Now, let's talk about changes
in the cardiovascular system.
So, as we talk about the cardiovascular system,
think about what needs to happen,
we're supporting an entire other human being.
That's a lot of work. Keep that
in mind as we go through this.
So, first of all, the heart, that's
responsible for moving all the blood
and the oxygen through our body,
has to work extra hard.
So, as we have an increase
of blood volume and fluid,
the heart's actually working
harder and because it's a muscle,
what happens when we work out muscles?
Well, not to mine, but everybody
else's muscle gets bigger.
So, the heart gets bigger and
we experience cardiomegaly.
So, this would be important for a nurse,
maybe working in the emergency
room or working somewhere else
and we get a chest x-ray and you see the heart,
now, ordinarily you might go,
“Wow, that's a big heart,”
but now, because you've listened
to this lecture, you'll go,
“That's cardiomegaly and
that's normal for pregnancy.”
Next, we want to think about
the position of the heart.
So, what happens, is it actually moves,
so, the heart sort of leans over to the left
and so when that happens we
call that, “Dextroversion.”
Cardiac output is actually also going to increase,
remember cardiac output is the
amount of blood that comes out,
during a pump, right?
We need more blood flow, this is
going to increase by 30 to 50%.
Our circulating blood volume is
also going to increase by 45%.
We may experience a drop in
blood pressure mid pregnancy
and this comes under the
influence of progesterone.
Now, I want you to remember this.
Estrogen makes things fluffy and big,
we've already talked about that,
in terms of proliferation of the breast.
Progesterone is the chill factor,
it makes things relax,
so, it causes relaxation, in the vessels.
So, the blood pressure, is actually
going to go down mid pregnancy,
in response to that relaxation of the vessels.
So, let's summarize those cardiovascular changes,
because that was a lot.
These are the things to remember,
so, the PMI is going to move.
We talked about how the heart leans,
we're going to find the point of maximum impulse,
in a different space, it's
going to move up a little bit.
Next, we need to remember that the
blood pressure is going to change.
The progesterone causes relaxation of the vessels,
which is going to decrease the blood pressure,
it's not unusual to see someone
with a blood pressure of 100/60,
when they're 15/16/17 weeks that's normal.
We may experience an increased heart rate.
Now, I'm saying increased,
I don't mean tachycardia.
Tachycardia, is never normal, but the heart,
remember is trying to push all
that extra blood through the body,
so, it's going to do that a little bit faster,
so, a 10 to 15 beat increase, totally normal.
We may also notice because of
all that extra blood volume
and this change in the heart
rate a low-grade systolic murmur.
Now, a really good practice is when
you hear something that's different,
is to ask the client, if they noticed that before,
have they ever been told they had a murmur.
So, ask that question as well, but
know, that a low-grade systolic murmur,
is normal in pregnancy.
Sometimes, you may also hear
a split second heart sound,
remember the effect of progesterone,
it chills things out, it can actually
chill out and relax the heart valves,
so, they're not as efficient when they close.
So, if you're listening with your stethoscope,
you may actually hear this.
In-fact just practicing listening to
your heart sounds on a pregnant client,
may give you some good practice in
hearing things that would be abnormal
any other time.
Also, vena cava syndrome.
What happens in this particular situation,
is when the client is lying flat on their back,
so, kind of get this picture in your head,
we have a big belly with cletus the fetus inside
and we lie down on our back
and then we have all the weight of our
uterus pushing down on our vena cava,
what do you think is going to happen?
Exactly, your blood pressure is going to drop,
the client is going to report
feeling dizzy and lightheaded,
so, what do we tell clients to do?
“Not lay flat on your back after 20 weeks,”
that's called, “Vena Cava syndrome.”
Now, let's talk about the hematologic system.
So, in the hematologic system again,
the systems are going to support the pregnancy,
we have a 50% increase in plasma volume,
so, the liquid part of the blood.
We're not talking about the red blood cells,
we're talking about the liquid, a 50% increase.
Clotting factors also
increase, let's talk about why.
So, we didn't always deliver
in our homes or in a hospital
in a nice safe place, where you
could rest after you have your baby,
we used to be nomadic creatures and so,
you might have your baby in a field
and everybody else is leaving
to go on to the next place.
