Hi, welcome to our video on interpreting arterial
blood gases or as we usually call them, ABGs.
I'm gonna show you how in just six easy steps,
you'll learn how to interpret these lab values,
and know what to do for your patient.
Okay, look at this guy, at least from
the looks of that foot I hope this is a guy
but we're talking about what's
the big deal about normal.
Look how comfortable this person looks around their
couch, at home they got their favorite blanket.
Well the big deal about normal is,
it's just like homeostasis in your body.
That means a state of balance,
your body is most comfortable there.
That's why I always say, "there's
no place like homeostasis".
Your enzymes work better, your cells work better
just everything functions the way it's supposed to be
when your body is in a state of homeostasis
Enter the couch.
We're gonna take that picture with the guy in the
couch, just kick back and relax and apply it to ABGs.
So I call this "the couch of homeostasis".
Think about it as where your body is
most comfortable and the most efficient.
So on the couch, we're gonna think
of that as a normal pH of 7.35 and 7.45
So in between 7.35 and
7.45, that's a normal pH.
Now that's the first value
I want you to write down.
So right down pH and
normal value is 7.35 to 7.45
Now we're using the couch to help you
see that that just represents the space
between 7.35 and 7.45 that's what the couch.
That's what the couch represents.
Now normal levels for CO2,
carbon dioxide are 35 to 45.
Woohoo, I was so excited when I first
figured that out because pH of 7.35 to 7.45,
it's super easy to remember the normal CO2
35 to 45 (mmHg).
Now let's look at the normal
bicarb: 22 to 26 (mmol/L)
So before we really get rolling, I want to make
sure that you've written down those three values:
the normal pH, the normal carbon
dioxide and the normal bicarb
Okay, ready? Let's go on..
Now we'ill start pretty slow in the beginning to
make sure you really have this concepts down well
then we'll pick up the pace toward the end.
Okay, so we're talking about the couch
of homeostasis right? We talked about pH.
T hat's the same pH you
did in junior high science labs.
Now, I threw up some numbers up there for
you because like the pH of Diet Coke is about 2.5
And for a lot of you, that's
what's running in your veins, right?
pH of blood is 7.35 to 7.45.
Now, we know we've got about 7.34
because I wanted to bring up the point
that different labs will have
different values but for us,
we're gonna to stick with
7.35 to 7.45 as being normal
Well, there I am sitting on the couch
right, right dead center in the middle.
7.35 to 7.45 is when you're
gonna be the most comfortable.
Now before we go on, I want you
to pause the video for just a minute,
and I want you to write down why do
we care about being in homeostasis.
Okay, so pause the video.
So welcome back.
Remember, the reason the body's
always wanting to get back to homeostasis
is because that's where
it's functions the best.
That's where our enzymes work, that's where our
cells work,that's what everything works the best
just like you feel the most comfortable
on your own couch back at home.
Okay, now you see me moved over
to the other side of the couch, right?
I'm moving toward the red side or the acidic
side that's going to represent less than 7.35
So when we're looking at
the pH, if it's less than 7.35,
remember that's because
you're becoming more acidic.
Okay, so I started out in the middle, that
was homeostasis in between 7.35 to 7.45
Now we're talking about bodies moving
at pH towards acidic, it's less than 7.35
Other end of the couch is greater than 7.45
So when the pH is greater than
7.45, I'm becoming more basic
So that's what the couch
is gonna represent for us,
it's just a way for you to kind of
conceptualize what pH looks like.
As my pH numbers get
bigger, I'm moving toward basic.
As my pH numbers get smaller, less than 7.35, I'm
moving toward acidic now as I'm moving toward acidic.
Now as I'm moving towards acidic, and I
get lower than 7.35, we call that acidosis.
If I'm getting more basic - greater
than 7.45, we call that alkalosis.
Okay, these words are
starting to sound familiar to you,
So we're gonna be talking about the things
that force the body towards acidosis or alkalosis.
That's what we're looking for.
What are the things that change my pH?
What causes my pH to go lower or
more acidic, or higher and more alkalotic?
