Understanding Arterial Blood Gas Analysis

There are different methods you can use to solve arterial blood gas problems and in this video I'm going to show you the tic-tac-toe and the ROAM method to do that. First let me demonstrate the ROAM method. So what are we looking for whenever we're solving these ABG problems? Well, we're looking for a potential acid-base imbalance. And for exams, they're going to give you three things, and you're going to have to look at the value of those things and determine what is going on with the patient. So they're going to give you the blood pH level, along with the carbon dioxide level, which is represented as CO2, and the bicarb level, which is represented as HCO3. And you want to remember that CO2... Carbidoxide represents the respiratory system and bicarb HCO3 represents the metabolic system. And what's really cool about our body is when this blood pH decreases too much where we have acidosis or it increases too much where we have alkalosis, these two systems, the respiratory metabolic system, will try to balance that blood pH to get it back to normal. So whenever you are solving these arterial blood gas problems, there are three things that you want to ask yourself along with applying the method that you are using to help you solve these problems. So the first question you want to ask yourself, is this a... respiratory or metabolic problem. Second, you want to ask yourself, do we have acidosis or do we have alkalosis? And then third, you want to ask yourself, do we have compensation? You're either going to have no compensation where it would be be uncompensated, or you're going to have partial compensation, or you're going to have full compensation. I'm going to show you how to solve those problems with all three different scenarios. Before you even try to solve an arterial blood gas problem, you have to have this table committed to memory because you're going to pull from your memory bank these values and apply it to whatever method you're using to solve that ABG problem. Let's quickly go over this table. A normal blood pH is 7.35 to 7.45. Anything less than 7.35 is considered acidotic. Anything greater than 7.45 is considered alkalotic. Then carbon dioxide, CO2, a normal level is 35 to 45. Anything greater than 45 is acidotic and anything less than 35 is alkalotic. Then we have HCO3, a normal level. A bicarb. is 22 to 26 and anything less than 22 is acidotic and anything greater than 26 is alkalotic. Now let's look at the acronym ROAM. R stands for respiratory, O for opposite, M for metabolic, and E for equal. And I like to keep the R and the O together and the M and the E together to help me keep my information separated. So what in the world does respiratory opposite mean? Well what value represented respiratory? So, whenever your carbon dioxide level is high and your blood pH is low, hence they're opposite, it's respiratory acidosis. When your CO2 level is low but your blood pH is high, again they're opposite, it's respiratory alkalosis. What does metabolic and equal mean? Malk was represented with bicarb. So, whenever your HCO3 is low and your blood pH is low, hence they're equal because they're both low, it's metabolic acidosis. When your bicarb is high and your blood pH is high, they're equal because they're both high, it's metabolic alkalosis. So now let's take this method and work some problems. So our problem tells us that we have a blood pH of 7.28, a carbon dioxide level of 50, and a bicarb level of 24. And I went ahead and set up a problem and I wrote out ROME, R-O-M-E, remember that's respiratory opposite, metabolic equal, and then I have our blood pH over there. So our blood pH, a normal level, is 7.35 to 7.45. We're at 7.28. So we're on the low side and it's abnormal and it's considered acidotic. So I'm going to put a down arrow over here, blood pH, and just write acid to let myself remember. Then we're going to look at the respiratory system, which is represented with CO2 or carbon oxide level, and it's 50. A normal carbon oxide level is about 35 to 45, and we're on the high side of this. So we're going to put elevated, and anything greater than 45 is considered acidotic. So we're going to write acid over there. And we're going to look at our bicarb level, and that's represented. And with the M of our acronym, metabolic, and it's 24. A normal level is 22 to 26. So we're actually normal with our metabolic level. Now, let's apply Rome. we have opposite going on. Our respiratory system's high, pH is low. So, according to Rome, we have respiratory acidosis. So, I'm gonna write that out, respiratory acidosis. We've answered our first two questions. We figured out that we have a respiratory problem and we figured out that we have acidosis going on. The third thing we need to figure out is do we have compensation? This is where you have to look further at your problem. Depending on whatever method you're using, you have to dive a little bit deeper with it. First, we'll ask