Question

In which of the following conditions is paradoxical respiration observed?

• A. Stove-in chest
• B. Flail chest
• C. Pneumothorax
• D. Haemopneumothorax

Hint:

Think about which injury frees a segment of the rib cage to move independently of the rest of the chest wall.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question is asking which of these chest injuries classically produces paradoxical respiration, where part of the chest wall moves in the opposite direction to the rest of the chest during breathing.

Step 2: Key Concept or Approach:
Paradoxical respiration happens when a segment of the rib cage loses its bony continuity with the rest of the chest wall on both ends, so it is no longer pulled outward by the chest wall as a whole during inspiration - instead it is pushed and pulled purely by the pressure changes inside the chest.

Step 3: Working Through the Options:
Flail chest occurs when three or more consecutive ribs are fractured in two places each, creating a free-floating segment of chest wall. During inspiration, while the rest of the chest expands outward, this flail segment is sucked inward by the negative intrathoracic pressure, and on expiration it bulges outward - this in-and-out movement opposite to the rest of the chest wall is exactly what paradoxical respiration means. A stove-in chest describes a severely depressed, crushed segment of the chest wall, but without the specific double-fracture pattern that frees a segment to move independently, it does not classically produce this sign. Pneumothorax and haemopneumothorax cause lung collapse and breathlessness but do not, by themselves, make a segment of chest wall move in reverse.

Step 4: Conclusion:
Paradoxical respiration is seen in flail chest.