A 74-year-old man is brought to the emergency department due to acute worsening of shortne… — USMLE Step 2 CK

A $74$ -year-old man is brought to the emergency department due to acute worsening of shortness of breath and severe agitation. He has a history of ischemic cardiomyopathy with a left ventricular ejection fraction of $35\%$ , severe chronic obstructive pulmonary disease (COPD), and hypothyroidism. Over the last $2$ days, he has had an increased cough productive of white sputum and progressive orthopnea. His current medications include lisinopril, carvedilol, tiotropium, levothyroxine, and as-needed albuterol.

Vital signs:
Temperature: $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ )
Blood pressure: $178/102\text{ mmHg}$
Heart rate: $118/\text{min}$
Respiratory rate: $28/\text{min}$
SpO $_2$ : $84\%$ on room air

Physical examination reveals an agitated man in severe respiratory distress, using accessory muscles of respiration. Jugular venous distension is prominent at $12\text{ cm H}_2\text{O}$ . Auscultation of the lungs reveals prolonged expiration with loud, diffuse bilateral wheezing, but no crackles are distinctly appreciated. Cardiac auscultation reveals a regular tachycardia; a third heart sound ( $S_3$ ) is present. Trace bilateral lower extremity edema is noted.

Arterial blood gas on room air:
pH: $7.28$
PaCO $_2$ : $60\text{ mmHg}$
PaO $_2$ : $52\text{ mmHg}$
HCO $_3^-$ : $27\text{ mEq/L}$

Thyroid-stimulating hormone (TSH) is $4.5\text{ \mu U/mL}$ (normal: $0.5$ - $5.0\text{ \mu U/mL}$ ), and free T4 is $1.1\text{ ng/dL}$ (normal: $0.9$ - $1.7\text{ ng/dL}$ ). A chest radiograph shows cardiomegaly and prominent interstitial markings without focal consolidation.

Which of the following is the most appropriate next step in the management of this patient?

A
Inhaled albuterol, inhaled ipratropium, and systemic methylprednisolone
B
Intravenous sodium bicarbonate administration
Intravenous furosemide and noninvasive positive-pressure ventilationAnswer
D
Intravenous levothyroxine and hydrocortisone
E
Intravenous levofloxacin and obtaining blood cultures

Answer

The most appropriate next step is administering intravenous furosemide and noninvasive positive-pressure ventilation.

The correct intervention addresses the patient's acute decompensated heart failure (ADHF) and associated respiratory failure. The clinical picture is heavily weighted toward ADHF: elevated jugular venous pressure, an

S_3

gallop, trace edema, and radiographic cardiomegaly with interstitial prominence. While the patient has a history of COPD and prominent wheezing, this presentation represents 'cardiac asthma'—airway narrowing caused by peribronchial edema rather than primary bronchospasm. The arterial blood gas demonstrates an acute respiratory acidosis (

pH

7.28

PaCO_2

60\text{ mmHg}

) secondary to respiratory muscle fatigue and pulmonary congestion. The most appropriate initial step is administering intravenous loop diuretics (e.g., furosemide) to reduce total body volume, combined with noninvasive positive-pressure ventilation (NIPPV). NIPPV is highly effective in ADHF as it forces alveolar fluid back into the interstitium, improves oxygenation, decreases the work of breathing, and lowers both cardiac preload and afterload by increasing intrathoracic pressure.

Step-by-Step Solution

Analyze the patient's hemodynamic and physical examination findings.

The patient exhibits severe hypertension, hypoxia, elevated jugular venous pressure, an

S_3

gallop, and cardiomegaly on chest radiograph.

These findings are hallmark signs of volume overload and acute decompensated heart failure (ADHF).

Interpret the pulmonary findings in the context of the cardiovascular exam.

The diffuse wheezing is identified as 'cardiac asthma'—bronchospasm secondary to pulmonary edema—rather than a primary COPD exacerbation.

Differentiating ADHF from COPD is critical because the initial treatments differ vastly; the presence of an

S_3

and elevated JVP confirms a cardiac etiology.

Select the appropriate therapeutic intervention for ADHF with respiratory failure.

Intravenous loop diuretics (furosemide) to reduce fluid overload and noninvasive positive-pressure ventilation (NIPPV) to support respiration.

NIPPV rapidly improves oxygenation, decreases the work of breathing, and beneficially reduces both preload and afterload in patients with ADHF.

Key Concept

The clinical differentiation of acute decompensated heart failure ('cardiac asthma') from COPD exacerbation, and the role of NIPPV in managing acute cardiogenic pulmonary edema.

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