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Difficulty: HardGeneral Internal Medicine

A 66-year-old man is brought to the emergency department by his wife due to severe, progressively worsening shortness of breath over the past 24 hours. He has a history of essential hypertension, type 2 diabetes mellitus, and a 45-pack-year smoking history. The patient reports a dry, hacking cough. His wife notes that he has been sleeping in his recliner for the past two nights because he feels like he is "smothering" when lying flat in bed.

Temperature is 37.0°C (98.6°F), blood pressure is 175/100 mm Hg, pulse is 112/min, and respirations are 26/min. Oxygen saturation is 89% on room air. The patient is diaphoretic, sitting upright, and using accessory muscles of respiration. Jugular venous pressure is estimated at 10 cm H2O. Pulmonary auscultation reveals a prolonged expiratory phase with diffuse, loud, bilateral expiratory wheezes; no crackles are appreciated. Cardiac auscultation reveals a regular tachycardia with a prominent S4 gallop. Trace bilateral pitting edema is present at the ankles.

Laboratory results are as follows:
Sodium: 138 mEq/L
Potassium: 4.2 mEq/L
Chloride: 104 mEq/L
Bicarbonate: 16 mEq/L
Blood urea nitrogen: 30 mg/dL
Serum creatinine: 1.6 mg/dL
Lactate: 4.1 mmol/L
Thyroid-stimulating hormone: 2.5 µU/mL (normal: 0.5-5.0 µU/mL)
Free T4: 0.6 ng/dL (normal: 0.9-2.4 ng/dL)

An arterial blood gas on room air reveals:
pH: 7.30
pCO2: 33 mm Hg
pO2: 64 mm Hg

A chest radiograph demonstrates cardiomegaly, peribronchial cuffing, and prominent upper lobe vessels, with no focal consolidations.

Which of the following is the most appropriate next step in management for this patient?

  1. Intravenous furosemideAnswer
  2. B
    Nebulized albuterol and intravenous methylprednisolone
  3. C
    Immediate endotracheal intubation
  4. D
    Empiric intravenous levofloxacin
  5. E
    Initiation of oral levothyroxine

Answer

Intravenous furosemide
The correct answer is the administration of a loop diuretic. This patient is presenting with acute decompensated heart failure (ADHF). Although his 45-pack-year smoking history and prominent wheezing might initially suggest a chronic obstructive pulmonary disease (COPD) exacerbation, several key features point to cardiogenic pulmonary edema. The presence of orthopnea (sleeping in a recliner), elevated jugular venous pressure, an S4 gallop (indicating a stiff, non-compliant left ventricle), and trace pedal edema are classic signs of fluid overload and heart failure. Furthermore, the chest radiograph shows cardiomegaly and peribronchial cuffing. The wheezing is a manifestation of 'cardiac asthma,' where perivascular and peribronchial interstitial edema compresses the small airways, mimicking primary bronchospasm. The most appropriate initial step in management is the administration of an intravenous loop diuretic to reduce intravascular volume and relieve pulmonary congestion.

Step-by-Step Solution

1
Evaluate the clinical presentation and radiographic findings to determine the primary diagnosis.
Identify that the patient has acute decompensated heart failure (ADHF) presenting as 'cardiac asthma.'
Despite the smoking history and prominent wheezing, the presence of orthopnea, elevated JVP, an S4 gallop, cardiomegaly, and peribronchial cuffing strongly point to cardiogenic pulmonary edema rather than a COPD exacerbation.
2
Analyze the basic metabolic panel and arterial blood gas to assess for potential respiratory failure.
Calculate the anion gap (18) and apply Winter's formula to find the expected pCO2 is 32 ± 2 mm Hg.
The actual pCO2 of 33 mm Hg falls within the expected range, confirming appropriate respiratory compensation for the lactic acidosis. The patient is not in hypercapnic respiratory failure.
3
Interpret the thyroid panel in the context of acute critical illness.
Recognize the low free T4 and normal TSH as euthyroid sick syndrome (non-thyroidal illness syndrome).
In acute illness, peripheral conversion of T4 to T3 is altered. Thyroid hormone replacement is not indicated.
4
Select the most appropriate next step in management based on the primary diagnosis.
Select intravenous furosemide to rapidly reduce volume overload.
Loop diuretics are the first-line therapy for symptomatic relief in acute decompensated heart failure.

Key Concept

Differentiating acute decompensated heart failure ('cardiac asthma') from COPD exacerbation, and interpreting mixed acid-base disorders using Winter's formula to guide management.
Estimated Time:2m 0s
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Topics

General Internal Medicine

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