Asystole (aka flatline) is the state of no cardiac electrical activity, hence no contractions of the myocardium, and no cardiac output or blood flow.

H's and T's, including:

• Hypovolemia
• Hypoxia
• Hydrogen ions (acidosis)
• Hypothermia
• Hyperkalemia, or hypokalemia
• Hypoglycemia
• Tablets or toxins (drug overdose)
• Cardiac tamponade
• Tension pneumothorax
• Thrombosis (MI or PE)
• Trauma (hypovolemia from blood loss)

Source: RNCeus

• CPR (cardiopulmonary resuscitation)
• IV vasopressors, e.g. 1mg epinephrine/adrenaline, every 3-5 mins, as required. Vasopressin 40 units by IV every 3-5 mins may be used in place of the 1st and/or 2nd doses of epinephrine, but doesn't enhance outcomes
• Defibrillation, although known to be ineffective on asystole, used ot be performed in case the rhythm was actually fine V-Fib, although it is no longer recommended
• IV atropine, although it is no longer recommended
• Identify and Tx underlying cause, if possible

• Survival rates in cardiac arrest Pt w/ asystole are much lower than in a Pt w/ a rhythm amenable to defibrillation
• Asystole itself is not a "shockable" rhythm
• Out of hospital survival rates, even w/ emergency intervention, are <2%

• 1 of the conditions that may be used for a Dr to certify clinical or legal death