Understanding Arterial Blood Gas Interpretation

What is going on guys? Don checking in. Welcome to Mint, where we bring nursing to you. So today we are going to talk about the easiest way to interpret your arterial blood gases. So if you're ready, we're ready. Let's go. Hello, this is the three-step ABG interpretation. But before we dive in into the actual steps, let us talk about basic concepts that you need to know for this lecture. Starting with... What is ABG? ABG stands for arterial blood gases. Arterial blood gases are simply the measurements of the acidity or alkalinity of the arterial circulation. It also measures gases such as oxygen and carbon dioxide. Now we are going to talk about four important components that are in your ABG and those are your pH, your CO2 or carbon dioxide, your HCO3 or bicarbonate, your PaO2 or oxygen. And we're going to talk about them one by one, starting with your pH. The pH is pretty much the measurement of how acidic or alkalotic the blood is. Your normal value for your pH is 7.35 to 7.45. And we're going to talk about the significance of these numbers later on. Next component would be your PaCO2. Your PaCO2 is pretty much the measurement of carbon dioxide. And our normal value for this is 35 to 45. Now it is easy to remember 35 to 45 because if you look at our pH, your pH is 7.35 to 7.45. So just remember 35 to 45 for carbon dioxide. Another concept that I need you guys to remember about PaCO2 or carbon dioxide is that it is being controlled by your lungs. Of course, we breathe out carbon dioxide. Another thing that I want you to relate with carbon dioxide would be acid. Now I'm not saying that Carbon dioxide is an acid. What we're trying to get here is that the amount of carbon dioxide is directly proportional to the number of hydrogen ions being produced, which is related to acid. We're not going to discuss biochemistry here, but all I'm saying is that the more carbon dioxide you have in your blood, the more acidic your blood is. If you look at your normal value here, 35 to 45, if your number is above 45, which indicates that there is more carbon dioxide in your blood, then your blood tends to be on the acidic side. On the other hand, if your value is less than 35, your blood tends to be on the basic side. Next up is your HCO3. Your HCO3 is your bicarbonate. Your normal value for your bicarbonate is 22 to 26. The bicarbonate is being controlled by your kidneys. And just to maintain the pH within the normal range, your lungs and your kidneys tend to work hand in hand to maintain a pH of 7.35 to 7.45. And we will talk about that later on today when we talk about compensation. Earlier, I mentioned that when you see carbon dioxide, relate that with acid. If you see bicarbonate, think about base. The more bicarbonate you have in your blood, the more basic your blood is. If your bicarbonate is more than 26, your blood tends to be on the basic side. On the other hand, if it's less than 22 that means you don't have enough bicarbonate in your blood. Your blood tends to be on the acidic side. Lastly is your PaO2 or oxygen. This is also being regulated by our lungs and our normal value for this is 80 to 100. Now although this is important for us to check when reading our patient's ABG, we don't really need the number when it comes to interpreting whether your patient is having respiratory or metabolic Acidosis or alkalosis. This simply will tell us whether your patient is having hypoxemia or not. But, am I saying disregard PaO2 all completely? Of course not. Just for the sake of the lecture, when you need to interpret your ABG whether it's metabolic or respiratory, acidosis or alkalosis, you just need to look at your pH, your PaCO2, and your HCO3. Does your patient have hypoxemia? Look at the PaO2. Again, your pH refers to the acidity or alkalinity of your blood and the normal value is 7.35 to 7.45. Your PaCO2 is your carbon dioxide which the normal value is 35 to 45 and when you see carbon dioxide think about acid. HCO3 your bicarbonate your normal value is 22 to 26 and when you think about bicarbonate think about base. And lastly your PaO2 your oxygen it is 80 to 100. Unfortunately, there is no other way around this but just to memorize these numbers. But if you do memorize these numbers, trust me on this, interpreting ABGs will be a breeze for you guys. Now, let us talk about the actual three-step ABG interpretation and these are identify if it is acidosis or alkalosis by looking at your pH, identify if it is respiratory or metabolic by looking at your carbon dioxide and bicarbonate, and number three would be identify if it is compensated or uncompensated. First step is identifying whether it is acidosis or alkalosis. Again our normal value for our pH is 7.5. 35 to 7.45. If your pH is less than 7.35, you have acidosis. If it is greater than 7.45, you have alkalosis. Let's see some examples. For a pH of 7.25, it's less than 7.35, so you have acidosis. Another example, pH of 7.55 is greater than 7.45. So what do you have? you have alkalosis. Step number two would be identifying if it is respiratory or metabolic and we're going to do this by simply looking at your bicarbonate and carbon dioxide and compare that to your pH. Through this we will know whether you have respiratory or metabolic condition and the method that we are going to be using will be the concept method. Now the most common method being taught in nursing school is what we call the Rome method where they ask you to use arrows in interpreting your ABGs. However, we will not be using this here because the row method doesn't really work well for compensated ABG. So for now, we are just sticking with the concept method. So what is the concept method? We talked about this earlier already and that is carbon dioxide is being regulated by your lungs while the bicarbonate is being regulated by your kidneys. If your carbon dioxide level is abnormal, well this bicarbonate is normal, you have a respiratory condition. On the other hand, if your carbon dioxide is normal while this is abnormal, you have a metabolic condition. And just to throw it out there, remember that carbon dioxide is to acid while bicarbonate is to base. It is best if we use examples for this method. 