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Pulmonary Embolism Explained Clearly - Risk factors, Pathophysiology, DVT, Treatment - YouTube
Channel: MedCram - Medical Lectures Explained CLEARLY
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okay well welcome to another MedCram
lecture today we're going to talk about
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pulmonary embolism and specifically
we're going to talk about the
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epidemiology and also the risk factors
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in the next lectures we'll talk about
other things for instance the diagnosis
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and treatment but let's talk about
pulmonary embolism its epidemiology risk
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factors things of that nature first of
all what is a pulmonary embolism well to
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look at this we've got to look at the
relationship between the heart and the
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lungs as we know we've got the heart
which pumps blood to the lungs and also
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the left side which pumps blood to the
rest of the body and in each side
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we've got the lungs which sits on the
left and the right now of course we know
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that the venous system not only from the
bottom but also from the top drains into
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the right side of the heart and from
there from the right atrium it goes to
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the right ventricle and the right
ventricle pumps blood specifically to
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the lungs because of this any blood clot
in any vein is eventually going to end
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its way up if it breaks forth into the
right side now because of that the right
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side of the heart pumps this clot into
the pulmonary arteries and because the
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pulmonary artery gets smaller and
smaller and smaller and smaller
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that blood clot is going to get caught
in the lungs and get lodged and that's
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what's known as a pulmonary embolism now
typically because blood flow typically
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goes more to the lower part of the lung
than it does the upper part of the lung
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and that's a result of gravity more or
less
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because of this you're going to see more
pulmonary embolisms in the lower portion
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of the lungs and less in the upper of
course it can happen anywhere but just
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as a general rule since more blood flow
goes to the lower portion of the lungs
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you're going to tend to see more blood
clots lodging in the lower portion of
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the lungs now is there any predilection
as to what side they tend to go on now
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the answer is not really but it's
possible for it to actually get stuck in
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the middle where the pulmonary artery
branches that's known as a saddle
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embolus and that can be fatal obviously
because of the large amount of blood
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flow that gets disturbed and that type
of pulmonary embolism okay so what is
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the incidence of pulmonary embolism
believe it or not it's about 600,000
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people per year get a pulmonary embolism
and this results in anywhere between
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50,000 and 200,000 deaths per year
that's a lot of people and so I think
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this is an important diagnosis to talk
about okay now that you know what they
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are let's talk a little bit about them
in general first of all we miss them a
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lot what do I mean by that we miss them
a lot they happen a lot in the emergency
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room and in the hospital and we fail to
pick them up because we don't realize
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this and how do we know that we miss
them a lot because of autopsies okay we
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see them on autopsies and we didn't even
think that the patient would have had
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them we also test for these a lot
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and what happens is they're negative so
we think that they're there and we test
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and they don't turn out to be positive
and in other cases we don't even think
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about them and on autopsy we see
pulmonary embolism what does that tell
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you tells you that we're not doing a
good job of picking these things up and
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it's probably one of the most
misdiagnosis in the hospital where do
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these things come from
well most pulmonary embolisms are from
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deep venous thrombosis and most
pulmonary embolisms from deep venous
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thrombosis come from the lower
extremities above the knee so they're in
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the legs above the knee that's where we
need to start looking for these things
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so well what is the pathophysiology the
pathophysiology specifically is is that
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these blood clots form down in the legs
because of a number of possible risk
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factors they break off they go up the
inferior vena cava to the right atrium
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to the right ventricle and then they
lodge themselves in the lungs now what
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happens there
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when the blood cut gets lodged in the
pulmonary artery there is no more
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perfusion to that area of the lung and
so what you're getting there is
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ventilation without perfusion and that
is basically dead space and more forward
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is that the blood that should have gone
to that area that has to get diverted to
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other areas of the lung and then you get
an increased flow of blood to the other
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areas and so the major mechanism is VQ
mismatch if you have any questions about
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the mechanism of VQ mismatch please see
our hypoxia lectures and the mechanisms
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of hypoxemia now you also get increase
in resistance to blood flow especially
