Investigation and Management of Pulmonary Embolism PDF

🫁 Investigation and Management of Pulmonary Embolism Lecturer Lecture Notes Type Introduction What is the definition of an Embolus something which dislodges, can...

🫁 Investigation and Management of Pulmonary Embolism Lecturer Lecture Notes Type Introduction What is the definition of an Embolus something which dislodges, can be septic, air and rarely amniotic fluid What is pulmonary embolism? The obstruction of one or more pulmonary arteries by an embolic solid, fluid or gas What are the causes of PE? Most Common deep venous thrombosis in the pelvis or legs which embolises to the lungs through the inferior vena cava Non-thrombotic fat, air or amniotic fluid embolism Rare RV thrombus (post-MI) septic emboli ( right-sided endocarditis) neoplastic cells Investigation and Management of Pulmonary Embolism 1  parasites What are the risk factors for PE? Immobility Recent surgery Thrombophilia → primary deficiency of anticoagulant proteins (protein C,S) Malignancy Pregnancy or postpartum OCP, HRT Previous PE Age → for each 10 year increase there is doubling Males → at a higher risk than females (also have a higher mortality) Cigarette smoking Air travel What are the haemodynamic effects of PE? RV dilatation, failure and secondary pulmonary arterial hypertension Desaturation Pathophysiology 🔑 The third most common cardiovascular diseases. Describe the mechanism of pulmonary embolism formation Thrombus formation which results in DVT embolisation of pulmonary arteries via the inferior vena cava partial or complete obstruction of pulmonary arteries Investigation and Management of Pulmonary Embolism 2  How can PE result from an embolus travelling through the superior vena cava? during or following central venous catheter insertion but is far less common than DVT. Explain Virchow’s triad of thrombus formation Stasis Endothelial injury - following a procedure like a central line inserted through the femoral veins Hyper-coagulability Describe the pathophysiological response of the lung to arterial obstruction Infarction and inflammation of the lungs and the pleura Pleuritic chest pain and hemoptysis Triggers respiratory drive - decreased PaCO2 and therefore results in respiratory alkalosis Impaired gas exchange Mechanical vessel obstruction results in a ventilation perfusion mismatch which results in arterial hypoxemia Cardiac compromise The elevated pulmonary artery pressure results in right ventricular pressure overload Investigation and Management of Pulmonary Embolism 3  Clinical Presentation Are small emboli normally symptomatic or asymptomatic? they are normally asymptomatic Describe the commonest features of pulmonary embolism Acute onset of symptoms Dyspnea Sudden pleuritic chest pain Haemoptysis Dizziness Syncope What are the commonest signs of PE? Pyrexia Cyanosis Tachycardia Investigation and Management of Pulmonary Embolism 4  Tachypneoa Hypotension Raised JVP Pleural rub Pleural effusion Loud P2 (sign of pulmonary hypertension) and split S2 What is the commonest feature seen in physical examination of PE? physical examination of pulmonary embolism is mostly unremarkable. They might be silent What are the clinical features of chronic PE? SOB tachypnoea When should PE be considered in the differential diagnosis? unexplained SOB collapse new onset AF signs of right sided acute HF pleural effusion 🔑 Asymptomatic DVT have the same potential for complications as symptomatic venous thrombosis. Investigations What are the scoring systems used to stratify risk for PE? Wells score (most imp) Investigation and Management of Pulmonary Embolism 5  Geneva score How high/low should a Wells’ score be for PE to be likely? more than 4 means its likely What could be done to exclude PE if the Well’s score is low? A D-dimer, and if this also comes low one can completely exclude PE What blood tests should be ordered to investigate PE? CBC → Hb and WCC, ESR, CRP U&E → renal function before sending a patient for a CTPA Baselines clotting - INR/APTT BNP → reflects the severity of RV strain and haemodynamic compromise Troponins → because an MI can mimic a PE CRP → Inflammation markers Investigation and Management of Pulmonary Embolism 6  D-dimers → if it is low it completely excludes PE but if high, it is not diagnostic ABG low PaO2 and (normal or low) PaCO2 (type 1 RF