A 64-year-old man is evaluated for worsening dyspnea on exertion. He has a 40-pack-year smoking history. The lungs are hyperresonant on percussion and there is diffuse wheezing on auscultation. Chest x-ray reveals a flattened diaphragm with a narrow mediastinum, and there are decreased bronchovascular markings in the peripheral lung region. Which of the following lung volume patterns is most likely to be present in this patient? (Each bar represents total lung capacity with different volumes as marked.)

Question

A 64-year-old man is evaluated for worsening dyspnea on exertion.  He has a 40-pack-year smoking history.  The lungs are hyperresonant on percussion and there is diffuse wheezing on auscultation.  Chest x-ray reveals a flattened diaphragm with a narrow mediastinum, and there are decreased bronchovascular markings in the peripheral lung region.  Which of the following lung volume patterns is most likely to be present in this patient?  (Each bar represents total lung capacity with different volumes as marked.)

Quizplus · Accepted Answer

11ec160b_3cdc_b015_9249_4f222a670bf7_MD0001_00 In chronic obstructive pulmonary disease (COPD), air flow obstruction and hyperinflation (air trapping) cause increased residual volume (RV) and a consequent increase in total lung capacity (TLC). Because the increase in RV is greater than the increase in TLC, the RV/TLC ratio is increased. Airway obstruction also causes decreased forced vital capacity (FVC) and a more profound decrease in forced expiratory volume in one second (FEV1), resulting in a decreased FEV1/FVC ratio. In the above graphs, the top section represents the inspiratory reserve volume, the middle section represents the tidal volume plus the expiratory reserve volume, and the bottom section represents the RV. In COPD, an increase in RV and TLC is expected, as is a decrease in FVC. (Choice A) In restrictive lung disease, the TLC, RV, FVC, and FEV1 are all reduced, but the FEV1/FVC ratio is normal or increased. (Choice C) This graph shows an increased TLC and FVC with a normal RV. Such an increase in FVC may be seen in elite athletes. (Choice D) This graph shows a decrease in TLC and an increase in RV. As changes in these parameters are not typically discordant, this would be a rare clinical finding. Educational objective: In chronic obstructive pulmonary disease, air-trapping leads to an increase in residual volume (RV) and total lung capacity (TLC), as well as an increase in the RV/TLC ratio. Airway obstruction causes a decrease in forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and the FEV1/FVC ratio.

A 64-Year-Old Man Is Evaluated for Worsening Dyspnea on Exertion