ourselves, do we have compensation going on at all? Whenever you have compensation going on, you're going to have to look at your respiratory on full compensation, that means the body has fully compensated, it's corrected itself, our blood pH should be normal. It is not normal. So whenever you're solving these problems and you see a normal blood pH level, you should be thinking full compensation. But we don't have that so we can rule that out. Now do we have partial compensation going on maybe or are we completely uncompensated for? So partial compensation would be another system that is trying to balance it out. For instance, we have a respiratory problem. We've determined that. Well, if we had partial compensation, our metabolic system should be abnormal because it should be trying to throw itself into like an alkalotic state so we can bring this, actually increase this blood pH back. Because remember, they're trying to balance each other out like how I talked about at the beginning. We don't even have that. Our metabolic system is still normal. It's just hanging out. It's like, hey, what's going on? Nothing's really going on, so I'm not going to be doing anything. It doesn't really know to compensate yet. So we have no compensation going on. So this is respiratory acidosis uncompensated. Our next problem says that our blood pH is 7.30, our carbon dioxide level is 40, and our bicarb level is 18. So let's analyze. Blood pH, normal, again, what was it? at 7.35 to 7.45. We're at 7.30. So we're on the low side, specifically acid side. Our respiratory system, which is represented with carbon dioxide, so we're going to put it up here, is 40. Normal level is 35 to 45. So we're actually normal here. And our bicarb is 18. Again, a normal is 22 to 26. So we're on the low side for our bicarb, and that was represented in the metabolic system. So we're low for that. And we're on the acidotic side. So with using Rome, we see we have an equal. Metabolic is low. pH is low. So we have metabolic acidosis. We've answered our first two questions. Now the third question. Do we have any compensation going on? Is our blood pH normal? No. We're not fully compensated, but are we partially compensated? Our system that should be helping balance this out, because we already have a metabolic problem, should be a respiratory system. A respiratory system right now is normal. It's not trying to make itself abnormal to help balance this acidotic blood pH out. So we don't. have any compensation going on. So we have metabolic acidosis uncompensated. Our next problem says that our blood pH is 7.42, our CO2 or carbon dioxide levels 26, and our bicarb is 18. So let's look at our blood pH. Normal level 7.35 to 7.45. We're at 7.42 so we're normal. So right now if you're thinking about compensation you should be thinking about thinking, ah, I bet we have full compensation. I bet you're right. But we've got to determine, is this a respiratory problem or metabolic problem? So whenever we're looking at this blood pH, we're normal, but what side of normal are we on? Are we on the acid oxide normal or the alkalotic side of normal? And to help you do that, remember that the absolute normal blood pH is 7.40. So anything greater than that would be on the alkalotic side of normal and anything less than would be on the acidotic side. So we're at 7.42, so we're on the alkalotic side. We're just going to put it's elevated and just put alkalotic to help us remember that. Now let's look at respiratory. That's represented in carbon dioxide and we are at 26. Normal level is 35 to 45 so we are on the low side so we're going to put low and it's alkalotic so And then our metabolic is 18 normal is by carb is 22 to 26 So we are on the low side. So we're gonna put low and We are on acidotic side because it's less than 22 so using the Rome method we look at our blood pH which is elevated we're looking at a respiratory metabolic system we have opposites going on on because metabolic isn't low and the pH isn't low so they're not equal. So we definitely have a respiratory problem going on. Specifically, we have respiratory alkalosis and we already know our third answer to our third question. We have full compensation going on because our blood pH is normal. Our body has thrown the metabolic system out of normal levels to help balance that blood pH and help get it back to normal. So we have respiratory alkalosis fully compensated. The next problem says our blood pH is 7.37, our carbon dioxide level is 32, and our bicarb is 17. So let's look at our blood pH. Normal level is 7.35 to 7.45. We're at 7.37, so we're normal. And again, if you're thinking about compensation, that third question, oh, we have full compensation going on. But we've got to figure out the other two questions. Is this metabolic or respiratory? Is this alkalosis or acidosis? So with our blood pH, it's normal. But what side of normal is it on? Absolute normal is 7.40, so it's 7.37, so it's lower than that. So we're on