caused by tachypnoea) low due to hyperventilation low PaCO2 pH will be normal unless the person will be really bad What is seen on an ECG if there is PE? T wave inversion Tachycardia ST depression AF, RBBB → indicate and increase in right sided strain SI,QIII,TIII is rare Q wave → a negative deflection before the R wave S wave - a negative deflection on the ECG A large PE can result in a right bundle branch block on ECG as increased pressure from the lung results in right ventricular overload, leading to poorer perfusion of the right bundle and the subsequent ECG change. The above ECG shows a right bundle branch block, which can occur secondary to pulmonary hypertension. This is characterised by 'MaRRoW'- M wave in V1, W wave in V6. What does an X-Ray show? normal or oligaemia of affected segment Investigation and Management of Pulmonary Embolism 7  dilated pulmonary artery, linear atelectasis, small pleural effusion, wedge- shaped opacities or cavitation Might show a pneumonia so its important to do it to rule out conditions mimicking a PE When is an ECHO useful? in the diagnosis of a massive PE What is the gold standard investigation of PE A CTPA however, if this is contraindicated, one can do a Ventilation- perfusion scan Has to be done within 1 hour of a suspected massive PE and 24 hours of a non-massive PE What other tests can be done? Venography Doppler US Colour duplex imaging Radionuclide labelling Thermography Management What is management of PE dependent on? Whether it is a massive PE or a small PE How would you know whether a PE is massive or non-massive? Low BP, give them fluids and they remain low, it is a massive PE, so therefore go for thrombolysis What is the management of a patient with suspected PE and haemodynamic instability? Investigation and Management of Pulmonary Embolism 8  bedside trans thoracic echo (TTE) if there is RV dysfunction, do an immediate CTPA, and if positive, provide treatment of higrisk PE Altaplase for thrombolysis What are the different types of thrombolytics given? Altaplase rtPA streptokinase urokinase Investigation and Management of Pulmonary Embolism 9  What are the different types of anticoagulation given for PE if the patient is stable? Low molecular weight heparin Unfractionated heparin Warfarin Direct oral anticoagulants How should warfarin (vitamin K antagonist) be started? warfarin + heparin until INR is more than 2 after which heparin is stopped and only warfarin is given This is because at the start, warfarin has thrombolytic potential 🔑 High INR → bleed Low INR → blood clots LMWH (low molecular weight heparin) Clexane same level of effectiveness as unfractionated heparin should be given to patient with intermediate or high pre-test clinical probability immediately prior to imaging When and How is Unfractionated heparin given? Infusion → has a very short half life and therefore has to be given as a continuous infusion in massive PE (faster onset of action); renal impairment and risk of bleeding Why should DOACs be given? apixaban, rivaroxaban, dabigatran, edoxaban lower bleeding risk than warfarin or LMWH Investigation and Management of Pulmonary Embolism 10  Which patients cannot be given DOACs? Cannot be given if patient has antiphospholipid syndrome, renal failure and extreme weights What does the length of treatment depend on? If the PE is provoked → 3 months If unprovoked → more than 6 months Cancer → till the end of treatment Pregnancy → LMWH until birth How is PE prevented? Heparin is given to all immobile patients What are the contraindications to fibrinolysis? absolute Hx of haemorrhagic stroke ischaemic stroke past 6 months CNS neoplasm major trauma, surgery, head injury previous 3 weeks bleeding diathesis (predisposition to certain disease) active bleeding relative TIA in previous 6 months oral anticoagulation pregnancy - 1 week post partum first time non-compressible puncture sites traumatic resuscitation refractory hypertension advanced liver disease Investigation and Management of Pulmonary Embolism 11  infective endocarditis active peptic ulcer Mnemonic for contraindications to fibrinolysis? SIT ON HAND Surgery - major, in the last 1 month Ischaemic stroke - in the last 1 year Trauma - major in the last 1 month (includes prolonged/traumatic CPR) / TIA (Transient ischaemic attack) Ongoing pregnancy Non-compressible punctures - (