[Music] all right welcome everybody back to another video lesson from ICU advantage and this is going to be our third lesson in our series of lessons on arterial blood gases and in this lesson this is really going to be the meat and potatoes of what we've been trying to build up to at this point which is our ABG interpretation and my name is Eddie Watson and I'm gonna be your presenter for this series of lessons and as always in order to stay up to date with our lessons make sure and subscribe to our channel below this way you'll be notified as soon as a new lessons available all right so to start this lesson off we're going to start with a little bit of an introduction and this is going to be a primer of information that's going to become really important when we start looking at these these ABG's and how we do our interpretation and so the first of these is to know that the body has a normal ph value of 7.4 and so our bodies in order to maintain this normal ph they'll use several mechanisms in order to keep that pH in that ideal normal range and when we look at these different mechanisms really the key component to maintaining that normal pH is going to be what we call the bicarbonate buffering system and this system really involves the blood lungs and kidneys and we did talk about this bicarbonate buffering system in the previous lesson which I'm going to link to up above but we do have these two primary organs which are going to respond to those changes to help correct any ph disturbances and like I said those are going to be the lungs and the kidneys and so with our lungs the first thing they can do is they can breathe faster or with a larger tidal volume and what this is going to do is make the blood more alkaline in response to a state of acidosis and in contrast to that we can breathe slower or with a reduced tidal volume to help lower the pH and create a more acidic environment in response to a state of alkalosis and one of the important things to know about this compensation mechanism is that this happens fast we can quickly change our respiratory rate or that volume of inspired air and we can pretty quickly make adjustments to our body's pH because of it and so when we look at our kidneys and how they're gonna respond to these changes in pH what we're gonna see the kidney do is they can either reabsorb more or less bicarb depending on whatever the disturbance is that's going on inside of our body and so if we absorb more bicarb we're going to increase our pH as opposed to if we absorb less bicarb then we're going to see our pH fall now this compensation mechanism unlike the process that's happening in the lungs is actually a slow process and so we're not often going to see these changes manifest themselves right away but over time over the course of many hours or sometimes even days and so there are really a couple important things that I need to point out to you guys here and it really relates to the point that I just made about the lungs and the kidneys and how they're different compensation mechanisms ultimately impact our body's pH and the first of these is to know that carbon dioxide or co2 as we had talked about in the previous lesson is a sitting and thus it's going to lower our pH and changes in this co2 or what we associate with a primary respiratory disorder on the other hand our bicarb or hco3 negative as we talked about is alkaline and therefore it will actually raise our body's pH and alterations in our bicarb are what we associate with primarily metabolic disorders and so it's really important that you guys understand this because when you're looking at your ABG's and trying to determine what's going on and what sort of compensation mechanism is taking place you really have to understand which direction our body's pH is going to adjust based on either our co2 or our bicarb all right and so with that said let's go ahead and talk about the primary alterations in our body's pH that we're going to see and the first of these is going to be what we call respiratory acidosis and so with this one we have a primarily respiratory dysfunction that has led us to be in a state of acidosis and so really what this means for us is that we have an increased amount of co2 and like we said which is an acid and therefore along with that we're gonna find ourselves with a decreased pH and what this tells us is that that lungs are not sufficiently ventilating and therefore that co2 is going to be building up in our lungs this leads to an increase in those hydrogen ions within that blood lowers our pH and leads to a state of acidosis so now on the other end of the spectrum we're going to talk about respiratory alkalosis and so what's happening here is the lungs are actually over ventilating or blowing off the co2 from the blood and this is going to again lead to a decrease in the hydrogen ions in the blood leading to a higher pH and ultimately a state of alkalosis and so essentially we have a decreased co2 so less of an acid around which is going to lead to an increase in our pH all right and so moving on the next of these that we're going to talk about is what we call metabolic acidosis and so what's happening here is we actually have a decreased amount of bicarb within our blood and thus less of an alkaline around this is going to make us more acidic and therefore lower our pH and this can really be the result of many disorders anything from within the GI system endocrine renal nutrition or other sorts of things and now again on the opposite of this we have what we call metabolic alkalosis and here when the bicarb level is raised in the blood we're going to have more of the alkaline around leading to a increase in our pH and again this can really be caused by a whole host of different things and so really the last thing that I want to cover with in this introduction here is I want to list out across the bottom here what are normal values for an ABG are because in order to successfully be able to interpret your ABG's you're gonna have to memorize and what these normal values are so the first of the values that we're gonna see on our ABG is going to be our pH and this is going to be with a normal value of 7.35 to 7.45 the next value we're going to see is the partial pressure of the arterial oxygen or the pao2 and this is going to have a normal value between 80 and 100 from there the next value that we're going to look at is the partial pressure of the arterial co2 or the PA co2 and this one's really easy to remember because it goes right along with our pH and this is going to be a normal value of 