A 73-year-old man presents to the emergency department with severe, progressively worsenin… — USMLE Step 2 CK

A 73-year-old man presents to the emergency department with severe, progressively worsening shortness of breath over the past 48 hours. His medical history is significant for ischemic cardiomyopathy with a left ventricular ejection fraction of 35%, severe chronic obstructive pulmonary disease, and stage 3 chronic kidney disease. The patient reports having to sleep upright in a chair to breathe. Temperature is 37.0°C (98.6°F), blood pressure is 168/94 mm Hg, pulse is 112/min, and respirations are 26/min. Pulse oximetry shows 86% on room air. Physical examination reveals use of accessory muscles of respiration. Jugular venous pressure is estimated at 10 cm $H_2O$ . Chest auscultation reveals bilateral basilar crackles extending to the mid-lung fields and prolonged expiration with diffuse end-expiratory wheezes. Lower extremities show 2+ pitting edema.

Laboratory results are as follows:
Sodium: 138 mEq/L
Potassium: 4.8 mEq/L
Chloride: 104 mEq/L
Bicarbonate: 16 mEq/L
Blood urea nitrogen: 42 mg/dL
Creatinine: 2.1 mg/dL (baseline 1.8 mg/dL)
Lactic acid: 3.8 mmol/L
Thyroid-stimulating hormone (TSH): 0.9 $\mu$ U/mL (Normal: 0.4-4.0 $\mu$ U/mL)
Free T4: 0.6 ng/dL (Normal: 0.9-1.7 ng/dL)

Arterial blood gas on room air:
pH: 7.30
$PaCO_2$ : 31 mm Hg
$PaO_2$ : 54 mm Hg

Chest radiograph demonstrates cardiomegaly, bilateral hazy perihilar opacities, and cephalization of the pulmonary vessels without focal consolidation. Which of the following is the most appropriate next step in management?

Intravenous furosemide and noninvasive positive pressure ventilationAnswer
B
Intravenous methylprednisolone and continuous nebulized albuterol
C
Intravenous piperacillin-tazobactam and admission to the intensive care unit
D
Intravenous levothyroxine and stress-dose hydrocortisone
E
Endotracheal intubation and mechanical ventilation for superimposed respiratory acidosis

Answer

Intravenous furosemide and noninvasive positive pressure ventilation

The correct choice directly addresses acute decompensated heart failure (ADHF) with cardiogenic pulmonary edema and hypoxemic respiratory failure. The patient's elevated jugular venous pressure, orthopnea, crackles, and classic chest radiograph findings (cardiomegaly, perihilar opacities) confirm fluid overload. Noninvasive positive pressure ventilation (NPPV) is indicated because it decreases the work of breathing and improves oxygenation, while simultaneously decreasing both preload and afterload. Intravenous loop diuretics (furosemide) are required to reduce the underlying volume overload.

Step-by-Step Solution

Identify the primary clinical syndrome from the patient's presentation.

The patient has elevated jugular venous pressure, orthopnea, bilateral crackles, pitting edema, and a chest radiograph showing cardiomegaly with perihilar opacities. This indicates Acute Decompensated Heart Failure (ADHF).

Recognizing the signs of cardiogenic pulmonary edema is necessary to select the correct initial treatment.

Differentiate the cause of wheezing in this specific patient.

Although the patient has a history of COPD, the wheezing is 'cardiac asthma' caused by peribronchial edema secondary to volume overload, rather than a primary COPD exacerbation.

Misinterpreting the wheezing leads to incorrect treatment with bronchodilators and steroids instead of diuretics.

Evaluate the acid-base status to rule out impending respiratory failure.

Using Winter's formula (

1.5 \times [HCO_3^-] + 8

), the expected

PaCO_2

1.5 \times 16 + 8 = 32 \pm 2

mm Hg. The patient's actual

PaCO_2

of 31 mm Hg indicates a simple metabolic acidosis (likely lactic acidosis from hypoperfusion) with appropriate respiratory compensation.

Confirming appropriate respiratory compensation prevents the incorrect assumption of a superimposed respiratory acidosis that might prompt premature intubation.

Select the most appropriate initial pharmacological and respiratory support.

Initiate intravenous furosemide for rapid diuresis and noninvasive positive pressure ventilation (NPPV) to improve oxygenation and decrease the work of breathing.

NPPV and loop diuretics are the first-line therapies for ADHF presenting with severe respiratory distress.

Key Concept

Management of Acute Decompensated Heart Failure (ADHF) and differentiation from COPD exacerbation

Estimated Time:1m 30s

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