Pulmonary Embolism Flashcards
What is PE
Pulmonary embolism (PE) describes a blood clot (thrombus) in the pulmonary arteries. An embolus is a thrombus that has travelled in the blood, often from a deep vein thrombosis (DVT) in a leg. The thrombus will block the blood flow to the lung tissue and strain the right side of the heart. DVTs and PEs are collectively known as venous thromboembolism (VTE).
Risk factors
Several factors can put patients at higher risk of developing a DVT or PE. In many of these situations (e.g., surgery), prophylactic treatment is used to reduce the risk of VTE.
Immobility
Recent surgery
Long-haul travel
Pregnancy
Hormone therapy with oestrogen (e.g., combined oral contraceptive pill or hormone replacement therapy)
Malignancy
Polycythaemia (raised haemoglobin)
Systemic lupus erythematosus
Thrombophilia
DICE = DVT, Immobility, Cancer (activates thrombin), Estrogen
Preventing VTE
Every patient admitted to hospital is assessed for their risk of venous thromboembolism (VTE). Higher-risk patients receive prophylaxis with low molecular weight heparin (e.g., enoxaparin) unless contraindicated. Contraindications include active bleeding or existing anticoagulation with warfarin or a DOAC.
Anti-embolic compression stockings are also used unless contraindicated (e.g., peripheral arterial disease).
Signs and symptoms
Symptoms:
- acute SOB
- pleuritic chest pain
- haemoptysis
- tachycardia
- cough
- dizziness, fever
Signs:
- increased HR, AF, JVP
- increased RR, pleural rub, pleural effusion
- cyanosis
May also be signs of DVT = unilateral leg swelling & tenderness
Management
Supportive management depends on the severity of symptoms and the clinical presentation, including:
Admission to hospital if required
Oxygen as required
Analgesia if required
Monitoring for any deterioration
1) Anticoagulation:
(Low molecular weight heparin -> warfarin or DOAC/DOACs can be 1st line)
2) Thrombolysis
There are two ways thrombolysis can be performed:
Intravenously using a peripheral cannula
Catheter-directed thrombolysis (directly into the pulmonary arteries using a central catheter)
3) Vascular radiologists:
Intrapulmonary thrombolysis
Clot agitation
4) IVC filter to be considered
If absolute Cl to anticoagulation in patient with proximal DVT/PE. Filter to be removed when anticoagulation no longer contra-indicated & established.
Recurrent VTE despite anticoagulation if other reasons for treatment failure have been excluded.
5)Surgery:
Acute pulmonary thrombectomy
Options for long-term anticoagulation
DOAC
Warfarin
LMWH
Continue anticoagulation for:
3 months with a reversible cause (then review)
Beyond 3 months with unprovoked PE, recurrent VTE or an irreversible underlying cause (e.g., thrombophilia)
3-6 months in active cancer (then review)
Diagnosis
A chest x-ray is usually normal in a pulmonary embolism but is required to rule out other pathology.
The Wells score is used when considering pulmonary embolism. The outcome decides the next step:
Likely: perform a CT pulmonary angiogram (CTPA) or alternative imaging (see below)
Unlikely: perform a d-dimer, and if positive, perform a CTPA
D-dimer is a sensitive (95%) but not a specific blood test for VTE. It helps exclude VTE where there is a low suspicion. It is almost always raised if there is a DVT. However, other conditions can cause a raised d-dimer:
Pneumonia
Malignancy
Heart failure
Surgery
Pregnancy
There are three imaging options for establishing a diagnosis of a pulmonary embolism:
CT pulmonary angiogram (the usual first-line)
Ventilation-perfusion single photon emission computed tomography (V/Q SPECT) scan
Planar ventilation-perfusion (VQ) scan