7.25, PaCO2 of 50, and bicarbonate of 24. Looking at the pH, we can tell that this is acidosis. Our normal is 7.35 to 7.45. It's less than 35 so it is acidosis. Look at the PaCO2. It's elevated. Our normal value is 35 to 45. We have 50. Just by simply looking at that, this is abnormal and if you look at the bicarbonate, it is normal. Our normal value is 22 to 26. So this is normal. This is abnormal. What do we have? We have a respiratory condition. Therefore, we have Respiratory Acidosis. And just by simply looking at the PaCO2, 50 that means you went beyond 45. If you have more CO2 your blood is more acidic so respiratory acidosis makes sense here. And of course your bicarbonate it's normal. Another example pH of 7.56, PaCO2 of 28 and bicarbonate of 22. The pH what does this tell us? Is it acidosis or alkalosis? It's alkalosis. It's more than 45. Looking at the PaCO2, our normal is 35 to 45. It's less than 35 to 45. Look at our bicarbonate. Is this normal? 22 to 26. It's normal. So since your PaCO2 is abnormal, we have a respiratory condition. Therefore, it's respiratory alkalosis. And If you look at the PaCO2, we don't have enough acid in our blood. That means it's making our blood more basic. So respiratory alkalosis will make sense. And of course, our bicarbonate is normal. What about this? 7.25, PaCO2 of 37, and bicarbonate of 21. Looking at our pH, is this acidosis or alkalosis? It is acidosis. Looking at our PaCO2, our normal is 35 to 45. So this is normal. Looking at our bicarbonate, our normal is 22 to 26. Since our abnormal is the bicarbonate and the CO2 is normal, do we have a metabolic or a respiratory? We have a metabolic condition. And since this is acidosis, we have metabolic acidosis. Think about this for a second. Our normal is 22 to 26. We don't have enough base in our blood. That means our blood is more on the acidic side. So metabolic acidosis does make sense. Another example 7.56 we have 44 carbon dioxide and bicarbonate of 35. Looking at the pH we have alkalosis. Our PaCO2 it's normal our normal is 35 to 45. And our bicarbonate is 35. Since our abnormal is bicarbonate and the CO2 is normal, we have a metabolic condition and we relate that with our pH. We have a metabolic alkalosis and this makes sense because the more bicarbonate you have, the more basic your blood is. Now, you guys might be wondering, what if your PaCO2 is abnormal and your bicarbonate is abnormal? Or what if your pH is normal and both of them are abnormal? You have to remember that the examples that we just used just now, these are examples of uncompensated APGs. If your pH becomes normal and both of them are abnormal, we have compensation going on. We're going to talk about that in step number three, which is identifying whether it is compensated or uncompensated. My twin brother Ben will be explaining more about this. So Ben, take it away. Thank you Don. So we have learned steps one and step two of reading ABGs. Step number three is identifying whether there is a full compensation or partial compensation. So let's get right to it. After identifying whether it's acidosis or alkalosis and whether it's respiratory or metabolic, we immediately go to the compensatory component of the problem. When we have a respiratory problem, always remember that our metabolic will compensate. That is our bicarbonate. Whether it's acidosis or alkalosis, the body will try to compensate by either increasing or decreasing the amount of bicarbonate in our system. When we have respiratory acidosis, the body will try to compensate by increasing the amount of bicarbonate in our system. Remember, bicarbonate is a base. So one of its function is to neutralize the acid that's causing the problem. When we have respiratory alkalosis, it's going to do the opposite. The body will compensate by decreasing the amount of bicarbonate. For us to conclude that there's compensation, the increase or decrease has to go outside the normal range. So it has to be higher than 26 or has to be less than 22. If the bicarb is still within normal limits, then there is no compensation going on. Okay, moving forward. When we have a metabolic problem, always remember that our respiratory system will compensate. So that is our carbon dioxide. So again, depending whether it's acidosis or alkalosis, the body will try to compensate by either increasing or decreasing the amount of CO2 in our system. When we have metabolic acidosis, the body will compensate by increasing the amount of CO2. Remember, CO2 is associated with acid. So when the body detects that there's acidosis, obviously it's going to try to decrease the amount of CO2 in our system. When we have metabolic alkalosis, it's going to do the opposite. The body will try to compensate by increasing the amount of CO2 in our system. And just like in respiratory, for us to conclude that there is compensation going on, The decrease or increase has to be outside the normal range. So it has to be less than 35 or greater than 45. Otherwise, there's no compensation going on. So let's use some examples. pH is 7.30, CO2 is 50, bicarbonate is 49. So first step is to identify whether this is alkalosis or acidosis. Looking at the pH, that's lower than the normal range. So we know that this is acidosis. Next step is to identify whether it's a respiratory or a metabolic problem. So let's go to our CO2. Our CO2 is 50. That's a lot of CO2. And remember, CO2 is associated with acid. So we can conclude that increased amount of CO2 is the reason why we have an acidosis problem. So we can put here respiratory acidosis. Because we have a respiratory problem, our next step is to look at our bicarb. And it's 49. This simply means that the body detected that there is respiratory acidosis and it tries to compensate by increasing the amount of base in our system. So we know that there is compensation. Now question, is this a full compensation or a partial compensation? To answer that question, all we have to do is look at our pH. Looking at this, Our compensation was not enough to bring pH back to normal. So this is only a partial compensation. So remember, partial compensation equals abnormal pH because the compensation is not enough to bring the pH back to normal. So let's try another example here. pH is 7.50, CO2 is 51, bicarb is 41. So first step. acidosis versus alkalosis. 