CPR - I need a myth buster!

  1. Hello all, so pretty simple question, or at least I hope it is. It seems every bls and acls instructor has a different set of opinions that typically end with ambiguity once investigated... does defibrillation start the heart back to a normal rhythm?

    It it is my understanding that defibrillation is obviously key, however the action it contributes is often unclear. I believe that a jolt of high voltage will literally stop the hearts ventricles from fibrillation and essentially put the heart in asystole aka flatline, and that it is compressions that 'restart' the hearts normal rhythm. So basically in my limited education I learned defibs stop the bad activity and kill the heart super duper dead and compressions get it firing proper aka defibrillation is 'reset' akin to pulling the plug on a computer and compressions is 'restart' like hitting the power button to resume functionality.

    Im aware there are other rhythms that require pacemaking and I'm NOT talking about that. In terms of vtac or vfib full arrest, does a pt ever Frankenstein post defibrillation? My current understanding is that defibrillation without compressions is essentially killing your pt immediately.

    educate me. And thanks in advance
  2. 10 Comments

  3. by   cpr,sucka
    Bump. 90 views no answers...?
  4. by   Double-Helix
    Defibrillation does provide sort of an electrical reset for the heart. However, compressions do not restart it. The normal electrical activity of the cardiac pacemaker cells do that. The cardiac pacemaker cells are capable of spontaneously generating and sending out their own electrical impulses. During fibrillation, those cells are all firing at random, and therefore can't create a coordinated contraction of the myocardium. The electricity in the defibrillator interrupts that firing. The hope is that, once interrupted, the pacemaker cells will then start sending out coordinated signals, resulting in coordinated myocardial contractions and a return of normal rhythm.

    Compressions manually circulate blood while the heart is not pumping or not pumping effectively. Each second without cerebral perfusion increases the likelihood of neurological damage. Minimizing that down time is essential in improving resuscitation outcomes. Compressions are restarted immediately after defibrillation not to restart the heart, but in case the heart does not restart. The heart may have restarted on it's own after defibrillation, but delaying compressions in order to perform a rhythm check can be detrimental if spontaneous circulation has not returned.

    Does that help?
  5. by   chare
    There shouldn't be any "different opinions" or ambiguity; defibrillation does not "start the heart back to a normal rhythm." What it does do.is depolarize the entire myocardium, with the thought that this will "kill" the ectopic foci and allow a normal rhythm to resume.

    And no, compressions don't "restart" a normal rhythm. Post defibrillation compressions, while not starting the heart, are required to ensure adequate perfusion, even in the setting of return of an orgained rhythm.

    As for a patient Frankenstein(ing) post defibrillation, I have no idea what you b are referring to. If
  6. by   Rose_Queen
    Quote from cpr,sucka
    Bump. 90 views no answers...?
    Those views don't necessarily come from registered members- AN is completely public and can be viewed by anyone. Unless a topic is of such interest that it convinces them to register, those folks are going to just move on.

    It is not compressions that "resets" the heart. In a normal heart, the heart rate is controlled by one of the heart's pacemakers (there's backups). The normal conduction of the heart begins in the sinoatrial node, and conducts along the normal pathways in an organized fashion. When the heart is fibrillating, the heart muscle is firing in unorganized fashion. Defibrillation basically causes all heart muscle to depolarize at the same time. Basically, it's enough energy that it causes all muscle to cease contraction for a brief amount of time and allows the sinoatrial node to take over again.

    The purpose of compressions is to circulate blood. While not at a full concentration during an arrest, blood carries at least some oxygen to the vital organs. However, a patient who is fibrillating needs defibrillated ASAP. Those compressions work on getting blood and oxygen to vital organs while the defibrillator is obtained, turned on, connected, and then it can analyze the rhythm. Why compressions are started immediately after delivery of a shock without a pulse check is to get that blood flowing again without wasting time- the defibrillation may not have worked, the heart may not beat at a pace high enough to provide enough circulation, or the rhythm may have deteriorated further into a non-shockable rhythm.
  7. by   cpr,sucka
    You all are fantastic. Thank you so much for the replies, I've spent hours googling this over the last few years and have taken numerous bls acls and basic ekg/anat/phis courses and have never found such clarity! Thank you thank you thank you!!!! I wish aha instructors especially at the bls level would have this basic information. I'm super excited to have read this and now I know better where to research and study as I continue to learn.
    Last edit by cpr,sucka on Jan 7, '17
  8. by   nursej22
    The heart is a fascinating organ. One of the special qualities of cardiac myocytes is automaticity: they generate an electrical impulse all on their own (given the proper conditions).

    This really came home to me while observing an open heart surgery. At the end, they allowed the stopped heart to warm, it began to fibrillate, and they used internal paddles to establish normal sinus rhythm.
  9. by   Mavrick
    Too much TV with the implied conclusion that the shock delivered "restarts" the heart. Sometimes the dialog is "We are going to restart the heart with a shock"

    I have corrected the TV so much that now when they say that my wife will blurt out, "NO you are NOT going to restart the heart, you are actually stopping the heart!"
  10. by   grizun
    Really, OP needs to read a book. OP would then understand things like overdrive suppression and why it's ineffective when the ventricles take over, etc.
  11. by   Canadavsus
    It's not necessarily that the heart may not be at pace high enough to provide circulation even if bpm are high your prefer fusion will never be adequate post defibrillator because the body now requires more than normal oxygenated blood due to metabolites built up within the system. And in cardiac surgery the paddles may look like they restart nsr on paper in reality they give the heart muscle enough energy to break the threshold that prevents it from restarting on its own and sometimes it does with or without a little squeezing or paddles. And if it quivered or fibrillates the paddles stop the heart again so it can restart so to speak. But I like rose queens description.
  12. by   amoLucia
    Quote from grizun
    Really, OP needs to read a book. OP would then understand things like overdrive suppression and why it's ineffective when the ventricles take over, etc.
    I always like 'refractory period' and 'ABSOLUTE refractory period' from chemistry class.