Critical Care · Year 4 · from Critical Care
Case 2: Obstructive Shock - Massive Pulmonary Embolism
Clinical Image
Source: Wikimedia Commons - Pulmonary Embolism - CC BY-SA 3.0
Case Presentation
A 58-year-old woman presents to the emergency department with sudden-onset severe dyspnea, chest pain, and near-syncope. She had an arthroscopic knee surgery 10 days ago and has been relatively immobile since. On examination, vital signs show heart rate 128 bpm, respiratory rate 32/min, blood pressure 76/50 mmHg (MAP 59), and SpO2 82% on 15L non-rebreather. She appears pale, diaphoretic, and in respiratory distress. JVP is markedly elevated. Cardiac examination reveals a loud P2 and right ventricular heave. Bedside echocardiography shows severe right ventricular dilation and dysfunction with a "D-shaped" septum indicating interventricular septal bowing into the left ventricle from RV pressure overload. ECG shows sinus tachycardia, S1Q3T3 pattern, and right heart strain pattern. Given the high clinical suspicion for massive PE with hemodynamic instability, she is immediately given IV unfractionated heparin bolus. However, her blood pressure continues to decline to 68/42 mmHg despite 1L fluid bolus, and norepinephrine is initiated. The team recognizes that supportive measures alone are unlikely to reverse the RV failure. Given the hemodynamic instability, contraindications to thrombolysis are reviewed (none present), and systemic alteplase (tPA) 100 mg IV is administered over 2 hours. Within 90 minutes of thrombolysis initiation, her blood pressure improves to 98/64 mmHg, and norepinephrine is weaned. CT pulmonary angiogram (obtained after stabilization) confirms large bilateral pulmonary emboli with right heart strain. She is transitioned to therapeutic anticoagulation and discharged on apixaban with plan for hypercoagulability workup.
Key Learning Points
- Obstructive shock from massive PE presents with sudden hypotension, elevated JVP, and right heart failure signs; bedside echo showing RV dilation is highly suggestive
- Massive PE with hemodynamic instability is an indication for systemic thrombolysis (tPA 100 mg over 2 hours) despite bleeding risks, as the alternative is death from RV failure
- In obstructive shock, fluid administration should be judicious - excessive fluids can worsen RV function by increasing wall tension; small boluses (250-500 mL) are appropriate
- The hemodynamic profile of obstructive shock shows elevated CVP, low cardiac output, and elevated SVR (similar to cardiogenic shock), distinguished by the acute obstruction to flow