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Difficulty: MediumPulmonary and Critical Care

Emergency medical services bring a 68-year-old woman to the emergency department after she collapsed in an airport terminal. She had just disembarked from a 12-hour international flight. On presentation, she is lethargic, diaphoretic, and in severe respiratory distress. Vital signs are temperature 36.8°C (98.2°F), blood pressure 76/44 mmHg, pulse 134/min, and respirations 32/min. Pulse oximetry shows 83% on room air. Physical examination reveals marked jugular venous distention when the head of the bed is elevated. The lungs are clear to auscultation bilaterally. Cardiac examination demonstrates a rapid, regular rhythm, a parasternal heave, and a loud pulmonic component of the second heart sound. The right lower extremity is edematous, warm, and tender from the calf to the mid-thigh. A bedside echocardiogram shows a dilated and hypokinetic right ventricle with bowing of the interventricular septum into the left ventricle. Arterial blood gas analysis on room air reveals a pHpH of 7.22, pCO2pCO_2 of 28 mmHg, pO2pO_2 of 54 mmHg, and HCO3−HCO_3^- of 11 mEq/L. Which of the following is the most appropriate next step in management?

  1. A
    Immediate transfer to the radiology suite for a computed tomography pulmonary angiogram
  2. B
    Intravenous administration of a loop diuretic
  3. C
    Intravenous infusion of sodium bicarbonate
  4. Intravenous administration of tissue plasminogen activatorAnswer
  5. E
    Empiric administration of broad-spectrum antimicrobial therapy

Answer

Intravenous administration of tissue plasminogen activator is the correct intervention for a hemodynamically unstable patient with a massive pulmonary embolism.
The correct intervention is the administration of a systemic thrombolytic agent, such as tissue plasminogen activator (alteplase). This patient presents with classic signs of a massive (high-risk) pulmonary embolism (PE), defined by the presence of sustained hypotension (systolic blood pressure < 90 mmHg) or shock. The history of prolonged immobilization, deep vein thrombosis symptoms, clear lungs, and right ventricular (RV) strain on echocardiography confirm the diagnosis of obstructive shock. In massive PE, the sudden increase in pulmonary vascular resistance leads to acute RV dilation and failure, which compromises left ventricular filling (evidenced by septal bowing) and systemic cardiac output. Thrombolytic therapy rapidly reduces the clot burden, decreasing pulmonary artery pressure and restoring hemodynamics.

Step-by-Step Solution

1
Identify the primary clinical syndrome from the patient's history and physical examination.
The combination of a long flight, sudden collapse, hypotension, tachycardia, jugular venous distention, clear lungs, and unilateral leg swelling strongly points to a massive pulmonary embolism causing obstructive shock.
Recognizing the triad of hypotension, clear lungs, and elevated central venous pressure is essential for diagnosing obstructive shock.
2
Evaluate the diagnostic findings, particularly the bedside echocardiogram and arterial blood gas.
The echocardiogram confirms acute right ventricular strain (dilated RV, septal bowing). The ABG shows a severe mixed metabolic acidosis (lactic acidosis from shock) and respiratory acidosis (impending failure, as the pCO2pCO_2 is higher than predicted by Winter's formula).
Diagnostic data solidifies the severity of the obstruction and the immediate threat to the patient's life, dictating aggressive intervention.
3
Determine the most appropriate immediate intervention for high-risk (massive) pulmonary embolism.
Systemic thrombolysis (tissue plasminogen activator) is indicated to rapidly dissolve the clot burden.
In hemodynamically unstable patients, reducing pulmonary vascular resistance is critical to restore right ventricular output and prevent cardiac arrest.

Key Concept

Management of massive (high-risk) pulmonary embolism with obstructive shock requires immediate restoration of right ventricular output, typically via systemic thrombolytic therapy, bypassing confirmatory CT imaging if the patient is hemodynamically unstable.
Estimated Time:1m 15s
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Topics

Pulmonary and Critical Care

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