The Canadian Journal of Neurological Sciences has published a study conducted by the University of Western Ontario Canada, examining brain activity in patients after their life support has been switched off and they were considered to be clinically dead. As a means of assessing brain activity, the researchers examined the electroencephalogram (EEG) recordings of four patients.
Ordinarily the time of death is given when the heart no longer registers activity on an electrocardiograph (ECG). However, these tests revealed that electrical activity in the brain can continue after the patient’s heart has flat-lined. The brain activity consisted of a burst of delta waves, usually associated with deep sleep. Although EEG activity had stopped before their ECG flat-lined in three out of the four patients, this burst of delta waves occurred in one patient 10 minutes post death for a reason the authors were unable to explain.
They noted that they found no evidence for a “death wave”, a surge in brain activity that can occur moments before death. No link was found between the moment the patient’s heart ceased and their EEG recordings. This study was on a small scale with patients who were severely ill and taking strong sedatives. Nonetheless, the researchers have speculated that such findings have the potential to complicate organ donation and the manner in which death is determined.