USMLE Step 1 Question of the Week #9

A 55-year-old man presents to physician with complain of difficulty in breathing for last two weeks. He mentions that he coughs frequently over last five years, but he has ignored the symptom because he thought it was due to smoking. He is a chronic smoker for last fifteen years. There is no history of fever or chest pain. On physical examination, his temperature is 98.8ºF (37.1ºC), respirations are 28/minute, pulse rate is 88/minute, and blood pressure is 124/84 mm Hg. Auscultation of chest reveals wheezing and decreased intensity of breath sounds over suprascapular and supramammary regions bilaterally. Hyperresonance is present over the same areas on percussion. Chest radiogram of the man shows hyperinflation of upper lobes of both the lungs. His pulmonary function testing shows FEV₁ 82% of predicted and FEV₁/FVC 0.65. His total lung capacity is increased and diffusing capacity is reduced. His serum α₁-antitrypsin level is normal. Which of the following parts of lower respiratory tract is most likely to be affected maximally in the patient?

A. Bronchioles

B. Terminal bronchioles

C. Respiratory bronchioles

D. Alveolar ducts

E. Alveolar sacs

QID #2311