35 to 45 and finally the last value that we're gonna look at here is going to be our bicarb or hco3 negative and again our normal value for this is going to be 22 to 26 now there are gonna oftentimes be other numbers that you get with your ABG results and those certainly are important to know and understand what's going on but for the purpose of this lesson and this ABG interpretation we're not going to be looking at these other values all right so with that out of the way let's go ahead and move on to the steps for basic interpretation and so for this we're going to be looking at performing our basic ABG interpretation no matter what's going on with your your ABG and with your patient you're always going to start with these first four steps in order to begin to analyze what's happening now one thing that's really important here is you're going to get a lot of information on on those ABG results and a couple big things that we often care a lot about are going to be the partial pressure of the arterial oxygen and the oxygen saturation and these absolutely are important for assessing our patient's oxygenation status but they really play no part in our interpretation of the ABG and so moving forward you're gonna see these numbers here but we're often gonna just disregard those for the purpose of this ABG interpretation and I know that sounds a little funny and again I don't mean to diminish their importance because again they play a vital role in determining how our patient's oxygenation is going but again for those those steps in deter are we in a respiratory acidosis or metabolic alkalosis or what's going on with our patient they're not going to have any part in that and so when we go to go through these steps of this basic interpretation there's really four main steps that we're going to go through one two three and four and so for our first step we actually want to look at the pH and determine is it normal acidic or alkaline and so if we find we have a pH that's less than seven point three five then this is going to mean we have an acidosis whereas if we find that we have a pH that's greater than seven point four five then this means we have alkalosis now for step two what we're going to want to do is assess our co2 so again if we think about those normal values 35 to 45 if we're greater than 45 we're gonna be high and if we're less than 35 we're gonna be low now for step three we're gonna do the same thing but this time assessing our bicarb so again we know the normal range 22 to 26 so if we're less than 22 then we're gonna be low and if we're greater than 26 then we're gonna be high now finally here for step 4 we want to determine is this respiratory or metabolic and so in the presence of an abnormal pH we want to look and see which of our values is abnormal is it the co2 or is it the bicarb and so if it's the co2 value that's abnormal like we had talked about this means that we have a primarily respiratory driven problem on the other hand if it's the bicarb that's the abnormal value and again we have a pH that's outside that normal range we know that it's a metabolic process that's driving things and so there is actually a pretty popular acronym that really can help you to memorize is this a respiratory or metabolic issue and it's something that we call Rome and what this stands for is respiratory opposite metabolic equal and what this really is trying to tell us is how is the pH going to respond in response to whichever one of our two molecules is the one that's in an abnormal range and so what will happen is the pH will rise in the opposite direction of co2 so if our co2 is high think more of an acid the pH is going to lower and vice-versa if our co2 is low we have less of an acid so our pH is going to rise and that's where we get the respiratory opposite from but in contrast to that the pH is actually going to go in the same direction as the change in our bicarb so again think if you have more bicarb around you have more of an alkaline therefore leading to a rise in our pH but on the other hand if you have less bicarb around you're gonna have you're gonna have less of an alkaline around and therefore you're gonna see a lower pH and so again the pH is going to move equal to or in the same direction as a metabolic problem and hopefully that makes sense with that acronym because we are going to be using that moving forward and so let's do that now let's go ahead and move on with some examples to really help solidify those four steps for you and so in each of these examples we're going to be looking at our pH our pao2 our paco2 our bicarb and our oxygen saturation alright so for this first example we're gonna walk through it slowly and go through each of these steps one by one and really show you how we're doing this so for this example we're gonna have a ph of 7.38 a pao2 of 110 a paco2 of 42 a bicarb of 23 and oxygen saturation of 98% now as we talked about for the purpose of this ABG interpretation we're not going to pay much attention in these steps to our pao2 and our oxygen saturation but we will look at and analyze these other values here so for step one if you remember we're gonna take a look at our pH and determine is this acidosis or alkalosis so in this case we have a ph of 7.38 and if you remember or look down here at the bottom you see our normal value is 7.35 to 7.45 you actually can see that this pH value is normal so now moving on to step two we're gonna want to assess our carbon dioxide and here we have a value of 42 so again if you remember or look down at the bottom you see our normal value is 35 to 45 well once again this value is going to be within that normal range and so now moving on to step three we're going to assess our bicarb and so here we have a bicarb of 23 and so again if you remember or referencing down below our normal bicarb is 22 to 26 well once again this value falls within that range and therefore it's a normal value and this brings us to a point which is something that we hadn't talked about yet but if you reach step three and you have a normal pH a normal co2 and a normal bicarb well guess what you've got a normal ABG alright so let's go ahead and move on to another example here so here we're gonna have a pH of seven point two seven a pao2 of 80 a paco2 of 53 a bicarb of twenty-four and an oxygen saturation of 94% so again for the purpose of this interpretation we're gonna we're going to go ahead and ignore our pao2 and our oxygen set and so to start with step one we're going to look at our pH and determine is this acidosis or alkalosis here we have a pH of