Death and Dying  Causes and Symptoms (Magill’s Medical Guide,
Sixth Edition)  Medicine determines that death has occurred by
assessing bodily functions in either of two areas. Persons with
irreversible cessation of respiration and circulation are dead;
persons with irreversible cessation of ascertainable brain
functions are also dead. There are standard procedures used to
diagnose death, including simple observation, brain-stem reflex
studies, and the use of confirmatory testing such as
electrocardiography (ECG or EKG), electroencephalography (EEG),
and arterial blood gas analysis (ABG). The particular
circumstances—anticipated or unanticipated, observed or
unobserved, the patient’s age, drug or metabolic intoxication,
or suspicion of hypothermia—will favor some procedures over
others, but in all cases both cessation of functions and their
irreversibility are required before death can be declared.
Between 60 and 75 percent of all people die from chronic
terminal conditions. Therefore, except in sudden death