• 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

• Unresponsive patient
• Pulseless
• No spontaneous respirations

History
Lightheadedness or Syncope may precede

• 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.

Lab
Arterial blood gas (potassium)

Imaging
Cardiac US

• Confirm cardiac standstill

Ventricular fibrillation

• 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)

• 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.

• 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.

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

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

• 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


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