the acidotic side of normal. normal so we are low and we're just going to put acid to help us remember okay respiratory normal carbon dioxide is 35 to 45 we're at 32 so we are low and we're on the alkalotic side so we're going to put alkalotic here our bicarb is 17 normal is 22 to 26. we are low so we are going to put low on the metabolic part of our acronym and what side of low are we on we're on the acidotic side so we're just gonna write acid here now using the row method when we look at our pH which is on the low side and we look at our metabolic it's also low so they're equal so this is where we're at we have metabolic acidosis and we are fully compensated. Our blood pH is back to normal, but our respiratory system, because remember these two systems balance each other out, also went abnormal on the alkalotic side to help balance those acidotic conditions we were having, so we are now fully compensated. Our next problem says that the blood pH is 7.51, carbon dioxide is 47, and our bicarb is 32. So let's analyze the blood pH. pH. Normal blood pH is 7.35 to 7.45. So we are elevated because we're at 7.51. So it's increased and it's alkalotic. Okay. Our respiratory system, which is represented with carbon dioxide is 47. Normal carbon dioxide level is about 35 to 45. So we are on the high end. So we are elevated and it's acidotic. Our bicarb which represents the metabolic is at 32. Normal bicarb is 22-26. We are elevated and we are elevated on the side of alkalosis. Okay and using the ROME method we see that we have something that's equal. We have metabolics elevated, pH is elevated. According to our ROME method that would make it metabolic alkalosis. So we're going to write that. Now we have To answer that third question, do we have compensation? And if so, are we uncompensated or are we partially compensated or fully? Well, let's look at the blood pH. It is abnormal, so we know we don't have full compensation. So we can write that off. Now do we have partial compensated cessation or are we uncompensated? Well let's look. pH is abnormal but we have a metabolic problem so is a respiratory system trying to help out? Did it go abnormal to try to correct our blood pH? And it did, but it hasn't achieved the results that we need yet because our blood pH isn't normal yet. So it's trying to compensate. So we have partial compensation. Now it would be uncompensated if this respiratory system, its value, the carbon dioxide is still normal. normal because it's not really trying to compensate to help us correct this metabolic alkalosis. Now let me demonstrate the tic-tac-toe method. Okay, the first problem I want to go over is something where we don't have any compensation going on and then we're going to add on partial compensation, full compensation, and you can see how these values are changing and how we're getting our answers using the tic-tac-toe method and looking at those normal values that we've committed to memory. So our problem is our pH is 7.22. Our PaCO2 is 49 and our bicarb is 24. So we have our tic-tac-toe set up and we have acid over here, normal over here, and alkalotic here. If you're not familiar with that, how to do the tic-tac-toe method, I'm going to show you. Okay, so we're going to look at each of these values and we're going to put them in the column that they go. And we're looking for a tic-tac-toe. And again, as I said at the beginning of the lecture, if we have some type of, especially full compensation going on, we're not going to get a tic-tac-toe. because our pH will be normal. Okay so pH is 7.22. What's the normal value? 7.35 to 7.45. So it's less than 7.35. So we know it's acidotic. So we're going to put our pH here. Our PaCO2, which represents the respiratory system, is 49. Normal PaCO2 is 35 to 45. Since it's 49, it's greater than 45. It's on the acidotic side. So we're going to put it over here. Oh, we have a tic-tac-toe right here, but we're not done yet. Let's mess with our bicarb. Our bicarb is 24. What's a normal bicarb? 22 to 26. This is normal. It's falling within normal range. So we'll put that here. Well looking at this we know that we have acidosis going on and we have respiratory acidosis because PaCO2 represents respiratory. So we have respiratory acidosis. Now do we have compensation going on? That's the next thing you ask yourself and the answer is no. And how do I know that we don't have compensation going on? Well Well, our blood pH is abnormal still. It hasn't been corrected. It's not falling within its normal range. And the system that helps balance everything out, either the respiratory or the metabolic system, it's still normal. Our bicarb isn't trying to throw itself in an abnormal range to help combat this acidotic. So it could, if it was going to compensate, it would start increasing itself to make things a little bit more... alkalotic but it's not doing that so this is uncompensated so we have respiratory acidosis uncompensated now let's look at that same problem again but