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Pulseless Electrical Activity Asystole

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Pulseless electrical activity (PEA) and asystole are related cardiac rhythms in that they are both life-threatening and unshockable cardiac rhythms. Asystole is a flat-line ECG (Figure 27). There may be a subtle movement away from baseline (drifting flat-line), but there is no perceptible cardiac electrical activity. Always ensure that a reading of asystole is not a user or technical error. Make sure pads have good contact with the individual, leads are connected, the gain is set appropriately, and the power is on. PEA is one of many waveforms by ECG (including sinus rhythm) without a detectable pulse. PEA may include any pulseless waveform with the exception of VF, VT, or asystole (Figure 28).

Hypovolemia and hypoxia are the two most common causes of PEA. They are also the most easily reversible and should be at the top of any differential diagnosis.

If the individual has a return of spontaneous circulation (ROSC), proceed to post-cardiac arrest care.

Rules for Asystole and PEA

A “flat line” is reserved for Asystole definition but PEA
includes flat line as well as any other wave (except VF,
VT, and SVT).

ACLS Pulseless Asystole Rythm

Figure 27

Asystole 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.

 

PEA Regularity Any rhythm including a flat line (asystole).
Rate Any rate or no rate.
P Wave Possible P wave or none detectable.
PR Interval Possible PR wave or none detectable.
QRS Possible QRS complex or none detectable.

Reversible Causes

ACLS Reversible Causes Rythm

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
  • Always verify that a reading of asystole is not an equipment failure. Make sure pads make good contact with the individual, all cables are connected, the gain is set appropriately, and the power is on.
  • Hypovolemia and hypoxia are easily reversed and are the two most common causes of PEA.

STANDARD DOSE EPINEPHRINE IS VASOPRESSOR OF CHOICE

Epinephrine is still the best choice according to 2020 guidelines. Of sixteen observational studies on timing in the recent systematic review, all found an association between earlier epinephrine and ROSC for patients with non-shockable rhythms, although improvements in survival were not universally seen.

For patients with a shockable rhythm, the literature supports prioritizing defibrillation and CPR initially and giving epinephrine if initial attempts with CPR and defibrillation are not successful.

Back to: Advanced Cardiac Life Support (ACLS) Certification Course > ACLS Cases