What is the definition of a pneumothorax and what are the causes?
- Air within the pleural cavity
- Traumatic, iatrogenic (biopsy, TBLB, aspiration) and spontaneous (primary - healthy, and secondary - underlying lung disease)
Why is tension pneumothorax so dangerous and how is it treated?
- Increased intrapleural pressure
- Venous return impaired, CO and BP fall, and PEA arrest occurs
- Venflow in 2nd intercostal space in midclavicular line to relieve pressure
What is the pathophysiology of primary spontaneous pneumothorax?
- 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
What is the pathophysiology of secondary spontaneous pneumothorax?
- Inherent weakness in lung tissue
- Increased airway pressure
- Pressure gradient leads to lung collapse
What are the diagnostic features of spontaneous pneumothorax?
- 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
How is spontaneous pneumothorax managed?
- Observation if small
- Intercostal drain with underwater seal
- VATS if not resolved after 5 days
What is the pathophysiology of pulmonary embolism?
- 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
What are the risk factors for pulmonary embolism?
- Surgery < 12 weeks previously
- Immobilisation >3 days in previous 4 weeks
- Previous DVT/PTE
- Long distance travel
- Oestrogen OCP use
- Protein S deficiency
- Protein C deficiency
- Factor V Leiden
- Prothrombin G20210A
What are teh signs and symptoms of pulmonary embolism?
- Pleuritic chest pain
- Tachycardia >100bpm
- Signs of peripheral DVT
What investigations are used for pulmonary embolism?
- D-dimer (rased >230mg/L)
- ABG (respiratory alkalosis, hypoxaemia)
- Troponin level
- ECG (sinus tachycardia, RV strain, SI-QIII-TIII)
- CT-pulmonary angiogram
What are the factors of the Modified Geneva Predictive Risk Score for pulmonary embolism?
- 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)
How is pulmonary embolism treated?
- For massive PE (BP <90mmHg or drop >40mmHg in <15 mins) give unfractionated IV heparinm fluids and thrombolysis with alteplase
- For sub-massive PR give LMWH then oral anticoagulation for 3 months