Pulmonary Embolism

Aetiology

Clot breaks off and passes through the veins and right heart before lodging in the pulmonary circulation

Rare Causes

Venous thrombosis in the pelvis or legs (iliofemoral veins)

Parasite

Amniotic fluid embolism

Septic emboli (right sided endocarditis

Neoplastic cells

RV thrombus post MI

Risk Factors

Prolonged bed rest/reduced mobility

Malignancy

Leg fracture

Pregnancy, postpartum, oral contraceptive pill, HRT

Thrombophilia e.g. antiphospholipid syndrome

Previous PE

Recent surgery: especially abdominal, pelvic, hip, knee

Pathophysiology

Acute RH failure

Small embolus will impact in a terminal, peripheral pulmonary vessel - may be clinically silent unless it causes pulmonary infarction

Sudden increase in pulmonary vascular resistance

Lung tissue is ventilated but not perfused, leads to impaired gas exchange

Massive embolism obstructs RV outflow tract

Symptoms

Haemoptysis

Dizziness

Pleuritic chest pain

Syncope

Acute breathlessness

Signs

Tachypnoea

Tachycardia

Cyanosis

Hypotension

Pyrexia

Pleural effusion + pleural rub

Raised JVP

Investigations

ABG may show low PaO2 and low PaCO2

Chest X-ray: dilated pulmonary artery, small pleural effusion

D-dimer test: negative D dimer excludes PE but positive doesn't mean it's PE, further imaging is needed

CT pulmonary angiography - shows clot

FBC, baseline clotting

ECG can show tachycardia, RBBB

Treatment

Long term anticoagulation: DOAC or warfarin

If haemodynamically unstable, then thromboylse with alteplase IV

Commence LMW heparin. Stop heparin once INR >2

Treat hypotension with fluids

Start treatment before definitive investigations as most deaths occur within 1 hour

Give oxygen if hypoxic

Prevention

Stop HRT and pill pre op

Compression stockings

Give heparin to immobile patients

Early mobilization post op

Calculate risk of PE by using Wells Criteria