PEA or Pulseless Electrical Activity refers to instances where an individual has a heart rhythm that is not creating a pulse. In other words the heart rhythm will show up on the electrocardiogram demonstrating that the heart is beating and that there is electrical activity in the body, but holding your hand on the wrist or the side of the neck will not yield any noticeable pulse. This can lead to people being mistaken for dead under some circumstances. Normally the pulse is caused by electrical activity in the cells of the body which briefly precede a contraction which is known as 'mechanical coupling', but this is absent in PEA. The electrical activity in question is picked up on an electrocardiogram – meaning that the ECG shows life, but the usual check for a pulse is less effective; no flatline, but no visible heart beat either.
PEA then is a puzzling condition and calls into question an individual's health. There are several causes for PEA and these are often referred to as the 6 Hs and 6 Ts. They are as follows: Hypovolemia, Hypoxia, Hydrogen ions, Hyperkalemia, Hypoglycemia, Hypothermia, Toxins (meaning drug overdose), cardiac Tamponade, Tension pneumothorax, Thrombosis (Myocardial infarction), Thrombosis (Pulmonary embolism) and Trauma. In other words then, there is a large range of reasons that someone might demonstrate these seemingly contradictory signs. If the cause can not be found and dealt with quickly the individual will be treated as though in 'asystole'. This is the state of complete lack of cardiac activity or electrical activity. This means they will receive an injection of epinephrine along with atropine and will be subjected to chest compressions and potentially mouth to mouth resuscitation. However defibrillators will not be used, as the problem will be with the response of the heart and circulatory system to electrical impulse rendering this method obsolete.
What PEA does do is to raise some interesting questions about the nature of life and death. When you find someone has no pulse you certainly should not assume they are dead instantly. At the same time, even when they are treated in a hospital, this demonstrates the abstract nature of the concept of death, and more than one case has been documented of individuals returning from periods where they have no heart beat at all, sometimes leading to premature burial. The precise definition of death, and the point at which someone is declared as officially dead is something that is still undergoing debate.