"Cardiac death isn't a diagnosis of death, it is a prognosis of death."
David Crippen, MD, FCCM
Department of Critical Care Medicine
University of Pittsburgh Medical Center
(private correspondence with the author)
The common belief that life and death are simple binary states misleads people into thinking that cryonics practiced after legal death is a hopeless enterprise, almost by definition. It is not realized that legal death is a statement of prognosis more than a statement of condition. The biological state of a patient declared legally dead can be highly variable. It can range from fully alive (but brain dead) when an organ donor is maintained on life support, to alive (but dying) when the heart of a terminally-ill patient stops beating, to completely dead when a decomposed body is found. Because of this complexity, cryonics cannot be dismissed solely based on a legal pronouncement of death. The biological circumstances of the pronouncement and subsequent cryonics care must be considered.
Perhaps the most misunderstood aspect of cryonics is that cryonics procedures can, in fact, be legally done on patients that are still biologically viable. For terminal patients with DNR ("Do Not Resuscitate") orders on their chart, legal death is determined when a qualified medical authority pronounces death based on cardiopulmonary arrest. In other words, the patient is legally dead when their heart stops beating. However, CPR (cardiopulmonary resuscitation) can maintain life when the heart is stopped if done promptly. "Do Not Resuscitate" orders are necessary precisely because such heroics would inappropriately extend the dying process if implemented in a conventional medical setting. In the context of cryonics, though, DNR status allows a cryonics team to use resuscitation techniques to keep the brain viable despite occurrence of legal death.
The objective of initial stabilization in cryonics is resuscitation of the patient in all respects except cardiac resuscitation. Within the first couple of minutes after cardiac arrest, vigorous CPR is begun on the patient using a device called a heart-lung-resuscitator (HLR). This is essentially a mechanical CPR machine that compresses the chest more effectively than human hands, and ventilates the patient with 100% oxygen. Despite continued cardiac arrest, breathing and circulation can be partially restored. Anesthetic drugs are used to reduce brain oxygen requirements and ensure that the patient remains unconscious. Rapid cooling also further reduces brain oxygen requirements.
Best Case Scenario
How viable is a cryonics patient during stabilization? Perhaps the most successful cryonics stabilization documented to date was that of CryoCare patient James Gallagher in 1995. Mr. Gallagher was a cancer patient who suffered cardiac arrest in his home under supervision of his family and personal physician after voluntary discontinuation of oxygen therapy. When his heart stopped beating, his physician pronounced legal death, and the cryonics transport team waiting in an ambulance outside began their work. The BioPreservation, Inc. team used a custom-modified Michigan Instruments HLR that was capable of delivering simultaneous Active-Compression-Decompression-High-Impulse CPR (ACDC-HICPR). HLR support was begun three minutes after cardiac arrest, and an arterial oxygen saturation over 90% was maintained for the next two hours until external life support with a blood pump and oxygenator was begun. This level of blood oxygenation is the same as that experienced by passengers in commercial airliners at cabin altitudes near 8000 feet, and it is certainly sufficient to maintain life. The blood gases, electrolytes, enzymes, and other clinical laboratory parameters of this patient have been published , and establish that this legally deceased patient was biologically viable during the initial cooling phase of his cryopreservation.
The Value of Cooling
Cryopatients must be cooled during stabilization before blood substitution and perfusion with cryoprotectants (anti-freeze compounds) can begin. Fortunately, prompt cooling following cardiac arrest is known to be profoundly protective of the brain. First Aid courses teach that the brain begins to die four minutes after the heart stops. However research has shown that resuscitation without brain injury is possible after up to ten minutes of cardiac arrest (plus another ten minutes of low flow CPR) if cooling is started at the same time as CPR .
The neuroprotective effects of cooling mean that not only can cryopatients be kept biologically viable during stabilization, but they can be kept viable with cardiopulmonary support that is started later and less efficiently than would ordinarily be the case. Even ordinary high impulse CPR (the type of CPR delivered by an off-the-shelf Michigan Instruments HLR) is probably adequate to maintain neurological viability of cryopatients during stabilization and cooling given the combined metabolism-reducing effects of cold and anesthesia. The trickle flows of manual CPR can keep a brain alive at normal temperatures for up to ten minutes . The combination of cooling, drugs, and high impulse mechanical CPR no doubt extend this time even longer.
The purpose of CPR in cryonics is to act as bridge until cardiopulmonary bypass (heart-lung machine) support can be established, in which an external blood pump and oxygenator take the place of the patient's heart and lungs. Under good conditions, the surgery to achieve this can be accomplished in less than an hour. Trained personnel and specialized equipment can initiate cardiopulmonary bypass even faster. In fact emergency cardiopulmonary bypass was recently used with good success in conjunction with CPR on out-of-hospital cardiac arrest patients in Japan .
The very low temperatures (<10°C) reached by cryopatients before cryoprotectant perfusion are also consistent with new approaches being explored by mainstream medicine for stabilizing and recovering patients after cardiac arrest due to exsanguinating trauma . In fact, in the 1980s Alcor president Michael Darwin and Jerry Leaf (vice-president) performed a pioneering series of experiments [6-8] in which dogs were blood-substituted and cooled to +4°C for four hours without heartbeat or breathing, and then recovered without neurological damage. This amazing work was conducted explicitly to verify that cryonics procedures as then conducted by Alcor were in principle reversible right up to the point of cryoprotective perfusion.