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on the right side specifically and that
can cause cardiac arrest in some
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situations you can actually get the
lungs to infarct about 10 percent of the
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time it's difficult because there's a
dual blood supply as many of you know
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the lungs have a dual blood supply we
know that the pulmonary artery goes to
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the lungs with deoxygenated blood
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okay so deoxygenated blood goes to the
lungs that way but also the aorta which
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is coming off from the left side of the
heart also sends branches over to the
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lung and so it's difficult to infer the
lung completely okay so let's talk about
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risk factors
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what are the risk factors for pulmonary
embolism now the reason why this is
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important as we'll talk about later is
that there is no test for pulmonary
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embolism that you would order in another
situation and accidentally pick up a
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pulmonary embolism what do I mean by
this I mean the only way you're ever
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going to make a diagnosis of a pulmonary
embolism is if you order a very specific
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test looking for pulmonary embolism
what does that mean that means if you're
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not thinking about pulmonary embolism
you'll never really make the diagnosis
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so it's very easy to miss it so what are
the things that should clue you in that
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this is a pulmonary embolism well it's
risk factors so what are some of the
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risk factors one it would be an ortho
pivec procedure okay so what do I mean
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by that we're talking hip replacements
knee replacements or repair of fractures
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these sorts of procedures cause patients
to not only be laid up in bed but also
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the endothelial damage that occurs
during these surgeries and the fact that
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these patients probably haven't been
moving around very much in the preceding
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days two weeks before this procedure so
if somebody has an orthopedic procedure
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and comes down with symptoms of
tachycardia to give me as we'll talk
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about then you need to think about a
pulmonary embolism number two patients
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without prophylaxis what do I mean by
prophylaxis this is like DVT prophylaxis
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well the things that we're thinking
about in hospitalized patients would be
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bilateral lower extremity sequential
compression devices or anticoagulants
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things like heparin lovenox warfarin
things of that nature even things during
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surgery so these are all possibilities
what's another risk factor number three
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abdominal or pelvic surgery especially
if it's done for cancer so cancer or
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abdominal pelvic surgery could increase
the risk and does increase the risk
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number four obesity increases the risk
number five women greater than thirty
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years of age and they are on OCPs
and they're smokers this is a serious
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combination right here that you
shouldn't forget I've seen personally in
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the intensive care unit in fact in one
month I saw two women over the age of
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thirty on oral contraceptives who were
smokers and they had problems they had
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pulmonary embolism so bad that in fact
they ended up on a ventilator
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number six hypercoagulable state
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okay what do I mean by this things for
instance like protein C and s
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deficiencies so you can have one or the
other
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that's a possible risk factor another
possibility would be something like
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factor v leiden that's another type of
hypercoagulable state finally the last
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one would be pregnancy okay so think
about these things when we are trying to
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think whether or not a patient may have
a pulmonary embolism because these risk
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factors certainly could be involved okay
what about the symptoms what will be the
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symptoms or the clinical findings well
the first one is a high heart rate known
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as tachycardia the first thing you'll
notice is that that is very nonspecific
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number two is just as bad and that's two
Kip Nia
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these things here are very nonspecific
and can be seen in a number of diseases
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like pneumonia like a myocardial
infarction for instance so you have to
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be specific and circumspect when you're
looking at these because these can fit
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into many different categories
hemoptysis or coughing up a blood
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especially if there is a lung infection
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that's impossible clinical finding also
signs of pulmonary hypertension so what
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are those types of signs
well you'd sometimes see elevated liver
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function tests or you would see an
increase in the sound of a p2 on
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auscultation you might also see signs of
right ventricular hypertrophy both on
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palpation and also on the EKG so these
are signs and symptoms of pulmonary
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embolism some of the clinical findings
join us for the next lecture when we
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start to talk about in terms of
pulmonary embolism the diagnostic
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modalities so how do we figure out
whether or not this patient really does
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have a pulmonary embolism it's gonna be
an interesting discussion thanks
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you
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