Asystole

colloquially referred to as flatline, represents the cessation of electrical and mechanical activity of the heart.

Asystole, colloquially referred to as flatline, represents the cessation of electrical and mechanical activity of the heart. Asystole typically occurs as a deterioration of the initial non-perfusing ventricular rhythms: ventricular fibrillation (V-fib) or pulseless ventricular tachycardia (V-tach). Additionally, pulseless electrical activity (PEA) can cease and become asystole. Victims of sudden cardiac arrest who present with asystole as the initial rhythm have an extremely poor prognosis (10% survive to admission, 0 % to 2% survival-to-hospital discharge rate). Asystole represents the terminal rhythm of a cardiac arrest.

In out-of-hospital cardiac arrest, prolonged resuscitation efforts in a patient who presents in asystole is unlikely to provide a medical benefit. Termination of resuscitation efforts should be considered in these patients, in consultation with on-line medical direction, as allowed by local protocols. The American College of Emergency Physicians (ACEP) and National Association of Emergency Medical Services Physicians (NAEMSP) both recommend emergency medical services systems and have written protocols that allow for termination of resuscitation efforts by emergency medical services providers for a select group of patients in which further resuscitative measures and transport to the local emergency department would be considered futile.

Treatment

Asystole should be treated following the current American Heart Association BLS and ACLS guidelines. High-quality CPR is the mainstay of treatment and the most important predictor of a favorable outcome. Asystole is a non-shockable rhythm. Therefore, if asystole is noted on the cardiac monitor, no attempt at defibrillation should be made. High-quality CPR should be continued with minimal (less than five seconds) interruption. CPR should not be stopped to allow for endotracheal intubation. Epinephrine (1 mg via intravenous or intraosseous line) should be delivered every three to five minutes and treatment of reversible causes addressed.

Vasopressin can be administered before or after epinephrine but the benefits remain questionable.

Even though transcutaneous pacing is widely done, there is no evidence that it improves survival.

Asystole is considered a terminal rhythm of cardiac arrest. Therefore, discussion of termination of resuscitation should be considered during an in-hospital cardiac arrest in the appropriate clinical picture. Out-of-hospital cardiac arrest patients in asystole should also be considered for the cessation of efforts according to local protocol.

Patients who are resuscitated need to be monitored in the ICU. Some experts recommend inducing hypothermia on all patients who survive cardiac arrest.