Guidelines recommend prompt defibrillation for treatment of in-hospital cardiac arrest due to an initial rhythm of ventricular fibrillation (or pulseless ventricular tachycardia) Epinephrine (adrenaline) is recommended only when patients remain in refractory ventricular fibrillation or pulseless ventricular tachycardia after many defibrillation attempts. Use of epinephrine before defibrillation is associated with lower odds of survival to discharge and of favourable neurological survival, probably due to lower odds of achieving return of spontaneous circulation