An emergency medical services team brings a 73-year-old man to the acute care bay with sev… — USMLE Step 2 CK

An emergency medical services team brings a $73$ -year-old man to the acute care bay with severe respiratory distress that began abruptly two hours ago. The patient is visibly agitated, diaphoretic, and cannot speak in full sentences. His wife reports that he has a history of essential hypertension, osteoarthritis, a $40$ -pack-year smoking habit, and treatment-resistant depression for which a new medication (phenelzine) was initiated three weeks ago.

Vital signs:
Temperature: $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ )
Blood pressure: $192/108\text{ mm Hg}$
Heart rate: $118\text{/min}$
Respiratory rate: $28\text{/min}$
Oxygen saturation: $86\%$ on room air

Physical examination reveals prominent jugular venous distention. Lung auscultation yields diffuse, high-pitched expiratory wheezing bilaterally with prolonged expiratory phases. Cardiac examination reveals a regular tachycardia with a prominent extra heart sound heard just after $\text{S}_2$ at the cardiac apex. The abdomen is distended with a palpable liver edge $4\text{ cm}$ below the right costal margin.

Arterial blood gas analysis on room air shows:
$\text{pH}$ : $7.49$
$\text{pCO}_2$ : $29\text{ mm Hg}$
$\text{pO}_2$ : $54\text{ mm Hg}$
$\text{HCO}_3^-$ : $22\text{ mEq/L}$

Chest radiography reveals bilateral perihilar opacities and blunting of the costophrenic angles.

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

A
Inhaled albuterol and oral prednisone
B
Intravenous sodium bicarbonate
Intravenous furosemideAnswer
D
Intravenous piperacillin-tazobactam
E
Oral sertraline

Answer

Intravenous furosemide

The correct intervention is Intravenous furosemide. This patient is presenting with acute decompensated heart failure (ADHF). Despite the heavy smoking history and prominent wheezing, the clinical picture is dominated by signs of profound fluid overload: jugular venous distention, a prominent S3 gallop, hepatomegaly, and radiographic evidence of pulmonary edema (perihilar opacities and pleural effusions). The wheezing in this scenario represents 'cardiac asthma,' a phenomenon where peribronchial interstitial edema compresses the small airways and causes expiratory wheezing that mimics primary airway disease. The immediate management of ADHF with pulmonary edema involves preload reduction and diuresis; therefore, intravenous loop diuretics (such as furosemide) are the most appropriate initial step.

Step-by-Step Solution

Analyze the patient's clinical presentation and physical examination findings.

The patient has severe dyspnea, hypertension, jugular venous distention, an S3 gallop, hepatomegaly, and bilateral wheezing.

Identifying the cluster of symptoms is crucial to differentiate between pulmonary and cardiac etiologies of acute respiratory distress.

Interpret the diagnostic data (ABG and Chest X-ray).

The ABG shows acute respiratory alkalosis secondary to hypoxemia. The chest X-ray shows perihilar opacities and pleural effusions (blunted costophrenic angles).

The combination of an S3 gallop, right-sided heart failure signs, and radiographic evidence of pulmonary edema confirms a diagnosis of acute decompensated heart failure (ADHF).

Determine the cause of the wheezing in this specific context.

The wheezing is 'cardiac asthma' caused by peribronchial interstitial edema narrowing the airways, mimicking a primary reactive airway disease.

Recognizing cardiac asthma prevents the misdiagnosis of a COPD exacerbation.

Select the most appropriate initial pharmacological therapy for the confirmed diagnosis.

Intravenous furosemide is selected to reduce intravascular volume, decrease cardiac preload, and relieve pulmonary congestion.

Loop diuretics are the first-line therapy for volume-overloaded patients presenting with ADHF.

Key Concept

Acute decompensated heart failure can present with prominent wheezing ('cardiac asthma') due to peribronchial edema, which must be differentiated from COPD exacerbations using clinical signs like an S3 gallop and JVD to guide appropriate diuretic therapy.

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