[Music] you [Music] all right welcome back to another video lesson from ICU advantage and in this video this is going to be part four in our series of videos covering arterial blood gases and in this lesson we're going to do a continuation of our previous lesson where we talked about the ABG interpretation and we're going to take things a little bit further and talk about some of the compensation that goes on inside of our patients bodies and how we expect to see these show on the ABG analysis for those of you who don't know my name is Eddie Watson and I'm gonna be your presenter for this series of lessons and if this is your first time here or your first time watching one of our videos we do invite you to subscribe to our channel below if you do make sure and hit that Bell icon and select all notifications this way you'll be notified as soon as our lessons become available all right and so to start out like I said in the previous lesson we really began our analysis of how to read an ABG and do that ABG interpretation in that previous lesson we talked about those four steps that you're going to go through in order to analyze each ABG result that you have and based on those four steps you were able to determine did you have a normal ABG as well as is your patient in a state of acidosis or alkalosis and is that being primarily driven by either a respiratory problem or a metabolic one but like I had said previously those first four steps are really only the first part in our interpretation of an ABG because if you will remember the body is going to want to compensate for those disturbances in the pH and so we can continue to do further evaluation of these ABG's in order to determine what's going on and what our patient's body is doing but it's really at this point where people often tend to get caught up but we're gonna go through we're gonna explain it hopefully we can break this down in a way that makes it easily understandable for you and really if you take your time and think through it you really can figure this out and so the first thing to really know what this is that if we have a primarily respiratory disturbance that's going on the body is going to compensate by adjusting the bicarb and therefore on the other hand if we have a primarily metabolic disturbance that's going on then the body is gonna compensate for things by adjusting our co2 but if you remember this adjustment of the co2 is that vast process versus the body's compensation by adjusting bicarb is that much slower process so key important things for you to remember co2 is acidic and bicarb is alkaline when talking about the co2 remember that the co2 and the pH are gonna go in opposite directions of each other therefore if we have an elevation in our co2 which is more of an acid we're gonna see a decrease in our pH and vice-versa if we have a drop in our co2 therefore less acid we're gonna have an elevation in our now on the other hand when we look at our bicarb remember that bicarb and pH are gonna go with each other in the same direction so if our bicarb is elevated we're gonna have more of an alkaline therefore an elevation in our pH versus if our bicarb is low we have less alkaline therefore a decrease in our pH and so when we look at the body and its compensation an important thing to really know with this is that the the body is going to compensate in the same direction and what I mean by that is if one of our values is elevated the other value is going to elevate in response to try to compensate so for example if we have an elevation in our co2 in order to bring that pH back up into a normal range it's gonna have to increase the amount of alkaline and it does this by increasing our bicarb so here you can see our co2 goes up and therefore our bicarb will go up in response to try and compensate and get that pH back up into the normal range conversely if our bicarb is low we have less alkaline around again meaning we're in a state of acidosis and in order to compensate for this metabolic disturbance the body is going to adjust the co2 which we know is acidic but we're already in an acidic environment we have that state of acidosis and so the way the body compensates for this is by blowing off co2 so that we have less co2 around and so when we have less acid we're going to raise the pH again raising that pH up into a normal value and so this is where you can kind of see where people can start to get caught up with this but if you really think about is that molecule or that value that we're dealing with is that an acidic or an alkaline and what state are we in right now and how would we adjust things to get back to that normal value there are a couple of they're important things to know - the first of these is that compensation will never fully normalize so the way these compensation mechanisms work is the body will compensate by changing either our co - our bicarb and it will continue to do so bringing things either higher or lower depending on which way it needs to go until we get back in that normal range and once we do then that compensation stops and therefore we tend to maintain a pH just inside the line of the normal values and so what this means is you're never gonna get compensation that takes you back fully to the perfect 7.4 if your patient was in a state of acidosis that compensation is going to bring us just above 7.35 or if your patient was in a state of alkalosis that compensation is gonna bring us down just below 7.45 and sort of going along with that it's important to know that the body will never over compensate we're never gonna go past 7.4 because we're never even gonna reach that point in the first place all right so knowing all of that once we've done the first four steps in our basic ABG interpretation really the next step is determining how much if any compensation is actually going on with your patient and there's really three states that we can find our patient we can find them either one uncompensated - fully compensated which we often refer to as just compensated and three partially compensated and so with each of these there's a couple things that we're really going to be looking for that will help us determine which one of these states of compensation they're in so in order for our patient to be in an uncompensated state we have to have a couple things the first of these is we have to have an abnormal pH next we have to have one of our one of our values of either co2 or bicarb being abnormal so one abnormal value and then along with that we have to have one normal value and so really if you think about this in the past examples that we were doing we consider this uncompensated one because we have that abnormal value so we haven't compensated back into that normal range but then we also only have one of our values