Internal Medicine · Year 3 · from Internal Medicine
Case 2: Pulmonary Embolism
Patient Presentation
A 45-year-old woman presents to the emergency department with sudden-onset shortness of breath and right-sided pleuritic chest pain that started 6 hours ago. She returned from a 12-hour international flight 3 days ago. She has a history of obesity and uses oral contraceptive pills. She denies cough, fever, or leg swelling.
Vital Signs
- Blood Pressure: 105/70 mmHg
- Heart Rate: 118 bpm
- Respiratory Rate: 24/min
- Oxygen Saturation: 91% on room air
- Temperature: 37.4°C
Physical Examination
- General: Anxious, mild respiratory distress
- Cardiovascular: Tachycardic, regular rhythm, prominent P2, no murmurs
- Pulmonary: Clear to auscultation bilaterally
- Extremities: No edema, no calf tenderness, negative Homans sign
Initial Workup
- D-dimer: 3,200 ng/mL (normal <500 ng/mL)
- Troponin I: 0.15 ng/mL (mildly elevated)
- BNP: 380 pg/mL (elevated)
- ABG: pH 7.48, PaCO2 28 mmHg, PaO2 68 mmHg on room air
- ECG: Sinus tachycardia, S1Q3T3 pattern, right axis deviation
Questions
- What is the most likely diagnosis?
- A) Acute coronary syndrome
- B) Spontaneous pneumothorax
- C) Pulmonary embolism
- D) Anxiety attack
- What is the most appropriate next diagnostic test?
- A) Transthoracic echocardiography
- B) CT pulmonary angiography
- C) Ventilation-perfusion scan
- D) Lower extremity Doppler ultrasound
- Calculate the Wells score for this patient. What does it indicate?
- What is the significance of the elevated troponin and BNP?
- What would be the initial anticoagulation approach?
Answers
- C) Pulmonary embolism - The patient has multiple risk factors (long flight, OCP use, obesity), sudden-onset dyspnea with pleuritic chest pain, tachycardia, hypoxemia, elevated D-dimer, and classic ECG findings (S1Q3T3).
- B) CT pulmonary angiography - CTPA is the gold standard diagnostic test for PE with sensitivity and specificity >95%. It can also assess clot burden and right heart strain.
- Wells Score Calculation:
- Clinical signs of DVT: 0 points (none present)
- PE most likely diagnosis: 3 points
- Heart rate >100: 1.5 points
- Immobilization >3 days or surgery in past 4 weeks: 0 points
- Previous PE/DVT: 0 points
- Hemoptysis: 0 points
- Malignancy: 0 points
- Total: 4.5 points - Moderate probability (2-6 points)
With elevated D-dimer and moderate-high pretest probability, imaging is warranted.
- Significance of elevated cardiac biomarkers:
- Troponin elevation: Indicates right ventricular strain and myocardial injury due to acute pressure overload. Associated with worse prognosis.
- BNP elevation: Reflects right ventricular dysfunction and wall stress. Combined with troponin elevation, suggests intermediate-high risk PE.
- Risk stratification: This patient has submassive (intermediate-risk) PE based on biomarker elevation without hemodynamic instability.
- Initial anticoagulation approach:
- Immediate: Therapeutic anticoagulation with:
- LMWH (enoxaparin 1 mg/kg BID) OR
- Unfractionated heparin (if high bleeding risk or need for potential intervention) OR
- DOAC (rivaroxaban or apixaban) can be started immediately
- Duration: Minimum 3 months, longer if unprovoked or persistent risk factors
- Consideration for escalation: If hemodynamic deterioration, consider systemic thrombolysis or catheter-directed therapy
Learning Points
- BNP interpretation helps differentiate cardiac from pulmonary causes of dyspnea - values >400-500 pg/mL strongly suggest cardiac etiology.
- ADHF management focuses on decongestion with IV diuretics, targeting 1-2 L negative fluid balance daily.
- The Wells score helps stratify pretest probability for pulmonary embolism and guides diagnostic testing.
- Right heart strain markers (troponin, BNP, echo findings) in PE indicate intermediate-high risk and may influence management decisions.
- Systematic approach to dyspnea should include assessment of onset, associated symptoms, vital signs, physical examination, and targeted investigations.