00:00
Hi, my name is Jill Beavers-Kirby and today
we're going to be talking about
Hemodynamics. So how do we monitor hemodynamics?
This system was something
a called a pulmonary arterial catheter, or you'll
also hear it referred to as a PA catheter.
00:19
This catheter is inserted under sterile
technique by a physician. The brand name
that most facilities use is by Swan-Ganz. It's
a hyphenated name. The Swan-Ganz
catheter has several ports that's used to
monitor several different parameters
of heart function and central circulation.
The catheter is inserted
into a large vein, such as the internal
jugular, the subclavian, and it will
terminate in the pulmonary artery. That's
a very important thing to remember.
00:53
So remember, the tip of the catheter ends in
the pulmonary artery. That's why it's called a
pulmonary arterial catheter. So one thing we
can measure with a Swan-Ganz
or PA catheter is the central venous pressure.
This is the measure of the
blood pressure in the right atrium and the
vena cava and it's from the proximal
lumen of the PA catheter. I'm not going to
review with you all the normals of all these
measurements, these are noted on the slides, but
you should know them for your test.
01:21
So why do we need to measure the central venous
pressure or CVP? This can
tell us how the right side of our heart
is functioning. It can tell us
systemic fluid status. We can also use central
venous pressures to know if
we need to give large amounts of fluid. And
we can also use the central venous
port to draw blood, to take blood tests on
patients. So your central venous
pressure can be elevated or higher than
normal when you have too much fluid
in your venous system. This increases your
venous return. Or if you have heart
failure, so in heart failure your heart muscle
becomes kind of boggy and it's not
a nice strong muscle. So if the heart muscle
instead of pumping like this, it just kind of
pumping like this,
you can have higher pressures because it's
requiring higher pressures to
circulate all that venous return.
02:18
You can also have pulmonary artery stenosis
which can cause a higher than
normal CVP. Or if your patient's on a
ventilator and they've got positive
pressure as the setting of their breathing,
this can also cause your
central venous pressure to be elevated.
Pulmonary artery pressure. So if we
remember that the pulmonary arterial catheter
terminates in the pulmonary
artery, pulmonary means lung, so this, the
PAP pressure, is measuring the blood
pressures in the pulmonary artery. So, like
I said, I'm not going to review normals or means,
but you should probably know them for your test.
02:59
So elevated PA pressures. So if you think this
is in the pulmonary artery that's
going to the lungs, you're going to have elevated
PA pressures pretty much with
anything that affects the lungs. So COPD,
chronic obstructive pulmonary disease or
emphysema, or if you have pulmonary artery
hypertension, there's certain
medications that cause this, or if you have a
pulmonary embolus, that would be a
clot in one of the pulmonary arteries. Or if
you have left ventricular heart
failure. Now why is that? That's because the
blood is returning from the lungs
and it goes into the left ventricle. Or if you
have pulmonary edema, that's fluid
overload that is affecting the circulation
in and around the lungs.
03:45
Another thing that might cause high PA pressures,
and this is a left to right
cardiac shunt. This is rare but it does happen.
This when if you have a small
ventricular septal defect, so you have a little
hole between the right ventricle
and the left ventricle, and this can make your
pulmonary artery pressures higher
than normal. Another hemodynamic parameter
that we monitor is the
pulmonary arterial wedge pressure. You'll see this
abbreviated as PAWP, and this
measures your left ventricular end diastolic
pressure. So remember that,
we're going to talk about that again
in a few minutes.
04:24
So if your PAWP or wedge pressure is high,
you can probably have left ventricular
failure. If the PAWP or wedge pressure is low,
you probably have hypovolemia.
04:40
You've lost blood, you've lost fluid, so you need
fluid resuscitation. So cardiac output
and cardiac index are two other parameters
you can measure with one of
these Swan-Ganz catheters. The cardiac output
measures the volume of blood that is
pumped out of the heart in one minute, and
varies with body size. Obviously if
you have a small person, they're going to have
a small total blood volume. You have a
large person, they can have a larger blood volume.
So it's not very sensitive, but it
is something we kind of take note of. A more
sensitive way to measure heart
function is the cardiac index, because this
is based on BSA, body size. So a low
cardiac index you will usually see in
cardiogenic shock. So if the heart
instead of pumping like a good strong muscle,
becomes acutely bogged down and isn't
pumping very effectively, the cardiac index
is going to be lower. So preload,
afterload, stroke volume and Frank Starling
mechanism. I remember when I was
trying to learn these for the first time as
a new registered nurse, and they drove
me crazy. So I'm going to try and
break this down for you.
05:49
Preload is the end diastolic pressure.
This is what stretches the ventricles, the
bottom chambers of your heart. So in
other words, it's the end diastolic
volume, the amount of blood that occurs at
the beginning of systole. Afterload is the
ventricular pressure at the end of systole.
So in other words, this is the
resistance that the heart has to overcome
with every beat. So your preload
is the pressure at end diastole, afterload is
what has to overcome at the end
of systole. Stroke volume is simply the amount
of blood that is pumped out of the heart with
every beat.
