Bilateral Decreased Excursion with Low Resting Diaphragm
The diaphragm moves less than three centimeters and rests abnormally low in the chest cavity, pushed down by chronically hyperinflated lungs.
Description
The examiner percusses downward on the patient's back to find the transition point from resonant lung tissue to dull abdominal tissue during both full inhalation and full exhalation. This classic physical exam skill identifies the mechanical displacement of respiratory muscles. It highlights how trapped air permanently alters the anatomical structure of the chest cavity.