Pulmonary Embolism

Question 1

What causes a pulmonary embolism (PE) usually?

Answer 1

Venous thrombosis in the pelvis or leg, clots break off forming emboli and pass through the veins and right side of the heart lodging into the pulmonary circulation.

Rare causes include right ventricular thrombosis (post-MI), septic emboli (right-sided endocarditis), fat, air or amniotic fluid emboli, neoplastic cells, paracites.

Question 2

What are the risk factors for PE?

Answer 2

• Recent surgery (esp abdo/pelvic or hip/knee)
• Thrombophilia (eg antiphospholipid synd)
• Leg fracture
• Prolonged bed rest/ reduced mobility
• Malignancy
• Pregnancy/ postpartum & pill/ HRT
• Previous PE

Question 3

What are the clinical features of PE?

Answer 3

Classically presents 10d post-op with collapse and sudden breathlessness while straining at stool.

Depends on number, size & distribution of E, small E may be symptomatic, large E are often fatal.

Symptoms;

• Acute breathlessness
• Pleuritic chest pain
• Haemoptysis
• Dizziness & syncope
• Red tender swollen calf - DVT

Signs;

• Tachypnoea, tachycardia, Hypotension, Raised JVP
• Cyanosis
• Pyrexia, Pleural rub (sounds like treading snow), Pleural effusion

Question 4

What investigations would you perform for PE and what could you find?

Answer 4

• ABG;
  
  • Respiratory alkalosis
  • low PaO2 (V/Q mismatch)
  • low PaCO2 (hyperventilation/ tachypnoea)
  • Alkalotic (hyperventilation & low gas exchange)
• CXR;
  
  • Normal
  • Hampton’s hump - wedge-shaped opacities
  • Westermark sign - Oligaemia of affected segment, blood goes to other lung (obvious vessels..)
  • Pleural effusion
  • Linear atelectasis, cavitation
• ECG may be;
  
  • SI QIII TIII pattern
    
    • Lead 1 - Deep S
    • Lead 3 - Deep Q & Inverted T
    • Any cor pulmonale situation
  • Tachycardia
  • Inverted T waves in V1 to V4 - RV strain
• Serum D-dimer;
  
  • High sensitivity but low specificity
  • -ve rules out
  • Increased if thrombosis, inflammation, post-op, infection or malignancy
• CT pulmonary angiography (CTPA)
  
  • Sensitive and specific!
• Other;
  
  • V/Q scan for mismacth [V = Xenou, Q = Tc99mMAA Technetium]
  • Leg doppler for DVT
  • Echo to assess RH function (indicates severity)
  • Pulmonary angiography or biltateral venograms (MRI venography or plethysmography)

Hospital guidelines;

If Well’s >4 or D-dimer positive

• Start LMWH

If Abnormal CXR, carioresp disease or previous PE or Perfusion scan abnormal

• Do CTPA

If CTPA positive - treat PE

If CTPA negative, if DVT likely do leg doppler, if not seek alternative diagnosis

Question 5

What is the scoring system for PE?

Answer 5

Well’s score for PE

Don’t die, tell the team to calculate criteria

• DVT symptoms & signs - 3 points
• Diagnosis likely? -3 points
• Tachycardia >100bpm - 1.5 points
• Three days immobile - 1.5 points
• Thirty day surgery history - 1.5 points
• Thromboembolism previously - 1.5 points
• Coughing blood (haemoptysis) - 1 point
• Cancer (malignancy) - b

PE likely if >4 points

PE unlikely if <=4 points

(Well’s has another score for DVT)

Question 6

What is the treatment for a non-massive PE?

Answer 6

General;

• Oxygen
• Analgesia for pleuritic pain
• AVOID diuretics

1. Delteparin when PE suspected (its LMWH)
   
   • 5 days or INR 2-3 for 2 days
2. Warfarin when diagnosis confirmed
   
   • _​​_Continue for 3 months (+ if recurrent or life-threatening PE)
3. Screen for cancer (CXR, FBC, LFT, calcium & urinalysis) in all confirmed PE

Other;

• If <45 & unprovoked - screen for thrombophilia

Question 7

What is the treatment for a massive PE?

Answer 7

General;

• Oxygen
• Analgesia for pleuritic pain
• AVOID diuretics

Assess clinical state, if;

• Cardiac arrest
  
  • Resuscitation
  • Alteplase 50mgIV (tPA)
  • Reassess after 30mins
• Deteriorating
  
  • Contact consultant
  • Alteplase 50mgIV (tPA)
  • Urgent ECG/ CTPA
• Condition seems stable
  
  • Immediate IV unfractionated heparin
  • Urgent ECG/ CTPA

Thrombolysis

• If life-threatening give Alteplase 50mgIV as bolus injection
• IF alteplase fails, haemodynamically unstable, ECG evidence of right ventricular dysfunction or free-floating right ventricular thrombus;
  
  • Do emergency direct thrombolysis, catheter thrombo-embolectomy or pulmonary embolectomy

Question 8

How do you prevent a PE?

Answer 8

• Heparin (dalteparin) to all immobile patients
• Compression stockings
• Early mobilisation
• Stop HRT/ pill pre-op
• Investigate for thrombophilia if past/ family history of thromboembolism