Pulmonary embolism Flashcards
Define
Occlusion of pulmonary vessels, most commonly by a thrombus that has travelled to the pulmonary vascular system from another site
Cause
Usually arise from a venous thrombosis in the pelvis/legs (95%) Clots break off and pass though the veins and the right side of the heart before lodging in the pulmonary circulation
Rarer causes
- RA thrombus (AF)
- RV thrombosis (post MI)
- septic emboli
- fat/air/amniotic fluid embolism
- neoplastic cells/ tumour
- parasites Mycotic emboli (post-endocarditis)
Risk factors
- Recent surgery, especially abdo/pelvic or hip/knee replacement
- Immobility
- Obesity
- Heart failure
- Thrombophilia, e.g. antiphospholipid
- Leg fracture prolonged bed rest/reduced mobility
- Malignancy
- Pregnancy/post-partum, OCP, HRT
- Previous PE
Symptoms
Depends on the SITE and SIZE of the embolus
Small - may be ASYMPTOMATIC
Moderate:
- Sudden-onset SOB
- Cough
- Haemoptysis
- Pleuritic chest pain
Large (or proximal)
As above and:
- Severe central pleuritic chest pain
- Shock
- Collapse
- Acute right heart failure
- Sudden death
Multiple Small Recurrent
Symptoms of pulmonary hypertension
Signs
Severity of PE can be assessed based on associated signs:
Small - often no clinical signs. There may be some tachycardia and tachypnoea
Moderate
- Tachypnoea
- Tachycardia
- Pleural rub
- Low O2 saturation (despite O2 supplementation)
Massive PE
- Shock
- Cyanosis
- Signs of right heart strain
- Raised JVP
- Left parasternal heave
- Accentuated S2 heart sound
Multiple Recurrent PE
Signs of pulmonary hypertension
Signs of right heart failure
Investigations
The Well’s Score is used to determine the best investigation for PE
- Low Probability (Wells 4 or less) - use D-dimer
- High Probability (Wells > 4) - required imaging (CTPA)
Additional investigations:
Bloods - ABG, thrombophilia screen
ECG :
- May be normal
- May show tachycardia, right axis deviation or RBBB
CXR - often NORMAL but helps exclude other diagnoses
Spiral CT Pulmonary Angiogram:
- FIRST LINE INVESTIGATION
- Poor sensitivity for small emboli
- VERY sensitive for medium to large emboli
Ventilation-Perfusion (VQ) Scan
- Identifies areas of ventilation and perfusion mismatch, which would indicate an area of infarcted lung
Pulmonary Angiography
- Invasive
- Rarely necessary
Doppler US of Lower Limb - allows assessment of venous thromboembolism
Echocardiography - may show right heart strain
Management
Primary Prevention
- Compression stockings
- Heparin prophylaxis for those at risk
- Good mobilisation and adequate hydration
If haemodynamically stable
- O2
- Anticoagulation with heparin or LMWH
- Switch over to oral warfarin for at least 3 months
- Maintain INR 2-3
- Analgesia
If haemodynamically UNSTABLE (massive PE)
- Resuscitate
- O2
- IV fluids
- Thrombolysis with tPA may be considered if cardiac arrest is imminent
Surgical or radiological
Embolectomy
IVC filters - sometimes used for recurrent PEs despite adequate anticoagulation or when anticoagulation is contraindicated
Complications
Death
Pulmonary infarction
Pulmonary hypertension
Right heart failure
Prognosis
30% mortality in those left untreated
8% mortality with treatment
Increased risk of future thromboembolic disease
