Hyperinflated lungs are present in many chronic chest conditions in particular COPD and asthma.
This may be evidenced by:
a. Flattened hemidiphragms
b. Hyperlucent lungs ( less bronchovascular markings per cm2)
c. More than 6 anterior or 10 posterior ribs in the mid-clavicular line at the lung diaphragm level.