7.50 is above normal range so we can put here alkalosis. Now let's look at our carbon dioxide. Our CO2 is 51. So that's a lot of CO2. But looking at the problem, we have alkalosis. Let's look at our bicarbonate. Our value here is 41. That's a lot of base in our system. So we can conclude here that we have a metabolic alkalosis. Since we have a metabolic problem, next step would be looking at our respiratory system. Our CO2 is 51. This simply means that our body detected that there is metabolic alkalosis and it tries to compensate by increasing the amount of CO2 in the system. So we know that there is compensation. Now let's identify whether this is a full or a partial compensation. Was the compensation enough to bring the pH back to normal? No. So this is only partial. So what we have here is a metabolic alkalosis with a partial compensation. Now let's try this problem right here. Our pH is 7.35. 35, CO2 is 49, bicarb is 30. We have a normal pH. We have an elevated CO2 which could indicate acidosis but at the same time we have an elevated bicarbonate which could indicate alkalosis. How do we read this one? There are two steps to interpret this. First one is to know your patient's diagnosis. This would be one of the most accurate ways to read this. this ABG. Because imagine this, if your patient came in for a respiratory problem, COPD or respiratory failure, then we could interpret this ABG as a patient retaining a lot of carbon dioxide because of the respiratory problem. So for all we know, this could be a respiratory acidosis because your patient came in for a respiratory problem and the body is trying to compensate by increasing the amount of bicarbonate. So that's one. But if your patient came in for diarrhea or vomiting, which means we're losing acid. We could interpret this ABG as the patient having metabolic alkalosis and the body trying to compensate by increasing the amount of CO2 in the system. So knowing our patient's diagnosis could actually help us interpret this ABG. However, if you're not given the patient's diagnosis or condition and you're only given the pH, the CO2, and the bicarb, then I usually use what I call the acidic side slash alkalotic site. We know that our normal pH is 7.35 to 7.45. The idea is that the lower our pH is, the more acidic our body is. The more pH you have, the more alkalotic your body is, even though they're normal. To paint a better picture, the numbers 7.35 to 7.39 belong to the lower half of the normal range. So, in theory, even though we have a normal pH, the body is more acidic than alkalotic. So I'll just put here acidic side and note the letter N that means it's normal. The numbers 7.41 to 7.45 belong to the upper half of the normal range. So again in theory the body in these ranges is more alkalotic than acidic. So I'll put here normal alkalotic. Now take this concept in mind and let's go back to our problem. We have a pH of 7.35. Now this is normal. However, the body is more acidic in this range. So we can put here acidosis. Looking at our CO2, it's elevated. So we can conclude that the ones causing our acidosis is the elevation of our CO2. So we can put here respiratory acidosis. Since we have a respiratory problem, we can go look at our bicarbonate whether it's compensating or not. And by looking at the value, it's 30. The body is trying to compensate with the acidosis by increasing the amount of base in our system. So we know that there's compensation going on. Now the question is, is this a partial or a full compensation? Let's look back at our pH. It's normal. So that means that the body compensated enough to bring our pH back to normal. So this is a full compensation. In full compensation, it's going to result to a normal pH. Let's try another example here. The pH is 7.44, CO2 is 48, and bicarbonate is 35. pH of 7.44 is normal but technically the body is in the alkalotic side. So I'll just put here alkalosis, normal alkalosis. Now looking at the CO2 is 48. This could cause acidosis. However, we have an alkalosis problem here so this is not what's causing the problem. By looking at our bicarbonate, bicarbonate is 35. So that's a lot of bicarb. and we have an alkalosis problem here. So we know that this is what's causing the alkalosis. So let's put here metabolic alkalosis and by looking at our CO2 since we have a metabolic problem, we can conclude that the body is trying to compensate by increasing the amount of CO2. So we know that there's compensation. Let's put here compensation and to identify whether it's a full or a partial compensation, we're just going to go look at our pH which is 7.44. So this means that the body compensated enough to bring our pH back to normal. So this is a full compensation. Dance break? That is it for today guys. I hope you guys found this video helpful and if you haven't already, please hit the like and subscribe button. By doing this, our videos will go straight to you. If you like this video, feel free to share this video to your friends and classmates. Once again, Mint signing out.