So let's talk about carbon dioxide.
Now the normal carbon dioxide is 35 to
45, right? and that is controlled by the lungs.
Remember, you got your hemoglobin carrying
CO2 back up to the lungs so you can expel it
you can pick up more oxygen
and deliver it to the tissues.
So carbon dioxide is
controlled by the lungs.
Bicarbonate is controlled by the kidneys.
That's why we've shown you what bicarbonate looks like
as a molecule and we've attached it with the kidneys,
same thing with carbon
dioxide and the lungs.
So the first concept we want to make sure
you have down solid is, what's the normal pH?
Right, 7.35 to 7.45
Now we have carbon dioxide is 35 to 45.
In the lungs, control the
level of carbon dioxide.
Now if I'm hyperventilating, what do you
think happens to my carbon dioxide level?
Right, it'll go down because
I'm blowing off all the CO2.
Now what happens if I'm
not breathing very much?
Let's say I'm on drug overdose and I'm
breathing very shallow and not very often.
CO2 levels are gonna go up.
Now bicarb is controlled by the kidneys.
The lungs can respond really quickly just
by changing my rate and depth of breathing.
Kidneys will try to help but it takes a lot
longer for you to see a change in the bicarb.
So for now, be clear what
the normal pH is 7.35 to 7.45
You know the normal values for
carbon dioxide and bicarbonate.
And you should be very clear what
controls the CO2 levels - the lungs
and what controls the bicarbonate levels, we're gonna
say the kidneys but it's the whole metabolic system.
Okay, so we're looking at the level of bicarbonate,
you already know it's controlled by the kidneys.
The more bicarbonate I have,
the more alkalotic or basic I become.
So when you look at the couch, you see that we've
got the two pillows there representing 7.35 and 7.45,
The more bicarbonate that's in the
body that will shove my pH past 7.45,
so the more bicarb, the more
basic or alkalotic I become,
you tell that by the changes in the pH
Now we look at the lungs, remember we talked they
can kick in and make a difference a lot quicker.
but the carbon dioxide
is controlled by the lungs
so the more CO2 in the blood the
more acidic or basic I'm gonna be?
Acidic, good job.
So lungs control the carbon dioxide.
And the more carbon dioxide that I have building
up in the blood,the more acidic I will be.
So if we're looking at the couch,
which way are you gonna go?
this way or that way, right, are you
gonna go towards the acidic or the basic?
Well if CO2 in the blood, I want
you to think about it as an acid,
and the increase CO2 in the blood
will definitely move me toward acidosis.
so we've looked at a normal pH, a
normal CO2 level, a normal bicarb level.
And we've looked at if we have excess
bicarb, our pH will be more basic or alkalotic.
If we have more CO2, we'll be more acidotic.
Okay, now I told you we'll be going kind of
slow because you really have to get these concepts
and we will fly to the other ones compare
to this I promise but let's do a quick review.
In order to determine acidosis or alkalosis, we will
primarily look at which 3 values from an arterial blood gas?
Pause the video and see if you can
write those three down before we go on.
Hey, welcome back.
And now before we talk about the answers, I just
want to encourage you to really take advantage
of the times when we recommend
or ask you to pause the video
and see if you can recall those numbers.
I'm not trying to tell you what to do,
nobody likes to get bossed around.
But I know as an an educational psychologist,
it's the best way for you to study as you go.
We're gonna give you a better
shot at remembering these concepts
and making sure you're really
solid on them before we go forward.
So again, I'm not trying to be bossy
and I hope it doesn't feel that way to you
but I just want to help you study right in the
moment because I know you have precious little time
because you're so busy in nursing school.
So let's look at the answers.
pH, CO2 and bicarb - those are
the three things we're gonna look at
when we primarily look at the
values for an arterial blood gas.
Now which organ primarily
controls the bicarb level in the body?
HCO3- is just a shorthand
way to write bicarb.
So which organ primarily
controls bicarb in the body?
Right, the kidneys.
Which organ primarily controls
CO2 or carbon dioxide level in the body?