So, you need to have clotting factors, in order,
to get your blood to stop after delivery,
so, you can keep going with everyone else,
so, this is a normal physiologic change,
that our clotting factors are going to go up.
Our red cell volume is going to
increase, in terms of the size.
So, not necessarily in terms of
the number, but how big it is,
and why does that matter?
Well, remember that our red blood
cells actually carry the oxygen,
so, if the red blood cells are bigger,
guess what they can carry more of?
Oxygen, exactly right.
We also have an increase in leukocyte production
and that's going to be important,
because we have a lot of factors
that are going on inside the body
and we need to be able to be responsive to that.
Let's talk about the functional
changes in the hematologic system,
we have an increase in oxygen carrying capacity,
we need more oxygen,
so, the red blood cells are
able to carry more oxygen,
we are hyper coagulable, that way, after delivery,
the bleeding will stop.
The Bohr effect, is in effect
and what that means is,
there is an increased affinity to
the red blood cells for oxygen,
which is, what we need, when
carbon dioxide levels are high.
Now, I have a table here and there's
a lot of information on this table,
so, I want to go over one
really important element,
I want you to take a look at the blood pressure,
if you can see, when we start
off in a non-pregnant state,
we have a baseline blood pressure and
then as we move into the first trimester
and into the second trimester,
you see that dip in blood
pressure that we talked about
and then by the time we
get to the third trimester,
the heart rate goes back up, almost to baseline.
We know that in the second trimester,
that is caused by the
relaxation of the vasculature,
the blood pressure drops.
So, what makes it go up in the third trimester?
Well guess what?
There's a big old uterus and
that big old uterus changes,
as the venous return and that makes
the blood pressure go a little bit up
and closer to normal.
Now, let's talk about renal system changes.
So, what's going on with the
kidneys as a result of pregnancy.
The kidneys are actually going to enlarge,
everything enlarges, because
it's under the influence of what?
Estrogen. Exactly remember
estrogen makes things fluffy.
The ureters, are also going to
dilate and become torturous,
now that sounds bad and it's a little weird,
but it just means that the ureters
are kind of not straight anymore,
they're wiggly, okay.
The dilation is under the
influence of what hormone?
Progesterone. The chill factor. Exactly.
Why is that important?
Well, let’s see?
If I dilate the structures that
are on the way to the kidneys,
that might allow bacteria to
also travel with it as well,
so, we want to be mindful that pregnant clients,
are at increased risk for infection,
because of the dilation of the ureters.
Also, bladder tone decreases, again,
when we think about tone
we think about relaxation,
who is the culprit?
So why does it matter that bladder tone decreases?
Well, let's think about it.
Let's talk about a balloon,
because that's what the bladder is like,
if I had a balloon and I
blew it up a couple of times,
would my balloon ever go back to its normal shape?
No. It would be a little
soggy and a little floppy.
The problem with the bladder, when it's
a little soggy and a little floppy,
is that we get urinary retention,
which potentially, could set us
up for a urinary tract infection,
which, we're already at risk for,
because our ureters are dilated and
allow more bacteria to go through.
Are you getting the picture?
We're going to have a lecture
about pregnancy discomforts
and you might want to think
about that, for that lecture.
When we think about our labs,
so, our labs are related to kidney function.
What we're going to find is the glomerular
filtration rate is actually going to increase,
so, I like to think about, the membranes
in the kidneys, like cheesecloth,
that, under normal circumstances,
everything is really tight and close together.
However, under the influence of progesterone,
we start to develop space
and that allows for things,
like protein and glucose and all
kinds of things, to leak through.
So, we may find that to be
the case in this situation.
We're going to have a
decrease in serum creatinine,
we're going to also have a decrease in BUN.
So, remember cheesecloth,
glucose urea and protein,
having a trace of that in the
urine, totally to be expected,
not one plus, not two plus or
three plus, that's not normal,
but a trace, completely
understandable and expected.
Let's take a second and review
the changes in the cardiovascular hematologic
and renal system.
We have increases in clotting
factors, heart rate, cardiac output,
blood volume, glomerular filtration rate,
proteinuria, RBC mass and the WBC count.
There are decreases in the systemic
vascular resistance or SVR,
the hematocrit, the
hemoglobin, BUN and creatinine,
did you get all of that?
Okay let's move on.