An emergency department physician is evaluating a patient who was brought in by family mem… — USMLE Step 2 CK

An emergency department physician is evaluating a patient who was brought in by family members due to severe breathing difficulties that began three days ago. The patient, a retired factory worker, has a known history of severe chronic obstructive pulmonary disease (COPD), heart failure with preserved ejection fraction, and a $40$ -pack-year smoking history. According to his daughter, he has been coughing up increased amounts of thick, yellow-green sputum.

On examination, the $72$ -year-old patient appears in moderate respiratory distress. His temperature is $37.8^\circ\text{C}$ ( $100^\circ\text{F}$ ), blood pressure is $142/86\text{ mm Hg}$ , pulse is $112/\text{min}$ , and respiratory rate is $26/\text{min}$ . Oxygen saturation is $86\%$ on room air. Physical examination reveals a barrel-shaped chest, diffuse expiratory wheezes, and a prolonged expiratory phase. Jugular venous pressure is $6\text{ cm H}_2\text{O}$ , and there is no peripheral edema.

Laboratory and diagnostic data are as follows:

Test	Result	Reference Range
Leukocyte count	$12,500/\text{mm}^3$	$4,500 - 11,000/\text{mm}^3$
Arterial pH	$7.26$	$7.35 - 7.45$
PaCO $_2$	$65\text{ mm Hg}$	$35 - 45\text{ mm Hg}$
PaO $_2$	$52\text{ mm Hg}$	$75 - 105\text{ mm Hg}$
HCO $_3^-$	$28\text{ mEq/L}$	$22 - 28\text{ mEq/L}$
TSH	$1.8\text{ }\mu\text{U/mL}$	$0.4 - 4.0\text{ }\mu\text{U/mL}$
Free T4	$0.7\text{ ng/dL}$	$0.9 - 1.7\text{ ng/dL}$

A sputum culture obtained during a routine clinic visit one week ago grew *Streptococcus pneumoniae* that is susceptible to amoxicillin, azithromycin, and levofloxacin. A chest radiograph demonstrates hyperinflated lungs and flattened diaphragms, without focal consolidation, pleural effusion, or pulmonary venous congestion.

Based on these findings, which of the following is the most appropriate next step in management?

Administer supplemental oxygen, inhaled bronchodilators, systemic glucocorticoids, and oral amoxicillinCevap
B
Administer intravenous furosemide and initiate noninvasive positive-pressure ventilation
C
Calculate the expected arterial carbon dioxide tension using Winter's formula
D
Initiate broad-spectrum empiric therapy with intravenous piperacillin-tazobactam and vancomycin
E
Diagnose primary hypothyroidism and begin levothyroxine therapy

Cevap

Administer supplemental oxygen, inhaled bronchodilators, systemic glucocorticoids, and oral amoxicillin

The patient presents with the three cardinal symptoms of an acute COPD exacerbation: increased dyspnea, increased sputum volume, and increased sputum purulence. The normal jugular venous pressure and lack of pulmonary congestion on the chest radiograph strongly point away from acute decompensated heart failure, despite his history of HFpEF. The arterial blood gas reveals an acute-on-chronic respiratory acidosis requiring immediate medical management. The standard care bundle for an acute COPD exacerbation includes supplemental oxygen (titrated to

88\% - 92\%

), inhaled short-acting bronchodilators, and systemic glucocorticoids. Because he has severe exacerbation symptoms including purulent sputum, antibiotics are indicated. Leveraging the recent sputum culture, targeted therapy with narrow-spectrum amoxicillin is the most appropriate antimicrobial choice, strictly adhering to principles of antibiotic stewardship.

Adım Adım Çözüm

Analyze the patient's presenting symptoms and physical exam findings.

The patient has the cardinal symptoms of a COPD exacerbation (dyspnea, increased sputum volume, and increased sputum purulence) without signs of volume overload (normal JVP, clear CXR).

To differentiate between a primary pulmonary exacerbation and acute decompensated heart failure.

Evaluate the arterial blood gas results.

The ABG demonstrates an acute-on-chronic respiratory acidosis (pH 7.26, PaCO2 65 mm Hg) without the need for Winter's formula calculation.

To determine the severity of respiratory failure and rule out concurrent metabolic acidosis.

Review the recent sputum culture and laboratory data.

A known pansusceptible Streptococcus pneumoniae isolate is identified, and thyroid labs indicate euthyroid sick syndrome rather than primary hypothyroidism.

To practice proper antibiotic stewardship and avoid misdiagnosing secondary conditions.

Formulate the optimal treatment plan.

Select a regimen of supplemental oxygen, short-acting bronchodilators, systemic glucocorticoids, and narrow-spectrum targeted antibiotics (amoxicillin).

This constitutes the standard, evidence-based care bundle for a purulent COPD exacerbation with a known susceptible pathogen.

Anahtar Kavram

Diagnosis and management of acute chronic obstructive pulmonary disease (COPD) exacerbations, including targeted antibiotic stewardship.

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