Paramedics arrive at the emergency department with an 80-year-old male who developed sudde… — USMLE Step 2 CK

Paramedics arrive at the emergency department with an $80$ -year-old male who developed sudden, severe shortness of breath one hour ago while watching television. The patient has a medical history significant for poorly controlled hypertension, type 2 diabetes mellitus, and a $45$ -pack-year history of smoking. Upon arrival, he is in acute respiratory distress, utilizing accessory muscles to breathe, and cannot speak more than a few words at a time. Vital signs include a blood pressure of $225/115 \text{ mm Hg}$ , a heart rate of $115/\text{min}$ , and a respiratory rate of $30/\text{min}$ . Oxygen saturation is $86\%$ on ambient air. Physical examination shows profound diaphoresis. Pulmonary auscultation reveals prominent expiratory wheezing diffusely, along with fine crackles at both lung bases. Cardiovascular examination is notable for a rapid, regular rhythm and a distinct fourth heart sound (S4). Evaluation of the neck shows flat jugular veins, and there is no peripheral edema. Which of the following is the most appropriate initial pharmacologic therapy for this patient?

Intravenous nitroglycerinAnswer
B
Nebulized albuterol
C
Intravenous methylprednisolone
D
Intravenous metoprolol
E
Intravenous moxifloxacin

Answer

Intravenous nitroglycerin

This patient's abrupt onset of severe dyspnea, extreme hypertension, S4 gallop, and diffuse wheezing with crackles are highly characteristic of acute flash pulmonary edema, specifically sympathetic crashing acute pulmonary edema (SCAPE). The wheezing is a result of peribronchial edema, often referred to as 'cardiac asthma'. In SCAPE, an acute sympathetic surge leads to massive vasoconstriction and an extreme increase in afterload. This causes a sudden shift of fluid from the systemic to the pulmonary circulation, which explains the absence of signs of total body volume overload such as jugular venous distention and peripheral edema. The most appropriate initial pharmacologic therapy is rapid afterload and preload reduction using an intravenous vasodilator like nitroglycerin. This intervention quickly redistributes fluid back to the systemic circulation, resolving the pulmonary congestion.

Step-by-Step Solution

Analyze the patient's vital signs and physical exam findings.

The patient exhibits extreme hypertension (

225/115 \text{ mm Hg}

), respiratory distress with hypoxia, an S4 gallop, and diffuse wheezing with basilar crackles, notably without jugular venous distention or peripheral edema.

Identifying the primary pathophysiologic process is essential to differentiate between causes of acute respiratory failure.

Differentiate between cardiogenic and pulmonary causes of wheezing.

Despite the smoking history, the abrupt symptom onset, severely elevated blood pressure, and S4 gallop strongly suggest acute flash pulmonary edema rather than a COPD exacerbation.

Heart failure can present with wheezing due to peribronchial edema, a condition clinically termed 'cardiac asthma'.

Select the most appropriate initial pharmacologic therapy for hypertensive emergency causing flash pulmonary edema.

Intravenous nitroglycerin is the treatment of choice.

It rapidly reduces both preload and afterload, shifting fluid from the pulmonary vasculature back to the systemic circulation to quickly relieve dyspnea.

Key Concept

Differentiating acute flash pulmonary edema ('cardiac asthma') from COPD exacerbation and selecting rapid afterload/preload reduction with intravenous vasodilators (e.g., nitroglycerin) as the initial management.

Estimated Time:1m 15s

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