Respiratory · Year 1 · from Respiratory

Case 1: Massive Pulmonary Embolism - Hemodynamic Instability

Clinical Image

Source: Wikimedia Commons - CT pulmonary angiography PE - CC BY-SA 3.0

Patient Presentation

A 58-year-old man collapses at home and is brought to the emergency department by ambulance. His wife reports he had been complaining of increasing shortness of breath over the past 3 days and had leg swelling for 2 weeks. He had surgery for a hip fracture 3 weeks ago. In the ambulance, he developed a syncopal episode with transient loss of consciousness.

Demographics

  • Age: 58 years
  • Sex: Male
  • Past Medical History: Hypertension, hip fracture (surgery 3 weeks ago), limited mobility during recovery
  • Medications: Lisinopril, aspirin (DVT prophylaxis stopped after discharge)
  • Social History: Former smoker

Chief Complaint

Sudden collapse with syncope, progressive dyspnea, and leg swelling

Physical Examination

  • Blood pressure: 78/52 mmHg (hypotensive)
  • Heart rate: 124 bpm
  • Respiratory rate: 32/min
  • Oxygen saturation: 82% on room air, 88% on 15L non-rebreather
  • Temperature: 37.2°C
  • General: Diaphoretic, anxious, cyanotic
  • Neck: Markedly elevated JVP
  • Cardiovascular: Tachycardic, loud P2, right-sided S3
  • Respiratory: Clear to auscultation
  • Extremities: Left leg swollen (3 cm larger than right), tender, erythematous

Workup

  • ECG: Sinus tachycardia, S1Q3T3 pattern, right bundle branch block, T wave inversions V1-V4
  • Troponin: 0.45 ng/mL (elevated)
  • BNP: 1,850 pg/mL (markedly elevated)
  • D-dimer: >5,000 ng/mL
  • ABG: pH 7.28, PaCO2 28 mmHg, PaO2 52 mmHg (on 15L O2), lactate 5.8 mmol/L
  • Bedside echocardiography: Severely dilated RV, RV free wall hypokinesis with apical sparing (McConnell sign), D-shaped septum, tricuspid regurgitation
  • CT pulmonary angiography: Saddle embolus at main pulmonary artery bifurcation with extension into bilateral main and lobar pulmonary arteries
  • Lower extremity duplex: Extensive DVT in left femoral and popliteal veins

Diagnosis

Massive (High-Risk) Pulmonary Embolism with Hemodynamic Collapse

Treatment

  1. Immediate anticoagulation: Unfractionated heparin bolus and infusion
  2. Systemic thrombolysis: Alteplase 100 mg IV over 2 hours
  • Indicated for massive PE with hemodynamic instability
  • No absolute contraindications in this patient
  1. Vasopressor support (norepinephrine) to maintain MAP
  2. Avoid aggressive fluid resuscitation (already RV overload)
  3. Consider surgical embolectomy or catheter-directed therapy if thrombolysis fails
  4. ICU monitoring
  5. Transition to long-term anticoagulation (warfarin or DOAC) for minimum 3 months (provoked by surgery/immobility)

Physiological Principles Demonstrated

  • Hemodynamic impact of massive PE: Acute obstruction of >50% of the pulmonary vascular bed causes acute RV pressure overload. The thin-walled RV cannot generate pressures >50-60 mmHg acutely, leading to RV failure.
  • RV-LV interdependence: RV dilation causes the interventricular septum to shift leftward (D-sign), impairing LV filling and reducing cardiac output.
  • McConnell sign specificity: RV free wall hypokinesis with apical sparing is specific for acute PE (apex is tethered to the LV).
  • V/Q mismatch and dead space: PE creates regions of ventilation without perfusion (dead space), causing hypoxemia and hypocapnia from compensatory hyperventilation.

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