Finally, the ABG explained in an easy to understand way! If you want to learn this lab test once and for all, check out this awesome video!
01:22 Introduction to the basics.
07:57 ABG Components and normal values
13:21 Interpretation of the numbers
14:51 Examples of acid-base disorders
18:44 Knowledge challenge questions!
Good luck in school!!
In this video about the arterial blood gas lab, the ABG, I'm gonna start with an introduction to the basic concepts about an ABG, and then, I will talk about the components individually and their normal values, followed by how to interpret the numbers or the interpretation of the ABG.
Then, I'll give you some examples and we'll finish off with some knowledge challenge questions.
All right, let's do it!
So, the first thing I want to point out, guys, is that an ABG is an Arterial Blood Gas test.
So, why is that important?
Basically because most of the time in the clinic or the urgent care or ER, your access point to the patient is an IV, an intravenous line, not an arterial line.
So, while you could pull blood from that IV and send it to the lab, the results that you got back would be a VBG, not an ABG, okay?
And it's for that reason that most often times, the ABG is used in critical care settings, like an ICU or somewhere like that where a team has come in and gotten arterial access, which is more difficult than venous access.
In less critical settings, like the clinic, the pulse oximetry is used more frequently, just because it's less invasive by far, it's faster, and definitely cheaper.
An ABG is important because it gives us an idea about what's dissolved in the blood and also, for acid-base homeostasis.
This is important because our bodies are extremely sensitive to swings in the pH.
One of the most important things that could happen is denaturing of proteins.
Now, that doesn't mean that they're gonna completely unfold.
It just means that they're not going to function like they should and you're just gonna feel miserable.
It's for this reason that our pH in our bodies is highly, highly regulated and that's done by two main systems, the respiratory system and the renal system, which I cover in this lecture.
If you want to learn a little bit more about buffering agents, check out one of the links in the YouTube cards.
The first thing that I want to talk about is the respiratory system and I think it's pretty easy to understand why the respiratory system has a big effect on the amounts of gasses dissolved in my blood and the reason is because hey, I mean, these are my lungs.
They deal with gases all day long, right?
But what about the pH?
Why do the lungs have an effect on the pH?
And the answer to that is found in carbon dioxide.
You see, carbon dioxide, when dissolved in the blood, is able to transform or shift to carbonic acid, which is the same thing that you see in a fizzy soda pop.
It's the fizz, it's the dissolved carbon dioxide, which turns into acid and then can re-express from the liquid in a gas form.
So, if I decrease the amount of carbon dioxide in my blood, then I decrease the amount of carbonic acid and you can taste that in a soda pop.
If a soda pop has been sitting out for a long time and has lost all its fizz, it tastes really too sweet and the reason is, is because it's not counterbalanced by that acidic taste, which kind of neutralizes the sweetness.
So, if I were to hyperventilate, (huffing in and out) for a minute or two, I would ventilate off or degas my blood of carbon dioxide and therefore, decrease the amount of carbonic acid and then therefore, increase the pH or make my blood more alkalotic.
The converse is also true.
If I stop breathing for a period of time, I can increase the acidity or decrease the pH of my blood and this is a pretty fast response.
If I were to hyperventilate for a few minutes, you would be able to notice a difference in the pH of my blood.
It happens pretty quickly.
Now, all of this applies to an ABG with the term, respiratory compensation and what that means is, let's say that I have a disease process in my body that's causing my blood to be too acidic.
Well, normal physiology, the respiratory compensation would be for me to breathe faster.
This happens automatically.
It's normal physiology.
I would breathe faster to degas or ventilate off carbon dioxide and that would decrease the amount of carbonic acid and bring my pH closer to normal, okay?
And again, that's a fast process.
This is normal physiology and it's called respiratory compensation and we'll talk a little bit more about it later on, okay?
Let's move on.
The second system that I want to talk about that's important for the ABG is the renal system.
The renal system can change the amount of dissolved substances in the blood by how much the nephrons retain or secrete those molecules of interest and in this case, for pH, we're interested in bicarbonate and hydrogen ions.