An emergency medical team brings a 68-year-old man to the acute care facility due to the s… — USMLE Step 2 CK

An emergency medical team brings a $68$ -year-old man to the acute care facility due to the sudden onset of severe respiratory distress that awoke him from sleep. Over the past month, he has noted progressive fatigue and a $4$ -kg ( $8.8$ -lb) weight gain. He has a $45$ -pack-year smoking history. He reports a mild, productive cough over the last week. A sputum culture collected at his primary care physician's office three days ago grew *Haemophilus influenzae* susceptible to amoxicillin.

Upon arrival, he is speaking in short phrases and appears anxious.
Temperature: $37.1^{\circ}\text{C}$ ( $98.8^{\circ}\text{F}$ )
Blood pressure: $172/96 \text{ mm Hg}$
Pulse: $115\text{ /min}$ , regular
Respirations: $26\text{ /min}$
Oxygen saturation: $88\%$ on ambient air

Physical examination reveals prominent distention of the external jugular veins when the patient is sitting upright. Cardiac auscultation demonstrates a normal S $1$ and S $2$ with an extra low-frequency diastolic sound. Pulmonary examination shows diffuse expiratory wheezing and bilateral inspiratory crackles extending to the mid-thoracic fields. The lower extremities exhibit $2+$ symmetric pitting edema.

Laboratory analysis reveals:
Thyroid-stimulating hormone (TSH): $1.4 \text{ }\mu\text{U/mL}$ (Normal: $0.5$ - $5.0$ )
Free thyroxine (T4): $0.6 \text{ ng/dL}$ (Normal: $0.9$ - $1.7$ )

Arterial blood gas analysis on ambient air:
pH: $7.46$
$\text{PaCO}_2$ : $32 \text{ mm Hg}$
$\text{PaO}_2$ : $56 \text{ mm Hg}$
$\text{HCO}_3^-$ : $22 \text{ mEq/L}$

Which of the following is the most appropriate next step in patient care?

A
Initiation of empiric vancomycin and piperacillin-tazobactam
B
Administration of nebulized albuterol and systemic glucocorticoids
C
Calculation of expected $\text{PaCO}_2$ using Winter's formula
Intravenous administration of furosemideAnswer
E
Intravenous administration of levothyroxine

Answer

Intravenous administration of furosemide

The patient's presentation of paroxysmal nocturnal dyspnea, elevated jugular venous pressure, an S3 gallop, bibasilar crackles, and peripheral edema is highly specific for acute decompensated heart failure (ADHF) with pulmonary edema. The presence of wheezing, often termed 'cardiac asthma,' occurs due to peribronchial edema and can mimic primary airway disease. The most appropriate initial step in the management of volume-overloaded ADHF is the intravenous administration of a loop diuretic, such as furosemide, which provides both rapid venodilation (decreasing preload) and subsequent diuresis.

Step-by-Step Solution

Analyze the clinical presentation and physical examination findings.

The combination of jugular venous distention, an S3 gallop, bilateral crackles, and peripheral edema in a patient with acute dyspnea indicates severe volume overload.

To differentiate between cardiogenic (heart failure) and pulmonary (COPD/asthma) causes of respiratory distress.

Evaluate the arterial blood gas and laboratory results.

The ABG shows hypoxemia with a respiratory alkalosis. Thyroid labs indicate euthyroid sick syndrome.

To rule out primary acid-base or endocrine emergencies driving the acute presentation.

Determine the most appropriate initial therapy.

Intravenous loop diuretics (e.g., furosemide) are indicated.

To rapidly reduce left ventricular preload and alleviate pulmonary venous congestion in acute decompensated heart failure.

Key Concept

Acute decompensated heart failure can present with wheezing ('cardiac asthma') and must be distinguished from COPD exacerbations using clinical signs of volume overload (JVD, S3 gallop, edema) to guide appropriate diuretic therapy.

Estimated Time:1m 30s

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