Online ACLS Course

Chapter 12 : Asystole

Asystole or ‘flatline’ is associated with no cardiac electrical activity, no contraction of the cardiac muscle and no cardiac output.  Flatline is when there is a straight line on the monitor, but asystole is when there is an actual absence of electrical activity. The first step is to ensure that it is an actual asystole by making sure of the following:

  • Leads are properly connected
  • Power unit is on
  • Signal gain/amplitude/strength is not turned down or too low
  • The rhythm doesn’t look like another pattern
Video Demonstration


Asystole can be caused by many factors and are represented as H’s and T’s:

Hypovolemia – Decreased blood volumeTension pneumothorax – air in the pleural space around the lung (lung collapses)
Hypoxia- decreased partial pressure of oxygen in bloodTamponade – compression of the heart produced by excess fluid surrounding the heart
Hydrogen ion (acidosis) – Increase in the concentration of H ions in bloodToxins – poisonous substances
Hyper-/hypokalemia –abnormally high or low potassium concentration in the bloodThromobosis (pulmonary) – formation of a blood clot which blocks a blood vessel in lungs
Hypothermia – body temperature less than 30 degrees C (86 degrees F)Thrombosis (coronary) –formation of a blood clot which blocks a blood vessel in heart

Scenario: You are a paramedic and arrive on the scene.  A man is lying on the floor unconscious and the neighbor tells you that she saw the man collapse as he was unlocking his front door.


  1. Check for responsiveness – Tap and shout “Are you alright?” and look at chest for movement.
  2. Check carotid pulse and note no pulse is present


  1. If no pulse, immediately start compressions at a rate of 100 compressions per minute and allow chest to recoil. 30 compressions to 2 breaths.
  2. Prepare to transport patient to the nearest hospital, while continuing effective CPR
  3. Attach monitor and check for shockable rhythm, if no shockable rhythm present, the patient is in asystole or PEA, start CPR for 2 mins and obtain IV/IO access

Management:  AT the hospital initiate the cardiac arrest algorithm on the right if the patient still has no pulse and does not respond to BLS. Get a code team in place.

  1. Once IV/IO access is obtained give the following drugs:
    1. Epinephrine 1 mg IV/IO and repeat every 3 to 5 minutes or
    2. Vasopressin 40 units IV/IO to replace first or second dose of epinephrine
  2. Maintain advanced airway and capnography if needed.
  3. Pause and check for shockable rhythm.  If not shockable , continue CPR for 2 minutes and try to treat the reversible causes

The following is an algorithm shows management of cardiac arrest due to asystole/PEA (left side of chart)