Let's go. Hello, this is the three-step ABG interpretation. But before we dive in into the actual steps, let us talk about basic concepts that you need to know for this lecture. Starting with... What is ABG?

ABG stands for arterial blood gases. Arterial blood gases are simply the measurements of the acidity or alkalinity of the arterial circulation. It also measures gases such as oxygen and carbon dioxide.

Now we are going to talk about four important components that are in your ABG and those are your pH, your CO2 or carbon dioxide, your HCO3 or bicarbonate, your PaO2 or oxygen. And we're going to talk about them one by one, starting with your pH. The pH is pretty much the measurement of how acidic or alkalotic the blood is. Your normal value for your pH is 7.35 to 7.45.

And we're going to talk about the significance of these numbers later on. Next component would be your PaCO2. Your PaCO2 is pretty much the measurement of carbon dioxide.

And our normal value for this is 35 to 45. Now it is easy to remember 35 to 45 because if you look at our pH, your pH is 7.35 to 7.45. So just remember 35 to 45 for carbon dioxide. Another concept that I need you guys to remember about PaCO2 or carbon dioxide is that it is being controlled by your lungs.

Of course, we breathe out carbon dioxide. Another thing that I want you to relate with carbon dioxide would be acid. Now I'm not saying that Carbon dioxide is an acid. What we're trying to get here is that the amount of carbon dioxide is directly proportional to the number of hydrogen ions being produced, which is related to acid.

We're not going to discuss biochemistry here, but all I'm saying is that the more carbon dioxide you have in your blood, the more acidic your blood is. If you look at your normal value here, 35 to 45, if your number is above 45, which indicates that there is more carbon dioxide in your blood, then your blood tends to be on the acidic side. On the other hand, if your value is less than 35, your blood tends to be on the basic side. Next up is your HCO3.

Your HCO3 is your bicarbonate. Your normal value for your bicarbonate is 22 to 26. The bicarbonate is being controlled by your kidneys. And just to maintain the pH within the normal range, your lungs and your kidneys tend to work hand in hand to maintain a pH of 7.35 to 7.45.

