Emergent Care / Stabilization:
Once the patient is determined to be pulseless, immediately begin cardiopulmonary resuscitation (CPR), minimizing any interruptions in chest compressions. Follow the age-appropriate cardiac arrest algorithm (Advanced Cardiac Life Support [ACLS] or Pediatric Advanced Life Support [PALS]) for this nonshockable rhythm. Focus should be placed on high-quality chest compressions; ventilation with advanced airway placement, if possible; epinephrine; and evaluation for any reversible causes of cardiac arrest.

Diagnosis Overview:
Asystole is the complete absence of electrical or mechanical signs of cardiac activity, and it can be referred to as "flatline" in appearance of the electrocardiogram (ECG) or cardiac monitor. It can be a primary rhythm or the terminal rhythm associated with unsuccessful resuscitation of other dysrhythmias.

Asystole can occur in any age group, but it is more commonly the presenting rhythm in the pediatric population, usually secondary to respiratory arrest. In adults, it is more likely the terminal rhythm following untreated ventricular dysrhythmias or failed attempts at defibrillation, which is a poor prognosticator.

Data from in-hospital cardiac arrests show that 81% of presenting rhythms are nonshockable (asystole or pulseless electrical activity). Patients who present with a shockable rhythm (ventricular tachycardia or ventricular fibrillation) have much higher sustained return of spontaneous circulation (ROSC), survival to hospital admission, and survival to hospital discharge rates compared to those who presented in asystole.

Risk factors include coronary artery disease, cardiomyopathy, cardiac arrhythmias, hypercoagulable state, infection, trauma, hypoxia, and toxins.