A 32-year-old primigravid woman at 36 weeks gestation comes to the emergency department du… — USMLE Step 2 CK

A $32$ -year-old primigravid woman at $36$ weeks gestation comes to the emergency department due to a one-week history of progressively worsening shortness of breath. She reports having to sleep propped up on three pillows and frequently waking up at night with a dry cough. Her medical history is notable for mild asthma during childhood and a $10$ -pack-year smoking history, though she quit smoking upon becoming pregnant. Her temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), blood pressure is $112/76$ mm Hg, pulse is $114$ /min, and respirations are $24$ /min. Pulse oximetry shows $92\%$ on room air. Physical examination reveals distended neck veins with a jugular venous pressure of $11$ cm H $_2$ O. Cardiac auscultation demonstrates a regular tachycardia with a distinct third heart sound (S $_3$ ) gallop. Pulmonary examination shows fine crackles at the lung bases bilaterally. There is $2+$ pitting edema extending to the mid-calves. An arterial blood gas analysis on room air shows a pH of $7.47$ , pCO $_2$ of $29$ mm Hg, and pO $_2$ of $64$ mm Hg. Which of the following is the most appropriate next step in the management of this patient?

A
Provide reassurance regarding the expected physiologic changes of pregnancy
B
Initiate inhaled bronchodilators and systemic glucocorticoids
C
Administer intravenous sodium bicarbonate based on Winter's formula calculations
Perform a transthoracic echocardiogramAnswer
E
Prescribe empiric broad-spectrum intravenous antimicrobial therapy

Answer

Perform a transthoracic echocardiogram

The correct answer is to perform a transthoracic echocardiogram. This patient presents with classic signs and symptoms of acute decompensated heart failure, likely secondary to peripartum cardiomyopathy given her gestational age. Key findings include orthopnea, paroxysmal nocturnal dyspnea (waking up at night with a dry cough), resting tachycardia, an S3 gallop, elevated jugular venous pressure, and pulmonary edema (crackles, hypoxemia). An echocardiogram is the essential next step to evaluate left ventricular systolic function, assess for wall motion abnormalities, and establish the diagnosis. The arterial blood gas demonstrates a primary respiratory alkalosis, which is a common physiologic change in pregnancy but here is exacerbated by hyperventilation from acute hypoxia.

Step-by-Step Solution

Analyze the patient's presenting symptoms and physical exam findings.

The patient exhibits orthopnea, paroxysmal nocturnal dyspnea, an S3 gallop, elevated JVP, and bibasilar crackles.

Identifying the constellation of signs and symptoms is necessary to differentiate between pulmonary and cardiovascular causes of dyspnea.

Distinguish between physiologic pregnancy changes and pathologic processes.

While mild peripheral edema and dyspnea can be normal in late pregnancy, an S3 gallop accompanied by elevated JVP and pulmonary crackles indicates pathologic acute decompensated heart failure.

Pregnancy involves significant hemodynamic changes that can mask or mimic disease, requiring careful differentiation.

Determine the diagnostic test of choice for suspected peripartum cardiomyopathy or new-onset heart failure.

A transthoracic echocardiogram is indicated to assess left ventricular ejection fraction and structural heart abnormalities.

Echocardiography is the gold standard, non-invasive imaging modality for diagnosing and characterizing heart failure.

Key Concept

Recognition and initial diagnostic evaluation of new-onset acute decompensated heart failure (e.g., peripartum cardiomyopathy) during pregnancy.

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic