Pneumothorax and Pulmonary Embolism

Question 1

What is the definition of a pneumothorax and what are the causes?

Answer 1

• Air within the pleural cavity
• Traumatic, iatrogenic (biopsy, TBLB, aspiration) and spontaneous (primary - healthy, and secondary - underlying lung disease)

Question 2

Why is tension pneumothorax so dangerous and how is it treated?

Answer 2

• Increased intrapleural pressure
• Venous return impaired, CO and BP fall, and PEA arrest occurs
• Cannula in 2nd intercostal space in midclavicular line to relieve pressure

Question 3

What is the pathophysiology of primary spontaneous pneumothorax?

Answer 3

• Development of blebs/bullae at lung apices caused by gravity due to lower intrapleural pressure in apices
• When blebs burst this leaves a tear in the visceral pleura

Question 4

What is the pathophysiology of secondary spontaneous pneumothorax?

Answer 4

• Inherent weakness in lung tissue
• Increased airway pressure
• Pressure gradient leads to lung collapse

Question 5

What are the diagnostic features of spontaneous pneumothorax?

Answer 5

• Signs and symptoms include pleuritic chest pain, breathlessness, respiratory distress, reduced air entry of affected side, hyper-resonance to percussion, reduced vocal resonance and tracheal deviation if tension
• CXR looks for lack of lung markings and pleural line away from the edges of the pleural spaces
• <2m small and >2cm large

Question 6

How is spontaneous pneumothorax managed?

Answer 6

• Chest drain inserted into the triangle of safety
  
  • 5th intercostal space
  • Mid axillary line (lateral edge of latissimus dorsi)
  • Anterior axillary line (or lateral edge of pectoris major)
• Needle is inserted just above the rib to avoid the neurovascular bundle that runs just below it
• CXR to confirm position

Question 7

What is the pathophysiology of pulmonary embolism?

Answer 7

• Obstruction of the pulmonary arteries by a clot from the veins of the systemic circulation
• More than 90% from DVT in pelvis or legs
• Acute changes invlove increased vascular resistance, RV strain, right to left shunting through PFO and increase in alveolar-arterial gradient
• Compensation involves lysis of clot, recovery of RV function, decreased perfusion in poorly ventilated areas and decreased surfactant in obstructed zones causing atelectasis

Question 8

What are the risk factors for pulmonary embolism?

Answer 8

• Surgery < 12 weeks previously
• Immobilisation >3 days in previous 4 weeks
• Long distance travel
• Pregnancy
• Oestrogen OCP use
• Malignancy
• Polycythaemia
• SLE
• Thrombophilia (factor V Leiden, protein S deficiency, protein C deficiency)
• Previous DVT/PTE
• FHx
• Prothrombin G20210A
• Hyperhomocysteinaemia

Question 9

What are the signs and symptoms of pulmonary embolism?

Answer 9

• SOB
• Pleuritic chest pain
• Dyspnoea
• Cough with or without haemoptysis
• Tachypnoea
• Hypoxia
• Tachycardia >100bpm
• Fever
• Haemodynamic instability causing hypotension
• Syncope
• Signs of peripheral DVT

Question 10

What investigations are used for pulmonary embolism?

Answer 10

• D-dimer (rased >230mg/L)
• ABG (respiratory alkalosis, hypoxaemia)
• Troponin level
• ECG (sinus tachycardia, RV strain, SI-QIII-TIII)
• CXR
• CT-pulmonary angiogram

Question 11

What are the scoring systems are used to deremine risk of pulmonary embolism?

Answer 11

• Wells score
  
  • Active cancer
  • Bedridden >3days or major surgery within 12 weeks
  • Calf swelling >3cm compared to other leg
  • Collateral (nonvaricose) superficial veins present
  • Entire leg swollen
  • Localised tenderness along deep venous system
  • Pitting oedema confined to symptomatic leg
  • Paralysis, pariesis, or recent plaster immobilisation of lower extremity
  • Previous DVT
  • Alternative diagnosis as likely or more likely (-2)
• Modified Geneva Predictive Risk Score
  
  • Age >65yrs (1)
  • Previous DVT/PE (3)
  • Recent surgery in part month (2)
  • Malignant disease in last year (2)
  • Unilateral lower limb pain (3)
  • Haemoptysis (2)
  • HR 75-94bpm (3)
  • HR ≥95bpm (5)
  • Pain in deep venous palpation of leg and unilateral oedema (4)

Question 12

Management of PE

Answer 12

• Diagnosis
  
  • History, examination andCXR
  • Perform Wells score
    
    • Likely - perform CTPA
    • Unlikely - d-dimer and if positive CTPA
  • Ventilation-perfusion (VQ) scan if:
    
    • Renal impairment
    • Contrast allergy
    • Unsuitable for CTPA due to risk from radiation (i.e. pregnancy)
• Management
  
  • O2 as required
  • Analgesia as required
  • LMWH - started immediately if suspected and delay in getting scan
• Long-term management
  
  • Any of :
    
    • Warfarin (target INR 2-3)
    • NOAC
    • LMWH (in pregnancy or cancer)
  • For:
    
    • 3 months if obvious reversible cause
    • >3 months if cause unclear, recurrent VTE or irreversible underlying cause
    • 6 months in active cancer (then review)
• Thrombolysis in masive PR with haemodynamic response

NB - Patients with PE often have a respiratory alkalosis due to their high RR blowing off CO₂

Question 13

Signs of a tension pneumothorax

Answer 13

• Tracheal deviation away from side of pneumothorax
• Reduced air entry to the affected side
• Increased resonance to percussion on affected side
• Tachycardia
• Hypotension

Question 14

Management of a tension pneumothorax

Answer 14

• Large bore cannula into the second intercostal space in the midclavicular line
• Once pressure is relieved with a cannula then a chest drain is required for definitive management

Question 15

VTE prophylaxis

Answer 15

• Every patient admitted to hospital should be assessed for their risk of VTE
• If at increased risk they should receive prophylaxis with LMWH (i.e. enoxaparin) unless contraindicated (i.e. bleeding, existing anticoagulation)
• They should also use anti-embolic stockings unless contraindicated (i.e. peripheral arterial disease)