An 82-year-old man arrives at the emergency department accompanied by his daughter due to … — USMLE Step 2 CK

An $82$ -year-old man arrives at the emergency department accompanied by his daughter due to a $3$ -day history of progressively worsening difficulty breathing. He states he cannot sleep lying flat and requires three pillows at night. Medical history is significant for coronary artery disease with a previous myocardial infarction, type 2 diabetes mellitus, and severe chronic obstructive pulmonary disease (COPD). His current medications include lisinopril, metoprolol succinate, and a daily tiotropium inhaler.

Vital signs are:
Temperature: $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ )
Blood pressure: $158/92\text{ mm Hg}$
Pulse: $115/\text{min}$
Respirations: $28/\text{min}$
Oxygen saturation: $85\%$ on room air

Physical examination shows a patient in acute respiratory distress using accessory muscles. The jugular venous pressure is distended to $12\text{ cm H}_2\text{O}$ . Auscultation of the chest reveals diminished breath sounds with prolonged expiration, diffuse expiratory wheezes, and dullness to percussion at the lung bases. Cardiac examination reveals a regular tachycardia, a normal $S_1$ and $S_2$ , and an extra low-frequency heart sound occurring just after $S_2$ .

Laboratory and arterial blood gas (room air) results are as follows:

Parameter	Value	Reference Range
B-type natriuretic peptide (BNP)	$920\text{ pg/mL}$	$<100\text{ pg/mL}$
Thyroid-stimulating hormone (TSH)	$5.1\text{ }\mu\text{U/mL}$	$0.4-4.0\text{ }\mu\text{U/mL}$
Free thyroxine (T4)	$1.0\text{ ng/dL}$	$0.9-1.7\text{ ng/dL}$
pH	$7.28$	$7.35-7.45$
pCO $_2$	$56\text{ mm Hg}$	$35-45\text{ mm Hg}$
pO $_2$	$52\text{ mm Hg}$	$75-105\text{ mm Hg}$
HCO $_3^-$	$25\text{ mEq/L}$	$22-28\text{ mEq/L}$

A portable chest radiograph displays an enlarged cardiac silhouette, perihilar alveolar opacities, and bilateral blunting of the costophrenic angles. The patient is placed on noninvasive positive-pressure ventilation.

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

Intravenous furosemide administrationAnswer
B
Nebulized albuterol and oral prednisone
C
Empirical administration of broad-spectrum antibiotics
D
Intravenous sodium bicarbonate infusion
E
Initiation of intravenous levothyroxine

Answer

Intravenous furosemide administration

The correct answer is intravenous furosemide administration. This patient presents with acute respiratory distress, orthopnea, an S3 gallop, elevated jugular venous pressure, cardiomegaly, and a markedly elevated brain natriuretic peptide (BNP) level. This clinical picture is diagnostic of acute decompensated heart failure (ADHF) resulting in pulmonary edema. Although the patient has a history of COPD and presents with wheezing, this represents 'cardiac asthma', a phenomenon where peribronchial edema leads to airway narrowing and wheezing. The presence of an S3 gallop is highly specific for heart failure in this context. The initial pharmacologic management for ADHF with volume overload consists of intravenous loop diuretics, such as furosemide, which promptly reduce preload and pulmonary venous pressure, thereby relieving dyspnea.

Step-by-Step Solution

Analyze the patient's symptoms and vital signs.

The patient has progressive dyspnea, orthopnea, hypoxemia, and hypertension, which suggests an acute cardiopulmonary process.

Identifying the primary symptom cluster directs the differential diagnosis.

Interpret the physical examination and imaging findings.

Findings include an S3 gallop, elevated jugular venous pressure, cardiomegaly, and bilateral pleural effusions. Although wheezing is present, these signs strongly indicate fluid overload and heart failure rather than an isolated COPD exacerbation.

Physical exam and imaging distinguish between cardiac asthma (wheezing due to pulmonary edema) and primary airway disease.

Evaluate the laboratory results.

The BNP is significantly elevated (

920\text{ pg/mL}

), confirming the diagnosis of heart failure. The mild TSH elevation is subclinical. The ABG shows acute respiratory acidosis without a metabolic component.

Biomarkers like BNP help confirm the clinical suspicion of heart failure in complex presentations where comorbid lung disease exists.

Determine the most appropriate pharmacologic intervention.

Given the diagnosis of acute decompensated heart failure with volume overload, preload reduction is required. Intravenous furosemide is the standard initial therapy.

Loop diuretics rapidly reduce pulmonary congestion and improve respiratory status in ADHF.

Key Concept

Patients with acute decompensated heart failure can present with wheezing ('cardiac asthma') mimicking a COPD exacerbation. An S3 gallop, elevated JVP, cardiomegaly, and markedly elevated BNP differentiate ADHF, which requires prompt management with intravenous loop diuretics.

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