A 73-year-old man is brought to the emergency department by his daughter due to a 3-day hi… — USMLE Step 2 CK

A $73$ -year-old man is brought to the emergency department by his daughter due to a $3$ -day history of progressively worsening shortness of breath and a severe, productive cough. The daughter reports that his sputum, which is usually scant and clear, has become thick, abundant, and yellowish-green. He has a $45$ -pack-year smoking history and was diagnosed with severe chronic obstructive pulmonary disease (COPD) $5$ years ago. His medical history is otherwise notable for hypertension. He has no history of heart failure or recent hospitalizations.

Vital signs are temperature $37.4^\circ\text{C}$ ( $99.3^\circ\text{F}$ ), blood pressure $142/86\text{ mm Hg}$ , pulse $112/\text{min}$ , and respirations $28/\text{min}$ . Pulse oximetry is $86\%$ on room air.

On physical examination, the patient is alert but in moderate respiratory distress, using accessory muscles of respiration. Lung auscultation reveals a prolonged expiratory phase with diffuse expiratory wheezes bilaterally. Heart sounds are normal with no murmurs or gallops. Jugular venous pressure is normal, and there is no peripheral edema.

A chest radiograph demonstrates hyperinflated lungs with flattened hemidiaphragms, without focal infiltrates or signs of pulmonary vascular congestion.

Arterial blood gas analysis on room air reveals:

Parameter	Value
$\text{pH}$	$7.26$
$\text{PaCO}_2$	$70\text{ mm Hg}$
$\text{PaO}_2$	$52\text{ mm Hg}$
$\text{HCO}_3^-$	$31\text{ mEq/L}$

Which of the following interventions are appropriate in the acute management of this patient? (Select all that apply)

Initiation of noninvasive positive-pressure ventilationAnswer
Administration of oral azithromycinAnswer
C
Intravenous administration of furosemide
D
Intravenous administration of piperacillin-tazobactam and vancomycin
E
Intravenous administration of sodium bicarbonate

Answer

The correct interventions are the initiation of noninvasive positive-pressure ventilation and the administration of oral azithromycin.

The correct answers are the initiation of noninvasive positive-pressure ventilation (NPPV) and the administration of oral azithromycin. This patient is experiencing a severe acute exacerbation of COPD. The arterial blood gas demonstrates an acute-on-chronic respiratory acidosis (pH 7.26, PaCO2 70 mm Hg). NPPV is the preferred initial ventilatory support for AECOPD patients with respiratory acidosis (pH < 7.35) or severe clinical dyspnea. It improves oxygenation, decreases the work of breathing, and significantly lowers both mortality and the need for endotracheal intubation. Additionally, because the patient has the classic triad of increased dyspnea, increased sputum volume, and increased sputum purulence, antibiotic therapy is indicated. A macrolide (like azithromycin), a respiratory fluoroquinolone, or amoxicillin-clavulanate provides appropriate targeted coverage against the most common pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis).

Step-by-Step Solution

Identify the primary diagnosis and clinical severity.

The patient is experiencing a severe acute exacerbation of COPD, presenting with respiratory distress and all three cardinal symptoms (increased dyspnea, increased sputum volume, and sputum purulence).

Recognizing the symptom triad dictates the need for specific medical interventions, such as empirical antibiotic therapy.

Analyze the arterial blood gas (ABG) findings.

The ABG shows an acute-on-chronic respiratory acidosis (pH < 7.35 and highly elevated PaCO2) with appropriate metabolic compensation (elevated HCO3-) and severe hypoxemia.

Acid-base status directly determines the need for advanced ventilatory support beyond standard bronchodilators.

Select the appropriate evidence-based interventions.

Noninvasive positive-pressure ventilation (NPPV) should be initiated for the acute respiratory acidosis, and a targeted antibiotic like oral azithromycin should be prescribed.

NPPV decreases mortality and the need for intubation in AECOPD with respiratory acidosis, while targeted antibiotics reduce treatment failure when cardinal signs of bacterial infection are present.

Key Concept

The acute management of a severe COPD exacerbation includes noninvasive positive-pressure ventilation (NPPV) for acute respiratory acidosis (pH < 7.35) and targeted antibiotics (e.g., macrolides) when patients present with increased sputum purulence.

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