Paradoxical movement may be absent in a patient with a flail chest due to

Paradoxical movement may be absent in a patient with a flail chest due to

• A. Deep hyperventilation
• B. Intercostal muscle spasms
• C. Decreased respiratory depth
• D. Compensation by the diaphragm

Answer: (B)

Paradoxical movement happens when a free-floating chest wall segment moves in the opposite direction to the rest of the chest during breathing. If the intercostal muscles over that fractured area go into spasm, they effectively clasp and immobilize the segment, preventing it from swinging inward on inspiration and outward on expiration. That stabilization eliminates the paradoxical motion, so you may not observe it even though a flail chest is present. Other ideas don’t explain the absence as reliably: deep hyperventilation would not fix the displaced segment; decreasing respiratory depth lowers overall movement but doesn’t stop the paradoxical shift; and diaphragmatic compensation can modify breathing but doesn’t directly immobilize the flail segment.

Paradoxical movement happens when a free-floating chest wall segment moves in the opposite direction to the rest of the chest during breathing. If the intercostal muscles over that fractured area go into spasm, they effectively clasp and immobilize the segment, preventing it from swinging inward on inspiration and outward on expiration. That stabilization eliminates the paradoxical motion, so you may not observe it even though a flail chest is present. Other ideas don’t explain the absence as reliably: deep hyperventilation would not fix the displaced segment; decreasing respiratory depth lowers overall movement but doesn’t stop the paradoxical shift; and diaphragmatic compensation can modify breathing but doesn’t directly immobilize the flail segment.