And we will talk about that later on today when we talk about compensation. Earlier, I mentioned that when you see carbon dioxide, relate that with acid. If you see bicarbonate, think about base.

The more bicarbonate you have in your blood, the more basic your blood is. If your bicarbonate is more than 26, your blood tends to be on the basic side. On the other hand, if it's less than 22 that means you don't have enough bicarbonate in your blood.

Your blood tends to be on the acidic side. Lastly is your PaO2 or oxygen. This is also being regulated by our lungs and our normal value for this is 80 to 100. Now although this is important for us to check when reading our patient's ABG, we don't really need the number when it comes to interpreting whether your patient is having respiratory or metabolic Acidosis or alkalosis.

This simply will tell us whether your patient is having hypoxemia or not. But, am I saying disregard PaO2 all completely? Of course not. Just for the sake of the lecture, when you need to interpret your ABG whether it's metabolic or respiratory, acidosis or alkalosis, you just need to look at your pH, your PaCO2, and your HCO3.

Does your patient have hypoxemia? Look at the PaO2. Again, your pH refers to the acidity or alkalinity of your blood and the normal value is 7.35 to 7.45.

Your PaCO2 is your carbon dioxide which the normal value is 35 to 45 and when you see carbon dioxide think about acid. HCO3 your bicarbonate your normal value is 22 to 26 and when you think about bicarbonate think about base. And lastly your PaO2 your oxygen it is 80 to 100. Unfortunately, there is no other way around this but just to memorize these numbers. But if you do memorize these numbers, trust me on this, interpreting ABGs will be a breeze for you guys. Now, let us talk about the actual three-step ABG interpretation and these are identify if it is acidosis or alkalosis by looking at your pH, identify if it is respiratory or metabolic by looking at your carbon dioxide and bicarbonate, and number three would be identify if it is compensated or uncompensated.

First step is identifying whether it is acidosis or alkalosis. Again our normal value for our pH is 7.5. 35 to 7.45.

If your pH is less than 7.35, you have acidosis. If it is greater than 7.45, you have alkalosis. Let's see some examples.

For a pH of 7.25, it's less than 7.35, so you have acidosis. Another example, pH of 7.55 is greater than 7.45. So what do you have? you have alkalosis. Step number two would be identifying if it is respiratory or metabolic and we're going to do this by simply looking at your bicarbonate and carbon dioxide and compare that to your pH. Through this we will know whether you have respiratory or metabolic condition and the method that we are going to be using will be the concept method.

Now the most common method being taught in nursing school is what we call the Rome method where they ask you to use arrows in interpreting your ABGs. However, we will not be using this here because the row method doesn't really work well for compensated ABG. So for now, we are just sticking with the concept method. So what is the concept method? We talked about this earlier already and that is carbon dioxide is being regulated by your lungs while the bicarbonate is being regulated by your kidneys.

If your carbon dioxide level is abnormal, well this bicarbonate is normal, you have a respiratory condition. On the other hand, if your carbon dioxide is normal while this is abnormal, you have a metabolic condition. And just to throw it out there, remember that carbon dioxide is to acid while bicarbonate is to base. It is best if we use examples for this method.

7.25, PaCO2 of 50, and bicarbonate of 24. Looking at the pH, we can tell that this is acidosis. Our normal is 7.35 to 7.45. It's less than 35 so it is acidosis.

Look at the PaCO2. It's elevated. Our normal value is 35 to 45. We have 50. Just by simply looking at that, this is abnormal and if you look at the bicarbonate, it is normal. Our normal value is 22 to 26. So this is normal. This is abnormal.

What do we have? We have a respiratory condition. Therefore, we have Respiratory Acidosis.

And just by simply looking at the PaCO2, 50 that means you went beyond 45. If you have more CO2 your blood is more acidic so respiratory acidosis makes sense here. And of course your bicarbonate it's normal. Another example pH of 7.56, PaCO2 of 28 and bicarbonate of 22. The pH what does this tell us? Is it acidosis or alkalosis?

It's alkalosis. It's more than 45. Looking at the PaCO2, our normal is 35 to 45. It's less than 35 to 45. Look at our bicarbonate. Is this normal? 22 to 26. It's normal.

So since your PaCO2 is abnormal, we have a respiratory condition. Therefore, it's respiratory alkalosis. And If you look at the PaCO2, we don't have enough acid in our blood. That means it's making our blood more basic. So respiratory alkalosis will make sense.

