5-Minute Emergency Consult



  • Absence of cardiac electrical activity
  • End-stage cardiac rhythm


  • May occur after progressive dysrhythmia:
    • Bradycardia
    • Prolonged ventricular fibrillation
    • Prolonged pulseless electrical activity
  • Patient is extremely unlikely to survive when asystole occurs outside the hospital:
    • ∼40% will have return of spontaneous circulation and survive to hospital admission, but <15% survive to hospital discharge.
  • Prognosis is similarly poor for those patients who develop asystole after countershock for ventricular tachycardia/ventricular fibrillation (VF); <10% survive to hospital discharge.
  • Potentially reversible causes include:
    • Hypoxia
    • Acidosis
    • Hyperkalemia
    • Hypokalemia
    • Drug overdose
    • Hypothermia
    • Pulmonary embolism
    • Myocardial infarction

Signs and Symptoms

  • Unresponsive patient
  • Pulseless
  • No spontaneous respirations

Lightheadedness or Syncope may precede

Essential Workup

  • Confirm asystole in two limb leads to exclude ventricular fibrillation.
  • Confirm lead and cable connections.
  • Confirm monitor power is on.
  • Confirm monitor gain is up.
  • Identify reversible causes.

Diagnostic Tests and Interpretation

Arterial blood gas (potassium)

Cardiac US

  • Confirm cardiac standstill

Differential Diagnosis

Ventricular fibrillation

Pre Hospital

  • No intervention should be made for patient with valid Do Not Resuscitate document.
  • No intervention if patient can be verified as dead:
    • Rigor mortis
    • Dependent livedo
    • Injury incompatible with life (eg, decapitation)

Initial Stabilization/Therapy

  • Initiate basic CPR.
  • Confirm asystole with defibrillator.
  • Place airway device and confirm placement.
  • Establish IV access.
  • Confirm asystole in two limb leads with monitor.
  • Consider early transcutaneous pacing (within 3–5 min of onset of asystole).
  • Epinephrine and atropine every 3–5 min.
  • Vasopressin as a one-time dose (optional)
  • Treat potentially reversible causes.
  • Sodium bicarbonate if hyperkalemia or drug overdose suspected
  • No proven benefit to an empiric single countershock.

Ed Treatment/Procedures

  • Consider induced hypothermia in comatose patients with return of spontaneous circulation
    • Target temperature 32–34°C for 12–24 hr
  • Consider termination of resuscitation efforts if the following conditions are met:
    • Adequate CPR
    • Tracheal intubation
    • Effective ventilation
    • IV access
    • VF excluded
    • Epinephrine and atropine given:
      • Discuss indications of vasopressin versus epinephrine
    • Reversible causes corrected
    • Documented asystole despite 10 min of above interventions


  • Atropine: 1 mg IV q3–5min:
    • Up to 3 mg total
  • Epinephrine: 1 mg (peds: 0.01 mg/kg) IV q3–5 min
  • Vasopressin: 40 U IV (single dose)
  • Sodium bicarbonate: 1 mEq/kg IV only if:
    • Pre-existing acidosis
    • Hyperkalemia
    • Tricyclic antidepressant overdose is suspected.


Admission Criteria
All patients with return of spontaneous circulation

Discharge Criteria
None—all patients with return of spontaneous circulation need at least a period of monitored observation in the hospital.

Follow-Up Recommendations

Appropriate use of a permanent pacemaker may prevent primary asystole:

  • High-grade heart block
  • Sinus arrest

Patient Monitoring
ICU for cardiac monitoring and induced hypothermia as appropriate

Pearls and Pitfalls

  • Confirm asystole in 2 limb leads to exclude ventricular fibrillation
  • Resuscitation is likely to be successful only if reversible causes corrected immediately

Additional Reading

  • Olasveengen TM, Sunde K, Brunborg C, et al. Intravenous drug adminisration during out-of hospital cardiac arrest: a randomized trial. JAMA. 2009;302(20):2222–2229.
  • 2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cadiovascular Care. Part 7.2: Management of Cardiac Arrest: 7.4: Monitoring and Medications: 7.5: Postresusciation Support. ECC Committee, Subcommittees and Task Forces of the American Heart Association. Circulation. 2005;112:(Suppl. 24):IV58–88.
  • Cummins RO, Graves JR, Larsen MP, et al. Out-of-hospital transcutaneous pacing by emergency medical technicians in patients with asystolic cardiac arrest. N Engl J Med. 1993;328:1377–1382.
  • Wenzel V, Krismer AC, Arntz HR, et al. A comparison of vasopressin and epinephrine for out-of-hospital cardiopulmonary resuscitation. N Engl J Med. 2004;350(2):105–113.
  • Bernard SA, Gray TW, Buist MD, Jones BM, et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med. 2002;346(8):557–563.


427.5 Cardiac arrest


397829000 asystole (disorder)


David F. M. Brown
Kohei Hasegawa

© Wolters Kluwer Health Lippincott Williams & Wilkins

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