The first scientific article I came across in my search for the latest thinking on NDEs, is dated 2010 and titled "The effect of carbon dioxide on near-death experiences in out-of-hospital cardiac arrest survivors: a prospective observational study," by Zalika Klemenc-Katis; Janko Kersnik and Stefek Grmec. This research paper appeared in BioMed Central's Open Access Journal "Critical Care" 2010 14:R56.
"Introduction: Near-death experiences (NDEs) are reported by 11-23% of cardiac arrest survivors. Several theories concerning the mechanisms of NDEs exist-including physical, psychological and transcendental reasons-but so far none of these has satisfactorily explained this phenomenon. In this study, we investigated the effect of partial pressures of 02 and C02 and serum levels of Na and K on the occurrence of NDEs in out-of-hospital cardiac arrest survivors.
Methods: A prospective observational study was conducted in the three largest hospitals in Slovenia. Fifty-two consecutive patients (median age 53.1, 42 males) after out-of-hospital cardiac arrest were included. The presence of NDEs was assessed with a self-administered Greyson's NDE scale. The initial partial pressure of end-tidal CO2, the arterial blood partial pressures of O2 and CO2 and the levels of Na and K in venous blood were analysed and studied. Univariate analyses and multiple regression models were used.
Results: NDEs were reported by 11 (21.9%) of the patients. Patients with higher initial partial pressures of end-tidal CO2 had significantly more NDEs (less than 0.01). Patients with higher arterial blood partial pressures of CO2 had significantly more NDEs (P=0.041). Scores on a NDE scale were positively correlated with partial pressures of CO2(P=0.017) and with serum levels of potassium (P=0.026.) The logistic regression model for the presence of NDEs (P=0.002) explained 46% of the variance and revealed higher partial pressures of CO2 to be an independent predictor of NDEs. The linear progression model for a higher score on the NDE scale (P=0.001) explained 34% of the variance and revealed higher partial pressures of CO2, higher serum levels of K and previous NDEs as independent predictors of the NDE score.
Conclusions: Higher concentrations of CO2 proved significant, and higher serum levels of K might be important in the provoking of NDEs. Since these associations have not been reported before, our study adds novel information to the field of NDEs phenomena."
The full article:
After reading the full article, I have noted the following additional points of interest:
1. "It is still not clear whether NDEs occur before, during or after the period of cardiac arrest...Our findings concerning the association between initial petCO2 and the occurrence of NDEs therefore supports the hypothesis that NDEs occur during the cardiac arrest... on the other hand, the association between higher pCO2 upon admission and the occurrence of NDEs might suggest that NDEs occur after the cardiac arrest..."
2. "...it is known that CO2 changes the acid-base equilibrium in the brain, which can provoke unusual experiences in the form of bright light, visions and out-of-body or even mystical experiences. Some earlier studies have shown that inhaled CO2, used as a psycho therapeutic agent could cause NDE-like experiences. Therefore, we can conclude that CO2 might be one of the major factors for provoking NDEs, regardless of when NDEs occur..."
3. "Previous prospective studies on NDEs reported an 11 to 23% incidence between cardiac arrest survivors, which is consistent with the incidence found in our study...Previous studies have shown that NDEs more often occur in patients younger than 60 years of age..."
I find the subject of NDEs as interesting and as challenging, as UFO abduction research. In the instance of an NDE we have a person who recalls a vivid experience; the content op which is often a trip down a "tunnel" to a place where they meet other entities, and then return. In a UFO abduction, a person is removed to an unearthly environment, interacts with other entities and is then returned.
I have interviewed experiencers of both NDEs and UFO abductions (one or the other, although sometimes there has been an incredible account which could be either) and can say that their recollections are both vivid, "real as real", told with appropriate emotion and real events to them.
In the NDE event we can be fairly certain where the experiencer was at the time of the event; that is, their body was physically present here on Earth, often in sight of another person.
In the case of a UFO abduction, most often there is no external witness present to say whether or not the individual was physically removed. There are cases where there are said to be external witnesses, who saw the UFO and abductee "in transit" but theses are few and far between.
I feel that much could be learnt by UFO researchers from a study of both NDEs and UFO abductions.