Respiratory System 1 out of 359
A 64-year-old man comes to the office because of a productive cough, limited exercise tolerance, and fatigue. He reports that he is always short of breath after climbing up the flights of stairs to his apartment. He has a 15-year history of type 2 diabetes mellitus and a 20-year history of hypertension. Current medications include insulin, amlodipine, ramipril, and a fish oil supplement. He has smoked one pack of cigarettes daily for 45 years. Temperature is 37.6°C (98.9°F), pulse is 83/min, and blood pressure is 133/80 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 96%. Pulmonary examination is shown. Which of the following is the most likely explanation of this patient's symptoms?
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Bacterial infection of the pulmonary parenchymaBacterial infection of the pulmonary parenchyma causes pneumonia, which can manifest with dyspnea and productive cough, both of which are found here. However, pneumonia is typically unilateral, and thus associated with unilateral coarse crackles on lung auscultation. Moreover, pneumonia is associated with fever, and this patient has a normal temperature. Accumulation of fluid in the pleural spaceAccumulation of fluid in the pleural space leads to pleural effusion, which can manifest with dyspnea and cough. However, the cough in pleural effusion is typically nonproductive, and lung auscultation usually discloses decreased breath sounds in the affected side, unlike the bilateral wheezing heard here. Accumulation of fluid in the alveoliAccumulation of fluid in the alveoli leads to pulmonary edema, which can manifest with cough and dyspnea. However, lung auscultation in pulmonary edema typically discloses bilateral fine or coarse crackles (depending on the severity of the edema), rather than wheezing. Obstruction of the lower airwaysThe bibasilar end-expiratory wheezing on lung auscultation in this patient suggests a turbulent passage of air through narrowed (obstructed) lower airways, which occurs both in asthma and chronic obstructive pulmonary disease (COPD) due to bronchial inflammation. These findings, in combination with this patient's productive cough, dyspnea on exertion, and history of heavy smoking, suggest COPD. Additional pulmonary examination findings characteristic of COPD include hyperresonant percussion, decreased breath sounds (“silent lung”), and rhonchi. This patient should undergo further evaluation with pulmonary function tests to confirm the diagnosis.
In a patient with COPD, pulmonary function tests show irreversible airflow limitation (postbronchodilator FEV1/FVC < 0.70). Entry of air into pleural spaceEntry of air into the pleural space leads to pneumothorax, which can manifest with dyspnea, as seen here. Furthermore, this patient's smoking history increases his risk of developing this condition. However, lung auscultation in pneumothorax typically shows unilaterally decreased or absent breath sounds, rather than the bilateral wheezing heard in this patient. Collapse of the alveoliCollapse of the alveoli causes atelectasis, which can manifest with dyspnea. However, lung auscultation in atelectasis typically discloses decreased or absent breath sounds over the affected lobe(s), rather than the bibasilar wheezing heard in this patient.
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