''These people had no medical training, but they could describe instruments used and what the doctors and nurses were saying''
Medical training not need as an explanation. I think that most people have watched medical procedures on TV, so are reasonably familiar with the set up, procedures and equipment. There is also evidence that the brain may be acquiring information even while sedated, which may be expressed later in a form of a lucid dream dream state. Floating and flying dreams being very common, and dreams do incorporate daily events, problems, etc, into their storyline.
''For instance, the feeling of being dead is not limited to near-death experiences—patients with
Cotard or "walking corpse" syndrome hold the delusional belief that they are deceased. This disorder has occurred following trauma, such as during advanced stages of typhoid and multiple sclerosis, and has been linked with brain regions such as the parietal cortex and the prefrontal cortex—"the parietal cortex is typically involved in attentional processes, and the prefrontal cortex is involved in delusions observed in psychiatric conditions such as schizophrenia," Mobbs explains. Although the mechanism behind the syndrome remains unknown, one possible explanation is that patients are trying to make sense of the strange experiences they are having.
Out-of-body experiences are also now known to be common during interrupted
sleep patterns that immediately precede sleeping or waking. For instance, sleep paralysis, or the experience of feeling paralyzed while still aware of the outside world, is reported in up to 40 percent of all people and is linked with vivid dreamlike hallucinations that can result in the sensation of floating above one's body. A 2005 study found that out-of-body experiences can be artificially triggered by
stimulating the right temporoparietal junction in the brain, suggesting that confusion regarding sensory information can radically alter how one experiences one's body.''
https://www.livescience.com/16019-death-experiences-explained.html
