A 74-year-old woman is brought to the emergency department by ambulance due to severe shor… — USMLE Step 2 CK

A $74$ -year-old woman is brought to the emergency department by ambulance due to severe shortness of breath that awoke her from sleep $2$ hours ago. She has a history of chronic obstructive pulmonary disease (COPD), essential hypertension, and osteoarthritis. Her home medications include a daily tiotropium inhaler and amlodipine. She reports a dry cough but denies fever, chills, or changes in sputum production. She appears in severe respiratory distress, sitting upright and using accessory muscles of respiration. Vital signs are temperature $37.0^{\circ}C$ ( $98.6^{\circ}F$ ), blood pressure $182/105$ mm Hg, pulse $112$ /min, and respirations $28$ /min. Pulse oximetry is $88\%$ on room air. Jugular venous pressure is $10$ cm $H_2O$ . Lung auscultation demonstrates diffuse expiratory wheezes and a prolonged expiratory phase; no crackles are appreciated. Cardiac examination reveals a regular tachycardia with a faint, high-frequency presystolic sound at the apex. There is no peripheral edema. Arterial blood gas analysis on room air reveals a pH of $7.28$ , $PaCO_2$ of $60$ mm Hg, $PaO_2$ of $55$ mm Hg, and $HCO_3^-$ of $27$ mEq/L. A bedside chest radiograph shows hyperinflated lungs, prominent upper lobe vessels, and peribronchial cuffing, without distinct alveolar infiltrates. Electrocardiogram shows sinus tachycardia and voltage criteria for left ventricular hypertrophy. Which of the following is the most appropriate next step in management?

Noninvasive positive-pressure ventilation, intravenous furosemide, and sublingual nitroglycerinAnswer
B
Inhaled albuterol, ipratropium, and systemic glucocorticoids
C
Intravenous sodium bicarbonate and high-flow nasal cannula oxygen
D
Intravenous ceftriaxone and azithromycin
E
Immediate endotracheal intubation and mechanical ventilation

Answer

Noninvasive positive-pressure ventilation, intravenous furosemide, and sublingual nitroglycerin

The patient's presentation of sudden-onset paroxysmal nocturnal dyspnea, severe hypertension, elevated jugular venous pressure, an S4 gallop, and chest radiograph findings of cephalization and peribronchial cuffing is classic for acute decompensated heart failure (ADHF) presenting as 'cardiac asthma'. The interstitial edema compresses the bronchioles, leading to diffuse wheezing and a prolonged expiratory phase that closely mimics a COPD exacerbation. Because the transudative fluid is isolated to the interstitium and has not yet flooded the alveoli, classic crackles may be completely absent. The most appropriate initial management for ADHF with acute pulmonary edema, severe hypertension, and hypoxia is noninvasive positive-pressure ventilation (NIV) (which decreases preload, afterload, and work of breathing), accompanied by intravenous loop diuretics (e.g., furosemide) and vasodilators (e.g., nitroglycerin) to reduce central venous pressure and left ventricular afterload.

Step-by-Step Solution

Analyze the patient's presenting symptoms and temporal onset.

The patient experienced a sudden onset of severe dyspnea waking her from sleep (paroxysmal nocturnal dyspnea) with no infectious symptoms like fever or purulent sputum.

Abrupt paroxysmal nocturnal dyspnea strongly differentiates acute decompensated heart failure from a more gradual COPD exacerbation.

Evaluate the physical examination findings and vital signs.

The patient has severe hypertension, elevated jugular venous pressure, an S4 gallop (presystolic sound), and diffuse wheezing without crackles.

An S4 gallop and elevated JVP point to left ventricular diastolic dysfunction and right-sided volume overload. The wheezing represents 'cardiac asthma' caused by peribronchial edema compressing the small airways.

Interpret the diagnostic data (ABG and CXR).

The ABG shows acute respiratory acidosis. The chest radiograph reveals cephalization (prominent upper lobe vessels) and peribronchial cuffing (interstitial edema).

These findings confirm cardiogenic pulmonary edema and hypercapnic respiratory failure requiring urgent ventilatory support, rather than a primary pulmonary pathology.

Determine the most appropriate initial management.

Initiate noninvasive positive-pressure ventilation (NIV), intravenous loop diuretics, and vasodilators.

NIV rapidly reduces the work of breathing and decreases both left ventricular preload and afterload. Furosemide and nitroglycerin aggressively treat the central volume overload and severe hypertension.

Key Concept

Patients with acute decompensated heart failure (ADHF) can present primarily with wheezing rather than crackles, a condition known as 'cardiac asthma'. Identifying ADHF in a patient with baseline COPD relies on recognizing clinical clues such as paroxysmal nocturnal dyspnea, an S4 gallop, elevated jugular venous pressure, and chest radiograph findings of interstitial edema (e.g., cephalization, peribronchial cuffing).

Estimated Time:1m 30s

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