And of course, our bicarbonate is normal. What about this? 7.25, PaCO2 of 37, and bicarbonate of 21. Looking at our pH, is this acidosis or alkalosis?

It is acidosis. Looking at our PaCO2, our normal is 35 to 45. So this is normal. Looking at our bicarbonate, our normal is 22 to 26. Since our abnormal is the bicarbonate and the CO2 is normal, do we have a metabolic or a respiratory?

We have a metabolic condition. And since this is acidosis, we have metabolic acidosis. Think about this for a second.

Our normal is 22 to 26. We don't have enough base in our blood. That means our blood is more on the acidic side. So metabolic acidosis does make sense. Another example 7.56 we have 44 carbon dioxide and bicarbonate of 35. Looking at the pH we have alkalosis.

Our PaCO2 it's normal our normal is 35 to 45. And our bicarbonate is 35. Since our abnormal is bicarbonate and the CO2 is normal, we have a metabolic condition and we relate that with our pH. We have a metabolic alkalosis and this makes sense because the more bicarbonate you have, the more basic your blood is. Now, you guys might be wondering, what if your PaCO2 is abnormal and your bicarbonate is abnormal? Or what if your pH is normal and both of them are abnormal?

You have to remember that the examples that we just used just now, these are examples of uncompensated APGs. If your pH becomes normal and both of them are abnormal, we have compensation going on. We're going to talk about that in step number three, which is identifying whether it is compensated or uncompensated. My twin brother Ben will be explaining more about this.

So Ben, take it away. Thank you Don. So we have learned steps one and step two of reading ABGs. Step number three is identifying whether there is a full compensation or partial compensation.

So let's get right to it. After identifying whether it's acidosis or alkalosis and whether it's respiratory or metabolic, we immediately go to the compensatory component of the problem. When we have a respiratory problem, always remember that our metabolic will compensate. That is our bicarbonate. Whether it's acidosis or alkalosis, the body will try to compensate by either increasing or decreasing the amount of bicarbonate in our system.

When we have respiratory acidosis, the body will try to compensate by increasing the amount of bicarbonate in our system. Remember, bicarbonate is a base. So one of its function is to neutralize the acid that's causing the problem.

When we have respiratory alkalosis, it's going to do the opposite. The body will compensate by decreasing the amount of bicarbonate. For us to conclude that there's compensation, the increase or decrease has to go outside the normal range.

So it has to be higher than 26 or has to be less than 22. If the bicarb is still within normal limits, then there is no compensation going on. Okay, moving forward. When we have a metabolic problem, always remember that our respiratory system will compensate.

So that is our carbon dioxide. So again, depending whether it's acidosis or alkalosis, the body will try to compensate by either increasing or decreasing the amount of CO2 in our system. When we have metabolic acidosis, the body will compensate by increasing the amount of CO2. Remember, CO2 is associated with acid.

So when the body detects that there's acidosis, obviously it's going to try to decrease the amount of CO2 in our system. When we have metabolic alkalosis, it's going to do the opposite. The body will try to compensate by increasing the amount of CO2 in our system. And just like in respiratory, for us to conclude that there is compensation going on, The decrease or increase has to be outside the normal range.

So it has to be less than 35 or greater than 45. Otherwise, there's no compensation going on. So let's use some examples. pH is 7.30, CO2 is 50, bicarbonate is 49. So first step is to identify whether this is alkalosis or acidosis.

Looking at the pH, that's lower than the normal range. So we know that this is acidosis. Next step is to identify whether it's a respiratory or a metabolic problem.

So let's go to our CO2. Our CO2 is 50. That's a lot of CO2. And remember, CO2 is associated with acid.

So we can conclude that increased amount of CO2 is the reason why we have an acidosis problem. So we can put here respiratory acidosis. Because we have a respiratory problem, our next step is to look at our bicarb.

And it's 49. This simply means that the body detected that there is respiratory acidosis and it tries to compensate by increasing the amount of base in our system. So we know that there is compensation. Now question, is this a full compensation or a partial compensation? To answer that question, all we have to do is look at our pH. Looking at this, Our compensation was not enough to bring pH back to normal. So this is only a partial compensation.

