Which of the following can cause decreased breath sounds? 1. Air or fluid in the pleural space 2. Hyperinflation of lung tissue 3. Mucus plugging of the airways 4. Shallow or slow breathing

a. 2 and 4 only
b. 1, 2, and 3 only
c. 1, 2, 3, and 4
d. 2, 3, and 4 only

ANS: C
Airways plugged with mucus and hyperinflated lung tissue attenuate sounds through the lungs. Air or fluid in the pleural space and obesity also reduce sound transmission through the chest wall.