all right everybody welcome back to another video lesson from ICU advantage this is going to be part two in our series of lessons covering ECG and EKG interpretation and in this lesson we're going to cover the five step method to interpretation [Music] all right you guys welcome back like I said this is gonna be part two in our series here on ECG and EKG interpretation and in this lesson we're gonna give you a breakdown of the five simple step method in order to interpret your ECGs but before we begin if this is your first time to the channel and you want to see more in-depth critical care education content such as this please do subscribe below and make sure you hit that notification bell to ensure that you're alerted as soon as our new lessons become available to you guys your support truly means a lot to us and it goes a long way to help support this channel including videos like this and so for that we do want to thank you and as always for those of you who don't know me my name is Eddie Watson and I'm gonna be your presenter for this lesson alright so the five step method you're probably wondering what the heck is that essentially this is going to be a very simple set of steps that you can go through when you're looking at your patient's ECG in order to help you break down the parts that you need to know in order to be able to interpret it appropriately so that you can figure out what's going on with your patient and so to start out we're gonna go through a couple basic concepts here we're gonna cover some information that you need to know in order to be able to do this ECG interpretation appropriately we're gonna cover the different parts of what a normal rhythm is supposed to look like and what parts of that you need to know and be able to identify and so really to start out here the first thing that we need to actually cover is to go over some basics about the ECG grid paper that the rhythm strips are gonna be on so this here is just a small sample of what a typical rhythm strip will print out on and so if you look carefully every time you have five of these small boxes it actually forms a thicker line and makes one of these large boxes alright and so we can see here that this is one of the small boxes that I'm talking about right down here but if you look closely going from about here to here this is actually that collection of five boxes that I was just talking about and what form to make one of the large boxes and the nice thing is these boxes aren't there just to make things look pretty into line up there actually a unit of measurement and what they're measuring here is time and so essentially if you measure or count the number of boxes going this direction you can actually get a measure of time on what you're seeing on your ECG strip and so if we look at our small box here every single one of these small boxes is going to be point zero four seconds so from here to here is point zero four seconds now if you do some basic math and you take a look and see that you have five of these small boxes forming a big box then you can come to the conclusion that you have 0.2 seconds going from here over to here and basically what we'll do is we'll use these boxes and look at the the ECG rhythm that's printed out against them and use those to determine how much time is taking place in certain parts of that that ECG rhythm now I do want to show you what a typical rhythm strip will look like and so this is an example of what the paper is gonna look like if you print out the the patient's rhythm strip now one important thing that you're going to want to look for on these is you're gonna want to look for some dashed lines up at the top so if we were looking at this strip here we would actually see a thick cache here and another thick hash over here and then right in the middle between these two big hashes as you're gonna find a thin hash and so basically here is you have one of these marks happening every one-and-a-half seconds or every 15 big boxes and so here we can see we have two sets of 15 big boxes which means that the strip that we're looking at here is a six second strip now this will come and play here in a little bit and be important for you to know but for right now just know that the time in between two of these big hash marks is going to be six seconds all right so now that we got that measuring part out of the way let's go ahead and start to cover the different parts of the electrical signal that you're gonna see when we're looking at a normal sinus rhythm now to go along with this in our last lesson we went pretty in-depth talking about the conduction system of the heart which I will link to up above for those who haven't watched it so I'm not going to go detailed into that here but as I'm going through and drawing this norm rhythm I'm also gonna follow along and kind of show you in the conduction system where this is happening and what this actually means in terms of what's going on inside the heart so on our diagram of the heart here I do want to draw and label a few of these parts for you guys within the conduction system so over here we know we have our SA node coming off that we have Bachmann's bundle which is going to spread that signal out to the left atrium located roughly about here within the atrial septal wall we have that AV node and then don't forget we have those three internodal pathways carrying that signal from the SA node to the AV node then coming down off the AV node we have the bundle of hiss which is going to split into our left and our right bundle branch the right bundle branch is going to come all the way down and service the right side of