So remember, partial compensation equals abnormal pH because the compensation is not enough to bring the pH back to normal. So let's try another example here. pH is 7.50, CO2 is 51, bicarb is 41. So first step.

acidosis versus alkalosis. 7.50 is above normal range so we can put here alkalosis. Now let's look at our carbon dioxide.

Our CO2 is 51. So that's a lot of CO2. But looking at the problem, we have alkalosis. Let's look at our bicarbonate. Our value here is 41. That's a lot of base in our system.

So we can conclude here that we have a metabolic alkalosis. Since we have a metabolic problem, next step would be looking at our respiratory system. Our CO2 is 51. This simply means that our body detected that there is metabolic alkalosis and it tries to compensate by increasing the amount of CO2 in the system.

So we know that there is compensation. Now let's identify whether this is a full or a partial compensation. Was the compensation enough to bring the pH back to normal?

No. So this is only partial. So what we have here is a metabolic alkalosis with a partial compensation. Now let's try this problem right here.

Our pH is 7.35. 35, CO2 is 49, bicarb is 30. We have a normal pH. We have an elevated CO2 which could indicate acidosis but at the same time we have an elevated bicarbonate which could indicate alkalosis. How do we read this one?

There are two steps to interpret this. First one is to know your patient's diagnosis. This would be one of the most accurate ways to read this.

this ABG. Because imagine this, if your patient came in for a respiratory problem, COPD or respiratory failure, then we could interpret this ABG as a patient retaining a lot of carbon dioxide because of the respiratory problem. So for all we know, this could be a respiratory acidosis because your patient came in for a respiratory problem and the body is trying to compensate by increasing the amount of bicarbonate. So that's one.

But if your patient came in for diarrhea or vomiting, which means we're losing acid. We could interpret this ABG as the patient having metabolic alkalosis and the body trying to compensate by increasing the amount of CO2 in the system. So knowing our patient's diagnosis could actually help us interpret this ABG.

However, if you're not given the patient's diagnosis or condition and you're only given the pH, the CO2, and the bicarb, then I usually use what I call the acidic side slash alkalotic site. We know that our normal pH is 7.35 to 7.45. The idea is that the lower our pH is, the more acidic our body is. The more pH you have, the more alkalotic your body is, even though they're normal. To paint a better picture, the numbers 7.35 to 7.39 belong to the lower half of the normal range.

So, in theory, even though we have a normal pH, the body is more acidic than alkalotic. So I'll just put here acidic side and note the letter N that means it's normal. The numbers 7.41 to 7.45 belong to the upper half of the normal range. So again in theory the body in these ranges is more alkalotic than acidic. So I'll put here normal alkalotic.

Now take this concept in mind and let's go back to our problem. We have a pH of 7.35. Now this is normal.

However, the body is more acidic in this range. So we can put here acidosis. Looking at our CO2, it's elevated. So we can conclude that the ones causing our acidosis is the elevation of our CO2.

So we can put here respiratory acidosis. Since we have a respiratory problem, we can go look at our bicarbonate whether it's compensating or not. And by looking at the value, it's 30. The body is trying to compensate with the acidosis by increasing the amount of base in our system.

So we know that there's compensation going on. Now the question is, is this a partial or a full compensation? Let's look back at our pH. It's normal. So that means that the body compensated enough to bring our pH back to normal.

So this is a full compensation. In full compensation, it's going to result to a normal pH. Let's try another example here. The pH is 7.44, CO2 is 48, and bicarbonate is 35. pH of 7.44 is normal but technically the body is in the alkalotic side.

So I'll just put here alkalosis, normal alkalosis. Now looking at the CO2 is 48. This could cause acidosis. However, we have an alkalosis problem here so this is not what's causing the problem. By looking at our bicarbonate, bicarbonate is 35. So that's a lot of bicarb. and we have an alkalosis problem here.

So we know that this is what's causing the alkalosis. So let's put here metabolic alkalosis and by looking at our CO2 since we have a metabolic problem, we can conclude that the body is trying to compensate by increasing the amount of CO2. So we know that there's compensation.

Let's put here compensation and to identify whether it's a full or a partial compensation, we're just going to go look at our pH which is 7.44. So this means that the body compensated enough to bring our pH back to normal. So this is a full compensation. Dance break? That is it for today guys.

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Transcript for:Understanding Arterial Blood Gas Interpretation

Transcript for:
Understanding Arterial Blood Gas Interpretation