A 72-year-old man is brought to the emergency department by emergency medical services due… — USMLE Step 2 CK

A 72-year-old man is brought to the emergency department by emergency medical services due to severe, progressively worsening shortness of breath that began abruptly $4\text{ hours}$ ago. Over the past week, he has noticed increased swelling in his lower legs and difficulty sleeping flat. He has a history of essential hypertension, type 2 diabetes mellitus, and a 50-pack-year smoking history. Current medications include metformin, sitagliptin, and amlodipine. On arrival, he is visibly distressed, diaphoretic, and using accessory muscles of respiration. Temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), pulse is $118/\text{min}$ , blood pressure is $178/102\text{ mm Hg}$ , and respirations are $28/\text{min}$ . Pulse oximetry shows an oxygen saturation of $88\%$ on room air. Physical examination reveals jugular venous distention to the angle of the mandible while the patient is sitting upright. Lung auscultation reveals prolonged expiration, diffuse expiratory wheezes, and fine crackles at both lung bases. Cardiac auscultation reveals a regular tachycardia and an S3 gallop. Bilateral 2+ pitting edema is present up to the mid-calves.

Laboratory studies show:
Leukocyte count: $8,400/\text{mm}^3$
Serum sodium: $136\text{ mEq/L}$
Serum potassium: $4.1\text{ mEq/L}$
Serum bicarbonate: $16\text{ mEq/L}$
Blood urea nitrogen: $32\text{ mg/dL}$
Serum creatinine: $1.4\text{ mg/dL}$
Serum lactate: $4.0\text{ mmol/L}$
Thyroid-stimulating hormone (TSH): $1.8\ \mu\text{U/mL}$ (Normal: $0.4 - 4.0\ \mu\text{U/mL}$ )
Free thyroxine (T4): $0.6\text{ ng/dL}$ (Normal: $0.9 - 1.7\text{ ng/dL}$ )

Arterial blood gas on room air:
pH: $7.34$
pCO2: $30\text{ mm Hg}$
pO2: $58\text{ mm Hg}$

A chest radiograph shows cardiomegaly, bilateral perihilar opacities, and fluid in the horizontal fissure. Gram stain of the frothy sputum shows rare polymorphonuclear leukocytes and abundant normal respiratory flora without predominant organisms.

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

A
Administration of inhaled albuterol and systemic glucocorticoids
B
Initiation of intravenous piperacillin-tazobactam
Intravenous administration of furosemideAnswer
D
Intravenous administration of levothyroxine
E
Intravenous administration of sodium bicarbonate

Answer

Intravenous administration of furosemide is the most appropriate next step to manage the acute volume overload and cardiogenic pulmonary edema.

The correct answer addresses the patient's acute decompensated heart failure (ADHF). The patient presents with classic signs of left and right-sided heart failure: severe dyspnea, jugular venous distention, an S3 gallop, bibasilar crackles, and peripheral edema. The chest radiograph confirms cardiogenic pulmonary edema with perihilar alveolar opacities and cardiomegaly. The primary goal in the acute management of ADHF is the rapid reduction of cardiac preload and pulmonary capillary wedge pressure, which is most effectively achieved with intravenous loop diuretics such as furosemide.

Step-by-Step Solution

Analyze the clinical presentation and physical examination findings.

The patient exhibits severe acute respiratory distress, jugular venous distention, an S3 gallop, bibasilar crackles, and pitting edema.

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

Differentiate the cause of wheezing using radiographic and laboratory data.

The chest radiograph shows cardiomegaly and perihilar opacities (pulmonary edema).

Despite a smoking history and wheezing ('cardiac asthma' caused by peribronchial edema), the imaging and physical exam confirm a cardiogenic etiology rather than a primary COPD exacerbation.

Interpret the acid-base and thyroid laboratory findings to rule out confounding complications.

Calculated expected

pCO_2 = 1.5 \times 16 + 8 = 32 \pm 2

. The measured

pCO_2

30\text{ mm Hg}

, indicating a fully compensated metabolic acidosis. TSH is normal with a low T4.

The acid-base status is perfectly compensated, eliminating the need for sodium bicarbonate. The thyroid labs indicate euthyroid sick syndrome, requiring no endocrine intervention.

Determine the most appropriate immediate intervention.

Select an intravenous loop diuretic.

First-line management for ADHF requires rapid preload reduction to relieve pulmonary congestion.

Key Concept

Diagnosis and acute management of acute decompensated heart failure (ADHF) presenting with cardiogenic pulmonary edema and cardiac asthma.

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