Pulmonary Embolism / Thromboembolism Updates Explained Clearly!
09
October

By Adem Lewis / in , , , , , , , , , , , , , , , , , , , , , , , , , , , /


welcome to another MedCram lecture
we’re going to talk about pulmonary embolism and as you can see here on our
CT scan here is the embolus right in the middle of the pulmonary artery and the
question is is why is it there how to get there and what do we do about it now
this video series contains a lot of information and charts that I want to
move through efficiently so we’re gonna do something a little different I’m
gonna mix in some background slides that I’ll illustrate on so what we’re gonna
talk about is the epidemiology the diagnosis treatment and treatment
involves a number of different aspects including assessing the stability of
your patient what kind of medication do you want to start how long do you want
to start for if they’re gonna be IVC filters or not some newer techniques and
then we’ll talk about complications so in terms of epidemiology a couple of
things to keep in mind that we see this in about a hundred out of a hundred
thousand cases and slightly higher in males and as you get older the risk is
gonna go up especially after the age of 75 there’s about a hundred thousand
deaths per year in the United States although the death rate is decreasing
because we’re getting better at detecting it and treating it
appropriately and now the risk ratio has gone from 138 down to about 36 in the
last 30 years the 38 mortality is four and 13% for one year it’s a common
disease you should know virchow’s triad and they are number one venous stasis
number two and the filiol injury and number three hyper coagula bolused eight
so one of the things that you’ve got to realize about the diagnosis is that it’s
easy to miss in fact there was a spanish study that showed it was misdiagnosed in
one of three IDI patients and a retrospective review of pulmonary
embolism and over 400 patients they found that 146 had a delayed diagnosis
some of the things that increase the risk of the diagnosis of course was
hemoptysis so anytime you see someone coughing up
blood you got to think of pulmonary embolism COPD you know that’s one of the
things that we would look for a the guys got COPD maybe he doesn’t have a
pulmonary embolism maybe his shortness of breath is from something else
actually that still increases the rest so don’t be fooled by if
patient has COPD pleuritic chest pain of course is pretty classic for pulmonary
embolism it increases the risk by three point six asthma believe it or not cough
all of these things could increase the risk of a delayed diagnosis why because
we’re thinking about all of these other possibilities now even though there was
a delayed in diagnosis in this there was no statistically significant increase in
mortality with that delay in diagnosis so in terms of diagnosis this is kind of
the money slide when it comes to figuring out what the patient has and
what to do about it one of the things that you’ve got to look at is how likely
does the patient actually have it and you don’t want to use the wels criteria
for that or the modified wels criteria basically what it is is you’re going
through and you’re assigning points based on what you see so the patient has
clinical signs of DVT like leg swelling pain with palpation the patient gets
assigned three points so what this means when it says that the PE is more likely
than another diagnosis is really let’s flip it around and say is there
something else that’s more likely other than a PE for instance if you’ve got
elevated neck veins and swelling in the lower extremities and you’ve got curly B
lines on the chest x-ray well maybe we’re dealing with congestive heart
failure probably more likely than that of a pulmonary embolism if the patient’s
got fevers night sweats chills and they’ve got to elevate a white count
they’re coughing up yellow sputum and they came in last week for a pneumonia
then you know pneumonia is probably more likely than a pulmonary embolism right
so if the patient’s got a pneumothorax then pneumothorax is probably more
likely to explain the clinical symptoms of the patient more likely than a
pulmonary embolism so in other words if you see a diagnosis that stands alone by
itself and it’s probably contributing to the signs and symptoms that we see then
go with that diagnosis and don’t give the three points for a pulmonary
embolism but on the other hand if you’re seeing all of these signs and symptoms
like tachycardia tachypnea shortness of breath and you don’t see a pneumonia you
don’t see a pneumothorax you don’t see congestive heart failure that’s when you
apply the three points the PE is more likely than some other diagnosis
if they have a prior history of any kind of clot 1.5 a heart rate greater than
100 gives them 1.5 if they’ve been immobilized for three or more days
that’s another 1.5 if they’ve got hemoptysis or I’ve got malignancy that
gives you another point so you add them up and if it’s four or less the
diagnosis is considered unlikely if it’s 5 or more it’s considered likely and so
what you do with those points is you determine what kind of tests you’re
going to get and we’ll talk about that but here on the right side are the gamut
of tests that are usually ordered now notice something about these tests the
first thing that you’ll notice is that these are tests that are ordered
specifically if you’re thinking about a pulmonary embolism notice that none of
these tests are really done routinely so you’re not going to ever be surprised in
the morning when the test comes back positive for PE whenever you get a
positive test for PE it’s because you’ve thought about it and herein lies the
real crux of the problem with PE is that if you never think about it
you’ll never really make the diagnosis so let’s talk about these CT angiogram
this is where a patient goes into the CT scan they have to hold their breath for
about 10 seconds or so and the scanner quickly gets these images that looks
specifically at the pulmonary artery so these are great tests if it is a large
PE and if it’s central what I mean by that it’s it’s big it’s in the large
central pulmonary arteries not gonna be so good if it’s chronic and if it is in
the peripheral vasculature because the radiologist has to actually see the PE
therefore it’s pretty specific so it’s central and you got to be careful
however of the GFR because you got to give contrast to these patients so the
kidney has to be able to take that contrast okay so if you’ve got bad
kidney function you can’t use this test the next one that’s used it’s a little
bit older is a VQ scan also relatively specific it looks better at peripheral
so this is the test that you want to use if you’ve got a patient with chronic
thromboembolic disease if they’ve had clots in the past or if you think that
