To be able to understand the term pulseless electrical activity (PEA), it’s important to first recognize the difference between a tactile pulse and the indication of a heartbeat on an ECG tracing. Just because it appears that the heart is beating as it should on an ECG does not necessarily mean blood is being pumped throughout the body. It simply means that the electrochemical signals sent out by the sinoatrial node are propagating throughout the heart and being captured by the ECG machine.
Being able to feel a person’s pulse means that blood is actually being pumped; when you place your fingers on the inside of your wrist, you’re feeling the rush of blood being pushed through the artery by your heart’s contraction.
So in the case of pulseless electrical activity, depolarization and repolarization of heart tissue is occuring but blood isn’t being pumped.
How does this happen? Most often it occurs when there has been a significant loss of fluid volume in the body, to the point that such small amounts of blood are being pumped with each contraction as to not be able to detect the pulsing of the blood through arteries and veins. Called hypovolemia, the loss of fluid volume could be from blood loss due to an injury, or surgery, severe dehydration or the use of diuretics (causing excessive urination).
Other causes for PEA include:
Hypoxia
Hydrogen ion (acidosis)
Hypokalemia/hyperkalemia
Hypoglycemia
Hypothermia
Toxins
Tamponade, cardiac
Tension Pneumothorax
Thrombosis (coronary or pulmonary)
Trauma
