Pulmonary embolism (PE)

• Usually arises from a venous thrombus in the pelvis or legs
• Rare causes – right ventricular thrombus (post MI), septic emboli (right sided endocarditis), fat, air, amniotic fluid embolism, neoplastic cells
• Most PE deaths occur within 1hr

Risk factors;

• Recent surgery – major abdominal/pelvic, hip or knee replacement
• Lower limb problems – fracture, varicose veins
• Recent stroke or MI
• Disseminated malignancy
• Thrombophilia/antiphospholipid syndrome
• Prolonged bed rest
• Pregnancy/post partum/C-section/the pill/HRT
• Having had a previous PE

Symptoms

• Acute breathlessness
• Pleuritic chest pain
• Haemoptysis
• Dizziness
• Syncope

Signs

• Pyrexia
• Cyanosis
• Tachypnoea
• Tachycardia
• Gallop rhythm , loud P2, RV heave
• AF
• Hypotension
• Raised JVP
• Pleural rub
• Pleural effusion
• Look for signs of cause – DVT, scar from recent surgery
• Classically presents 10 days post op with collapse and sudden breathlessness whilst straining at stool

Tests

• FBC, U&Es, baseline clotting, D-dimers
• ABG – may show low PaO2 and a low PaCO2
• CXR – may be normal, show oligaemia of affected segment, dilated pulmonary artery, liner atelectasis, small pleural effusion, wedge shaped opacities
• ECG – may be normal or show tachycardia, RBBB, right ventricular strain (inverted T in V1 and V4). SIQIIITIII pattern is rare

Investigating a suspected PE

• Assess the probability;
• Scoring system
  • Active cancer or treatment within 6mth
  • Paralysis, paresis or recent immobilsatio of lower limbs
  • Recently bed ridden (>3days) or major surgery (<4wk)
  • Localised tenderness along the venous system
  • Entire leg swollen
  • Calf circumference >3cm more than the other side
  • Pitting oedema> that in asymptomatic leg
  • Collateral superficial veins
    • Each of the above are worth one point, if there is an alternative diagnosis as or more likely than a PE then lose 2 marks
    • Total score 0 = low probability, 1-2 moderate probability, > or equal to 3 high probability
• D-dimers only do in a patient without a high probability, a negative D-dimer excludes PE in those with a low or intermediate probability. A positive test means that imaging is required
• Imaging
  • Recommended 1^st line is a CTPA which can see clots down to the 5^th order pulmonary arteries
  • V/Q scan looks for perfusion defects with no ventilation defects – if normal exclude PE, if non diagnostic other imaging may be required, may give some false positives
  • Bilateral leg ultrasounds cant rule out but can confirm PE in patients with a co-exisiting DVT

Treatment

• Anticoagulate with low MW heparin and start oral warfarin
• Stop heparin when INR is >2 and continue heparin for at least 3mth – aim for an INR of 2-3
• Consider placing a vena caval filter in patients with emboli despite adequate anticoagulation

Prevention

• Get heparin (e.g. dalteparin 2500U/24hr SC) to all immobilised patients
• Prescribe compression stockings an encourage early mobilisation
• Stop HRT and the pill pre-op

Acute management of a massive PE

• Oxygen 100%
• Morphine 10mg plus antiemetic if patient is in pain or very distresses
• If critically ill consider immediate surgery
• IV access, start heparin low MW tinzaparin 175u/kg/24hr
• If the systolic BP is <90
  • Start rapid colloid infusion
  • If BP still down after 500ml, give dopamine 10?g/kg/min IV, aim for systolic >90
  • If BP still low consider adrenalin
  • If BP still <90 after 30-60mins of standard treatment, and there is clinically a definite PE and no CI give thrombolysis
• If systolic is >90 s
  • Start warfarin 10mg/24hr PO
  • Confirm diagnosis