Pulmonary embolism Flashcards
Define pulmonary embolism
Occlusion of the pulmonary vessels as a consequence of a thrombus travelling to the vascular system
Aetiology of pulmonary embolism
Thrombus formation in the deep veins which then travels to the pulmonary vessels and occludes them
Thrombus formation is due to Stasis, Vessel injury or hypercoagulability (Virchow’s triad)
95% of thrombi are formed from a DVT in the lower limbs
Thrombi may develop from the right atrium in AF
Other embolitic agents: amniotic fluid, air, fat, tumour, mycotic (endocarditis)
Risk factors for pulmonary embolism
Previous VTE
Genetic: protein C & S deficiency | factor V leiden | FHx
Acquired: recent surgery | immobility | cancer | inflammatory disease | recent flight | pregnancy | COCP | HRT
Symptoms of pulmonary embolism
Small: asymptomatic
Moderate: Sudden onset dyspnoea, cough, haemoptysis and pleuritic chest pain
Large: Moderate PE + severe central pleuritic chest pain, shock, collapse, acute RHF, sudden death
Multiple, small recurrent
Signs of pulmonary embolism on examination
General
- Cyanosis
- Calf-swelling/tenderness
Obs
- Tachnypnoea
- Tachycardia
- Low sats
Resp
- Pleural rub
Cardio
- RHF (raised JVP, left parasternal heave, accentuated S2)
Differentials for pulmonary embolism
MI
Angina
Pneumonia
Pneumothorax
Bronchitis
Asthma/COPD exacerbation
CHF
Pericarditis
Cardiac tamponade
Costchondritis
Investigations for pulmonary embolism
2-level PE Wells score (alt. PESI, revised Geneva)
Low probability (4 or less) → D-dimer
- D-dimer +ve -> CTPA
High (>4) → immediate CTPA OR CTPA + interim anticoagulation
- +ve → diagnose PE
- -ve → proximal leg vein USS
ECG: Sinus tachycardia (or normal), RAD or BBB, S1Q3T3, T wave inversion, P pulmonale,
ABG: hypoxaemia and hypocapnia
Clotting screen: for anticoagulation considerations
CXR: often normal
FBC
U&Es
Troponin
CTPA: Thrombus visual in pulmonary artery
V/Q scan: Identifies PE (used in renal failure)
Pulmonary angiogram: Gold standard but invasive
Doppler USS lower limb: VTE
Echo: May show right heart strain and dilatation, abnormal ejection pattern (60-60 sign and hypokinesis and reduced contractility (used in haemodynamically unstable patients
What scoring system is used for suspected PE
Low risk: PERC (PE rule out criteria)
- If 0 points - can exclude PE (probability of post-test PE Is <2%)
High risk: 2-level well’s score
Management of pulmonary embolism if haemodynamically stable
- A-E
- sats low → oxygen
- Analgesia + anti-emetic - Anticoagulate
(interim = LMWH/unfractionated heparin)
- First line: DOAC e.g. rivaroxaban
- Second line: IVC filter
provoked = anticoagulation for 3 months
unprovoked = 6 months – life-long
Management for pulmonary embolism if haemodynamically unstable
- A-E
- sats low → oxygen
- Analgesia + anti-emetic - Determine if they can have thrombolysis
- thrombolysis possible → streptokinase/urokinase/tPA/alteplase (peripheral vein or directly into pulmonary arteries via catheter)
- Not possible → unfractionated heparin → DOAC
Consider noradrenaline OR dobutamine (choice if anticoagulation is also CI)
Consider surgical embolectomy
What surgical options are there for pulmonary embolism
IV filters
- Inferior vena cava (IVC) filters: designed to trap fragmented thromboemboli from the deep leg veins en route to the pulmonary circulation (whilst preserving blood flow in the IVC filter).
- Thrombolytic therapy may be used to remove the embolic material from the pulmonary arteries by promoting lysis of blood clots.
Embolectomy (surgical removal of clots in the pulmonary arteries)
Complications of pulmonary embolism
Death
Pulmonary infarction
Pulmonary hypertension
Right heart failure
Prognosis for pulmonary embolism
30% untreated mortality
8% mortality with treatment
Increased risk of future thromboembolic diseases
