I've now had a chance to read the two Skeptiko interviews with Gerald Woerlee and Jeffrey Long regarding near-death experiences. One of Dr. Woerlee's main points is that people undergoing cardiac arrest are often given heart massage, which restores some flow of blood to the brain and thus might allow some degree of consciousness.
As Alex Tsakiris points out in one of his his questions, heart massage is often not applied except as a last resort after defibrillation has failed, so it is not clear that heart massage is a factor in the majority of NDEs. And there are NDEs in which the person reports being out of body long before any CPR is administered.
Another question raised by both Alex Tsakiris and Jeffrey Long is whether the minimal blood flow to the brain -- technically known as hypoperfusion -- would be sufficient to produce the unusually clear awareness and perception reported by most near-death experiencers. Typically, people who report an out-of-body experience during an NDE say that their thinking was sharper and more focused than usual, and that their perception -- especially their visual perception -- was unusually vivid, allowing them to see even the smallest details and sometimes to see in every direction at once.
I don't have much to contribute to this debate, since obviously I am not a medical doctor. But I do have one personal story I can share. It is, of course, anecdotal, and it is only one case, but perhaps it will shed a little bit of light on this question.
About 25 years ago I was in the doctor's office having blood drawn from my arm. The nurse, who did not seem to be very good at her job, had a great deal of difficulty finding the vein. Instead of removing the needle and trying again, she kept the needle lodged in my arm while wrenching it around in an attempt to penetrate a blood vessel. This went on for some time. The pain was excruciating. I began to feel lightheaded and I thought I would pass out. I started to tell her this, but was unable to get the words out before I fainted.
I was unconscious for probably only a few seconds. When I came to, I was slumped in my chair, and the doctor had entered the room and was looking me over. He asked me how I was feeling. The answer I gave was, "Everything's ... white." At that point he said to the nurse, "We'd better get him horizontal." They lifted me off the chair and laid me the flat on the floor, obviously to allow better blood flow to the brain. After I lay that way for a minute or two, I felt okay again.
During the period when I was unconscious, I had no awareness that I can now recall. Upon resuming consciousness, I felt confused and sluggish. When I said, "Everything's ... white," what I was trying to convey was that my vision was bleary, as if I were looking at the world through a fog or through a sheet of frosted glass. I did not mean that I was seeing some sort of radiant supernatural light, or a "being of light," or anything of the kind. I meant that my vision was weak, lacking detail, and everything seemed somehow overexposed.
Moreover, I had trouble coming up with any words to describe my condition. My mind was not working clearly or very fast. My vocabulary was limited and inexact.
When I think back on this episode, I still find it unpleasant. Before this happened, I don't think I had more than the normal aversion to needles and blood tests. Ever since, however, I have been apprehensive about getting blood drawn. Apparently the episode left me at least mildly traumatized.
Now if we compare this to a near-death experience, the differences are obvious. Let's list them:
1. In a near-death experience, the person feels he is outside his own body, observing his physical body from an external vantage point. In my experience, I never felt I was outside my body.
2. In a near-death experience, the person typically feels that his thinking is at least as clear as usual, and often much clearer. He feels he is obtaining knowledge of the nature of the universe and the meaning of life, and that this information is becoming known to him with astonishing rapidity. In my case, my thinking was sluggish, confused, and fragmentary.
3. In a near-death experience, the person typically feels that his perception -- notably his visual perception -- is extraordinarily vivid and sharp. In my experience, my visual perception was dulled and feeble.
4. After a near-death experience, the person typically regards the event as a positive thing and sometimes longs to return to that blissful state of consciousness. After my experience, I regarded the event as negative and traumatic, and it left me with minor negative aftereffects that persist 25 years later.
Clearly my fainting spell was caused by a rush of blood from my head, and the symptoms were resolved only when normal blood flow was fully restored. During the time when I was sort of half conscious, there must have been some blood circulating in my brain, but not enough to provide full awareness. The symptoms that I experienced with a reduced blood flow to the brain were completely different from the symptoms described by the typical near-death experiencer.
Moreover, I would think that the symptoms I experienced are pretty much those that would be expected if there is reduced blood flow to the brain. The doctor certainly didn't seem surprised by my condition, and immediately diagnosed it as insufficient blood supply to the brain, which is why he and the nurse put me flat on my back without delay.
At least in my personal experience, then, a reduced blood flow to the brain does not produce heightened perception, heightened thought processes, or even a subjective, delusional impression of heightened thought processes. In fact, the symptoms are quite the opposite.
Of course, this is just one case, and maybe other people react differently. But from my own experience, I would be skeptical of the claim that someone who suffers an interruption of blood flow to the brain, and then has this blood flow restored to a minimal level by heart massage, would find his consciousness and visual perception enhanced. I think it is more likely that consciousness (if any) and visual perception (if any) would be compromised and unsatisfactory, as they were for me.