Pulmonary Embolism PART I (Overview)

so in this video we're going to talk

about pulmonary embolism and we're going

to look at the signs and symptoms the

risk factors the pathophysiology the

investigations the diagnosis and then we

look at the treatment the management so

to complete a video looking at pulmonary

embolism so here I'm doing a person who

has pulmonary embolism I'm drawing the

heart the lungs the inferior vena cava

and the descending aorta the signs and

symptoms of pulmonary embolism included

this Nia pleuritic chest pains

tachycardia hypotension and signs of

deep vein thrombosis which includes a

swollen leg and pain in the legs the

lower legs and even samosas are very

important because it's one of the it's

one of the causes of pulmonary embolism

about 95 or 90% of pulmonary emboli as a

result of a thrombosis that occurs a

deep in it from the deep veins but there

are other risk factors that can lead to

pulmonary embolism and these are surgery

such as major abdominal and pelvic

surgeries orthopedic surgeries

obstetrics such as pregnancy being

pregnant cardio respiratory are problems

such as COPD and congestive heart

failure or also risk factors lower limb

problems such as varicose veins

fractures malignant diseases increasing

age immobility and lastly thrombotic

disorders so these are the risk factors

that can lead to pulmonary embolism or

pulmonary emboli from buttock disorders

is what we will focus on because as I

mentioned 95% of cases of pulmonary

embolism as a result of thrombosis from

the deep veins so where do these

thrombosis thrombi occur will they occur

from Mote mainly from the lower limb

deep veins and these include you know

common and less common ones so the

common ones are your external iliac vein

your femoral vein your deep femoral vein

your popliteal vein your

stereo tibial vein and then the less

common sites where thrombi can occur and

that can lodge into the lungs are your

right-sided from your right side of the

HUD of the natal veins you try and veins

and your great saphenous so again these

are sources where thrombi can occur and

then break off lodging into your

pulmonary arteries causing pulmonary

embolism so what is a thrombus thrombi

well let's zoom into this let's just say

these external iliac vein and here I'm

drawing the external iliac vein and

thrown by a thrombus is essentially a

collection of red blood cells or clump

together with platelets and fibrin so

here I'm drawing I'm drawing this to

represent a thrombus so here we have a

vein and this red thing is the thrombus

so that's a representation of a thrombus

and thrombus is caused by a variety of

things mainly cause the main cause of it

are is known as virtuous triad and this

essentially is a triad of things that

leads to a thrombus formation so just to

recap what a thrombus is it's

essentially again you got red blood

cells clumping together with platelets

and then you have fibrinogen which is a

clotting factor which gets converted by

thrombin which is 2a here into fibrin

and then you get these fibrin fibrin

fibrin mesh work or like clumping

together causing a thrombus formation

and again virchow's triad are tried of

things that essentially promotes

thrombus formation and these three

things are one abnormal blood flow such

as absence of blood flow to

hypercoagulable 'ti such as

thrombophilia and three altered vessel

wall abnormal vessel wall so again these

three things which make up virtuous

triad promote thrombus formation once a

thrombus is formed it has a few fates

we'll talk about

five in this video thrombus can just

resolve so it can disappear so

resolution is one outcome the second

outcome is propagation the thrombus can

just keep growing along the vein three

the thrombus can break off lodge forming

an emboli so embolism a thermos can also

wreak annualize essentially having holes

in it changing its structure and then it

can organize organization and this

essentially means when the thrombus goes

within the layers of the vessel wall in

this video we will mainly focus on

embolism so when the thrombus breaks off

so in this diagram here you can see an

embolus and emboli which broke off and

it will travel up to the inferior vena

cava and then up towards the heart so

here I'm drawing the heart and here I'm

drawing the lungs

so the emboli travels up it goes into

the right atrium then goes down to the

right ventricle and then it goes up the

pulmonary trunk and it can go either way

to the pulmonary arteries let's just say

lodges here so this is a pulmonary

emboli it has lodged into one of the

small smaller branches of the pulmonary

artery we will now look at the

pathophysiology so a pulmonary embolism

can lead to depending how big it is an

increase in pulmonary vascular pressure

an increase in pulmonary vascular

pressure cause a slight backflow of

blood to the right side of the heart and

this will lead to an increase in right

ventricular pressure an increase in

right ventricular pressure will dilate

the ventricles it will cause dilation of

the right ventricle which can

subsequently lead to right-sided heart

failure when you have right-sided heart

failure it will obviously decrease the

stroke volume and decrease the cardiac

output and so logically decrease the

blood pressure and this is on the right

side of the heart room

