. Mostly dead is slightly alive. With all dead, well, with all dead there’s usually only one thing you can do.” Before the 1960s, clinical death in today’s sense was just dead. In practical terms, there was no difference. But today clinical death can often be reversed.  

Someone who is clinically dead will remain biologically alive for some time after cardiac arrest. That is the period in which emergency medicine comes into play. First line providers and emergency medical services jump in to prevent clinical death becoming biological death. Their job is to stop you deteriorating beyond the point at which today’s medicine can rescue you. Emergency medical personnel will do what they can on the spot and then transport you to a location with more sophisticated capabilities.

Cryonics is an extension of emergency medicine

Cryonics comes into play when today’s emergency medical personnel have done all they can, when hospitals can no longer sustain you. At that point, the standard response is to declare you legally dead. This differs from clinical death and it differs from biological death. It is essentially a declaration by an authorized party that nothing more can be done to help you. That simplifies the situation. In quite a few cases, a doctor may be able to resuscitate you but declines to do so. You may even leave instructions to this effect, known as “no code” – your formal request to refrain from extraordinary efforts to drag out your life when there is no hope of real recovery.

When a doctor today pronounces you legally dead, could they be making the same kind of mistake as someone before 1960 deciding that you were dead? That depends on whether there is anything that could be done that might give you a chance to live. If doctors believed that such a means was available, they would use it rather than giving up on you. Such a means is available but not widely known and less understood.

Advocates of cryonics are pleading with us not to give up, not to abandon the patient simply because today’s medicine cannot help them. The limits of medicine change over time. The “dead” person of 1960 is today someone in need of resuscitation. The “dead” person of today is someone in need of the advanced technology of the future. Today’s emergency medicine transports you from one place to another where greater capabilities are available. Cryonics transports you from the current time to a future time where medical technology will be vastly more advanced. You can think of cryonics as a sophisticated kind of ambulance ride to the future.

Cryonics – from the Greek kryos meaning icy cold – is the extremely low-temperature preservation of humans who can no longer be sustained by contemporary medicine, in the expectation they can be healed and resuscitated in the future using more advanced medical technologies. Cryonics preserves life by pausing the dying process. It is the bridge between pronouncement of legal death and future medical technologies.

To understand the basis for cryonics, you need to understand three things:

1. True, final, irreversible death is different from clinical or legal death.

2. Deep cold can halt the dissolution of biological systems and enable us to pause the dying process.

3. In the future, we will have more advanced cell repair methods and cures for diseases and aging.

Death

The intention of cryonics is to stop the process of dying.  It is true that cryonics procedures do not begin until patients are clinically and legally dead. In fact – so far – cryonics is only practiced following pronouncement of legal death. A crucial point of understanding is that neither clinical death nor legal death are the same as death in any irreversible or final sense.

Clinical death occurs when heartbeat and respiration stop. Legal death may follow soon after or not until resuscitation efforts have been tried and failed. doctors declare legal death when they cannot resuscitate a patient with current medical technologies. This amounts to saying: “Given the skills and technologies available, I can do no more for this patient.”

A person declared legally dead today is usually still biologically alive. We’ve developed medical technologies to donate organs from legally dead people to save lives because the donated organs are still biologically alive. What if we can intervene in the dying process after clinical death but well before biological death? What if we can pause the dying process?

We have made progress in reviving people from longer and longer periods of clinical death. It’s hardly unreasonable to expect that progress to continue. So long as we stop the dying process early enough, eventually we may have the medical technology to repair the damage done and revive the patient. What we believed to be irreversible in 1960 can be reversible today. What we believe to be irreversible today – with today’s technologies – may be reversible in the future.

So long as the dying process has been paused, the person is not truly dead. The person is only truly dead when they could not be rescued by any conceivable and physically possible technology. The goal of cryonics is not to reverse death.  The cryopreservation process halts the dying process. The goal is to extend life. This is why I see cryonics as an extension of emergency medicine. It provides a means of getting people the help they need even though it’s not available today.

To review: If by “death” we mean a condition that is absolutely final and irreversible, then clinical death is not death and legal death is not death. Even biological death is not true death because it is defined in terms of the reversibility of the cessation of cellular functions by means of existing technology. Biological death is not a point in time. It’s a process of increasing cellular disorder and dysfunction. Some cells cease functioning sooner than others. Some living brain cells have been extracted even several days after clinical death.

The central point is that death is the end of a process and so long as we pause that process, a person is not dead. Whether or not they can be recovered depends on how well we prevent deterioration and our capabilities in restoring function. That’s true whether we are considering minutes, hours, or decades. Today, we can sometimes revive someone who has been clinically dead for an hour or more. By pressing the pause button, we may be able to extend that to decades.

Cold

Cold slows chemical reactions. It’s a simple statement but profound in its implications. We use the cool temperature of our refrigerators to keep our food fresh for days or a few weeks. We use the lower temperature of our freezers to keep food fresh for months. On an absolute scale, freezers are not cold at all. Domestic freezers maintain a temperature of -18° C or 0° F. Absolute zero is the temperature at which all molecular motion ceases. That’s −273.15 degrees on the Celsius scale or −459.67 degrees on the Fahrenheit scale or 0 Kelvin.

The lower the temperature, the slower chemical reactions take place. Dying is a process of dissolution through disruptive and destructive chemical reactions.

A fundamental principle of cryonics is that metabolism, and therefore the dying process, slows down as temperature falls. Today, surgeons cool their patients to give them more time to operate or for the patient to heal. Each reduction of 10°C slows metabolism down by 50%, a principle known as the Q10 rule. Thus, reducing someone’s temperature from 37 °C to 7 °C (98.6 °F to 44.6 °F) slows their metabolism by 87.5%.

