 Welcome to Nursing School Explained and this video on cardioversion versus defibrillation. This is a very important topic to know and understand because we want to make sure that we deliver the shock to the patient's heart at the exact correct time. If you haven't already done so, please watch my video on the basic electrophysiology where I go into explaining the different waves of the cardiac cycle as well as the depolarization and repolarization as it applies to the contraction of the heart. So let's look at this over here. Here we have our normal cardiac contraction P, Q, R, S and T waves. And recall that we have two different refractory periods. The first is called the absolute refractory period which occurs from the start of the Q wave to the peak of the T wave. And it basically means that this occurs during the contraction of the ventricles and part of the beginning of the relaxation of the ventricles. And what this means is that the cells are not going to be able to respond to a further stimulus that we would apply to the patient's heart by externally shocking the patient. In contrast, the relative refractory period is also called the vulnerable period. It starts at the peak of the T wave and ends at the peak, I'm sorry, at the end of the T wave. So it's a very short pyramid of time here. But it is vulnerable because some of the cardiac cells have repolarized and are basically getting ready for the next impulse to occur. And if we now apply a stimulus to the patient's heart by shocking them, these cells can be simulated. And if we shock them, there's a high risk that we might put them in ventricular fibrillation. So during this relative refractory period, we have to be very careful because if there is still some sort of an organized underlying cardiac rhythm that produces a cardiac output and the patient has a pulse, we might throw them into ventricular fibrillation, which is not a good thing. So over here, the top of the R wave is what we will select that the synchronization of the cardioversion will happen where we will shock the patient at the top of this R wave when we need to synchronize it in order to deliver the cardioversion. And we'll look at rhythms and how it applies to those here in a bit. Down here, I have drawn out the monitor of the fibrillator. Here we have our wave and these are white complex tachycardia. So this is a patient in ventricular tachycardia and a rate of 230. Down below, we have the corresponding curve for the O2 set measurement. Over here on our patient, we have the pads applied to their chest, just like you would in basic life support when you're using the AED. Now on the defibrillator, usually we follow the exact same steps every time that we turn it on. So we turn it on, just like with the AED and BLS, then you would select the jewels that you would like to shock the patient at and that will depend on multiple factors as I'll be discussing in a moment. Then you hit the charge button and then you hit shock. But if the patient needs to be cardioverted rather than defibrillated, we need to make sure we hit that sync button. That is the most important part of the synchronized cardioversion. And when we hit that button, what happens that the defibrillator puts an arrow on every QRS complex of the patient's cardiac rhythm. So it corresponds with this R wave up here so that we make sure that we don't shock the patient in this vulnerable period, but rather in the absolute refractory period where the cells are not able to respond to the stimulus, the shock that we will be delivering to the patient. And then the defibrillator usually has a couple of other settings for rate and amp setting for the pacemaker version. So the defibrillator is a very nice tool that gives us the options of treating the patient whether they need synchronized cardioversion, defibrillation or external pacing. And you can watch my different video about that. Now keep in mind that the defibrillator is a machine that will not be able to detect whether your patient needs defibrillation or synchronized cardioversion. So it will be up to you to know if you need to hit that sync button or if you need to actually defibrillate the patient. So let's look at the differences over here and the indications for one or the other modalities. So in synchronized cardioversion, the rhythm set it is indicated for is ventricular tachycardia with a pulse. So this patient might be conscious, they might have altered level of consciousness depending on how long they've been in this rhythm. But we want to shock them as soon as possible to get them out of these potentially lethal rhythms. Because if ventricular fibrillation or tachycardia go on for too long, the patient might lose their pulse. And other rhythms that are indicated for synchronized cardioversion are atrial fibrillation, atrial flutter, as well as supraventricular tachycardia. So those are impulses or tachycardias that are irregularities that come from the atria or from the top chambers of the heart. And sometimes the rate can be too fast or sometimes we just want to convert the patient back or attempt to convert them back into a sinus rhythm if they're an atrial fibrillation because we know the associated risks of developing clotting and associated complications such as strokes that we mostly worry about. So in synchronized cardioversion, the shock is delivered with that synchronized button with that sync button we just discussed just after the R wave up there on that R wave during that absolute refractory period. And the energy that we typically use for cardioversion depends on if we have a monophasic or a biphasic defibrillator. And monophasic basically means that the energy on the patient's chest from the pads travels one way, so mono, where it's biphasic, it travels both ways. And of course, that goes very quickly and it goes one two. So biphasic, two directional. And so if we shock the patient biphasic, typically we don't need as high of an energy because the heart gets shocked both ways. And these are current guidelines from the American Heart Association. Of course, these might change in terms of the energy that you would select. But of course, they also depend on your patient. You wouldn't shock a patient who weighs 90 pounds with the same jewels that you would shock a patient with that weighs 300 pounds, for example. So it'll all depend. So make sure that you check with the leader of your advanced cardiac life support to see what jewels they want to select. So monophasic for synchronized cardioversion will be anywhere generally from 100 to 200 jewels. Where if it's biphasic, it's a little bit less. Again, because the energy travels both ways. So 50 to 100 jewels. And again, it'll depend on the patient and their overall body build and whatever energy they need. Now in contrast for the fibrillation, the patient already is in a shockable rhythm but does not have a pulse. And those two will be in ventricular tachycardia or ventricular fibrillation. So the patient here will not have a pulse. They might have started with V-Tag or V-Fib with a pulse, but now they've lost their pulse. So that's why in advanced cardiac life support, as well as really basic life support, we have to check the patient's pulse to see if they're responding and if they are producing a cardiac output. So the fibrillation V-Tag V-Fib without a pulse. Shock delivery doesn't really matter. We don't have to hit that sync button because we can shock them in the absolute or the relative refractory period because the patient currently is not producing a cardiac output. We are just attempting by giving them that shock with the defibrillator to kind of restart the heart and get the cells back into an organized rhythm. And for energy selection, so for monophasic, it can be all the way up to 360 joules. Well, for biophasic, it might be 100 to 200 joules depending again on the patient and the provider who is in charge their preference. So keep in mind that this R wave and the two refractory periods are very important to know here. And when you do a synchronized cardiac version, it is very important or the most important thing to turn on that sync button on your defibrillator so that you can sync the shock delivery with the R wave during the absolute refractory period. Thanks for watching this video on Nursing School Explained. Please subscribe and like this video if you've enjoyed it. I'm always open for suggestions for more content. So please subscribe and I will see you soon right here on Nursing School Explained. Thanks for watching.