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Asystole or “flatline”

EKG Asystole Rhythm Strip

Asystole is not actually a true rhythm but rather is a state of no cardiac electrical activity. The main treatment of choice for asystole is the use of epinephrine and CPR.

Asystole is treated using the right branch of the puslesless arrest arrest algorithm. Click below to view the pulseless arrest algorithm diagram. When done click again to close the diagram.
Pulseless Arrest Algorithm Diagram.

During asystole, there is no blood flow to the brain and other vital organs. This results in very poor outcomes if resuscitation is successful.

If asystole is visualized on the monitor, you should ensure that all leads are connected properly. If all leads are properly connected, you should rapidly assess for any underlying causes for the asystole.

As with pulseless electrical activity (PEA), asystole can have possible underlying causes which can be remembered using the H’s and T’s mnemonic.

In the following video, asystole is depicted on the defibrillator monitor and suggestions for treatment are given. Please allow several seconds for the video to load.


Question: What can sometimes be mistaken for asystole during a code?
click here for answer

fine ventricular fibrillation

  68 Responses to “Asystole”

  1. How do you confirm or know for sure if it is fine vfib?

    • This can be a difficult thing. Here is one tip. If the patient has not been in cardiac arrest for any significant length of time, if you see something that looks like fine VF it probably is. It take a dying person a while to finally achieve asystole.
      If in doubt and you think the pt. is in VF, shock the pt. according to the left branch of the cardiac arrest algorithm.

      Kind regards,

  2. This is my second membership. The first time was for three months, this time for a year because I am now assisting in teaching the ACLS course. This site has been so helpful as I do not work in a critical care area so I need to review frequently. Thank you so much for taking the time to prepare this site!

  3. Came across your site while studying for NCLEX. Thanks for all your work, which is definitely helping me streamline my EKG/ACLS review!


  5. How do you change the signal gain on the defibrillators to view the possible asystole better?

    • You would have to look at the manufacture guide for your defibrillator to figure out how to adjust the gain. I believe that the machine what we use has a feature that we dial over to and then can adjust the gain. This is manufacture specific and there is not a one size fits all answers for this.
      Some machines even do it automatically and don’t provide a signal gain option.

      Kind regards,

  6. Jeff, you are awesome. Your site has helped me out so much! I work in a clinic setting so I don’t come around stuff like this too often! But this is an awesome refresher. Thank you!

  7. Thanks a million Jeff! Your sight has helped me to prepare for my upcoming ACLS re-certification with much more confidence than ever. I have always gone to the exams insecure. This time I’m very confident in myself.

  8. Great site, very helpful.thx

  9. I would like to know when exactly do we have to follow DNR orders when given? is it at he time an ASYSTOLE is seen on the monitor?

    • If a patient is a DNR, any time any form of cardiac arrest exists, you would not initiate any recessive tape efforts. This includes any form of cardiac arrest whether it is asystole, pulseless ventricular tachycardia, ventricular fibrillation, or any form of PDA. It also includes respiratory arrest.
      DNR means “do not resuscitate.”
      This means if there is any resuscitative effort that is needed, it is not initiated.

      Kind regards,

  10. a little confused in the case of fine VF is defibrillation the treatment since VF is a shockable rhythm?

  11. Thanks Jeff!!!
    I love this site

  12. Asper the rule of the game for managing patient with VF/VT we have to use VF/VT algorithm which involve quick assessment, analize nad clear for shock, then follow with high quality CPR and the use of epinephrine, amediorone without assessment of the pulse during intervention, instead we are to observe for the righthm
    So why dont we put it as VF / Pulseless Ventricular Tarchycardia to make it more clearly,
    since we have other form of tachycardial with pulse.
    Thank you.

    • I’m not sure that I understand the question. Pulseless ventricular tachycardia is how we identify any tachycardia rhythm that does not have a pulse. This is the appropriate way to identify VT without a pulse. Please clarify if you have any other questions.
      Kind regards,

  13. “During asystole, there is no blood flow to the brain and other vital organs. This results in very poor outcomes if resuscitation is successful.”

    Above is your information after Pulseless Arrest Algorithm Diagram. »

    I think there is typo error; it should be “unsuccessful” or “NOT successful”
    instead of ‘successful”??

    • If the a patient is successfully resuscitated after being in asystole, the patient will often have a very poor recovery with effects such as brain damage and organ damage from hypoxia. So the outcomes of a successful resuscitation are not always positive for the patient that is successfully resuscitated.
      Kind regards,

  14. I do understand that with Asystole,you treat with CPR and Epi. How long do you have to go on with cycles of Epi and CPR ( if pt continues to be in Asystole ) before you give up on the pt ?

    • It depends on your protocols. I think in my county, we work asystole for 20 mins on scene unless it turns into VF/VT and possibly PEA.

  15. so fine vfib would go down the left of the algorhythm, and include shocks….that’s the reason to distinguish right? any way to confirm fine vfib rather than asystole? like a challenge med, or challenge shock?

  16. I am so grateful to find this site and at such a reasonable price, i am RN with 30 years experience, mostly in long term care and labor and delivery, ACLS is always a chore, no longer!! Thanks again

  17. Why defibrillation is not recommanded for Asystole and PEA.

    • A heart that has no electrical activity cannot be stunned and will not respond to defibrillation. The pacemakers are not functioning and therefore “resetting” them with defibrillation will do not good.
      Kind regards,



  20. Wow! This is a great site. I’m a 1st year dental resident getting ready to take ACLS for the first time ever and so far this has really summarized every important point. I’m going to continue to go over everything this weekend and hopefully it helps. Thanks so much for providing this information in an easy to understand format.

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