A 68-year-old man comes to the emergency department due to a 3-day history of worsening sh… — USMLE Step 2 CK

A 68-year-old man comes to the emergency department due to a 3-day history of worsening shortness of breath, increased cough, and a change in sputum color from clear to yellow-green. He has a history of severe chronic obstructive pulmonary disease (COPD) and ischemic cardiomyopathy with a left ventricular ejection fraction of 35%. His home medications include an albuterol inhaler, tiotropium, lisinopril, and carvedilol.

On presentation, his temperature is $38.0^\circ C$ ( $100.4^\circ F$ ), blood pressure is 138/86 mm Hg, pulse is 98/min, and respirations are 24/min. Pulse oximetry is 92% on room air. Physical examination reveals a barrel chest, prolonged expiratory phase, and diffuse bilateral expiratory wheezes without crackles. Jugular venous pressure is 7 cm $H_2O$ . There is trace bilateral lower extremity edema, which the patient states is his baseline.

Laboratory results show:
Leukocyte count: $11,500/mm^3$
B-type natriuretic peptide: 150 pg/mL

Arterial blood gas (room air):
pH: 7.36
$PaCO_2$ : 52 mm Hg
$PaO_2$ : 64 mm Hg
Calculated $HCO_3^-$ : 28 mEq/L

A chest radiograph shows hyperinflated lungs with flattened diaphragms and no focal consolidations or pleural effusions. He is started on supplemental oxygen, nebulized albuterol and ipratropium, and systemic glucocorticoids.

Which of the following is the most appropriate additional step in management?

Oral azithromycinAnswer
B
Intravenous furosemide
C
Intravenous piperacillin-tazobactam and vancomycin
D
Intravenous sodium bicarbonate
E
Intravenous ceftriaxone and oral azithromycin

Answer

Oral azithromycin

The patient is experiencing an acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Antibiotic therapy is indicated in AECOPD when patients exhibit all three cardinal symptoms (increased dyspnea, increased sputum volume, and increased sputum purulence) or two cardinal symptoms if one is increased sputum purulence. This patient clearly meets these criteria. First-line empiric antibiotic options include macrolides (e.g., oral azithromycin), second- or third-generation cephalosporins, or doxycycline. These provide targeted coverage against common respiratory pathogens like Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Selecting a targeted oral agent aligns with antibiotic stewardship principles by avoiding unnecessarily broad or intravenous coverage.

Step-by-Step Solution

Analyze the patient's symptoms against diagnostic criteria.

The patient has increased dyspnea, increased cough, and purulent (yellow-green) sputum, meeting all three cardinal criteria for an acute exacerbation of COPD (AECOPD).

Establishing the presence of cardinal symptoms is necessary to determine if antibiotic therapy is indicated.

Evaluate for alternative or concurrent diagnoses that could explain the presentation.

An acute heart failure exacerbation is ruled out by the normal BNP and absence of pulmonary edema. Community-acquired pneumonia (CAP) is ruled out by the clear chest radiograph.

Patients with COPD often have comorbidities like ischemic cardiomyopathy, requiring careful differentiation to avoid incorrect treatments such as unnecessary diuresis.

Select the appropriate pharmacotherapy based on antibiotic stewardship.

Oral azithromycin is selected because it provides targeted coverage against typical AECOPD pathogens (S. pneumoniae, H. influenzae, M. catarrhalis) without the unnecessarily broad spectrum of piperacillin-tazobactam or ceftriaxone.

Guidelines recommend narrow-spectrum agents (macrolides, advanced cephalosporins, or doxycycline) for uncomplicated AECOPD to minimize resistance and side effects.

Key Concept

Antibiotic therapy is indicated for acute exacerbations of COPD in patients exhibiting increased sputum purulence along with increased dyspnea or sputum volume. First-line targeted agents include macrolides (e.g., azithromycin), and their use over broad-spectrum intravenous regimens is a key principle of antibiotic stewardship.

Estimated Time:1m 30s

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