let's change the value let's change our bicarb instead of being 24 let's make it 28 so we know that we still have respiratory acidosis going on because our blood pH is low and our paco2 is high putting it on the acidotic side side. However, our bicarb now is not normal. It's 28. So it is greater than 26. So it's on the alkalotic side. So we'll put it over here. Now, next thing we want to ask ourselves, do we have compensation going on? Yes, we do. Now, is it full compensation or partial compensation? It is partial compensation. How do I know that? Well, it would be only full compensation if our blood pH was normal. Once that blood pH is normal, either the respiratory or metabolic system has helped balance that blood pH out and got it normal. However it's not normal here, it's still abnormal so it's partially compensated. We have the metabolic system trying to increase our bicarb to help balance out these acidotic conditions because by trying to make it more basic the blood will hopefully push that blood pH a little bit higher to make it normal. So we have respiratory acidosis that is partially compensated. Now let's look at our next problem. Okay, our blood pH is 7.42, our PaCO2 is 32, and our bicarb is 18. So what we're going to do is we're going to plug it into our tic-tac-toe. So our blood pH, what's a normal blood pH? 7.35 to 7.45 and this falls within normal range so our ph is normal now right now you should be thinking compensation full compensation because we have got our blood ph back to normal but let's look at those other values. Okay, pCO2 which represents the respiratory system is 32. Normal range is 35 to 45. It's on that low side so it's alkalotic. So we'll put it under here. And our bicarb is 18. Normal bicarb is 22 to 26. It's less than 22 so it's on the acidotic side. Now this is when you've set up your tic-tac-toe and you look and you're like, I don't have a tic-tac-toe. But we know that we have full compensation going on because our blood pH is back to normal. However, we have to determine is this respiratory or metabolic problem? And to help us do that, we have to further look at this blood pH. So even though our blood pH is within range at 7.42, what side of the spectrum is it falling on? Is it on that acidotic side or is it on the alkalotic side? And it falls on the alkalotic side. So what's happened is that our bicarb has decreased and it's trying to make things a little bit more acidic in that blood to bring that high alkalotic blood back down. So our bicarb is out of whack because it's been trying to do that and it's achieved it because we have full compensation. But it's still a little bit that blood pH on the alkalotic side and it's originated from a respiratory issue. So it's Respiratory alkalosis with full compensation. Now let's look at our next problem. Our blood pH is 7.37. Our PaCO2 is 33. And our bicarb is 17. So let's plug it in. Our pH falls within normal range. It falls within 7.35 to 7.45. So we'll put it here. And you should already be thinking, ooh, compensation. Our pH. is normal we probably have full compensation but let's look at our other values our PaCO2 is 33 normal is 35 to 45 it falls less than 35 so it's on the alkalotic side so put it here and again that represents the respiratory system and then our bicarb is 17 so it's less than 22 so it's on the acidotic side and bicarb again represented the metabolic part so we see that we have full compensation going on we don't have a tic-tac-toe so we had to look further at our blood pH and it's normal so we have full compensation but is this respiratory or metabolic so we have to look at blood pH closely a normal blood pH the absolute normal is 7.40 ours is 7.37 so it's on the acidotic side so we have metabolic acidosis going on that is fully compensated and how it got fully compensated is because that respiratory system tried to decrease the carbon dioxide and whenever it does that it's making things more alkalotic to help push that blood ph higher into that normal range and it did but it's still on the acidotic side but it finally got it to normal and it achieve what it was supposed to do. Now let's say that this was 7.27 instead. So that changes things a little bit here. Our blood pH is now 7.27. So it's not normal anymore. It's fell less than 7.35. So it's on the acidotic side. So let's move it over here. Now this has changed things a little bit. Do we have full compensation? going on anymore? Nope. We have partial compensation. And I want you to see that because we have our tic-tac-toe. So we have metabolic acidosis and we have partial compensation. The PaCO2 has taken itself out of normal range to make things more alkalotic, but it hasn't corrected it yet by making that blood pH become normal. So this would be metabolic acidosis partially compensated. Okay, so that wraps up this compilation on how to solve ABGs using these two methods. And if you'd like more practice, you can access the quiz in the YouTube description below.