our heart the left bundle branch is going to split once again and it's gonna split into our left posterior fascicle and our left anterior fascicle both of these servicing the left side of the heart and ensuring that we get that signal all throughout that left ventricle and finally coming off of these bundle branches we're gonna have our Purkinje fibers which again are gonna take that impulse that depolarization and spread that evenly and organize throughout the ventricles all right so let's go ahead and start taking a look at a normal ECG rhythm and so the first thing that I want to draw on here and really make mention to you guys is something that we call the isoelectric line and basically what this line signifies is our Neutral no charge and so really you can think of this as our baseline and anything above the isoelectric line is going to be a positive charge and everything below the isoelectric line is going to be negative and there's positive and negative is oftentimes going to depend which leads you're using but for the purpose of this example we're gonna consider that this is lead to so now the first thing that we're gonna see if you think back and remember we have our SA node which is going to depolarize on its own sending a signal out throughout the atrium that signal is also going to travel along that Bachmann's bundle and at the same time it's going to be depolarizing the left atrium as well and so if we go back and look and see what we're actually going to see on our strip here is we now have a depolarizing event that's taking place and so we're gonna see a bump form on here and so essentially as that wave of depolarization moves across the atria you're gonna see that wave of signal move across your ECG tracing and this here is what we are going to call our P wave so now if you remember we have those signals now which have worked their way through these internodal pathways and reached the AV node and the AV node being that gatekeeper is going to take that signal and it's going to hold on to it again ensuring that we don't have that competition of the atria and the ventricles both contracting against each other at the same time and so what you're gonna continue to see is flat along the isoelectric line here and so now after the 120 milliseconds the AV node is gonna pass that signal along down the bundle branches heading out to the ventricles via the Purkinje fibers and with this happening this is where we're gonna see the next bit of changes on our ECG strip and so now here you can see that this wave is going to be much bigger than that P wave but if you really think about it those ventricles are a lot bigger and consists of a lot more muscles and the atria do so that explains why we're gonna see a big wave showing up as that depolarization happens and so within this wave you're actually going to see three different waves we have our Q wave our R wave and our s wave and together these form our QRS complex now one thing to note is you're not always gonna see a Q wave or a defined s wave and so really the main thing we're looking for is that our wave and we'll get to that here in a bit but for the purpose of this perfect normal sinus rhythm that we're going to use it as an example here we're going to have all these waves in here so once again we're going to be back on our ISO electric line and we're not gonna see anything happened for just a little bit here and then from here the next wave we're gonna see is gonna be a little bit bigger than what we saw with our P wave and then continue along our isoelectric line and this final wave on here is what we call the T wave and really what's happening in the T wave is we've now had that ventricle that has depolarized and all those ions have shifted out of the cell and so after that depolarization and contraction has taken place everything is going to relax and those ions are going to move their way back inside the cell an event that we call repolarization and so this T wave that you're seeing is actually the repolarization of the ventricles and so you might look back at our rhythm that we have here and be thinking I don't remember them talking about atrial repolarization and in fact you'd be right because we didn't and the reason for that is the atria they do repolarize after a depolarization and contraction but the problem is that the atria are repolarizing at the time the ventricle is depolarizing and so as you can see when we look at the ventricular repolarization that T wave is significantly smaller than our QRS complex and so our atrial repolarization would actually be much smaller than even our P wave and in fact it's in there it's just being buried and masked by the giant QRS complex that's taking place so both the atria and the ventricle are going to go through a depolarization and repolarization phase but the only one that we're going to see on our ECG tracing is going to be our ventricular repolarization so now on this strip here there's all sorts of different parts and areas of this that we can give measurements for but really for our basic interpretation which is what we're going to be covering here there's only going to be two segments that we really care about their time the first of these is going to be what we call the PR interval and essentially the PR interval is going to go from the start of our P wave and will end at either the start of our queue or our our wave if we don't have a Q wave and so essentially we're looking at this whole section here and this is going to be our PR interval now the other interval that we're gonna look at is the interval of our QRS complex and so that's gonna go from the