they’ve been having increasing clots and their pulmonary artery pressures going
up don’t get the CT angio because that’s going to tell you about acute clots
centrally what you want to do is actually look at
the VQ scan because it uses a nuclear med and not contrast the GFR is not an
issue so you don’t have to worry about kidney function however if there is a
pneumonia then it may obscure the ability to tell whether or not there is
ventilation but no perfusion so usually if you’ve got a patient with a pneumonia
and a good GFR the one that you’re gonna use is a CT scan if you’ve got a patient
with a bad GFR bad kidney function but I just clear chest x-ray then a VQ scan is
probably the one that you’re gonna use okay next ones that you can use
ultrasound of the bilateral lower extremity it’s very specific what I mean
by that is if you have a negative test you cannot rule out DVT or PE if you
have a positive study though you could probably rule in both definitely rule in
a DVT and also rule in a pulmonary embolism here’s the thing you ought to
know about this test it is portable so you can actually bring it to the patient
if the patient’s unstable in the emergency room in the ICU
you’re not going to induce any risk of taking the patient downstairs because
this can come to you also in that line is the d-dimer however it’s not specific
so whereas an ultrasound if it is positive it helps you tremendously and
if it is negative it doesn’t help you much at all here the opposite is the
case if the d-dimer is negative it’s very helpful in telling you that there’s
probably no clots going on at all but if it’s positive there’s a hundred and one
different things that could make this positive other than a blood clot for
instance inflammation surgery things of that nature echos are nonspecific there
is the occasional sign that you’ll see where the apex may or may not be moving
there’s also EKG that’s going to be nonspecific you can think of an s-1 q3
t3 chest x-ray is also nonspecific you can think of Hamptons hump or
Westermarck sign again these are not specific or sensitive but interesting
and helpful to know okay so how do you actually treat a
patient whom you suspect of having a pulmonary embolism so you’re here at
this point either inpatient or outpatient and so the first thing that
you’re going to do is apply welles criteria and you add it up and if it’s
zero to four points then it’s going to be unlikely if it’s five to twelve and a
half points it’s good to be likely so the next thing you do for an unlikely is
check a d-dimer if the d-dimer’s negative you’re good the pulmonary
embolism is ruled out and by negative I mean less than five hundred nanograms
per milliliter now if it’s positive then you treat it exactly as you would if you
had a likely result from the wels criteria that we talked about before and
in which case what you do is you do a CT PA provided of course that the kidney
function is good enough now if you do a CT PA it’s possible that you could miss
some of those peripheral pulmonary embolisms but the question is is are
those peripheral pulmonary embolisms significant to the point where it would
be fatal if you didn’t anticoagulate and that was the question that was set out
for the Christopher study so what they did was they used this algorithm then
they went and did a CT PA and if it was positive in this case then you’ve ruled
in the pulmonary embolism but if it was negative they would send it and say no
you’ve ruled out the pulmonary embolism so what they said was is this as good as
the d-dimer and his other point so what they did was they looked at the false
positive rate and they wanted to see if we anticoagulated all these people that
were positive and didn’t anticoagulate all the ones that were negative on the
CT PA how did it turn out in terms of DVT non fatal PE or fatal PE and we have
those numbers right here in respective order and you can see here that these
false positive rates are pretty darn low and this is basically what we do now in
the emergency room is we look at a patient do the Welles criteria if you’ve
got an unlikely with a negative d-dimer you’re done if you have either and
unlikely with a d-dimer that’s positive or a likely you go to see TPA if the C
TPA is positive well you’ve made the diagnosis if the CTA is negative well in
that case you’re done and here’s an example of what a CT PA looks
like and you can see here that you’ve got clot blocking up this entire limb of
the right pulmonary artery this is the pulmonary artery right here this is the
aorta here and here you can see it bifurcate so this goes to the right and
this goes to the left and of course you’re seeing a clot in the lumen that’s
preventing the contrast from illuminating you can see why a CT PA is
better at detecting large central lesions rather than peripheral lesions
so here’s an example of a pulmonary embolism here’s an example of a
ventilation perfusion scan so there’s a gas that you inhale and it determines
where in these lungs do you see any decrease in ventilation and of course we
do a technetium perfusion scan and you can see clearly here areas that are not
being perfused and these of course don’t match up with areas over here and so
what you have is a mismatch in perfusion ventilation and therefore that’s a high
probability for a pulmonary embolism here’s an example of a very specific
finding would be very surprised if you were to see this is a Hamptons hump and
you can see here this wedge-shaped infarct in the periphery of the lung and
that is classic and very specific for a pulmonary embolism
okay well that completes this portion of the epidemiology and diagnosis join us
for the next video when we talk about treatment you


11 thoughts on “Pulmonary Embolism / Thromboembolism Updates Explained Clearly!

  1. See the rest of this course here: https://www.medcram.com/courses/pulmonary-embolism-explained-clearly

  2. The Diagnosis slide – most of it is correct except I noticed a key difference when you mentioned what to do if Wells score is 5 – 12 … (the following is sourced from 2019 U-World) >> Wells > 4 or 5-12 >> 1st do CTA / VQ .. if CTA / VQ negative (it does not rule out PE) — in fact you're supposed to do the next step = US of BLE >>> if CTA / VQ & US BLE negative >> next step >> Pulmonary angiogram …. This is what i have from an algorithm from Uworld – what do you say to this ? is this correct or not? >>>> There was also a question on Uworld stating that if the diagnosis of PE is likely based off the question stem presentation – Treat with TPA if hemodynamically stable otherwise give LMWH if hemodynamically unstable right away .. forego testing because if there is no difference to be made from testing – dont delay the treatment (ie = if CTA / VQ negative but US BLE positive, youre going to give the said therapies anyways) <<< True?

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