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Our online ACLS certification course includes understanding the physiology of the heart, overview of BLS and ACLS, ACLS Pharmacology, and AED training. The course is best suited for healthcare/medical professionals. It has 2 years validity. A group of 5 or more can take advantage of group discounts.

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Chapter 12 : Asystole - Understanding H's and T's

ACLS Asystole or ‘flatline’ is associated with no cardiac electrical activity, no contraction of the heart muscle and no cardiac output.  Flatline is when there is a straight line on the monitor in the situation of post cardiac, 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

Asystole ACLS Training Video:

chapter9-1-1 CPR Certification Online

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 Cardiopulmonary Resuscitation (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
  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 a flat line situation or asystole/PEA (left side of chart)

 CPR Certification Online

chapter8-3-scaled-1-scaled CPR Certification Online

Note: When conducting the BLS and ACLS survey on a patient with asystole, there may be times when you should hold resuscitative efforts; those include:

  • Signs of irreversible death like rigor mortis
  • DNAR – Do Not Attempt Resuscitation
  • Threat to safety of the providers
  • Living Will/Family Wishes
Learning Outcomes:

You have completed Chapter XII. Now you should be able to:

  1. Apply the Cardiac Arrest Algorithm to Asystole
  2. Recognize asystole in a patient
  3. Understand the H’s & T’s in relation to Asystole/PEA
  4. Understand when it is necessary to hold resuscitation
  5. Understand the treatments used in Asystole