I went into another MedCram lecture we're going to talk about the jugular
venous pulse specifically we're going to talk about how to measure it what it's
good for and what the diagnostic considerations are in terms of
interpreting the waveforms so if you take a look at the heart you've got the
left side and the right side this is primarily something we're going to look
at here on the right side where we put in a central line into the internal
jugular vein and down into the SVC which is usually where the tip is now this is
a hollow tube and so we're actually able to actually measure in a central line
what's going on in this vessel which is a extension of the right atrium now you
can also do this and we'll talk about this later you can also do something
called a right heart catheter where we actually float a right heart cath in
here into the right atrium into the right ventricle into the pulmonary
artery and we wedge the catheter here which as you recall after it goes to the
lungs we'll come back and actually measure what's going on in the left
atrium so yes we are able to actually measure what's going on the left atrium
but for right now let's just talk about the jugular venous pulse which is a
measurement that we get in the internal jugular vein the tip of which is in the
SVC so again to review there's two ways that you can look at a jbp you can
either look at the output from a central line that you've placed or number two
you can just look at the patient's jvp jugular venous pulse and that's the
internal jugular vein so it's when they're lying down you can actually look
at that area that's just around the sternocleidomastoid or the SCM and look
at the waveform as it comes up the rest of today's discussion is going to be on
specifically the central line wave output cuz that that's one way we can
actually look at the waveform and see what the waveform is doing
and actually measure the waveform so we'll talk about that before we get to
that I wanted to sort of clarify a little bit though when we should measure
the central venous pressure in a central line and that is when someone is
breathing spontaneously versus when Solan is breathing on the ventilator so
this is supposed to signify what the intrathoracic pressure is and the
intrathoracic pressure also affects the central venous pressure because the
veins are running in the thorax so when someone is breathing spontaneously this
is their intrathoracic pressure before they take a breath in and then when they
take a breath in the intrathoracic pressure goes down and then when they
breathe out it comes back up again well this is exactly what's going to happen
to the central venous pressure and so when you're looking at the waveforms
it's going to be changing and so depending on what point during the
respiratory cycle you're at you're going to get a different waveform and so the
key point here is to always measure at the end of exhalation this is the true
point of measurements the same thing goes for when you're breathing on a
ventilator except however when you're breathing on
a ventilator instead of breathing in and having a negative pressure in your chest
the ventilator is pushing air into your chest and as a result of that the
intrathoracic pressure doesn't go down but instead it goes up the same
principle applies you should always check the central venous pressure at the
end of exhalation as a result of that you'll see here indifferently that when
you're measuring it on someone who is breathing spontaneously without positive
pressure ventilation that measurements always good to be at the top of the
cycle on an exhalation when someone is breathing on a ventilator it's always
good to be at the bottom but still and exhalation so I just want to make that
point for those of you who actually measure central venous pressure I think
I want to now switch to actually talking about the actual waveforms that we see
on the jugular venous waveform and the point that I want to bring up here again
is specifically where actually we're measuring remember the
central line is going into the internal jugular vein and it's resting just at
the tip of the SVC and where the right atrium is anywhere along this line and
so think about the things that are going to make the pressure here go up and
think about the things that are gonna make the pressure go down okay so let's
think about things that would make the pressure go down and that'll make sense
later so things that are gonna make the pressure go down is gonna be if we have
the atria the right atrium if it's relaxing if the volume is getting bigger
so atrial relaxation it's gonna make the pressure go down okay what else could
make the pressure go down well if the tricuspid valve opens and blood is
allowed to leave the right atrium and go into the right ventricle so tricuspid
valve open alright what would make the pressure go up in this area well we know
that the right atrium can contract and so when it does contract it's going to
squish that blood into a smaller space that's going to make the pressure go up
so atrial contraction it's gonna make it definitely go up and also the closure of
this valve so if the opening of the valve makes it go down the closure of
this valve so tricuspid closure
what's gonna happen when this valve closes remember that blood is always
coming towards the heart and so as a result of that if everything is in a
closed system the pressure is always going to start to rise if this valve is
closed because this this chamber is continuously filling up with blood so
with that kind of knowledge actually go over what the waveform looks like so
here's a sample of what the waveform looks like now at first it looks kind of
complicated but it actually is not and we've got certain waves here and you'll
see that over and over again the first wave I want to bring your attention to
is the a wave okay that's that first bump the second is the C wave okay and
then we have an X descent then we have a V wave and then finally we have the wide
ascent and it starts all over again and so this area right here corresponds to
this area right here and so this is one cycle
now based on what we said before remember where we're measuring this
we're measuring this and the superior vena cava so what is this a wave here
this a wave is simply atrial contraction
and as such you're going to see that when the atria contract you're going to
be going through starting from from about right here atrial systole this is
where the right atrium is actually contracting to about this point right
here and then you've got atrial diastole okay so when the atria when the actual
muscle of the atria contract you're going to get this upswing in pressure at
that point and it's right about here
you'll get closure of the tricuspid valve this is because systole occurs
ventricular systole occurs okay we'll put that up here on trick Euler systole
as a result of that when the right ventricle contracts it's going to close
the tricuspid valve now there are some people that believe that this bump right
here is the tricuspid valve actually closing and coming up into the right
atrium causing a little bit of a bump some people also believe that the C
stands for carotid artery because the carotid artery runs right next to the
jugular venous pulse and that that pulsation is also going to cause an
increase in the pressure that is sensed in the internal jugular vein whichever
way you like to think about it this see here is ventricular the beginning of
ventricular contraction now that the valve is closed however what occurs is
the atria continues to relax as it started here it continues to relax down
because remember we're measuring pressure on the right side and so X
specific is atrial relaxation and that's
important to remember now that the atria has relaxed and the X
wave has as we see here the X wave is causing a descent which means that the
pressure is going down in the right atrium there's gonna come a point where
the blood is continuing to come in to that right atrium and it's going to
start to fill up again until it reaches a certain point here right about the top
here where the tricuspid valve opens and as a result of that the blood then
leaves the right atrium and goes into the right ventricle and you have the
wide ascent so what is the wide ascent is blood from the atria going down into
the ventricle so what is V V is specifically filling of the right atrium
I like to say V stands for veiling okay imagine a German saying filling filling
there is villain of the right atrium so again to review a is atrial contraction
then you have the C wave which is caused by right ventricular contraction after
that you have relaxation of the right atrium which causes the ex descent then
the tricuspid valve finally opens at the top of the V wave so you have relaxation
and then filling when the valve opens again the pressure drops again and you
have the right ventricle is now filling during the Y wave and then finally you
get back up to the top again and you're back at another a wave so to review
again a is atrial contraction see is a ventricular contraction ex descent is
atrial relaxation V is atrial filling passively and then finally Y descent is
blood going from the atria down to the ventricle on the way back up to another
atrial contraction thank you for joining us look for the second in the series
where we talk about the pathology and how this waveform can actually help us
make diagnoses
you