start of our Q wave to the end of our s wave so that's gonna cover right across here and like I said that's gonna be measuring our QRS now there is one last interval that I do want to point out and kind of make mention of here but we're not really going to talk about it much in this lesson in fact that's really going to be geared towards another lesson that we'll probably do in the future here but there's this segment right through here which is our ST segment and as you can see here in our example as after we went through the entire ventricular depolarization we came back to that isoelectric line before going to our t wave and so sometimes you might see a depression of this ST segment or sometimes you might actually see an elevation of the ST segment and these are important to monitor for because they can be signs of either myocardial ischemia or myocardial infarction when we're looking at the elevation side of things but again I just wanted to make mention of that we're not really gonna talk about that any further in this lesson like I said for this lesson the main thing you want to focus on is the PR interval and that QRS complex length all right so I hope so far this has made sense for you guys like I said we've talked about just what a normal perfect sinus rhythm tracing is going to look like on the ECG as well as to give you some conceptualization of what's actually happening inside the heart in the conduction system to go along with what you're seeing on the paper alright so now that we've got that out of the way we're gonna move on and talk about our actual interpretation and in particular using the five-step method and so with this five-step method like I said this is going to be a series of five steps that you're going to go through every single time when you're looking to interpret your patient's ECG rhythm and by doing these five steps and gathering this information you'll be able to use that to effectively make a good interpretation of what you see and so to start off with step one what you want to do here is you want to locate your P wave and your QRS complex and identify those now again for this interpretation we want to be using lead 2 for this interpretation and so when we're looking at our P wave and lead 2 we want to look and see is that P wave upright like we drew in our example here it's going to be important if that P wave is either not present or going the opposite direction as that can be an indication of some sort of problem that's going on or where that initial impulse has originated from but like I said look and see is that P wave present and upright and now if you have found a P wave and you've identified your QRS complex the other thing you want to check and see is is there a P wave for each QRS complex again following that path of conduction we should have that P wave immediately followed by a QRS complex so if you guys aren't seeing that or you're seeing P waves without QRS complexes or vice-versa then there could be some other sort of problem that's going on and in fact those are things that we are going to talk about in future lessons in this series so pretty easy for step one and so moving on to step two if you remember we talked about those two measurements that we really care about the PR interval and the QRS complex so for step two we're gonna actually get those measurements and so at this point we've talked about these measurements but we haven't actually given you a normal value in what you guys want to expect to see for these so to start that off let's go ahead and talk about our PR interval and for our PR interval remember think about this is the time from the time that the atria is contracting until the time that the ventricle is contracting and if you remember that signal has made its way over to the AV node where it's been delayed ideally for 120 milliseconds and so with a PR interval we expect to see an interval within the normal range of 0.12 and 0.20 seconds now typically for simplicity we really don't worry about a short PR interval but if that PR interval is long it could tell you that there's something else going on again stuff that we'll talk about here later in these lessons and so then with our QRS complex our normal value is going to be point zero six to 0.1 zero seconds although really we just care that we're less than 0.1 two seconds again a short QRS complex for simplicity is not something that we're really gonna worry about but a long QRS complex technically anything over 0.1 seconds but really what we care about is anything longer than 0.12 seconds which is going to be potentially a pathological condition that's going on with our patient so these numbers are gonna be important and you guys are gonna need to memorize these so you might be wondering how am I gonna get these measurements how do I know how long these are well if you remember back we talked about those boxes that are on that ECG paper well those boxes tell us amount of time and so if we just measure the amount of boxes that something is taking place at we know how long the time is for that to happen now this is my plug where I know a lot of the newer monitor systems have built in a calipers in which you can click and get your measurements on there but not everybody has those and you may be running into issues and so it does help to know how these Box measurements work in order to be able to get your measurements yourself manually so for the first one we're going to talk about our PR interval so if you remember we're going to start from here and measure over to here and so here you can see that we have one two three a little over three boxes we know that