Pulmonary Embolism Flashcards
Causes
DVTs (major cause) Air Tumour Tissue Fat
Risk Factors
Obesity Prolonged bed rest Travel Pregnancy Active malignancy Recent trauma/surgery Hx of DVT Haematological disorders
Pathophysiology
Usually arise from thrombi in the deep venous system of the lower extremities. Accretion of platelets and fibrin causes infammation of the vein (phlebitis) and the formation of a thrombus, which may embolise. The emboli breaks off from the thrombus, passes through the peripheral vein, into the IVC and right heart to eventually lodge in the pulmonary circulation
Commonly affected lobes
Lower lobes > upper lobes
Small emboli
Tend to block distal pulmonary arterioles
May be completely asymptomatic and may go on undiagnosed
Moderately sized emboli
May cause acute respiratory and associated cardiac strain and will be at greater risk of further emboli
Massive emboli
Cause sudden death if not treated immediately
Most common site is at the bifurcation of the pulmonary arteries “saddle embolus”
Leads to reduced perfusion, V/Q mismatch, atelectasis, hypoxia and infarction of the lung
Clinical Presentation
Haemoptysis Pleuritic chest pain Dyspnoea Tachypnoea Syncope Hypotension "Feeling of apprehension"
Investigations
Vitals CTPA - first test V/Q scan CXR ECG ABG INR/aPTT D-dimer
CXR findings
Prominent pulmonary artery
Increased opacity of the pleural bases
Band atelectasis
Elevation of the hemi-diaphragm
ECG findings
S1Q3T3
Tachycardia
Right axis deviation
RBBB
Management
Supportive - oxygen, opiates, IV fluids
Haemodynamically stable - LMWH
Haemodynamically unstable - Heparin and Warfarin combination (heparin ceased when INR > 2.0)
tPA used for those with massive PEs
IVC filter can be used if there is recurrence despite anticoagulation or if contraindicated
Heparin Induced Thrombotic Thrombocytopaenia
Causes low platelets and clotting
Heparin causes antibody formation, which binds to activated platelets.
DO NOT TRANSFUSE - stop heparin and change to another anticoagulant
