Asystole: ACLS Quick Study Guide to Causes & Treatment

Identifying Asystole

Asystole is usually diagnosed following a physical examination where no pulse is detected or through cardiac monitoring such as an electrocardiogram (ECG). On an ECG tracing, asystole appears as a flatline:

“Asystole” on the ECG monitor may be caused by a disconnected electrode. Also, certain cardiac conduction disturbances can create transient pauses. The differential diagnosis should be made by considering the mechanism (e.g., suddenly happens then suddenly reverses). The condition of the patient prior to the event will provide the most relevant information for making the diagnosis.

Treating Asystole

Standard asystole treatment involves cardiopulmonary resuscitation, or CPR, and intravenous administration of epinephrine given every three to five minutes as needed. When a reversible underlying cause is found, that cause should be treated directly to reverse asystole. Some theoretically reversible causes of asystole include:

  • Cardiac Tamponade
  • Coronary and Pulmonary Thrombosis
  • Hypovolemia
  • Hypoxemia
  • Hydrogen ion (acidosis)
  • Hyperkalemia
  • Hypokalemia
  • Hypothermia
  • Toxins
  • Tension pneumothorax

Because asystole is not a shockable rhythm, defibrillation is not an effective asystole treatment. Researchers estimate that less than two percent of people who suffer asystole outside of the hospital will survive–even with trained emergency intervention.

Asystole Treatment Algorithm

  • Conduct an initial patient assessment, checking for respirations and pulse
  • If patient is not breathing and has no pulse, start CPR
  • Establish an airway and administer oxygen to keep oxygen saturation above 94%
  • Attach monitor/defibrillator to confirm asystole in at least two leads
  • Continue CPR at 100-120 compressions per minute being sure to change emergency team members every 2 minutes to sustain quality CPR
  • Establish IV or IO access while someone else on the team continues CPR, and administer 1mg epinephrine every 3 to 5 minutes as needed
  • Check for heart rhythm after 2 minutes of CPR
  • Check for reversible causes of asystole and treat those
  • As soon as return of spontaneous circulation (ROSC) occurs, begin Post Cardiac Arrest Care

For more information on asystole and to review the cardiac arrest algorithm, check the ACLS Provider Manual. You can purchase the manual here or receive it as part of your tuition when you register for ACLS certification.