hi welcome to another MedCram lecture we're going to talk about the jugular venous pulse specifically we're going to talk about how to measure it but 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 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 jvp 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 that'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 sew-on is breathing 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 going to be at the top of the cycle on an exhalation when someone is breathing on a ventilator it's always going 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 we're 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 it's gonna be if we have the atria the right atrium if it's relaxing if the volume is getting bigger so atrial relaxation is 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 going to 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 going to 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 that's actually go over what the waveform looks like so here's a sample of what the waveform looks like 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 and then we have a V wave and then finally we have the wide descent 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 gonna see that when the atria contract you're going to be going through starting 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 ern tricular 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 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 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 specifically 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 going to 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 by descent 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 filling 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