Well, we're looking for a potential acid-base imbalance. And for exams, they're going to give you three things, and you're going to have to look at the value of those things and determine what is going on with the patient. So they're going to give you the blood pH level, along with the carbon dioxide level, which is represented as CO2, and the bicarb level, which is represented as HCO3. And you want to remember that CO2... Carbidoxide represents the respiratory system and bicarb HCO3 represents the metabolic system.

And what's really cool about our body is when this blood pH decreases too much where we have acidosis or it increases too much where we have alkalosis, these two systems, the respiratory metabolic system, will try to balance that blood pH to get it back to normal. So whenever you are solving these arterial blood gas problems, there are three things that you want to ask yourself along with applying the method that you are using to help you solve these problems. So the first question you want to ask yourself, is this a... respiratory or metabolic problem.

Second, you want to ask yourself, do we have acidosis or do we have alkalosis? And then third, you want to ask yourself, do we have compensation? You're either going to have no compensation where it would be be uncompensated, or you're going to have partial compensation, or you're going to have full compensation. I'm going to show you how to solve those problems with all three different scenarios.

Before you even try to solve an arterial blood gas problem, you have to have this table committed to memory because you're going to pull from your memory bank these values and apply it to whatever method you're using to solve that ABG problem. Let's quickly go over this table. A normal blood pH is 7.35 to 7.45. Anything less than 7.35 is considered acidotic.

Anything greater than 7.45 is considered alkalotic. Then carbon dioxide, CO2, a normal level is 35 to 45. Anything greater than 45 is acidotic and anything less than 35 is alkalotic. Then we have HCO3, a normal level. A bicarb.

is 22 to 26 and anything less than 22 is acidotic and anything greater than 26 is alkalotic. Now let's look at the acronym ROAM. R stands for respiratory, O for opposite, M for metabolic, and E for equal.

And I like to keep the R and the O together and the M and the E together to help me keep my information separated. So what in the world does respiratory opposite mean? Well what value represented respiratory? So, whenever your carbon dioxide level is high and your blood pH is low, hence they're opposite, it's respiratory acidosis. When your CO2 level is low but your blood pH is high, again they're opposite, it's respiratory alkalosis.

What does metabolic and equal mean? Malk was represented with bicarb. So, whenever your HCO3 is low and your blood pH is low, hence they're equal because they're both low, it's metabolic acidosis. When your bicarb is high and your blood pH is high, they're equal because they're both high, it's metabolic alkalosis. So now let's take this method and work some problems.

So our problem tells us that we have a blood pH of 7.28, a carbon dioxide level of 50, and a bicarb level of 24. And I went ahead and set up a problem and I wrote out ROME, R-O-M-E, remember that's respiratory opposite, metabolic equal, and then I have our blood pH over there. So our blood pH, a normal level, is 7.35 to 7.45. We're at 7.28.

So we're on the low side and it's abnormal and it's considered acidotic. So I'm going to put a down arrow over here, blood pH, and just write acid to let myself remember. Then we're going to look at the respiratory system, which is represented with CO2 or carbon oxide level, and it's 50. A normal carbon oxide level is about 35 to 45, and we're on the high side of this. So we're going to put elevated, and anything greater than 45 is considered acidotic.

So we're going to write acid over there. And we're going to look at our bicarb level, and that's represented. And with the M of our acronym, metabolic, and it's 24. A normal level is 22 to 26. So we're actually normal with our metabolic level.

Now, let's apply Rome. we have opposite going on. Our respiratory system's high, pH is low. So, according to Rome, we have respiratory acidosis.

So, I'm gonna write that out, respiratory acidosis. We've answered our first two questions. We figured out that we have a respiratory problem and we figured out that we have acidosis going on.

The third thing we need to figure out is do we have compensation? This is where you have to look further at your problem. Depending on whatever method you're using, you have to dive a little bit deeper with it.

First, we'll ask ourselves, do we have compensation going on at all? Whenever you have compensation going on, you're going to have to look at your respiratory on full compensation, that means the body has fully compensated, it's corrected itself, our blood pH should be normal. It is not normal. So whenever you're solving these problems and you see a normal blood pH level, you should be thinking full compensation.