Importance of Good CPR
The maximum benefits of post-cardiac arrest cooling are seen when cooling occurs rapidly after CPR is begun. The most rapid way to cool a body is to use circulating blood as the cooling medium. The more rapidly blood is circulated (carrying heat from inside the body to skin cooled by ice) the more rapidly the body will cool. This makes effective CPR doubly important to cryonics: It reduces brain injury caused by inadequate blood flow, and enhances the most powerful injury protection mechanism (cooling).
The effect of good CPR on cooling is most vividly illustrated by the cooling rate achieved in the case of cryopatient James Gallagher (the "best case scenario" patient already discussed). The combination of ACDC-HICPR and colonic and peritoneal lavage with ice-cold saline achieved a cooling rate of over 1°C per minute during the first ten minutes of CPR, which is three times greater than the fastest cooling rate previously observed in a cryopatient.
Recently a new technology for rapidly cooling resuscitated cardiac arrest victims has been developed by Mike Darwin and Steve Harris that involves cold fluorocarbon lung lavage [9, 10]. By performing heat exchange through the lungs rather than skin, this simple and convenient technology could remove the need for patient ice baths in cryonics. However, this technology also critically depends on good blood circulation for effectiveness.
The Importance of Feedback
Because the cryogenic (below freezing) phase of cryonics is still unperfected and dependent upon future technology for reversal, there is an ever-present temptation to pass off problems to the future for solution. What has historically distinguished Alcor from other cryonics organizations, and the legacy established by Leaf and Darwin, is a resistance to this temptation. In practice, this means aggressive use of existing and emerging technologies for post-cardiac arrest life support.
Maintaining neurological viability up to the late stages of cryoprotective perfusion improves feedback, chances of success, and medical credibility of the whole enterprise. By imposing real-time feedback with parameters such as blood oxygenation, end-tidal CO2, and pH, quality control is maintained. By keeping procedures reversible for as long as possible, the least speculative and most conservative course is being pursued, thereby increasing the chance of success. And the future road to true suspended animation is left clear and paved.
Death as a Cultural Obstacle
Alcor activist Thomas Donaldson frequently points out that suspended animation and cryonics are not the same thing. There will always be patients who are so badly injured that they are irreversibly "dead" to the medicine of their time, regardless of resuscitation efforts. Donaldson and others argue that these patients should be preserved anyway because future technology may still be able to recover them. In other words, short of total destruction, you can't be sure what the future definition of "death" will be, so the conservative course of action is to preserve all "dead" patients. This moral argument is perhaps the most general meaning of the term "cryonics".
While the cryonics argument may be noble, many people are unreceptive to this argument based on cost/benefit grounds. Even more people are unreceptive on religious grounds. The vast majority of people will not take cryonics or suspended animation seriously unless it is done before death.
But does death always matter? In cases where death is expected, there need be no biological difference between cryonics implemented before legal death or immediately after if proper procedures are used. For such cases, the occurrence of legal death is a purely cultural issue.
1) CryoCare Report, January, 1996, "Cryopreservation of James Gallagher." See also BPI Tech Brief #18 Part II.
2) Critical Care Medicine 19, 1991, 379-389 "Mild hypothermic cardiopulmonary resuscitation improves outcome after prolonged cardiac arrest in dogs" Sterz F, Safar P, Tisherman S, Radovsky A, Kuboyama K, Oku K.
3) American Journal of Emergency Medicine 3, 1985, 114-119 "Survival of out-of-hospital cardiac arrest with early initiation of cardiopulmonary resuscitation" Cummins RO, Eisenberg MS, Hallstrom AP, Litwin PE.
4) Journal of the American College of Cardiology 36, 2000, 776-783 "Cardiopulmonary cerebral resuscitation using emergency cardiopulmonary bypass, coronary reperfusion therapy and mild hypothermia in patients with cardiac arrest outside the hospital." Nagao K, Hayashi N, Kanmatsuse K, Arima K, Ohtsuki J, Kikushima K, Watanabe I.
5) Critical Care Medicine 28, 2000, N214-N218 "Suspended animation for delayed resuscitation from prolonged cardiac arrest that is unresuscitable by standard cardiopulmonary-cerebral resuscitation." Safar P, Tisherman SA, Behringer W, Capone A, Prueckner S, Radovsky A, Stezoski WS, Woods RJ.
6) Cryonics Magazine, November, 1984.
7) Cryonics Magazine, February, 1985.
8) Cryonics Magazine, March, 1985.
9) Discover Magazine, October, 2001, "Here, Breathe This Liquid"
10) Resuscitation 50, 2001, 89-204 "Rapid (0.5°C/min) minimally invasive induction of hypothermia using cold perfluorochemical lung lavage in dogs" Harris SB, Darwin, MG, Russell SR, O'Farrell JM, Fletcher M, Wowk B.