A 72-year-old man is brought to the emergency department by his daughter due to two days o… — USMLE Step 2 CK

A $72$ -year-old man is brought to the emergency department by his daughter due to two days of progressively worsening shortness of breath. He reports orthopnea and a nonproductive cough. His medical history is significant for severe chronic obstructive pulmonary disease (COPD), ischemic cardiomyopathy with a left ventricular ejection fraction of $40\%$ , and benign prostatic hyperplasia. Current medications include a long-acting muscarinic antagonist, a long-acting beta-agonist, and low-dose aspirin.

Temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure is $162/94\text{ mm Hg}$ , pulse is $115/\text{min}$ , and respiratory rate is $28/\text{min}$ . Pulse oximetry shows $85\%$ on room air.

Physical examination reveals an anxious man in respiratory distress using accessory muscles of respiration. The jugular venous pressure is estimated at $10\text{ cm H}_2\text{O}$ . Cardiac auscultation reveals tachycardia with a regular rhythm and a distinct third heart sound (S3). Lung auscultation demonstrates diffuse expiratory wheezes bilaterally with a prolonged expiratory phase. Bilateral 1+ pitting edema is present in the lower extremities.

Arterial Blood Gas (Room Air)	Result	Reference Range
pH	$7.25$	$7.35-7.45$
PaCO $_2$	$72\text{ mm Hg}$	$35-45\text{ mm Hg}$
PaO $_2$	$54\text{ mm Hg}$	$75-105\text{ mm Hg}$
HCO $_3^-$	$31\text{ mEq/L}$	$22-28\text{ mEq/L}$

Laboratory Test	Result	Reference Range
Leukocyte count	$8,400/\text{mm}^3$	$4,000-11,000/\text{mm}^3$
Procalcitonin	$0.03\text{ ng/mL}$	$<0.15\text{ ng/mL}$
Thyroid-stimulating hormone (TSH)	$0.3\text{ }\mu\text{U/mL}$	$0.4-4.0\text{ }\mu\text{U/mL}$
Free T4	$0.6\text{ ng/dL}$	$0.9-1.7\text{ ng/dL}$

A chest radiograph shows cardiomegaly, prominent interstitial markings with cephalization of the pulmonary vasculature, and hyperinflated lung fields, but no focal consolidation.

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

Noninvasive positive-pressure ventilation and intravenous furosemideAnswer
B
Systemic glucocorticoids, nebulized ipratropium-albuterol, and oral azithromycin
C
Intravenous piperacillin-tazobactam and vancomycin
D
Intravenous sodium bicarbonate infusion
E
Intravenous levothyroxine and hydrocortisone

Answer

Noninvasive positive-pressure ventilation and intravenous furosemide

The patient is experiencing acute decompensated heart failure (ADHF) leading to acute-on-chronic hypercapnic respiratory failure. The classic signs of ADHF are present: elevated jugular venous pressure, an S3 gallop, orthopnea, and cardiomegaly with prominent interstitial markings on the chest radiograph. The diffuse expiratory wheezing is a manifestation of peribronchial edema, often termed 'cardiac asthma.' The arterial blood gas shows a primary respiratory acidosis (pH

7.25

, PaCO

_2

72\text{ mm Hg}

) with partial metabolic compensation (HCO

_3^-

31\text{ mEq/L}

), consistent with acute-on-chronic respiratory failure in a patient with underlying COPD. The most appropriate next step in management is noninvasive positive-pressure ventilation (NIPPV) and intravenous furosemide. NIPPV improves oxygenation, decreases the work of breathing, and critically reduces left ventricular preload and afterload, which is highly beneficial in ADHF. Intravenous furosemide is indicated to aggressively manage the volume overload.

Step-by-Step Solution

Interpret the clinical presentation and physical examination findings.

The patient exhibits orthopnea, elevated jugular venous pressure, an S3 gallop, and cardiomegaly on imaging.

These signs strongly indicate acute decompensated heart failure (ADHF). The bilateral wheezing represents 'cardiac asthma' secondary to peribronchial edema, rather than a primary COPD exacerbation.

Analyze the arterial blood gas and laboratory results.

The ABG reveals an acute-on-chronic respiratory acidosis (pH

7.25

, PaCO

_2

72\text{ mm Hg}

, HCO

_3^-

31\text{ mEq/L}

). Thyroid studies show low TSH and low free T4, and procalcitonin is normal.

The acid-base status requires ventilatory support (NIPPV) rather than metabolic buffering. The thyroid profile indicates euthyroid sick syndrome, not primary hypothyroidism. The normal procalcitonin rules out a bacterial source.

Determine the most appropriate management.

Initiate noninvasive positive-pressure ventilation (NIPPV) and intravenous furosemide.

NIPPV provides ventilatory assistance, improves oxygenation, and reduces both left ventricular preload and afterload. Furosemide directly addresses the volume overload.

Key Concept

Acute decompensated heart failure can present with wheezing (cardiac asthma) and must be differentiated from COPD exacerbations; NIPPV and diuresis are the cornerstones of acute management.

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