But we don't have that so we can rule that out. Now do we have partial compensation going on maybe or are we completely uncompensated for? So partial compensation would be another system that is trying to balance it out.

For instance, we have a respiratory problem. We've determined that. Well, if we had partial compensation, our metabolic system should be abnormal because it should be trying to throw itself into like an alkalotic state so we can bring this, actually increase this blood pH back.

Because remember, they're trying to balance each other out like how I talked about at the beginning. We don't even have that. Our metabolic system is still normal.

It's just hanging out. It's like, hey, what's going on? Nothing's really going on, so I'm not going to be doing anything.

It doesn't really know to compensate yet. So we have no compensation going on. So this is respiratory acidosis uncompensated. Our next problem says that our blood pH is 7.30, our carbon dioxide level is 40, and our bicarb level is 18. So let's analyze. Blood pH, normal, again, what was it?

at 7.35 to 7.45. We're at 7.30. So we're on the low side, specifically acid side. Our respiratory system, which is represented with carbon dioxide, so we're going to put it up here, is 40. Normal level is 35 to 45. So we're actually normal here. And our bicarb is 18. Again, a normal is 22 to 26. So we're on the low side for our bicarb, and that was represented in the metabolic system.

So we're low for that. And we're on the acidotic side. So with using Rome, we see we have an equal. Metabolic is low. pH is low.

So we have metabolic acidosis. We've answered our first two questions. Now the third question.

Do we have any compensation going on? Is our blood pH normal? No. We're not fully compensated, but are we partially compensated?

Our system that should be helping balance this out, because we already have a metabolic problem, should be a respiratory system. A respiratory system right now is normal. It's not trying to make itself abnormal to help balance this acidotic blood pH out. So we don't. have any compensation going on.

So we have metabolic acidosis uncompensated. Our next problem says that our blood pH is 7.42, our CO2 or carbon dioxide levels 26, and our bicarb is 18. So let's look at our blood pH. Normal level 7.35 to 7.45. We're at 7.42 so we're normal. So right now if you're thinking about compensation you should be thinking about thinking, ah, I bet we have full compensation. I bet you're right.

But we've got to determine, is this a respiratory problem or metabolic problem? So whenever we're looking at this blood pH, we're normal, but what side of normal are we on? Are we on the acid oxide normal or the alkalotic side of normal?

And to help you do that, remember that the absolute normal blood pH is 7.40. So anything greater than that would be on the alkalotic side of normal and anything less than would be on the acidotic side. So we're at 7.42, so we're on the alkalotic side. We're just going to put it's elevated and just put alkalotic to help us remember that. Now let's look at respiratory.

That's represented in carbon dioxide and we are at 26. Normal level is 35 to 45 so we are on the low side so we're going to put low and it's alkalotic so And then our metabolic is 18 normal is by carb is 22 to 26 So we are on the low side. So we're gonna put low and We are on acidotic side because it's less than 22 so using the Rome method we look at our blood pH which is elevated we're looking at a respiratory metabolic system we have opposites going on on because metabolic isn't low and the pH isn't low so they're not equal. So we definitely have a respiratory problem going on. Specifically, we have respiratory alkalosis and we already know our third answer to our third question. We have full compensation going on because our blood pH is normal.

Our body has thrown the metabolic system out of normal levels to help balance that blood pH and help get it back to normal. So we have respiratory alkalosis fully compensated. The next problem says our blood pH is 7.37, our carbon dioxide level is 32, and our bicarb is 17. So let's look at our blood pH. Normal level is 7.35 to 7.45. We're at 7.37, so we're normal. And again, if you're thinking about compensation, that third question, oh, we have full compensation going on.

But we've got to figure out the other two questions. Is this metabolic or respiratory? Is this alkalosis or acidosis?