but whatever happens on the right side

of the heart it will also affect your

left side of the heart and so what you

get is from the left side you're going

to also a decrease in cardiac output so

when you have actually a decrease in

cardiac output

there will be receptors that will detect

this and that will stimulate the

sympathetic response and the sympathetic

response will work to increase heart

rate so you get tachycardia and also

cause vasoconstriction so it will try to

increase blood pressure but it won't

work you will leave the result the net

result will be hypotension because even

if you constrict your vessels to

increase blood pressure because you have

the pulmonary emboli in the law in the

pulmonary artery you will still get a

decrease in cardiac output and so this

will have a net decrease in blood

pressure if that makes sense so that was

the effect emboli has on the

cardiovascular system let's see what

effects it has in the lungs during

respiration so here I'm drawing the

alveoli the pulmonary arteries in blue

and the pulmonary veins in red

ventilation is the air moving in and out

of the lungs and that's denoted as V and

then the perfusion is the blood flow to

and out of the lungs so this is your Q

and here is our emboli let's just say

now because the emboli lodges here it

causes two main things firstly it causes

inflammation second it causes VQ

mismatch so ventilation/perfusion

mismatch so an pulmonary emboli causes

abnormal gas exchange

so pulmonary embolism leads to an

obstruction which leads to VQ mismatch

and inflammation inflammation results in

a lot of cytokines being released which

will lead to bronchoconstriction

bronchoconstriction which will do

decreases the oxygen coming in and

because of this the decrease in oxygen

will stimulate hyperventilation so

you're breathing rapidly which will lead

to hypocapnia a decrease in carbon

dioxide so the VQ mismatch and

inflammation both contribute to

hypoxemia and hypocapnia which leads to

respiratory alkalosis respiratory

alkalosis is what we can find when we do

an ABG test and arterial blood gas test

i hope that made sense so a person

presenting with pulmonary ambulance

pulmonary embolism like symptoms may

come in but how do you know it's

pulmonary embolism and how do you rule

out other differentials

well investigation can be performed

which is what we will look at next

so investigations we can do an x-ray the

x-ray is very important for any

respiratory problems but x-rays usually

come back normal for pulmonary embolism

and x-rays are used to exclude other

differentials such as pneumonia and

pneumothorax but you can find some

common features in pulmonary embolism in

PE so here let's just draw this x-ray

image out here of the lungs the

mediastinum the heart so one thing you

can see is that you can potentially see

an enlarged pulmonary artery because of

pulmonary vascular how are increasing

pressure - you can see a wedge wedged

shape shaped opacity which is somewhat

like a consolidation but it's due to

infarction of that area there's no blood

supply to that area due to the emboli 3

you can see an elevated hemidiaphragm

and 4 you can see a pleuritic effusion

the second investigation you can do

which should be done is ECG this you

also usually comes back normal but it's

used to exclude myocardial infarction

and pericarditis but you do find some

common findings in PE

in pulmonary embolism so let's have a

look so here I'm drawing an ECG sort of

image strip but we're only looking at

just the main ones so in lead to let's

just look at what a normal ECG looks

like we have this it looks like this

we have the PQRS t-wave and between the

RR interval is your rate and the rhythm

should be normal right

well in PE you can see sinus tachycardia

in about 50 percent of cases and this is

essentially when your rate increases so

your RR interval shortens and this you

can see and lead to another thing you

can see MPE in about 35 percent of cases

is right ventricular strain and right

ventricular strain can be seen in leads

v1 to v4 and essentially if we draw it

out what you see is that the T wave is

inverted of course in ECG this doesn't

actually look like this the actual pqrst

wave but the T wave is inverted for

right ventricular strain another thing

you can see in ECG is what's known as a

s-one q-three t3 and you're essentially

looking at leads 1 and leads 3 and what

you're seeing is that you're seeing deep

deep versions of this wave in that lead

so for example for lead 1 you see a deep

S wave so the S wave is deeper than

usual in leads 3 you see a deep Q wave

and you see a deep T wave I hope that

made sense other investigations that can

be performed is your CT pulmonary

angiogram which is your gold standard

for for finding out if the person s PE

you also have you can also do a VQ

perfusion scanning test which is used

what I mean by not really used is that

people it's it's it's not definitely

using that usually use a CT pulmonary

angiogram v you can do a bedside

echocardiogram and 6 you can do a

d-dimer SA which we will look into in

more detail next soon

okay so diagnosing or the clinical signs

of PE is very difficult to differentiate

from other differentials so what's

important when when trying to see if a

person has PE it's important to look at

their risk factors