Hibernating animals slow their metabolism down and maintain a temperature of around 0°C. Humans have been recovered from over an hour in hypothermic conditions where their body cools to match the freezing temperature of the environment. (If the environment is water, the person cools faster than if it’s air.) Fertilized human eggs and embryos are routinely stored at -196° C or -321° F, often for a decade or longer. When the mother is ready, the egg or embryo is carefully rewarded and implanted. It then grows to become a healthy baby.

In cryonics, patients are typically also maintained at -196 °C. At that temperature, cellular activity ceases. Other measures taken in tandem further prevent chemical activity, especially ice formation. Chemical activity does not slow down at a linear rate. The decrease from 0° C to -20°C is much less than that from -60° C to -80° C. Tissues stored at 196° C – the temperature of liquid nitrogen – don’t decay just five or ten times more slowly than those at body temperature. They decay many millions of times more slowly. Even after decades or centuries, a cryopreserved person will be unchanged biologically. The person will be in stasis while the outside world moves on – and as technology advances.

Repair

Death is a process that we can pause using extreme cold. For cryonics to work we have to also be able to restart biological processes while repairing damage so that the person can continue functioning and living.

Less thoughtful critics of cryonics often ask, “Have you ever revived anyone?”, knowing the answer is negative. They apparently think that this fact makes the practice of cryonics pointless. They are missing a crucial piece of the puzzle. Our inability to reverse the process today is regrettable but beside the point. So long as we can maintain a patient in an unchanging state, they may make it to a day when we do have that capability.

Consider that can already cryopreserve and successfully rewarm and transplant skin, corneas, heart valves, blood vessels, eggs, sperm, and even embryos. Researchers have had some limited success in reversibly cryopreserving human organs. Success in this endeavor would greatly improve the survival rate of people in need of an organ transplant.

It is not technically feasible to reverse the cryopreservation process successfully today. But research into tissue cryopreservation, including brain cryopreservation, continues and advances. Can the critic really declare that no further progress is possible? Have they foreseen every possible pathway to repair and disproved it? Of course not.

To the cryopreserved patient, years pass with no subjective awareness of the passage of time and with no biological decay. Biological time has stopped while technology marches ahead.

You might grant that a critic cannot reasonably conclude that technologies for revival will never be developed but might ask: Can you prove that these technologies will be developed? The answer is no, we cannot be certain cryonics patients will one day be repaired, revived, and restored to better health. Nor can we accurately predict when it will be possible. Cryonics is essentially a bet on technological progress and future capabilities. There isn’t much of a downside to being wrong. If it doesn’t work, you’ll be no worse off than if you hadn’t taken the chance. Further, nothing about cryonics conflicts with the laws of physics or biology.

Suppose that someone said, back in 1920, that it is possible to land a human on the moon. A similar critic would demand: “Prove to me that it can be done. Show me how to do it!” The space enthusiast can only point out that a moon trip violates no laws of physics and chemistry. It’s physically possible. True, we don’t know how to do it. In 1920, we didn’t have the rocket technology, the information technology, the guidance systems, or the life support capability to make it happen. But it was a matter of technological progress, not physical possibility. The cryonics advocate today is in a similar position to someone in 1920 claiming that eventually it’s likely that we will be able to achieve a moon landing.

We can only speculate about the kinds of technologies that might be deployed to repair and revive cryopatients. Perhaps it will be an extension of existing tissue regeneration techniques. Or it might be some form of molecular nanotechnology.

Getting our terms straight

The editor of the journal Cryogenics a few years ago wrote an editorial complaining about people using the term “cryogenics” when they meant “cryonics”. Naturally, she didn’t want her respectable, established field to be mixed up with the controversial idea of cryonics. I see this confusion of terms frequently. I have found it to be almost an inevitability in any media coverage – unless I’ve been given a chance to fact check or if the writer is unusually diligent.

 The root term stems from Greek κρύος (cryos) – “cold” + γενής (genis) – “generating”. Not any kind of cold will do, however. A cryogenic temperature is very, very cold. 

In physics, cryogenics is the production and behavior of materials at very low temperatures. How low is “very low”? No one standard exists.

• The National Institute of Standards and Technology considers the field of cryogenics as that involving temperatures below −180 °C (93 K; −292 °F).

• In 1971, the 13th IIR International Congress of Refrigeration endorsed a universal definition of “cryogenics” and “cryogenic” by accepting a threshold of 120 K (or –153 °C) to distinguish these terms from conventional refrigeration.

The latter is a practical definition in that the normal boiling points of the “permanent gases” (such as helium, hydrogen, neon, nitrogen, oxygen, and normal air) lie below −120 °C while the Freon refrigerants, hydrocarbons, and other common refrigerants have boiling points above −120 °C.

Cryogenic temperature, in biology, means a temperature low enough for stability of biological materials for periods of years or more, typically below -150° Celsius.

Cryobiology is the branch of biology involving the study of the effects of extremely low temperatures on organisms – most often for the purpose of achieving cryopreservation.

Cryopreservation means the preparation, cooling, and storage of biological cells and tissues at temperatures low enough for stability for periods of years or more, typically below -120 degrees Celsius. 

Cryonics means the study and practice of cryopreserving human bodies, human brains, or other human tissue with the intention of future revival of a person.

Biostasis is not a cryo term but encompasses cryonics along with other long-term preservation methods. Both cryopreservation and chemical preservation are forms of biostasis.

Suspended animation can have several meanings but, in the context of biostasis, means stopping all biological activity without doing any significant damage. It refers to a perfected form of biostasis.