A 59-year-old woman arrives at the emergency department via ambulance with acute, severe r… — USMLE Step 2 CK

A 59-year-old woman arrives at the emergency department via ambulance with acute, severe respiratory distress. She awoke from sleep two hours ago gasping for air. Her medical history includes hypertension, diet-controlled type 2 diabetes mellitus, and a 35-pack-year smoking history. She has not seen a physician in three years and does not take any daily medications. On arrival, the patient is diaphoretic, sitting bolt upright, and using accessory muscles of respiration. She is unable to speak in full sentences. Vital signs show a temperature of $37.1^\circ\text{C}$ , blood pressure of $220/115$ mm Hg, pulse of $128$ /min, and respiratory rate of $34$ /min. Pulse oximetry shows an oxygen saturation of $83\%$ on room air. Physical examination reveals an estimated jugular venous pressure of $12$ cm H $_2$ O. Chest auscultation demonstrates loud, diffuse expiratory wheezing bilaterally with a prolonged expiratory phase; no crackles are appreciated. Cardiac examination reveals a regular tachycardia with a prominent S4 gallop. There is no peripheral edema. A portable chest radiograph shows prominent pulmonary vasculature and peribronchial cuffing, without focal consolidation. Arterial blood gas analysis on room air reveals:

pH: $7.14$
PaCO $_2$ : $65$ mm Hg
PaO $_2$ : $52$ mm Hg
HCO $_3^-$ : $21$ mEq/L

The patient is immediately placed on noninvasive positive-pressure ventilation (NIPPV). Which of the following is the most appropriate next step in pharmacologic management?

Intravenous nitroglycerinAnswer
B
Intravenous methylprednisolone
C
Intravenous sodium bicarbonate
D
Intravenous levofloxacin
E
Inhaled ipratropium bromide

Answer

The most appropriate next step is the administration of intravenous nitroglycerin to rapidly reduce left ventricular afterload and preload.

The correct intervention is intravenous nitroglycerin. This patient is presenting with Sympathetic Crashing Acute Pulmonary Edema (SCAPE), a severe and rapid-onset form of acute decompensated heart failure. The extreme hypertension (afterload) causes left ventricular failure, leading to rapid fluid accumulation in the pulmonary interstitium (peribronchial cuffing). This interstitial edema compresses small airways, producing widespread wheezing known as 'cardiac asthma.' The elevated JVP and S4 gallop further confirm a cardiac etiology rather than a primary pulmonary one. In addition to noninvasive positive-pressure ventilation (NIPPV), the definitive immediate treatment is rapid afterload and preload reduction using a titratable intravenous vasodilator like nitroglycerin. This shifts fluid out of the pulmonary circulation and improves forward cardiac output.

Step-by-Step Solution

Analyze the patient's symptoms and vital signs.

The patient has sudden-onset respiratory distress waking her from sleep, extreme hypertension (

220/115

mm Hg), and significant hypoxemia.

This establishes a picture of a severe, acute cardiopulmonary crisis driven by a massive sympathetic surge.

Differentiate between primarily pulmonary (COPD/Asthma) and cardiac (ADHF) etiologies based on the physical exam.

Despite the wheezing and smoking history, the presence of an elevated JVP (

12

cm H

_2

O), an S4 gallop, and peribronchial cuffing strongly point to acute decompensated heart failure.

Wheezing can occur in heart failure ('cardiac asthma') due to peribronchial edema compressing small airways. The S4 indicates a stiff, non-compliant left ventricle heavily impacted by the acute hypertension.

Determine the optimal pharmacologic intervention for Sympathetic Crashing Acute Pulmonary Edema (SCAPE).

Intravenous nitroglycerin is indicated.

In SCAPE, extreme afterload prevents forward flow from the left ventricle, causing rapid fluid backup. High-dose nitroglycerin rapidly vasodilates, reducing both afterload and preload, which allows the ventricle to pump effectively and clears the pulmonary edema.

Key Concept

Sympathetic Crashing Acute Pulmonary Edema (SCAPE) can present with severe wheezing ('cardiac asthma') and requires rapid afterload reduction with vasodilators (e.g., nitroglycerin) alongside noninvasive ventilation.

Estimated Time:2m 0s

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