Pulseless electrical activity (PEA) is a form of cardiac arrest in which the electrocardiogram shows a heart rhythm that should produce a pulse, but does not. Pulseless electrical activity is found initially in about 20% of out-of-hospital cardiac arrests and about 50% of in-hospital cardiac arrests.

Under normal circumstances, electrical activation of muscle cells precedes mechanical contraction of the heart (known as electromechanical coupling). In PEA, there is electrical activity but insufficient cardiac output to generate a pulse and supply blood to the organs, whether the heart itself is failing to contract or otherwise.

Signs and symptoms

Pulseless electrical activity leads to a loss of cardiac output, and the blood supply to the brain is interrupted. As a result, PEA is usually noticed when a person loses consciousness and stops breathing spontaneously. This is confirmed by examining the airway for obstruction, observing the chest for respiratory movement, and feeling the pulse (usually at the carotid artery) for a period of 10 seconds. See Hs and Ts

  • Hypovolemia
  • Hypoxia
  • Hydrogen ions (Acidosis)
  • Hyperkalemia or Hypokalemia
  • Hypoglycemia
  • Hypothermia
  • Tablets or Toxins<!--Either-or; no need for .-->
  • Cardiac Tamponade
  • Tension pneumothorax
  • Thrombosis (e.g., myocardial infarction, pulmonary embolism)
  • Tachycardia
  • Trauma (e.g., hypovolemia from blood loss)

The possible mechanisms by which the above conditions can cause pulseless in PEA are the same as those recognized as producing circulatory shock states. These are (1) impairment of cardiac filling, (2) impaired pumping effectiveness of the heart, (3) circulatory obstruction and (4) pathological vasodilation causing loss of vascular resistance and excess capacitance. More than one mechanism may be involved in any given case.

Diagnosis

thumb|upright=1.6|Pulseless electrical activity, it is possible to observe by invasive blood pressure (red) the transition from a normal mechanical activity of the heart, which progressively changes in rhythm and contractile quality to [[asystole, even in the presence of normal electrical activity (green), also confirmed by the pulse oximeter detection even if with artifacts (blue)]]

The absence of a pulse confirms a clinical diagnosis of cardiac arrest, but PEA can only be distinguished from other causes of cardiac arrest with a device capable of electrocardiography (ECG/EKG). In PEA, there is organised or semi-organised electrical activity in the heart as opposed to asystole (flatline) or to the disorganised electrical activity of either ventricular fibrillation or ventricular tachycardia. Epinephrine too has a limited evidence base, and it is recommended on the basis of its mechanism of action.

Sodium bicarbonate 1meq per kilogram may be considered in this rhythm as well, although there is little evidence to support this practice. Its routine use is not recommended for patients in this context, except in special situations (e.g. preexisting metabolic acidosis, hyperkalemia, tricyclic antidepressant overdose). and