abnormal and as we know the body compensates by matching that value either elevating or lowering along with the the other abnormal value but in this case only one of these values is abnormal therefore our second value hasn't even adjusted and so really if we kind of think of an example where if we had a patient in a state of acidosis so a low pH and they had a high co2 that was driving this in an uncompensated State we would still have a normal bike Harpe we would expect to see the body raise that bicarb in order to match that elevated co2 again trying to get us back into that normal range but that just hasn't happened yet therefore the patient is uncompensated and so now looking at our fully compensated or just our compensated state here is where we're actually going to have a normal pH but to go along with that normal pH as we're gonna have to abnormal matching values so again think the body is now attempting to correct that pH disturbance and so in the last example where co2 was elevated the body has now elevated the bicarb and response therefore we have two matching elevated values and when this happens far enough and brings our pH far enough along back in line and we end up in that normal range of 7.35 to 7.45 we then consider that compensated and so now finally moving on to the last these is potentially the trickiest of these but again if you really kind of think about it it makes sense what's happening here but this is our partially compensated so what we're looking for here is we still actually are going to have an abnormal pH but in this case of the abnormal pH we are going to have the matching values but what this tells us is that that compensation just is not complete and so again back to this example of a state of acidosis due to an elevated co2 the body will start to raise that bicarb level but it's going to take raising it to a certain point to bring that value back to a normal pH and so if in that process of raising we find the bicarb raises beyond the range of what's normal but still not quite far enough to raise our pH back into that normal range then this is where we call it partially compensated because the body is compensating it just hasn't done it fully and therefore only partially compensated so hopefully that makes sense for you guys like I said this is probably the most difficult part of these ABG interpretations but if you guys just take your time and go slow with it I promise you you can figure this out and we are going to do some more examples starting off slowly to help work you guys through this now lastly before we move on to these examples I do want to give a quick mention to another state that we can find our patient in and this is what we call our mixed disorders now this is going to be beyond the scope of this lesson but it is important to know that you can have a combination of disorders going on with your patient both metabolic and respiratory that really can make things more complicated and trying to figure out what's going on and like I said we're not going to cover working through some of those here but if you find yourself where you have a patient who just is not compensating as you would expect them to then they potentially could have some other underlying metabolic disturbance that's going on so let's go ahead and move on to some more examples where we go through and fully interpret these ABG's to include how much compensation our patients have all right so in this first example we're gonna have a pH of 7.27 a po2 of 80 a co2 of 53 a bicarb of 23 and an oxygen saturation of 92% once again we're going to disregard our pao2 and our oxygen set and to start out we're going to go through those first four steps of our basic interpretation so in this example our pH is seven point two seven is going to be low meaning we have a state of acidosis our co2 is going to be high at 53 and our bicarb is normal at 23 so here we have a state of acidosis with an abnormal co2 we have a low pH and a high co2 so again we know these are going in an opposite direction and co2 being a primarily respiratory disorder we know we have a respiratory acidosis so I think we've got that part down so let's go ahead and move through our assessment of what kind of compensation we have going on here and so if you remember four are three types of compensation we have either uncompensated fully compensated or partially compensated there are some key characteristics that we're going to be looking for so if we look to see if this is an uncompensated patient first we want to see do they have an abnormal pH well yeah in this example we do we have a state of acidosis next we're wanting to look to see if we have one abnormal value and one normal value and here again yeah we do see that in this patient we've got a high co2 but a normal bicarb and so right away we can see that we've met all of the criteria that we need in order to determine that our patient is actually in a state of uncompensated respiratory acidosis again if you think about it our pH is low because our co2 is high our body should be working to elevate our bicarb in order to bring that pH back to a normal value but it just hasn't started yet therefore we are not compensating all right let's go ahead and do another example here for this we have a pH of seven point three six a pao2 of seventy a paco2 of forty nine a bicarb of twenty eight and an oxygen saturation of ninety percent once again we'll go ahead and disregard these here and so starting with our basic four steps our pH of seven point three six well in this case we actually have a normal pH looking at our co2 of 49 we can tell that this is high for our bicarb we have a value of 28 which once again we can tell that this is high but when we try to do step four it's not really clear because here we have what looks to be a normal pH and two values that are abnormal so you might be wondering which of these values is the value that's actually the primary problem it's sort of that chicken or the egg question did the co2 rise first and the bicarb rose to compensate for it or was the bicarb elevated and the co2 rose to compensate for that so if you find yourself in this situation what you're going to need to do is go back and look at your pH and if you remember when we talked about that compensation mechanism we mentioned how it's never gonna fully compensate back to or overshoot a normal pH so we know are perfectly normal pH is 7.4 but in this case our patient has a value of seven point three six so we're lower than what that normal value is which means this compensation has taken place it has gone to the point to where we maintained a normal pH and then it shut off and so if we look at these two values both the co2 and the bicarb are high but at one point our patient had a low pH we have to think which