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What happens during a cardiac arrest

The international definition of death is no respiration, no cardiac output and absent brainstem reflexes. This is the exact clinical state after a cardiac arrest. Simultaneous recording of heart rate and brain electrical activity show that within 11 seconds of the heart stopping, the brainwaves go flat. You are clinically dead.

Consciousness is lost in a matter of seconds when the heart stops, and may not be regained until hours to days after it restarts.

Even if cardiopulmonary resuscitation (CPR) begins straight away, blood pressure will not rise high enough to establish an adequate blood flow through the brain. Doine Stub and Graham Nichol found that only 7% of cardiac arrest patients survived and most had some evidence of brain damage; and the mental state during recovery is confusional (Stub & Nichol, 2012).

The flat EEG indicating no brain activity during cardiac arrest and the high incidence of brain damage afterwards both indicate that unconsciousness is total.  The brain can’t create images under such circumstances, so it should be impossible to have clearly structured and lucid narrative experiences within the brain and because memory is not functioning; and if experiences did occur they should not be remembered. The brain does not begin to function again until the heart restarts.

So. in theory. it is impossible for anyone in this state to a) experience or b) remember anything that occurred during it. And if an experience occurred during the gradual return to consciousness, it would be confusional — not the clear, lucid story characteristic of actual death experiences.

However, to muddy the waters some studies, have found that in patients who are being monitored and have begun the actual death process, there is a sudden recurrence of brain activity, containing faster frequencies which may last up to five minutes (Lang, 1989) (Grigg et al., 1987). Materialists have jumped on this as the explanation for the ADE. But this is random cortical activity which does not integrate different areas of the brain, and certainly could not restore consciousness.  

Conventional science cannot explain how an ADE could occur at any point during the death process, and there are special difficulties in accepting that it happens when those reporting the experience say it happens — during unconsciousness. However, about 10% of those who survive a cardiac arrest do report an ADE .

It is very difficult to judge the exact timing of an ADE during a cardiac arrest.  But two prospective studies were of people who had had cardiac arrests and were resuscitated in coronary care units,  where their medical records show exactly what had happened; the patients had the same medication and resuscitation procedures and could be questioned as soon as they were well enough (van Lommel, 2011) (Parnia et al., 2001).

Aim of the studies

To discover:

  • How many patients had an ADE
  • Whether the ADE was similar to the traditional NDE
  • Exactly when the experiences occurred (before or during unconsciousness, or during or after recovery?)

Of the 63 cardiac arrest survivors interviewed, 89% had no memories and about 10% reported ADEs, which they said had occurred while they were unconscious. These ADEs were, as was expected, very similar to those NDEs already reported in the literature.  The authors also found that the ADEs were not due to medication, electrolytes, blood gases, religious belief or any other cultural factors.

Other research groups have found similar results. In a Dutch study of 344 cardiac arrest survivors, 41 (about 12%) reported ADEs (van Lommel, 2011). Their occurrence was not influenced by the duration of unconsciousness or cardiac arrest, or by medication but more ADEs were reported in the group of survivors who died shortly after their experience. In another study, a higher rate of 23% was reported (Schwaninger et al., 2002); about 10% were found by  Greyson, (2003) , while others (Sartori et al., 2006) report about 25%. What is clear is that actual death experiences do occur in association with cardiac arrest, and their contents are similar to those reported in the NDE literature.

No studies have so far been able to provide definitive scientific proof of when an ADE occurs. Parnia, with Fenwick and others (Parnia et al., 2001) found that the patients themselves felt that the experiences occurred during unconsciousness — important because we have no idea how clear consciousness can be experienced during a period of clinical death with a flat EEG. This question is absolutely crucial to one of the biggest problems facing neuroscience: Is consciousness entirely a product of brain function? And is it confined to the brain?

ADE research may be the most promising way of filling the ‘consciousness gap’ in neuroscience. From the point of view of science, the ADE cannot occur during unconsciousness — yet there is tantalising evidence that that is just when they do occur.

Evidence supporting Out-Of-Body Experiences (OBE)

About a third of ADEs are preceded by an Out-Of-Body experience, in which the experiencer says they leave the body and rise to the ceiling and can see the resuscitation taking place. Anecdotal evidence points to the OBE and, therefore, the ADE occurring during unconsciousness. Certain subjects even described their own resuscitation procedures accurately, suggesting that their ADE had occurred when the brain was ‘down’ (Sabom, 1982).

Dr Penny Sartori studied a group of cardiac arrest survivors in a coronary care unit, several of whom said they had left their bodies and witnessed the resuscitation process.  She compared their accounts of their resuscitation with those of another group of patients who had had no ADE during their resuscitation but were asked to describe what they thought had happened. It is usually argued that everyone sees so much resuscitation on TV that they know the procedure. Dr Sartori was able to convincingly show that the patients who claimed to have seen their resuscitation, described it much more accurately than those who could only guess what had happened and who made significant errors (Sartori et al., 2006).

Criticisms of the spiritual interpretation of NDEs and ADEs

The FJN put some of these criticisms to Dr Peter Fenwick (Emeritus neuropsychiatrist at the Maudsley Hospital in London)

Q. One of the central beliefs of most religions is in some sort of afterlife. Scripture and belief cannot be counted as scientific evidence, but could they count as evidence against survival? Most people naturally fear death and find it hard to imagine their narrative consciousness just ending. Religions have nurtured this fear with ideas of heaven and hell, thus encouraging hopes for an afterlife.  So, as rational minds, should we not distrust ideas of an afterlife as products of indoctrinated fear?

Dr Fenwick: These experiences do not map onto religious belief. They can happen with similar frequency to atheists, Christians, Muslims, Jews, Hindu, et cetera.

Q. Couldn’t ADEs and NDEs simply be like dreams or fantasies generated in the brain?

Dr Fenwick: The similarity of these experiences makes this unlikely.

Q. ADEs and NDEs have been very widely reported in popular books since the 1980s. Couldn’t many now be being generated through hopes and expectations of those dying?

Dr Fenwick: Following an early TV programme about NDEs in 1989, before the phenomenon had had much publicity, I received over 400 letters about  NDEs. They were from an English population who all maintained that at the time of their NDE they had not heard about them. 

Q. Can’t the tunnel, the light and even the feeling of love be a result of brain processes starting to fail due to lack of oxygen?

Dr Fenwick: There is no clear evidence that tunnels, light or love are generated by anoxia. For example, in obstructive sleep apnoea oxygen levels fall to below 60%  and none of these phenomena occur.

Q. People say they have difficulty putting their ADE into words and a linear sequence. Could they not just be the recovering brain trying to make sense of the confusional blur of unconsciousness and not something actually experienced by those who do not recover?

Dr Fenwick: The experiences of the ADE occur in a very clear sequence and are not a blur as they appear to occur in clear consciousness.

Q.  This evidence for NDEs is based on anecdote. Clearly it’s not ethical to conduct trials, but is there any quantitative evidence?

Dr Fenwick: This is incorrect. A number of studies have collected multiple cases and analysed these according to a strict proforma for various components of the NDE. So although the data are subjective accounts, the analysis of this data shows objective quantification of the result.

Compiled by Martin Redfern for FJN

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