A 68-year-old man comes to the office for gradually increasing shortness of breath. He initially experienced symptoms with exertion but now feels short of breath at rest. The patient has smoked 2 packs of cigarettes per day for 40 years. Blood pressure is 138/78 mm Hg, pulse is 80/min, and respirations are 22/min. The chest x-ray is shown in the image below: Which of the following measures is most likely increased in this patient?

Question

A 68-year-old man comes to the office for gradually increasing shortness of breath.  He initially experienced symptoms with exertion but now feels short of breath at rest.  The patient has smoked 2 packs of cigarettes per day for 40 years.  Blood pressure is 138/78 mm Hg, pulse is 80/min, and respirations are 22/min.  The chest x-ray is shown in the image below:  Which of the following measures is most likely increased in this patient?

Quizplus · Accepted Answer

11ec160b_3b35_1b59_9249_8d0f30393ee0_MD0001_00 This patient's presentation with progressive shortness of breath, significant smoking history, and hyperinflation on chest x-ray (flattened diaphragm, narrowed mediastinum) is consistent with chronic obstructive pulmonary disease (COPD). COPD causes air trapping and hyperinflation of the lungs, so these patients breathe at higher baseline lung volumes (higher functional residual capacity). The volume of air in the lungs that is not respired, the residual volume (RV), is substantially increased. The total lung capacity (TLC) increases as well, but to a lesser extent than RV. Therefore, the fraction of air in the lungs that is not involved in respiration, the RV/TLC ratio, is also increased. A high RV/TLC ratio correlates with poor outcomes in patients with COPD. (Choice A) Diffusing capacity of the lung for carbon monoxide (DLCO) is decreased in COPD due to emphysematous destruction of the alveolar-arterial membrane. (Choices B, C, and D) Both forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) are decreased in COPD due to airway obstruction. Because FEV1 is decreased more than FVC, the FEV1/FVC ratio is also decreased (<0.7 in COPD). Educational objective: Chronic obstructive pulmonary disease causes air trapping and hyperinflation; consequently, these patients breathe at higher baseline lung volumes (higher functional residual capacity). The volume of air in the lungs that is not respired (residual volume) increases substantially, as does the fraction of air in the lungs that is not involved in respiration (residual volume/total lung capacity ratio). __________ References: The prognostic value of residual volume/total lung capacity in patients with chronic obstructive pulmonary disease. (http://www.ncbi.nlm.nih.gov/pubmed/26425043)

A 68-Year-Old Man Comes to the Office for Gradually Increasing