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 it's a complete uh video looking at pulmonary embolism so here I'm drawing a person who has pulmonary embolism I'm drawing the heart the lungs the inferior vava and the descending aorta the signs and symptoms of pulmonary embolism um include disia puic chest pains tachicardia hypotension and signs of deep vein thrombosis which includes a swollen leg and pain in the legs the lower legs and theosis is very important because it's one of the it's it's one of the causes of pulmonary embolism about 95 or 90% of pulmonary emilii is a result of a thrombosis that occurs deep in the from the deep veins but there are other risk factors that can uh lead to pulmonary embolism and these are surgery such as major abdominal and pelvic surgeries Orthopedic surgeries obstetric such as pregnancy being pregnant um cardiorespiratory uh problems such as COPD and congestive heart failure are 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 emilii uh thrombotic 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 thrombos thrombi occur well they occur from uh mainly from the lower limb deep veins and these include um you know Common and less common ones so the common ones are your external iliac vein your femoral vein your deep femoral vein your poal vein your posterior tibial vein and then the less common sites where thrombi can occur and that can Lodge into the lungs are your right sided uh from your right side of the heart gradal veins utrine veins and your great saffin 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 a thrombi well let's zoom into this let's just say this external iliac vein and here I'm drawing the external iliac vein and thrombi a thrombus is essentially a collection of red blood cells or clumped together with platelets and fibrin so here I'm drawing uh 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 um cause the main cause of it um is known as virtuous Triad and this essentially is a Triad of things that leads to a thrombus formation um 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 fibin and then you get these fibin fibin fibrin mesh work all like clumping together causing a thrombus formation and again virtu Triad are a Triad of things that essentially promotes thrombus formation and these three things are one abnormal blood flow such as absence of blood flow two hypercoagulability 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 thomus can break off Lodge forming an emilii so embolism a thus can also recanalize 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 embis an emble which bro broke off and it will travel up to the inferior Vina Cava and then up towards the heart so here I'm drawing the heart and here I'm drawing the L so the emali 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 it lodges here so this is a pulmonary Emi it has lodged into one of the small smaller branches of the pulmonary archery 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 causes slight backf flow 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 hot failure when you have right-sided hot 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 remember 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 get a 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 tachic cardia and also cause Vaso constriction so it will try to increase blood pressure but it won't work you will leave um the result the net result would be hypotension because even if you constrict your vessels to increase blood pressure because you have the pulon emilii in the LA 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 uh emble has on the cardiovascular system let's see what effects it has in the lungs during respiration so here I'm drawing the Alvi 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 uh denoted as V and then the profusion is the blood flow to and out of the lungs so this is your CU and here is our emble let's just say that because The emble Lodges here it causes two main things firstly it causes inflammation second it causes VQ mismatch so ventilation profusion mismatch so an pulmonary Emi causes abnormal gas exchange so pulmonary embolism leads to an obstruction which leads to VQ mismatch and inflammation inflammation results in a lot of cyto kindes being released which will lead to Bronco constriction Bronco constriction which will 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 osis is what we can find when we do an ABG test an arterial blood gas test I hope that made sense so a person presenting with pulmonary em uh pulmonary embolism um like symptoms um may come in but how do you know its 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 now 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 uh image out here we have the lungs the media stum the heart so one thing you can see is that you can potentially see an enlarged pulmonary archery because of pulmonary vascular H uh increase in pressure two you can see a wedg 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 emilii three you can see an elevated Hemi diaphragm and four you can see pic uh effusion the second investigation you can do which should be done is ECG this 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 um so here I'm drawing an ECG sort of image strip but we're only looking at just the main ones so in lead two let's just look at what a normal uh ECG looks like we have this it looks like this we have the pqrst wave and between the RR interval is your rate and the Rhythm should be normal right well in PE you can see sinus Tachi cardia in about 50% of cases and this is essentially when your rate uh increases so your RR interval shortens and this you can see in lead 2 another thing you can see in PE in about 35% of cases is right ventricular strain and right V strain can be seen in leads V1 to V4 and essentially if we draw it out what you see is that the t wve is inverted of course in in ECG this doesn't actually look like this the actual pqrs t-wave but the t-wave is inverted for right ventricular strain another thing you can see in ECG is what's known as S1 Q3 T3 and you're essentially looking at leads one and leads three and what you're seeing is that you're seeing deep deep versions of this wave in that lead so for example for lead one you see a deep swave so the swave is deeper than usual in leads three you see a deep qwave 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 a gold standard for uh for finding out if the person has PE you'll also have you can also do a VQ profusion scanning test which is used what I mean by not really used is that people um it's it's it's not definite using that you usually use a C2 pulmonary angiogram um five you can do a bedside echo cardiogram and six you can do a d dimer essay which we will look into in more detail um next soon okay so diagnosing or the clinical signs of PE is very difficult to differentiate from other uh differentials so what's important when when trying to see if a person has PE it's important to look at their risk factors