Asystole

In medicine, asystole /əˈsɪstəliː/, colloquially known as flatline, is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow. Asystole is one of the conditions that may be used for a medical practitioner to certify clinical or legal death.

Asystole is treated by cardiopulmonary resuscitation (CPR) combined with an intravenous vasopressor such as epinephrine (aka adrenaline). Sometimes an underlying reversible cause can be detected and treated (the so-called 'Hs and Ts', an example of which is hypokalaemia). Several interventions previously recommended—such as defibrillation (known to be ineffective on asystole, but previously performed in case the rhythm was actually very fine ventricular fibrillation) and intravenous atropine—are no longer part of the routine protocols recommended by most major international bodies. Asystole may be treated with 1 mg epinephrine by IV every 3–5 minutes as needed. Vasopressin 40 units by IV every 3–5 minutes may be used in place of the first and/or second doses of epinephrine, but doing so does not enhance outcomes.