Hemithorax Asymmetry

Hemithorax is Symmetrical in Size

• Asymmetry of hemithorax can occur whenever the pleural pressures are not equal on both sides.
• Size of hemithorax is determined by pleural negative pressure.
  • Smaller hemithorax, when the pleural negative pressure is high
  • Larger hemithorax, when the pleural negative pressure is lost
• Chest wall tends to spring out, while lung likes to recoil to resting state, when not held by the negative pleural pressure.
• The balance of forces between chest wall and lung recoil determines the position of hemithorax .
• The maximum is, total lung capacity position, as the ribs are anchored to the sternum and vertebra.