each box is point zero four so three of them would put us at 0.1 two if we went for the full fourth box we'd be at point one six but we know that we're maybe roughly about halfway in here so you know we're probably something like point one for again either way both of those numbers are going to be within our normal value and with this being a normal sinus rhythm we would expect to see that and so again if we look at our QRS complex we're going to be measuring from here to here and we can see we start off not directly on the line so here we have about a half a box and then one box and two box so we have two and a half boxes so again we know the small box is point zero four seconds so two boxes would be 0.08 seconds and another half a box we'd add another point zero two for a grand total of point one zero which again falls within our normal limit not surprisingly with a normal sinus rhythm that we have here all right so moving on to step three for this step we actually want to look at the whole rhythm strip and make a determination of whether our rhythm is a regular rhythm or an irregular rhythm and so in order to really show you guys this I'm gonna take you back to our six second strip that we talked about earlier I'm gonna go ahead and put up a full strip of a normal sinus rhythm so don't mind the drawing I tried to do my best in order to get everything the same and to keep it within what we would expect for a normal sinus beat here but if you take a look at the the patient strip here and you look at each of our our waves on our QRS complex if you kind of follow them along you can see that they seem pretty regular and oftentimes if you have some very irregular rhythms that'll be very obvious just from looking at that that you do have a regular rhythm going on but one of the best things you can do in order to ensure that this is a regular rhythm is to take either an index card or a piece of paper and put it up against your rhythm strip and what you want to do is you want to make a mark right where each of these our waves are and then essentially what you do is you just move your card right along and you line them up and you see does everything line up and again you move it along continuing to check and see that each of these line up and so in this case you see that they all pretty much line up they don't have to be perfect but they all pretty much line up with the ticks that we made from the first three hour waves and this basically tells us that these are waves are happening at a pretty regular rate and therefore we would know that that rhythm was regular so again we want to make note do we have a regular or irregular rhythm and step three here and so now on to step four for step four we want to determine what is our heart rate now there are a few different ways in which we can do this the first of these which i call the cheater method is you can just look and see if you happen to have a real time strip that you just print it out on your patient is you can look at the monitor and see what that rate says but that's too easy for you guys like I said for this lesson we want to give you the ways in which you can actually manually calculate out what your patient's heart rate is and so again we're going to go to our example here with the six second strip and so when we're talking about what our patient's heart rate is what we want to know is how many times is the heart contracting in a sixty second period or one minute and this essentially gives us our beats per minute so I'm gonna give you guys four different ways in which you can look at your six second strip here and determine what your patient's heart rate is the first of these is what we call the six second method and so for this method essentially what you're gonna do is you're gonna count the number of QRS complexes within this six second strip and you're gonna multiply that by ten because we know there's 60 seconds in a minute and this will give you your patient's heart rate and beats per minute the beauty of this method is it actually works for both regular and irregular rhythms so in this example here we would just count out one two three four five six seven eight so we have eight beats and 60 seconds we'll multiply that by ten and here we know that our patient's heart rate is right around 80 probably the easiest of these methods but it's also not the most accurate because our heart rate could be a little below 80 or a little bit above 80 but again for the most part one we're looking at this basic interpretation that little bit of variance isn't going to make much of a difference now the next method that we're gonna cover here is what we call the big box method now for the big box method what we're going to do is we're going to count the number of big boxes in between our waves and then from there we're going to take that number and divide it into 300 and this is going to give us our patient's heart rate so like I said essentially we're going to take 300 and divide that by the number of big boxes and again that's going to equal our heart rate so for this example here let's go ahead and start back over here with this one and here we can see that we actually have 1 2 3 almost 4 perfect big boxes and so if we were to take 300 and divide it by 4 we would actually get 75 and so here's where you can see some of the difference that you're gonna see between some of these methods the last one on the sixth second method we got a heart rate of 80 here with the big box method we got a heart rate of 75 again the difference between your patient's heart rate of 75 and 80 isn't really gonna make much of a difference but we're starting