Near-death experience (NDE) is a term for a set of “visions” and “feelings” to a consecutive clinical death or advanced coma. These experiments represent a recurrent and specific characterization containing including: disembodiment, full vision of his own existence, the vision of a tunnel, meeting with spiritual entities, the vision of light, a feeling of infinite love, peace and tranquility, felt an ineffable experience and union with the divine or supernormal principles. However, few NDE which combine all these elements and some inter-individual variation was observed.
Following this type of experience, patients infer the possibility that consciousness survives death. Neuroscientists usually explain , partially, this phenomenon impaired brain consciousness whose physiological mechanisms have been widely studied. A minority of neuroscientists question the explanatory power of these mechanisms and develop theories that make possible the existence of consciousness apart from brain activity.
Other terms are sometimes used, such as “experience the frontiers of death”, “experience approached death”, “death experience trip”.
Clinical death is a brief period of unconsciousness caused by insufficient blood supply to the brain due to poor circulation, respiratory failure, or both. It is a different state of reversible brain death. During a near-death experience following a cardiac arrest, the flat electroencephalography route does not mean that the brain is dead. According to Steven Laureys, Coma Science Group researcher (Cyclotron Research Centre, University of Liège, Belgium), analysis by PET scan of the brain during cardiac arrest indicates that it retains a residual physiological activity that differentiates a dead brain.
Several studies have examined the frequency of near-death experiences. These studies have been the subject of a 2008 meta-analysis in the University of Liège. According to this meta-analysis, conducted by Marie Thonnard et al., NDE frequency varies from 2 % to 12 %. The study by Pim van Lommel in 2001 reported that of 344 patients interviewed, 62 (18 %) had some memories of the period of unconsciousness, and 41 of them (12%) experienced an NDE base. Parnia in 2001 reported 6% and Greyson in 2003 reported 2%. Moreover, in 2011, a new study by Vanessa Charland – Verville reported in 5%. The difference lies in the methodology, van Lommel using questionnaire WCEI established in 1980 while the other three use a more nuanced questionnaire that Greyson established in 1983. According to the meta- analysis Thonnard Marie et al , NDE frequency is inversely proportional to age, is higher among people under 60, and inversely proportional to the length induced memory deficit post – cardiopulmonary resuscitation. The frequency and depth of the NDE (see scale Greyson) is against by not correlated with factors such as pharmacological substances administered, the duration of coma or cardiac arrest. Have experienced an NDE increases the likelihood of a new experiment. However, this result can also be induced by age, in fact, this group of patients in the different studies are mostly young people.
Effects of depth of NDE on survival
The depth of the near-death experience, defined for example by the WCEI Index (Weighted core experience index) of Bruce Greyson to measure the “quality” of NDE as a scale of qualification evidence is correlated with risk of death within 30 days after cardiac arrest. The depth of the NDE is related to sex, it is usually called “deeper” in women, and having had a cardiopulmonary resuscitation outside hospital. However, since patients in this second group were younger than other patients in the different studies, this finding on the depth of the EMI may result from a difference in age.
Translated and adapted from Wikipedia.