A 66-year-old man comes to the emergency department due to shortness of breath. The symptoms started a week ago with a dry cough and exertional dyspnea. Medical history includes hypertension and recent stenting for double-vessel coronary artery disease. He was hospitalized 6 months ago for pneumonia. He has a 35-pack-year smoking history. Temperature is 37.2 C (98.9 F), blood pressure is 160/90 mm Hg, and pulse is 90/min and regular. On examination, the patient is in mild respiratory distress, but he can speak in full sentences. Chest auscultation reveals decreased breath sounds at the lung bases, bilateral crackles, and occasional wheezes. His arterial blood gas shows: Which of the following is the most likely explanation for this patient's symptoms?

Question

A 66-year-old man comes to the emergency department due to shortness of breath.  The symptoms started a week ago with a dry cough and exertional dyspnea.  Medical history includes hypertension and recent stenting for double-vessel coronary artery disease.  He was hospitalized 6 months ago for pneumonia.  He has a 35-pack-year smoking history.  Temperature is 37.2 C (98.9 F), blood pressure is 160/90 mm Hg, and pulse is 90/min and regular.  On examination, the patient is in mild respiratory distress, but he can speak in full sentences.  Chest auscultation reveals decreased breath sounds at the lung bases, bilateral crackles, and occasional wheezes.  His arterial blood gas shows:  Which of the following is the most likely explanation for this patient's symptoms?

Quizplus · Accepted Answer

This patient most likely has an exacerbation of congestive heart failure (CHF). His history of coronary artery disease (with risk factors of uncontrolled hypertension and smoking) puts him at risk for heart failure due to left ventricular dysfunction. On pulmonary examination, patients with worsening CHF will commonly have bibasilar crackles. Decreased breath sounds at the bases could be due to pleural effusions from CHF. Wheezing can occasionally be present in heart failure (ie, cardiac asthma). Although this patient with an extensive smoking history may have concomitant chronic obstructive pulmonary disease (COPD), a CHF exacerbation is more likely than a COPD exacerbation given his crackles and his arterial blood gas (ABG) findings of hypoxia as well as hypocapnia and respiratory alkalosis; by contrast, a COPD exacerbation is less likely to cause bilateral crackles and more likely to cause significant (rather than occasional) wheezing and respiratory acidosis (acute or acute-on-chronic) due to CO₂ retention (Choice B). More specific testing for CHF would include assessment of the B-type natriuretic peptide (BNP) and the pulmonary capillary wedge pressure. (Choice C) Pulmonary embolism presents with acute-onset dyspnea, tachypnea, and pleuritic chest pain. Patients have hypoxemia and respiratory alkalosis with a widened A-a gradient. This patient's bilateral crackles and progressive course make CHF exacerbation more likely. (Choice D) Pneumothorax typically presents with acute-onset pleuritic chest pain and dyspnea when it is symptomatic. Physical examination reveals hyperresonance to percussion, diminished tactile and vocal fremitus, and decreased or absent breath sounds in the affected area. (Choice E) Adult respiratory distress syndrome can have a similar presentation but tends to be acute. This patient's history of progressively worsening dyspnea and his risk factors of coronary artery disease suggest CHF as the most likely diagnosis. (Choice F) A panic attack is unlikely to progress over a week or to cause crackles or hypoxia. Educational objective: Congestive heart failure exacerbation can cause tachypnea as left ventricular dysfunction allows fluid to pool in the lungs, causing a pleural effusion and hypoxemia due to reduced ventilation. Tachypnea causes hypocapnia and respiratory alkalosis. Examination typically shows signs of fluid overload, S3 and S4 gallops, cardiomegaly, and bibasilar crackles in the lungs.

A 66-Year-Old Man Comes to the Emergency Department Due to Shortness