06:36
This is around 70 milliliters. And then
Frank Starling mechanism. If you
think of a rubber band, so the Frank Starling
mechanism simply states that if
I put more blood into my heart chambers, my
ventricles have to stretch out
further. If I keep doing that to my heart, just
like a rubber band, it's eventually
going to get overstretched and it's not going
to be as stretchy as it once was,
and it becomes very broken down. That's simply
what the Frank Starling
mechanism says. So what is systemic vascular resistance?
It's the amount of resistance
in the systemic circulation.
07:21
Increased systematic vascular resistance can
be due to vasoconstriction, so
instead of your blood vessels being opened like this,
they're clamped down like this.
07:31
That's going to increase the pressure. You
kind of think like a garden hose. You
have a big hose, this big, the water
pressure's going to come out very
slowly. If you have a smaller hose, the
water pressure is going to come out normal.
07:43
If you get a teeny tiny hose, the water
pressure is going to be increased.
07:48
So an increased systemic vascular resistance
or SVR can be due the vasoconstriction, shock or
decreased circulating volume. The opposite of
that is a decreased SVR. This will be
due to anything that vasodilates those
blood vessels. So something like
morphine, nitrates, nitroglycerine, or any
other type of vasodilator. So nursing
actions when it comes to the Swan-Ganz
catheter or the PA catheter. Often times
we'll be called in to help assist putting
this in, because these are
done in ICUs and they're frequently done
at the bedside. Sometimes they're
done in the pre-op holding area when a
patient's getting ready to go in for
surgery. So what you're going to want to do, you're
going to want to gather all the equipment, all the tubing
and all those sterile gowns and gloves that are
needed. You want to make sure
you maintain sterile procedure. You'll usually
put the patient in Trendelenburg
position, this is when the head is lower
than the feet, or strictly supine.
08:52
Most physicians prefer the Trendelenburg
position because it causes the blood
flow to go up towards the veins that they
need to access. Sometimes patients
will need a little bit of sedation or pain
medicine prior to putting this in.
09:05
Additional nursing actions when it comes to
inserting a PA catheter or a Swan-Ganz
catheter, includes levelling the transducer.
The transducer is a square
thing on the Swan-Ganz catheter that has to
be levelled with the center of the
heart in order to help measure the pressures
inside the heart. So this has
to be levelled with the patient's surrounding
atmospheric pressure. So in
order to do this,
you level the transducer at the phlebostatic axis,
this is at the 4th intercostal
space, mid-axillary line. So you can literally
raise somebody's arm and
count down four rib spaces, and the transducers
are usually attached to a
pole at the bedside. You'll level the transducer
at that fourth intercostal
space, and that also coincides with the middle of
the person's heart. This will
give you the most accurate readings. After you've
done that, you also have to get
a chest x-ray to verify placement of these
catheters before you instill any type of
fluids into them. You can get some preliminary
hemodynamic parameters
before the chest x-ray is done, but before you
put any type of fluid into that line
you have to get a chest x-ray for placement.
So after chest x-ray, you'd
want to attain the initial hemodynamic readings,
record them, let the physician
know. And you'd also want to monitor your patient's
response to the therapies that you're
giving based on these numbers. So what are
potential complications of inserting
a PA catheter? Any time you break the skin,
one of the potential complications
is infection.
10:48
Well this catheter is going directly into the
central circulation, so you can also
cause sepsis. This is when bacteria gets into
the central circulation such as
your blood stream. You'll usually see infection
or sepsis occur when the
catheter is inserted, or it can be from a
dressing change that has not been done
under sterile technique. Another potential
complication is an embolus.
11:13
This is when a blood clot or a plaque becomes
dislodged in the catheter and
can float through the circulation once again.
Another potential complication,
this is a short acting complication, you'll
see irritation of the ventricle
when they are putting in the catheter. So you
have to remember the catheter is
going into the subclavian, it goes down the
vena cava, into the right atrium,
right ventricle, left ventricle and finally
up into the pulmonary artery.
11:43
Usually when the catheter is passing through
the right ventricle, on the
cardiac monitor you'll see a little this,
this is very short lasting, lasts
less than a second. Once you're through the
right ventricle you usually
don't see that anymore. However, if you do see
additional ectopy, you need to let the
physician know because the catheter has been
mispositioned. Another potential
complication, and this is rare, is perforation
of the pulmonary artery.
12:10
When you're getting a wedge pressure reading, this
is done by inflating the balloon on
the end of the catheter, if you over inflate
the balloon you can rupture that
artery. Pneumothorax is simply air that is
leaked into the pleural space.
12:26
This can be caused during insertion from the
physician when they can accidentally nick
the lining of the lung and caused air to enter
that pleural cavity. A thrombus.
12:38
Your lines have to be heparinized, this
means they have to have a little bit of
heparin in them so that the lines don't
clot off. So if you don't use a
heparinized solution when you're initially
priming these lines, you can
get blood that clogs off that catheter
somewhere throughout heart.
12:56
Thrombus and infection are the two most common
types of complications you'll see
with these PA catheters. You might see that in
the future on your test. Thank you.
13:08
This has been Jill Beavers-Kirby discussing hemodynamics.