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Difficulty: HardGeneral Internal Medicine

An emergency medical services team transports a 6868-year-old retired teacher to the emergency department due to rapidly progressive breathlessness that awoke her from sleep. She has a medical history significant for a myocardial infarction three years ago and moderate chronic obstructive pulmonary disease, for which she uses an as-needed albuterol inhaler. Over the past 1212 hours, her inhaler has provided no relief. Her home medications include aspirin, metoprolol, and lisinopril.

On arrival, her temperature is 37.0∘C37.0^\circ \text{C} (98.6∘F98.6^\circ \text{F}), blood pressure is 178/104 mm Hg178/104 \text{ mm Hg}, pulse is 112/min112/\text{min}, and respiratory rate is 28/min28/\text{min}. Oxygen saturation is 86%86\% on room air. The patient appears highly anxious and is sitting upright on the stretcher. Physical examination reveals distended jugular veins when sitting at a 45∘45^\circ angle. Pulmonary auscultation reveals diffuse expiratory wheezing with a prolonged expiratory phase, as well as bilateral bibasilar crackles. Cardiac examination demonstrates a regular tachycardia with a prominent early diastolic extra heart sound.

Arterial blood gas analysis on room air shows:
- pH: 7.287.28
- PaCO2\text{PaCO}_2: 56 mm Hg56 \text{ mm Hg}
- PaO2\text{PaO}_2: 54 mm Hg54 \text{ mm Hg}
- HCO3−\text{HCO}_3^-: 25 mEq/L25 \text{ mEq/L}

Which of the following is the most appropriate initial pharmacological intervention for this patient?

  1. Intravenous furosemideAnswer
  2. B
    Intravenous methylprednisolone
  3. C
    Continuous albuterol nebulization
  4. D
    Intravenous ceftriaxone and azithromycin
  5. E
    Intravenous sodium bicarbonate

Answer

Intravenous furosemide is the most appropriate initial management to reduce preload and treat acute decompensated heart failure.
The correct answer provides a medication that rapidly reduces cardiac preload. The patient is experiencing acute decompensated heart failure (ADHF) manifesting as flash pulmonary edema. This is evidenced by her acute dyspnea, hypertension, hypoxemia, jugular venous distention, crackles, and an S3 gallop (an early diastolic extra heart sound strongly associated with elevated left ventricular end-diastolic pressure). The diffuse wheezing is 'cardiac asthma', a condition where peribronchial edema causes airway narrowing that mimics primary lung disease. Initial management for ADHF relies on intravenous loop diuretics (like furosemide) and/or vasodilators to relieve pulmonary congestion.

Step-by-Step Solution

1
Analyze the patient's history and vital signs.
The patient has a history of ischemic heart disease and COPD. She is presenting with severe acute hypoxemia, tachypnea, and significant hypertension (178/104 mm Hg178/104 \text{ mm Hg}).
Identifying the baseline risk factors and hemodynamic status helps narrow the differential diagnosis for acute respiratory distress.
2
Synthesize the physical examination findings.
The exam shows jugular venous distention, bibasilar crackles, an S3 gallop (early diastolic extra sound), and diffuse wheezing.
An S3 gallop and elevated jugular venous pressure are highly specific for left and right-sided heart failure. The wheezing represents 'cardiac asthma' resulting from peribronchial edema, not a primary bronchospastic event.
3
Interpret the arterial blood gas (ABG) results.
The ABG reveals pH 7.287.28, PaCO2\text{PaCO}_2 56 mm Hg56 \text{ mm Hg}, and HCO3−\text{HCO}_3^- 25 mEq/L25 \text{ mEq/L}, indicating acute respiratory acidosis secondary to poor ventilation from pulmonary edema.
Correctly identifying the acid-base disorder prevents the inappropriate administration of alkalizing agents like bicarbonate.
4
Determine the next best step in management.
The diagnosis is acute decompensated heart failure (ADHF) presenting as flash pulmonary edema. The standard initial therapy is intravenous loop diuretics (e.g., furosemide) or vasodilators (e.g., nitroglycerin).
These agents rapidly decrease central venous pressure and pulmonary capillary wedge pressure, immediately improving pulmonary congestion and gas exchange.

Key Concept

Patients with acute decompensated heart failure may present with wheezing (cardiac asthma) that mimics a COPD exacerbation; the presence of an S3 gallop, jugular venous distention, and bibasilar crackles confirms a cardiogenic etiology requiring diuresis or vasodilation.
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Topics

General Internal Medicine

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