Number one, whether or not someone is determined as clinically dead is irrelevant because I'm not making the argument that NDE's show that people have "died" and moved on. Rather I'm using them to show that consciousness is not dependent upon brain activity and that the soul exists independent of the body. If a persons physical body has been severely damaged to the point where the soul can no longer use that body they will never recover that body, the soul will move on. But instances where accidents occur before a persons time is up here on this planet and the body is still fit for recovery that soul may be permitted or even encouraged to continue their experience within that body.
And the key feature of an NDE is that they occur after a person has "flatlined", in other words no longer show signs of heart or brain activity. There's a great documentary series called "I Survived...Beyond and Back" which gives detailed accounts of NDE's and the correlating medical facts and even Doctor statements in relation to each case. Even if you scoff at the testimonials one is forced to recognize the medical statistics that support the facts of each occurrence, so I would recommend setting aside some time to at least watch the program. This is not the only series either there are more but this one I like because it's un-biased and it gives you the medical facts behind the testimonies.
The fact of the matter is, it can be shown that NDE's occur even during complete brain death and up to hours later.
So how can this be "shown"?
You can start by watching the documentary above, or you can research it yourself.
"FLATLINE Neurology A popular term for a complete lack of cerebral activity as measured by EEG, a finding equated with 'brain death'."
"Medical Definition of flatline 1 : to register on an electronic monitor as having no heartbeat or brain waves : to experience cessation of heart contractions or brain wave activity as indicated by a flat line on a electrocardiogram or electroencephalogram"
"To show a horizontal line on the monitor of an electrocardiogram or an electroencephalogram, indicating no electrical activity."
"A flatline is an electrical time sequence measurement that shows no activity and therefore, when represented, shows a flat line instead of a moving one. It almost always refers to either a flatlined electrocardiogram, where the heart shows no electrical activity (asystole), or to a flat electroencephalogram, in which the brain shows no electrical activity (brain death). Both of these specific cases are involved in various definitions of death."
"People Have Near-Death Experiences While Brain Dead"
"three clinical tests commonly determine brain death. First, a standard electroencephalogram, or EEG, measures brain-wave activity. A "flat" EEG denotes non-function of the cerebral cortex - the outer shell of the cerebrum. Second, auditory evoked potentials, similar to those [clicks] elicited by the ear speakers, measure brain-stem viability. Absence of these potentials indicates non-function of the brain stem. And third, documentation of no blood flow to the brain is a marker for a generalized absence of brain function."
When all of Pam's vital signs were stopped, the doctor turned on a surgical saw and began to cut through Pam's skull. While this was going on, Pam reported that she felt herself "pop" outside her body and hover above the operating table. Then she watched the doctors working on her lifeless body for awhile. From her out-of-body position, she observed the doctor sawing into her skull with what looked to her like an electric toothbrush. Pam heard and reported later what the nurses in the operating room had said and exactly what was happening during the operation. At this time, every monitor attached to Pam's body registered "no life" whatsoever."
"Current research contends the strongest lines of evidence supporting the veracity of the near-death experience remain OBEs, NDEs in the congenitally blind, and those which occur under general anesthesia, and during cardiac arrest. Each of these lines of reasoning arrive at the same postulate to explain NDE’s: that heightened, lucid consciousness occurs when the heart stops beating, the brain demonstrates no measurable activity or function, and breathing ceases. NDEs which occur during cardiac arrest however, remain the closest model of the process of dying, and are considered the most objective and scientific method to study brain, mind, and consciousness at a time of clinical death. This is because from a biological standpoint, cardiac arrest is the same as clinical death, or “flatline”. The medical community uses these terms interchangeably.
Clinical death has traditionally been defined when three biological parameters are met; there is no heartbeat, there is no breathing, and there is no brain function-this is determined when a light is shone into the eyes and there are fixed, dilated pupils which indicate a lack of brain stem activity. Death, as indicated from the above three parameters, follows very quickly from the moment when the heart stops beating. This is due to a lack of blood flow into the vital organs including the brain itself."
"EEG Expert Can’t Explain Near Death Experience Data… and, Dr. Penny Sartori Finds More Than Hallucinations in NDE Accounts"
"For near death experience skeptics, medical evidence of a flat EEG during an out of body experience has always been a stumbling block."
"Near-death experiences are one of the most puzzling phenomena in psychology. A near-death experience is when a person appears to be clinically ‘dead’ for a short period—when their heart stops beating, their brain registers no sign of activity, and the other vital signs indicate death—and yet they report a continuation of consciousness."
"Some People Were Dead For Several Days"
"Dannion Brinkley had a near-death experience (NDE) that lasted 28 minutes."
"CRYSTAL-CLEAR CONSCIOUSNESS. The level of conscious alertness during NDEs is usually greater than that experienced in everyday life - even though NDEs generally occur when a person is unconscious or clinically dead. This high level of consciousness while physically unconscious is medically unexplained. Additionally, the elements in NDEs generally follow the same consistent and logical order in all age groups and around the world, which refutes the possibility that NDEs have any relation to dreams or hallucinations."
"NDEs by the Numbers Near-death experiences (NDEs) are reported by an estimated 200,000 Americans a year, and studies around the world suggest NDEs are a common human experience."
"Up to 2005, 95% of world cultures are known to have made some mention of NDEs."
"the most popular interpretation is that the NDE is exactly what it appears to be to the person having the experience". The NDE would then represent evidence of the supposedly immaterial existence of a soul or mind, which would leave the body upon death. An NDE would then provide information about an immaterial world where the soul would journey upon ending its existence on earth."
"NDEs Absolutely, Positively NOT Caused By Malfunctioning Brains"
“The most reasonable neuroscientific explanation of NDEs, the one that accounts best for all the data, is that NDEs are not a product of brain activity at all. They result, instead, from the removal of the brain’s filtering activity."
“The sheer volume of evidence for survival after death is so immense that to ignore it is like standing at the foot of Mount Everest and insisting that you cannot see the mountain.”
“No one physiological or psychological model by itself explains all the common features of NDE. The paradoxical occurrence of heightened, lucid awareness and logical thought processes during a period of impaired cerebral perfusion raises particular perplexing questions for our current understanding of consciousness and its relation to brain function. A clear sensorium and complex perceptual processes during a period of apparent clinical death challenge the concept that consciousness is localized exclusively in the brain."
"Near-death experiences have been well documented all over the world. They do not seem to be culturally motivated nor do they have bias when it comes to age or gender."
"The International Association for Near-Death Studies says: “Every day in the U.S. 800 near-death experiences occur.”
"Around 85% of the people who experienced near-death states say that their lives were forever changed by the experience. These changes can have a profound positive effect on the individual.
Psychological changes include no longer having a fear of death, and becoming more spiritual rather than religious and having increased psychic abilities. They are known to become engaged in abstract thinking, that on a philosophical level."