Pulmonary Embolism Flashcards
What are the types of embolism?
Thrombus
Fat
Air
Amniotic fluid
Foreign material
What is a venous thromboembolism?
Embolism caused by thrombus formed in the venous system e.g. DVT
What will happen to thrombi from a systemic vein?
- travels though the right side of the heart
- impacts the lungs
What is part of virchow’s triad?
- haemodynamic changes: stasis/turbulence
- hypercoagulability
- vessel wall damage
What is the highest risk factor of pulmonary embolism?
Increasing age
Risk factors for PE
- increasing age
- surgery
- prolonged immobility
- previous proven VTE
- long haul flight
- abdominal/pelvic surgery
- pregnancy
- obesity
- smoking
- malignancy
What can cause vessel wall damage?
- vascular access
- injury/trauma
- varicose veins
- increasing age
- surgery
What are causes for haemodynamic changes?
- prolonged immobility
- pregnancy
- obesity
- varicose veins
- increasing age
What are causes for hypercoagulability?
- thrombophilia - high platelets
- oestrogen containing meds
- cancer
- smoking
- pregnancy
- obesity
- increased age
What are the three main impacts of pulmonary embolisms?
Acute right heart strain
Respiratory failure
Pulmonary infarction
How do pulmonary embolism cause acute right sided heart failure?
- increased pressure in pulmonary artery
- causes RV dilatation > acute right sided heart failure
- inotropes released to maintain systemic BP
- causes vasoconstriction of pulmonary artery
- increases pressure even more
Symptoms of a pulmonary embolism
- dyspnoea
- pleuritic chest pain
- cough
- syncope
- haemoptysis
- unilateral leg pain/swelling (DVT)
- diaphoresis
Signs of pulmonary embolism
- dyspnoea
- tachycardia
- Tachypnoea
- low BP
- raised JVP
How can pulmonary embolisms cause pulmonary infarction?
- small emboli cause alveolar haemorrhage + infarction of lung tissue
- causes haemoptysis, pleuritis + small pleural effusion
How do pulmonary infarction appear on a CXR?
Wedge or Hampton hump
What are the classic findings on an ECG of a patient with pulmonary embolism?
sinus tachycardia
SI QIII TIII
- Deep S wave in lead I
- Pathological Q wave in lead III
- Inverted T wave in lead III
Investigations of PE
- ABG: shows respiratory alkalosis
- chest X ray: exclude differentials
- ECG: sinus tachycardia SI QIII TIII
- D dimers
- Wells score
- CT pulmonary angiogram
- V/Q scan
Diagnosis of PE
- CT pulmonary angiogram - gold standard
- V/Q single photon emission CT scan
- plantar VQ scan
A PE can be ruled out if patient is D dimer … and … risk
A PE can be ruled out if patient is D dimer negative and low risk
When is a D dimer test useful for PE?
Only when a patient is at a low risk of PE
(Negative test = rules out PE)
Well’s score <4
How do we decided if a patient is at high or low risk of a pulmonary embolism?
Well’s score
What is the normal level for D dimer?
0.5
What can cause raised D-dimer?
- PE
- pneumonia
- malignancy
- heart failure
- pregnancy
- surgery
What is the first line drug treatment of a PE?
Low molecular weight heparin
Treatment of pulmonary embolisms
- O2 if hypoxic
- analgesia if pain
- sc LMWH whilst awaiting CTPA
- fully anticoagulated once confirmed diagnosis
Thrombolysis contraindications
absolute:
- stroke <6 months ago
- CNS neoplasia
- GI bleed <1 month ago
- recent trauma or surgery
- aortic dissection
.
relative:
- DOAC/warfarin
- pregnancy
- advanced liver disease
- infective endocarditistiis
Further treatment of pulmonary embolism in severe cases (massive PE)
Haemodynamic support
Respiratory support
Surgical intervention
When patients are discharged after a PE they are normally switched to a oral anticoagulant, how long do they need this for?
- 3 months if identifiable temporary risk factor
- indefinitely if no identifiable risk factor
VTE prophylaxis
- LMWH e.g. enxaparin given to high risk patients
- warfarin or DOAC if contraindicated
Prevention of pulmonary embolisms
- anticoagulants
- mobilisation
- TED stockings/AES
- intermittent pneumatic compression
- fall prevention
- avoid unnecessary invasive procedures
How can pulmonary embolisms cause respiratory failure?
- low RV output
- reduced perfusion to lungs
- V/Q mismatch
- low pO2
How does heparin induced thrombocytopenia occur?
- antibodies form against heparin
- bind to heparin platelet complexes
- platelets become activated + clump together
- thrombi form
- thrombi spread through body
- risk of causing stroke, MI + limb ischameia
Main differential diagnosis for PE
- pneumothorax
- pneumonia
- MSK chest pain
- MI
Why is distended neck veins (raised JVP) a sign of PE?
Increased pulmonary artery pressure
More difficult for RV to empty
IJV drains into subclavian vein > superior vena cava > right side of the heart
What should be considered in an unprovoked PE?
Underlying malignancy or thrombophilia
What is massive haemoptysis defined as?
> 240mls in 24 hours
OR
100mls/day over consecutive days
Management of massive haemoptysis
- lie patient on side of suspected lesion
- oral tanexamic acid for 5 days
- stop NSAIDs, aspirin, anticoagulants
- consider vitamin K
- CT aortogram
- antibitoics if suspected RTI
What is a massive PE?
A PE that causes haemodynamic instability e.g. hypotension, shock, RV dysfunction on imaging
Treatment of massive PE
Thrombolysis with IV alteplase
Surgical or catheter directed thrombectomy
