A 71-year-old man is brought to the emergency department due to severe shortness of breath… — USMLE Step 2 CK

A $71$ -year-old man is brought to the emergency department due to severe shortness of breath that has worsened over the past $48$ hours. The patient reports waking up in the middle of the night gasping for air and feeling unable to breathe while lying flat. He has a history of chronic obstructive pulmonary disease (COPD), essential hypertension, and a myocardial infarction three years ago. His current medications include an as-needed albuterol inhaler, lisinopril, and atorvastatin. His temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), pulse is $115/\text{min}$ , respirations are $28/\text{min}$ , and blood pressure is $168/95\text{ mm Hg}$ . Pulse oximetry shows an oxygen saturation of $88\%$ on room air. Physical examination shows a patient in moderate respiratory distress using accessory muscles of respiration. The jugular venous pulsation is visible $10\text{ cm}$ above the sternal angle. Auscultation of the lungs reveals bilateral crackles extending to the mid-lung fields and diffuse expiratory wheezing. Cardiac examination reveals a regular tachycardia with a third heart sound (S3). Trace bilateral lower extremity edema is present. Arterial blood gas analysis on room air shows a pH of $7.28$ , PaCO2 of $56\text{ mm Hg}$ , PaO2 of $58\text{ mm Hg}$ , and HCO3- of $25\text{ mEq/L}$ . Chest radiograph reveals bilateral interstitial infiltrates, prominent pulmonary vasculature, and an enlarged cardiac silhouette. Which of the following is the most appropriate initial step in the management of this patient's respiratory failure?

Intravenous furosemideAnswer
B
Systemic corticosteroids and nebulized ipratropium
C
Intravenous piperacillin-tazobactam
D
Intravenous sodium bicarbonate
E
Rapid infusion of $0.9\%$ normal saline

Answer

Intravenous furosemide

The correct intervention is administering intravenous furosemide. This patient is experiencing acute decompensated heart failure (ADHF) leading to acute respiratory failure. Despite his history of COPD and the presence of wheezing on examination, the clinical findings of paroxysmal nocturnal dyspnea, elevated jugular venous pressure, an S3 gallop, basilar crackles, and radiographic evidence of cardiomegaly with interstitial infiltrates strongly confirm cardiogenic pulmonary edema. The expiratory wheezing in this context, often termed 'cardiac asthma,' is caused by peribronchial edema compressing the airways. The standard initial management for ADHF includes upright positioning, supplemental oxygen (often utilizing noninvasive positive-pressure ventilation), and intravenous loop diuretics such as furosemide to rapidly decrease intravascular volume and relieve pulmonary congestion.

Step-by-Step Solution

Analyze the patient's history and vital signs.

The patient has progressive dyspnea, orthopnea, and paroxysmal nocturnal dyspnea. Vital signs demonstrate significant hypertension, tachycardia, tachypnea, and hypoxemia.

Establishing the clinical trajectory (rapid onset, orthopnea) helps differentiate cardiac causes from primary pulmonary causes.

Interpret the physical examination findings.

Findings include elevated jugular venous pressure (JVP), an S3 gallop, basilar crackles, and wheezing.

An elevated JVP and S3 gallop are highly specific for left ventricular failure and volume overload. The wheezing represents 'cardiac asthma' caused by peribronchial edema.

Evaluate the objective diagnostic data (ABG and Chest Radiograph).

The ABG shows an acute respiratory acidosis (pH

7.28

, PaCO2

56\text{ mm Hg}

). The chest radiograph confirms cardiomegaly and pulmonary edema.

Objective data confirms acute uncompensated respiratory failure driven by fluid accumulating in the alveolar spaces, impairing gas exchange.

Select the most appropriate immediate intervention.

Intravenous loop diuretics (such as furosemide) alongside oxygen therapy/noninvasive ventilation.

Diuresis rapidly decreases preload, reducing pulmonary capillary hydrostatic pressure and clearing the pulmonary edema, which will resolve the hypoxemia and hypercarbia.

Key Concept

Patients with acute decompensated heart failure can present with wheezing (cardiac asthma) mimicking a COPD exacerbation; key differentiating features include elevated jugular venous pressure, an S3 gallop, and cardiomegaly with pulmonary edema on chest imaging.

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