Pneumothorax Flashcards
What happens to pressure in the lungs on inspiration?
- Intrathoracic pressure drops
- Air moves from high pressure (outside body) to low pressure (inside lungs)
- Pleural space is sealed off so no air can move into potential space
What happens to pressure in the lungs at the end of inspiration?
- Pressures have equalised between lung and atmosphere
- Larger pressure difference between pleural space and inside of lungs
What allows a pneumothorax to form?
- If pleura is broken, air will move into potential pleural space
- Because pleural space has much lower pressure than both inside lung and outside body
What happens if a pneumothorax is small?
- If damage to pleura is small, it may seal itself spontaneously
- Especially if there is little pressure difference between pleural space and inside lungs
What are the categories of pneumothorax?
- Primary (healthy)
- Secondary (underlying lung pathology)
- Iatrogenic
- Can be simple or tension pneumothorax
What symptoms might someone having a pneumothorax experience?
- Sharp and stabbing pain
- Can point to location of pain with a finger
- Pain doesn’t move or worsen
- Normal breathing
- Normal ECG and bloodwork
What is an important diagnostic test if a pneumothorax is suspected?
- CXR
What is a simple spontaneous primary pneumothorax?
- Small tear in visceral pleura
- Air leaks into pleural space when breathing in
- Pleura seals itself
- Air in pleural space is reabsorbed
How are small pneumothoraxes treated?
- If patient is not breathless and pneumothorax is <2cm
- Patient can be discharged home from A&E
- Follow up in 2 weeks with CXR
What is a simple spontaneous secondary pneumothorax?
- Underlying lung pathology punctures pleura
- More air escapes into pleural space
- Puncture seals itself once pressure is reduced
What might cause a pneumothorax in COPD patients?
- Blebs/Bullae can rupture
- Outpouchings from COPD - they are thin walled
How is a simple spontaneous secondary pneumothorax treated?
- Needle aspiration of up to 2.5L
- High flow oxygen + observe for 24 hours
- May need a chest drain
Outline how needle aspiration is carried out?
- Using a needle, valve and syringe
- Small amount of water in syringe
- Push through chest wall until air bubbles appear in syringe (indicates that an airspace has been entered
- Can aspirate up to 2.5L
How do we know where to insert a needle for aspiration of a pneumothorax?
- Anatomical safe triangle
- Insert into 4th or 5th intercostal space
- No major blood vessels
- Avoid neurovascular bundle
What are the borders of the anatomical safe triangle?
- Anterior border of Latissimus Dorsi
- Posterior edge of pectoral major
- Axilla superiorly
- Inferior border is 5th intercostal space
What kind of oxygen therapy is used to treat pneumothorax?
- High flow oxygen even if sats are normal
- High concentration of O2 in pleural space
- Oxygen is reabsorbed faster than nitrogen (body can reabsorb O2 in pleural space)
- Significantly better resolution compared to no oxygen therapy
What does low pO2 mean in a pneumothorax?
- Concentration of dissolved O2 in blood is low
- Gas exchange significantly impaired due to reduced SA of lung
Why does the lung shrink in pneumothorax?
- Lung collapses
- Pleural seal is lost
- No suction holding lung to wall
- Elastic recoil of lung causes it to shrink/collapse
What could cause a simple iatrogenic pneumothorax?
- Punctured parietal and visceral pleurae e.g. caused by needle
- If too much of visceral layer tears, air enters pleural cavity
- Harder for pleural cavity to seal itself
How are larger simple pneumothoraxes treated?
- Very symptomatic
- Type 1 respiratory failure
- Unlikely to resolve spontaneously
- Will need a chest drain
How does a water-sealed chest drain work?
- Inserted in safe triangle
- Tube left in pleural cavity
- Free end submerged in water
- Creates a 1-way valve
- Keep drainage below patient to prevent siphoning
- ‘Swinging and bubbling’ means drain is working
What is a tension pneumothorax?
- Sometimes damaged pleura forms a one way valve
- Very bad!
- Each breath fills pleural cavity and increases its pressure
- Air can’t escape on exhalation so pleural cavity is filled with more and more air
- Increased pressure collapses lung and compresses heart
- Squashed heart can’s pump blood
How is emergency needle decompression carried out?
- If tension pneumothorax is suspected, decompress before any investigations
- Do not wait to get a CXR
- 2nd intercostal space midclavicular line
- Will buy time for a chest drain
- 30% failure rate
What are the signs of a pneumothorax?
- Reduced breath sounds
- Hypoxia
- Hyper resonance
- Flail segment
- Surgical emphysema
