Pulseless Electrical Activity (PEA) & Asystole

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Two cardiac rhythms that are similar due to the fact that they are both unshockable and life-threatening are pulseless electrical activity (PEA) and asystole (Figure 27).

Despite a slight movement from baseline, no perceptible cardiac electrical activity can be observed. It must always be made sure that no user or technical errors are made when reading asystole. Patches must be in secure contact with the patient, gain must be appropriately set, all leads must be connected, and the device must be turned on. There are several waveforms lacking a detectable pulse by ECG (including sinus rhythm), and PEA is one of those. In addition to VF, VT, or asystole, PEA can potentially include any pulseless waveform.

PEA can cause conditions such as hypovolemia and hypoxia, two common results of PEA. These are also, thankfully, the easiest to reverse, and should always be assessed on top of differential diagnosis.

The patient requires post-cardiac arrest care if he or she has ROSC, or return of spontaneous circulation. In cases of PEA or asystole, atropine is no longer recommended.

Rules for PEA and Asystole

ACLS Rhythm - Pulseless Asystole

Figure 27

Regularity The rhythm will be a nearly flat line.
Rate There is no rate.
P Wave There are no P waves present.
PR Interval PR interval is unable to be measured due to no P waves being present.
QRS There are no QRS complexes present.

Reversible Causes

ACLS Rhythm - Reversible Causes

Figure 28

Reversible Causes of Cardiac Arrest
The H’s The T’s
Hypovolemia Tension pneumothorax
Hypoxia Tamponade
H+ (acidosis) Toxins
Hypo/Hyperkalemia Thrombosis (coronary)
Hypoglycemia Thrombosis (pulmonary)
Hypothermia Trauma (unrecognized)

Table 9

Take Note
  • Be certain that you are not dealing with user or equipment failure when reading asystole. Patches must always have secure contact with the patient, cables must be connected, gain appropriately set, and the device turned on.
  • PEA can cause things such as hypovolemia and hypoxia, two common results of PEA, though these are also easily reversible.


Studies have shown that routinely using atropine during PEA or asystole has little to no therapeutic benefit. Therefore, the ILCOR updated its guidelines to remove atropine from cardiac arrest.


While preliminary research showed that high doses of epinephrine can possibly produce better results for resuscitation, research conducted after the publication of the 2010 guidelines haven’t proven any better results from administering epinephrine over the standard dose of 1 mg. The 2010 ILCOR guidelines suggested vasopressin as an alternative vasopressor, to be used to supplement or to replace the epinephrine. Since studies have failed to prove the effectiveness of either vasopressor, high-dose epinephrine and vasopressin have been stripped from the guidelines, trimming the ACLS algorithm.

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