of these two values would be the one that would lower our pH well in this case we know the co2 is the acid therefore elevation of co2 would mean a lower pH therefore we can determine that this was a primarily respiratory disturbance and thus our patient has a respiratory acidosis and so now we want to look and determine how compensated is our patient and so if we look at the values for being uncompensated first you have to have an abnormal pH which we don't have here we actually have a normal pH and so if we move on to our fully compensated this is actually the only one of these three in which we would have a normal pH and therefore this should be a pretty pretty telltale sign that we actually have a fully compensated patient but as we talked about just a minute ago the body has compensated by elevating that bicarb to the point to where our pH has gone back into the normal range therefore we have a patient who has a compensated respiratory acidosis alright so in that last example you can see we had to do a few more steps to really analyze and determine what was going on with our patient but again if we know what our normal values are and how those changing values impact our pH disturbances we can really figure out what's going on with them so let's go ahead and move on to another example here in this example we're going to have a pH of 7.4 for we have a pao2 of 90 a paco2 of 49 a bicarb of 29 and an oxygen saturation of 95% again we're gonna disregard these two here and quickly go through the first four steps we'll see that with a pH of 7.4 for that that is normal with a co2 of 49 we can tell that that's high and with a bicarb of 29 we know that that's also high as well so once again we can't really easily determine step four unless we look at our pH we do have some abnormal values and which end of the normal spectrum is our pH well it's actually on the high end at seven point four four so we know our patient was previously in the state of alkalosis and so if we look and see which of these two values would lead to a state of alkalosis we know a high bicarb would do that therefore we have a patient that's in a metabolic alkalosis and once again we have our telltale sign since we have a normal pH and two abnormal but matching values so to elevated values we know that this is a fully compensated or a compensated metabolic alkalosis all right continuing on with another example here we have a pH of 7.3 to a pao2 of 85 a paco2 of 34 a bicarb of twenty and an oxygen set of 94 we'll go ahead and disregard these here and looking at our pH of seven point three two here we can see that this is low meaning we have an acidosis our co2 is 34 which is also low and our bicarb is twenty which is also low as well and so now here we find ourselves where we have an abnormal pH and two abnormal values and so and so just as when we looked at our patients being compensated we need to look at these two values and determine which of these values is going to contribute to a state of acidosis well if our co2 is low we would expect a high pH so it's not that therefore a low bicarb is going to lead to a low pH therefore a meeting that we have a metabolic acidosis and so now we need to assess our patients compensation and so if we look at our pH our pH is abnormal but we know our patient isn't uncompensated because we would expect to see one normal value and one abnormal value but here both of our values are abnormal telling us that the body is beginning to compensate but due to the fact that our pH isn't normal we just haven't reached that fully compensated state yet therefore we know that we have a partially compensated metabolic acidosis all right hopefully you guys are getting this so we're gonna move on to our last example and so for this example we have a pH of seven point four nine a pao2 of seventy five a co2 of twenty nine a bicarb of twenty and an oxygen saturation of 89% and what I'd like you to do for this example is before I begin go ahead and pause the video work through this example yourself and in the comments below tell us what you think this ABG interpretation would be whoo you guys were able to figure that out so to start out we're gonna go ahead and ignore these values here we're gonna look at our pH 7.49 we know this is high meaning we have an alkalosis our co2 is 29 which is low our bicarb is 20 which is also low and so we need to look at our pH and determine is it the co2 or the bicarb that is contributing to this and so if we had a low co2 we know we'd have less of that acid around meaning we would be left with a higher pH which is exactly what we have going on here telling us that we have a respiratory alkalosis now from here we need to determine how much compensation we have going on and so if we look at our pH 7.49 we can see that that's not normal so we do have an abnormal pH but again we don't have one abnormal value and one normal value therefore we know this isn't an uncompensated ABG and thus we can see that the body has attempted to compensate for our low pH by lowering or by carbon response but once again it hasn't gone low enough to fully compensate for that state of alkalosis and so our pH has not gone back into our normal range therefore leading us to know that we actually have a partially compensated respiratory alkalosis all right well congratulations on making it this far through I know we went over a lot of information but we also did a lot of examples to hopefully help walk you guys through that process in what we're doing my best advice to you if you're still having trouble with this or you really want to solidify this information is that there are all sorts of examples online that you can go and find example ABG's and work through them and try to see if you can go through those steps and determine what your ABG interpretation will be as an extra bit of a little bit more practice down in the comment section I'm gonna go ahead and give a few more examples and go ahead and work through those and reply in the comments with what you think those answers are and we'll check them and see how you guys did and so with that said I do want to thank you guys for watching this video I really hope that you guys found this information useful if you did please hit that like button down below as it really does help to spread the word about our Channel and as always we invite you to subscribe to our channel to get notified of our lessons as they become available and make sure and check out the next and final lesson than this series and which are going to be covering a very popular method to help in ABG interpretation using what they call the tic-tac-toe method as well as you can also check out another one of our great series of lessons on shop thank you so much for watching and we'll see you guys in the next lesson