seven point two seven again we know our normal value is 7.35 to 7.45 and so this time our value is actually lower than the normal values therefore meaning that this is a more acidic environment therefore we have a state of acidosis so now on to step two we're going to assess our co2 here we have a co2 of 53 and again we know our normal value is 35 to 45 so at this point we see that our co2 is higher than the normal range perhaps that might mean something now moving on to step three we're going to assess our bicarb and in this case we have a bicarb of 24 again we know our normal bicarb is 22 to 26 therefore this bicarb is actually normal so now at this point we don't have a normal ABG and so we're going to move on to step four which is determining is this a primarily respiratory or metabolic disturbance and so if you remember we want to look and find out which value is abnormal in the presence of an abnormal pH so now in this example I think it's pretty clear we do have an abnormal pH and the value that's abnormal is going to be our co2 and if you remember we said that co2 is a primarily respiratory disturbance and so based on that we can actually make a determination of what this ABG interpretation would be but again we also can use the acronym roam our ome respiratory opposite metabolic equal and here we can see that we have a decrease in our pee but an increase in our co2 going the opposite direction therefore this must be a respiratory problem and so putting all that together we then can determine that in this case our patient has a respiratory acidosis all right hopefully that made sense of what we did there as we went through those steps but we are going to go through some more examples to help solidify that for you so for this next example we're gonna have a pH of 7.5 102 of 95 a co2 of 29 a bicarb of 22 and an oxygen saturation of 97% once again we're going to go ahead and disregard our pao2 and our oxygen saturation and so again back to step 1 we're gonna look at our pH of seven point five one we know our normal value is 7.35 to 7.45 therefore in this case our pH is high meaning we have in alkalosis for step two we're going to assess our co2 and here we have a co2 of 29 again knowing our normal co2 is 35 to 45 we can then determine that this co2 value is actually low and finally for step three we're gonna look at our bicarb see that our bicarb is 22 again our normal is 22 to 26 therefore in this example while we're close to being out of range our bicarb is actually still normal and so now at this point we don't have a normal ABG so we're gonna go on to step 4 and determine is this respiratory or metabolic so now again here in this example we have an abnormal pH and the value that's abnormal here is again our co2 and so we should know that this is going to be a respiratory problem but again if we think Rohm respiratory opposite metabolic equal here we have a high pH and a low co2 going in the opposite direction so again we can conclude that this is a respiratory problem and therefore we can come to the conclusion that this patient has a respiratory alkalosis all right so we're going to do a couple more examples here real quick hopefully at this point you guys are starting to get these and so we're gonna roll through these a little bit quicker just to make sure that we do have that understanding all right the next example we're gonna have a pH of 7.30 a pao2 of 87 a paco2 of 37 a bicarb of 20 and the oxygen saturation and 95% once again we'll go ahead and disregard these here and so for step 1 we're gonna look at our pH and we can see this value of 7.3 is actually going to be lower than our normal value therefore we have an acidosis next we're going to assess our co2 which is 37 which is actually within our normal range of 35 to 45 and then for step 3 we're going to assess our bicarb and here we know that the value of 20 is actually low when compared to our normal of 22 to 26 so again we don't have a normal ABG so we want to determine is this respiratory or metabolic and so in this example we have an abnormal bicarb with an abnormal pH but here you can see that our pH is low and our bicarb is low and since we know that it's the bicarb that's the abnormal value here we can tell that this is a metabolic disturbance but once again if we utilize the acronym roam here we can see these values are moving equal or within the same direction and therefore we can tell that this is a metabolic problem and thus this patient has a metabolic acidosis alright one last example for you guys here for this example we're gonna have a pH of seven point four nine a pao2 of a hundred a paco2 of forty two a bicarb of twenty nine and an oxygen saturation of a hundred percent and once again let's go and disregard these values here and so first let's look at our pH seven point four nine we know that this value is high meaning we have an alkalosis step two we're gonna assess our co2 here this value of 42 is actually going to be normal and then for step three we're going to assess our bicarb here our bicarb is 29 and therefore we know that this is high so once again we don't have a normal ABG and our abnormal value in this case is the bicarb again again telling us that this must be a metabolic disturbance and just to verify using roam we have a high pH in the presence of a high bicarb therefore they're moving equal or in the same direction therefore again we can confirm this as a metabolic disturbance meaning that our patient has a metabolic alkalosis alright well hopefully you guys were able to follow along with that and you could kind of see what was happening and the thought process that goes into evaluating those basic ABG's but really that's only the first step in what we want to do and so in our next lesson we're gonna take a look at the compensation mechanisms how those work in the body as well as how we analyze these ABG's to determine what kind of compensation or lack thereof is going on inside our patients body 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 do invite you to subscribe to our Channel which you can do down below make sure and turn on all notifications as well as if you found this useful do share the video as well so other people can find it helpful too as well as make sure and check out the next lesson in this series which is going to be part four in which we talk about compensation and what's going on and how we analyze that as well as feel free to check out another one of our great series of lessons that we have on shop and as always you guys have a great day and we'll see in the next lesson