There's dead, and then there's mostly dead: the most recent eSkeptic newsletter features an article by Mark Crislip titled "Near Death Experiences & the Medical Literature". The article primarily looks at NDE studies - in particular the famous Lancet paper published by Pim van Lommel et al, which is one of the most important of the NDE literature.
I read the article from the perspective of a practicing physician who spends all his time in an acute care hospital and has been involved with many cardiac arrests over the years. The NDE question in this study hinges on whether the [sic] were dead or nearly dead. In the article the authors “defined clinical death as a period of unconsciousness caused by insufficient blood supply to the brain because of inadequate blood circulation, breathing, or both. If, in this situation, CPR is not started within 5–10 min, irreparable damage is done to the brain and the patient will die.”
Crislip's article brings up some good points in regards to how we define death, and is intelligently written. Nevertheless, there are elements of nonsense debunkery which should be set straight:
a) The whole article appears to take on the validity of the Lancet paper, on the basis of the "clinically dead" definition ("The NDE question in this study hinges on whether the [sic] were dead or nearly dead"). However, this is only a part of the paper. In fact, the Lancet article explicitly points out that NDE's happen in contexts that are not related to brain-death, such as "fear-death" situations in which bodily health is never affected...the experiencer just believes they are about to die.
a) Crislip points out discrepancies in reports over time, noting that "Some of the NDEs were, it seems, implanted memories." While this may be so, historical surveys show quite clearly that the NDE is a real phenomenon, not simply implanted. NDEs have been written about well before they entered the public consciousness. Crislip's statement may be of note though in giving percentages of people who have had NDEs - but not in the reality of the experience (reality as in 'it occurs', not that what is experienced is real).
b) Crislip finishes by saying "I am certainly not going to disagree with the idea that nearly dying is transformative..The knowledge that you are truly mortal is life altering. Cancer survivors can have the same epiphany without the cardiac arrest." However, the Lancet article explicitly notes that "The process of transformation after NDE took several years, and differed from those of patients who survived cardiac arrest without NDE", discussing these findings in detail within the article based on a longitudinal study. The study notes that the transformation was not because of the knowledge of mortality, but "a significant increase in belief in an afterlife and decrease in fear of death compared with people who had not had this experience"
There's a few other things, but just wanted to point out these items while they were in my head. Both articles are well worth the read though.