to get a little bit more accurate in terms of the the number that we have here one caveat to the big box method is this is only gonna work on our regular rhythms all right so let's go ahead and go on to our third method here and this one's gonna be very similar to the big box method and it's what we call the little box method now you probably can figure out what we're gonna do here is instead of counting the big boxes we're actually going to count the small boxes and we're gonna divide that into 1,500 and again that's gonna give us our heart rate now just like the big box method this one is only going to be able to be used on our regular rhythms and this method is really best for our fast rhythms where you're not having to count a whole bunch of these boxes but just to make the point of having a little bit more accurate of a heart rate I'm gonna go ahead and count these out for you guys and we're gonna start from our second QRS complex and we count out 21 small boxes we divide 21 into 1500 and we actually get seventy one point four so either rounding down to 71 or up to 72 depending on the accuracy of my measurement but again we see that we have a slightly different number than the big box method and again a different number than the six-second method and again I don't recommend using this one for our normal wide spaced rhythms like this really if we're you you're looking at your faster rhythms that's where you're gonna want to use this small box method alright and so on to our last method of getting our patient's heart rate this is going to be one that we call the sequence method and for the sequence method we're actually going to go back to counting the big boxes but we're gonna do that and count down with the following number sequence we're gonna count down and go 300 150 175 60 50 and so again if we use our first QRS complex as an example here would be 300 here would be 150 here would be 100 here would be 75 which you can see this is where our QRS complex lines up if we continued along our next one would be 60 and then 50 and so again depending how much space is in between each of your are waves you can use this method to quickly count those and as long as you memorize that sequence you can come to a pretty close and pretty accurate determination of your patients heart rate pretty quickly now once again just like the others here this is going to require a regular rhythm in order to do this so if you have any irregular rhythm really your only option is to use the six second method and to figure out what your patient's heart rate is that way otherwise you've got four different methods and depending on what's going on and what you want to do or really which one works best for you you can use any one of those and come to a pretty close determination of what your patient's heart rate actually is and one last little thing to add when we're looking at determine our patient's heart rate we need to know that our patient's normal heart rate is going to be between 60 and 100 beats per minute all right so we've gotten this far and so that means we're going to move on to our fifth and final step in the five-step method and for this step we're going to take all the information that we gathered up above look at our patient's rhythm strip and we're gonna interpret the rhythm and so in this lesson we've really only talked about a normal sinus rhythm and we've identified that by having an upright P wave a P wave for every QRS complex a QRS complex that's less than 0.1 2 seconds with that we'd have a PR interval of 0.12 to 0.2 zero seconds we'd have a regular rhythm and our heart rate would be between sixty and a hundred if we meet all of those criteria then we know that our patient has a normal sinus rhythm now it turns out there's actually a heck of a lot more rhythms that your patient can be in and so in the next couple lessons we're going to talk about many of these different variations that you're gonna see and how to identify those but no matter what's going on with your patient no matter what rhythm they're in you're always gonna start following the same five-step method completing that final step by making your final determination or interpretation of what the rhythm is alright I hope you guys followed along with all of that I hope that I was able to explain these different concepts and a way that really makes them understandable for you because it's really important that you guys are able to look at your patient's rhythm strip and be able to make a determination of what's going on because sometimes depending what you see it may require urgent or emergent intervention and you being able to catch that and get somebody on the phone or get somebody to the bedside in order to address it can really make the difference for your patient and so with that said that's gonna finish up this lesson and I really do want to thank you guys for watching I truly hope that you guys found this information useful if you did please go down and hit that like button down below it really makes a difference to show your support and that helped to build this channel and as always we invite you to subscribe what you can do below or I'll pop a link up here for you and make sure you keep an eye out for the next lesson in the series part 3 and which we're gonna start to take a look at all these other rhythms that your patient might be in and show you the many different forms of arrhythmias that your patient can have in the meantime that you can also feel free to check out another one of our great series in which we cover arterial blood gases as always thank you guys so much for watching and you have a great day