A 72-year-old woman is brought to the emergency department for sudden-onset severe shortne… — USMLE Step 2 CK

A $72$ -year-old woman is brought to the emergency department for sudden-onset severe shortness of breath, lightheadedness, and right-sided chest pain. She recently returned from a $12$ -hour international flight two days ago. Her medical history includes moderate chronic obstructive pulmonary disease (COPD) and hypertension.

On arrival, she is somnolent but arousable. Temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure is $82/50\text{ mm Hg}$ , pulse is $118/\text{min}$ , and respirations are $28/\text{min}$ . Oxygen saturation is $85\%$ on room air.

Physical examination reveals elevated jugular venous pressure. Lung auscultation is clear bilaterally.

Bedside transthoracic echocardiography demonstrates a severely enlarged right ventricle with hypokinesis of the free wall and normal apical contraction. The left ventricle is small and hyperdynamic.

An arterial blood gas on room air shows:
pH: $7.29$
$\text{PaCO}_2$ : $26\text{ mm Hg}$
$\text{PaO}_2$ : $54\text{ mm Hg}$
$\text{HCO}_3^-$ : $12\text{ mEq/L}$

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

Administration of systemic alteplaseAnswer
B
Transport for computed tomography pulmonary angiography
C
Intravenous administration of furosemide
D
Intravenous administration of piperacillin-tazobactam
E
Endotracheal intubation and mechanical ventilation

Answer

Administration of systemic alteplase

The correct answer is the administration of systemic alteplase. This patient presents with classic signs of a massive (high-risk) pulmonary embolism (PE): sudden-onset dyspnea, hypoxia, and hemodynamic instability (hypotension) following a major risk factor (prolonged travel). In patients with suspected massive PE who are too unstable to safely undergo definitive imaging (CT pulmonary angiography), bedside transthoracic echocardiography is the diagnostic test of choice. The presence of right ventricular dilation and free wall hypokinesis with apical sparing (McConnell's sign) provides sufficient evidence of acute right heart strain to justify immediate intervention. The treatment of choice for massive PE in the absence of absolute contraindications is systemic thrombolysis (e.g., alteplase). Thrombolytics rapidly lyse the clot, reducing pulmonary vascular resistance, alleviating right ventricular strain, and improving cardiac output.

Step-by-Step Solution

Identify the primary clinical syndrome.

The patient presents with sudden-onset dyspnea, hypoxia, right-sided chest pain, and profound hypotension (

82/50

mm Hg) following a period of prolonged immobilization.

Establishing the severity and likely etiology (massive pulmonary embolism causing cardiogenic shock).

Interpret the diagnostic data.

Bedside echocardiography shows right ventricular dilation and hypokinesis with apical sparing (McConnell's sign), confirming acute right heart strain. The ABG shows a primary metabolic acidosis (lactic acidosis from shock) with appropriate respiratory compensation.

To confirm the diagnosis of massive PE and safely rule out other causes of shock or acute respiratory failure.

Determine the most appropriate next step in management.

In a hemodynamically unstable patient with high clinical suspicion for PE and bedside echo evidence of RV strain, systemic thrombolysis (alteplase) is indicated immediately without waiting for definitive CT imaging.

To rapidly dissolve the thrombus, reduce right ventricular afterload, and restore cardiac output.

Key Concept

Massive (high-risk) pulmonary embolism is defined by hemodynamic instability (systolic BP

< 90

mm Hg) and should be managed with systemic thrombolytics if bedside echocardiography shows right heart strain, as these patients are often too unstable for CT pulmonary angiography.

Alternative Method

In advanced centers, catheter-directed thrombolysis or surgical pulmonary embolectomy may be considered as alternative emergent treatments for massive PE, particularly if systemic thrombolysis has failed or is absolutely contraindicated.

Estimated Time:1m 30s

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