So with our blood pH, it's normal. But what side of normal is it on? Absolute normal is 7.40, so it's 7.37, so it's lower than that. So we're on the acidotic side of normal.

normal so we are low and we're just going to put acid to help us remember okay respiratory normal carbon dioxide is 35 to 45 we're at 32 so we are low and we're on the alkalotic side so we're going to put alkalotic here our bicarb is 17 normal is 22 to 26. we are low so we are going to put low on the metabolic part of our acronym and what side of low are we on we're on the acidotic side so we're just gonna write acid here now using the row method when we look at our pH which is on the low side and we look at our metabolic it's also low so they're equal so this is where we're at we have metabolic acidosis and we are fully compensated. Our blood pH is back to normal, but our respiratory system, because remember these two systems balance each other out, also went abnormal on the alkalotic side to help balance those acidotic conditions we were having, so we are now fully compensated. Our next problem says that the blood pH is 7.51, carbon dioxide is 47, and our bicarb is 32. So let's analyze the blood pH. pH. Normal blood pH is 7.35 to 7.45. So we are elevated because we're at 7.51. So it's increased and it's alkalotic.

Okay. Our respiratory system, which is represented with carbon dioxide is 47. Normal carbon dioxide level is about 35 to 45. So we are on the high end. So we are elevated and it's acidotic.

Our bicarb which represents the metabolic is at 32. Normal bicarb is 22-26. We are elevated and we are elevated on the side of alkalosis. Okay and using the ROME method we see that we have something that's equal.

We have metabolics elevated, pH is elevated. According to our ROME method that would make it metabolic alkalosis. So we're going to write that. Now we have To answer that third question, do we have compensation? And if so, are we uncompensated or are we partially compensated or fully?

Well, let's look at the blood pH. It is abnormal, so we know we don't have full compensation. So we can write that off. Now do we have partial compensated cessation or are we uncompensated?

Well let's look. pH is abnormal but we have a metabolic problem so is a respiratory system trying to help out? Did it go abnormal to try to correct our blood pH? And it did, but it hasn't achieved the results that we need yet because our blood pH isn't normal yet. So it's trying to compensate.

So we have partial compensation. Now it would be uncompensated if this respiratory system, its value, the carbon dioxide is still normal. normal because it's not really trying to compensate to help us correct this metabolic alkalosis. Now let me demonstrate the tic-tac-toe method. Okay, the first problem I want to go over is something where we don't have any compensation going on and then we're going to add on partial compensation, full compensation, and you can see how these values are changing and how we're getting our answers using the tic-tac-toe method and looking at those normal values that we've committed to memory.

So our problem is our pH is 7.22. Our PaCO2 is 49 and our bicarb is 24. So we have our tic-tac-toe set up and we have acid over here, normal over here, and alkalotic here. If you're not familiar with that, how to do the tic-tac-toe method, I'm going to show you.

Okay, so we're going to look at each of these values and we're going to put them in the column that they go. And we're looking for a tic-tac-toe. And again, as I said at the beginning of the lecture, if we have some type of, especially full compensation going on, we're not going to get a tic-tac-toe. because our pH will be normal. Okay so pH is 7.22.

What's the normal value? 7.35 to 7.45. So it's less than 7.35. So we know it's acidotic. So we're going to put our pH here.

Our PaCO2, which represents the respiratory system, is 49. Normal PaCO2 is 35 to 45. Since it's 49, it's greater than 45. It's on the acidotic side. So we're going to put it over here. Oh, we have a tic-tac-toe right here, but we're not done yet.

Let's mess with our bicarb. Our bicarb is 24. What's a normal bicarb? 22 to 26. This is normal. It's falling within normal range. So we'll put that here.

Well looking at this we know that we have acidosis going on and we have respiratory acidosis because PaCO2 represents respiratory. So we have respiratory acidosis. Now do we have compensation going on? That's the next thing you ask yourself and the answer is no. And how do I know that we don't have compensation going on?

Well Well, our blood pH is abnormal still. It hasn't been corrected. It's not falling within its normal range. And the system that helps balance everything out, either the respiratory or the metabolic system, it's still normal. Our bicarb isn't trying to throw itself in an abnormal range to help combat this acidotic.

So it could, if it was going to compensate, it would start increasing itself to make things a little bit more... alkalotic but it's not doing that so this is uncompensated so we have respiratory acidosis uncompensated now let's look at that same problem again but let's change the value let's change our bicarb instead of being 24 let's make it 28 so we know that we still have respiratory acidosis going on because our blood pH is low and our paco2 is high putting it on the acidotic side side. However, our bicarb now is not normal. It's 28. So it is greater than 26. So it's on the alkalotic side.

So we'll put it over here. Now, next thing we want to ask ourselves, do we have compensation going on? Yes, we do.

Now, is it full compensation or partial compensation? It is partial compensation. How do I know that? Well, it would be only full compensation if our blood pH was normal. Once that blood pH is normal, either the respiratory or metabolic system has helped balance that blood pH out and got it normal.

However it's not normal here, it's still abnormal so it's partially compensated. We have the metabolic system trying to increase our bicarb to help balance out these acidotic conditions because by trying to make it more basic the blood will hopefully push that blood pH a little bit higher to make it normal. So we have respiratory acidosis that is partially compensated.

Now let's look at our next problem. Okay, our blood pH is 7.42, our PaCO2 is 32, and our bicarb is 18. So what we're going to do is we're going to plug it into our tic-tac-toe. So our blood pH, what's a normal blood pH?

7.35 to 7.45 and this falls within normal range so our ph is normal now right now you should be thinking compensation full compensation because we have got our blood ph back to normal but let's look at those other values. Okay, pCO2 which represents the respiratory system is 32. Normal range is 35 to 45. It's on that low side so it's alkalotic. So we'll put it under here. And our bicarb is 18. Normal bicarb is 22 to 26. It's less than 22 so it's on the acidotic side. Now this is when you've set up your tic-tac-toe and you look and you're like, I don't have a tic-tac-toe.

But we know that we have full compensation going on because our blood pH is back to normal. However, we have to determine is this respiratory or metabolic problem? And to help us do that, we have to further look at this blood pH. So even though our blood pH is within range at 7.42, what side of the spectrum is it falling on? Is it on that acidotic side or is it on the alkalotic side?

And it falls on the alkalotic side. So what's happened is that our bicarb has decreased and it's trying to make things a little bit more acidic in that blood to bring that high alkalotic blood back down. So our bicarb is out of whack because it's been trying to do that and it's achieved it because we have full compensation. But it's still a little bit that blood pH on the alkalotic side and it's originated from a respiratory issue. So it's Respiratory alkalosis with full compensation.

Now let's look at our next problem. Our blood pH is 7.37. Our PaCO2 is 33. And our bicarb is 17. So let's plug it in. Our pH falls within normal range. It falls within 7.35 to 7.45.

So we'll put it here. And you should already be thinking, ooh, compensation. Our pH. is normal we probably have full compensation but let's look at our other values our PaCO2 is 33 normal is 35 to 45 it falls less than 35 so it's on the alkalotic side so put it here and again that represents the respiratory system and then our bicarb is 17 so it's less than 22 so it's on the acidotic side and bicarb again represented the metabolic part so we see that we have full compensation going on we don't have a tic-tac-toe so we had to look further at our blood pH and it's normal so we have full compensation but is this respiratory or metabolic so we have to look at blood pH closely a normal blood pH the absolute normal is 7.40 ours is 7.37 so it's on the acidotic side so we have metabolic acidosis going on that is fully compensated and how it got fully compensated is because that respiratory system tried to decrease the carbon dioxide and whenever it does that it's making things more alkalotic to help push that blood ph higher into that normal range and it did but it's still on the acidotic side but it finally got it to normal and it achieve what it was supposed to do. Now let's say that this was 7.27 instead. So that changes things a little bit here.

Our blood pH is now 7.27. So it's not normal anymore. It's fell less than 7.35.

So it's on the acidotic side. So let's move it over here. Now this has changed things a little bit. Do we have full compensation?

going on anymore? Nope. We have partial compensation.

And I want you to see that because we have our tic-tac-toe. So we have metabolic acidosis and we have partial compensation. The PaCO2 has taken itself out of normal range to make things more alkalotic, but it hasn't corrected it yet by making that blood pH become normal.

So this would be metabolic acidosis partially compensated. Okay, so that wraps up this compilation on how to solve ABGs using these two methods. And if you'd like more practice, you can access the quiz in the YouTube description below.

Transcript for:Understanding Arterial Blood Gas Analysis

Transcript for:
Understanding Arterial Blood Gas Analysis