"We've added these images as objective markers," says Sam Parnia, a critical-care physician and lead investigator of the study, which hopes to include 1,500 resuscitated patients.

If trends continue as predicted, they will find that most critical hospital care will be provided by new, inexperienced and sometimes inadequately-trained nurses.

Several studies, such as a study by Slovenian researchers published in the journal Critical Care last year, have found that NDEs are quite common.