During an overnight shift in the emergency department, a 73-year-old woman is evaluated fo… — USMLE Step 2 CK

During an overnight shift in the emergency department, a $73$ -year-old woman is evaluated for severe, acute-onset respiratory distress. She reports waking up abruptly with a choking sensation and an inability to catch her breath. Her medical history includes chronic obstructive pulmonary disease, hypertension, and type 2 diabetes mellitus. Her home medications include amlodipine, metformin, and a tiotropium inhaler. Her temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), blood pressure is $182/104\text{ mm Hg}$ , pulse is $115\text{/min}$ and regular, and respirations are $28\text{/min}$ . Pulse oximetry shows an oxygen saturation of $86\%$ on room air. The patient is visibly anxious, diaphoretic, and speaking in short phrases. Jugular venous pressure is estimated at $10\text{ cm H}_2\text{O}$ . Chest auscultation reveals diffuse, bilateral expiratory wheezes and prominent fine crackles in the lower lung fields. Cardiac examination demonstrates a normal $S_1$ and $S_2$ with an audible $S_3$ gallop. Trace bilateral pitting edema is present at the ankles. Which of the following is the most appropriate initial pharmacotherapy for this patient?

A
Inhaled albuterol and intravenous methylprednisolone
B
Intravenous ceftriaxone and azithromycin
Intravenous furosemideAnswer
D
Intravenous piperacillin-tazobactam
E
Intravenous magnesium sulfate

Answer

Intravenous furosemide

The patient is presenting with acute decompensated heart failure (ADHF), characterized by paroxysmal nocturnal dyspnea, hypoxemia, severe hypertension, elevated jugular venous pressure, bibasilar crackles, and an

S_3

gallop. The diffuse wheezing observed is a phenomenon known as 'cardiac asthma', which results from peribronchial edema secondary to elevated pulmonary capillary wedge pressure compressing the small airways. Because the primary pathophysiology is fluid overload and elevated left ventricular filling pressures, the most appropriate initial pharmacotherapy is an intravenous loop diuretic (e.g., furosemide). This rapidly reduces intravascular volume, decreases pulmonary congestion, and alleviates respiratory distress. In the setting of severe hypertension, intravenous vasodilators (such as nitroglycerin) are often used adjunctively to reduce preload and afterload.

Step-by-Step Solution

Identify the primary clinical syndrome from the patient's presentation.

The patient presents with paroxysmal nocturnal dyspnea, severe hypoxia, and hypertension, indicating an acute cardiopulmonary event.

Establishing the acuity and predominant symptoms narrows the differential diagnosis to emergent respiratory or cardiac etiologies.

Differentiate between an exacerbation of underlying COPD and acute decompensated heart failure (ADHF).

Physical examination reveals an

S_3

gallop, elevated jugular venous pressure, and bibasilar crackles alongside wheezing.

While the patient has a history of COPD and presents with wheezing, the specific presence of a gallop rhythm, venous congestion, and crackles points definitively to cardiogenic pulmonary edema (volume overload) rather than isolated bronchospasm.

Determine the most appropriate initial management for acute decompensated heart failure.

Intravenous furosemide (a loop diuretic) is selected as the primary pharmacotherapy.

First-line therapy for ADHF with volume overload focuses on rapid diuresis to reduce pulmonary capillary hydrostatic pressure, thereby relieving pulmonary edema and improving oxygenation.

Key Concept

Patients with acute decompensated heart failure can present with prominent wheezing ('cardiac asthma') mimicking a COPD exacerbation; differentiation relies on signs of left-sided (e.g.,

S_3

gallop, crackles) and right-sided (e.g., elevated JVP) volume overload, with initial treatment requiring intravenous loop diuretics.

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