it is mentioned that foreign body causes decreased air entery inti the lungs.Then how is hyperinflation of lungs possible?
Also in the explanation, it is mentioned that foreign body does allow air to enter lungs and does not allow it to escape.
Hyperinflation of lungs in case of foreign body occurs in partial or incomplete obstruction leading to ball valve mechanism. The air entry will also be reduced due to partial obstruction .
Complete obstruction leads to atelectasis .