What is the management for someone presenting with symptoms suggestive of pulmonary embolism (PE)?

Management of Suspected Pulmonary Embolism

For patients presenting with symptoms suggestive of pulmonary embolism (PE), a structured diagnostic approach using risk stratification followed by appropriate testing and treatment is essential to reduce mortality and morbidity.

Initial Assessment and Risk Stratification

Clinical Presentation

• Most patients with PE present with:
  • Sudden onset dyspnea (78-81% of cases) 1
  • Chest pain (39-56%)
  • Fainting or syncope (22-26%)
  • Hemoptysis (5-7%)
• At least one of these symptoms occurs in 94% of PE cases 1
• Patients with massive PE may present with:
  • Collapse/hypotension
  • Unexplained hypoxia
  • Engorged neck veins
  • Right ventricular gallop 2

Risk Stratification

• Either objective criteria (clinical decision rules) or gestalt clinical assessment can be used to risk stratify patients with suspected PE 2
• Common risk factors include:
  • Recent immobility/major surgery
  • Lower limb trauma or surgery
  • Pregnancy/post-partum
  • Major medical illness
  • Previous venous thromboembolism 2

Clinical Probability Assessment

1. Low probability: Neither risk factor nor another diagnosis unlikely
2. Intermediate probability: Either risk factor or another diagnosis unlikely
3. High probability: Both risk factor and another diagnosis unlikely 2

Diagnostic Algorithm

Step 1: Clinical Assessment

• Record respiratory rate in all patients with suspected PE
• Perform chest radiography, ECG, and arterial blood gas measurements 2
• PE can be excluded in the absence of all three: tachypnea (>20/min), pleuritic pain, and arterial hypoxemia 2

Step 2: D-dimer Testing

• When to use D-dimer:
  • Only with reasonable suspicion of PE
  • Not for routine "screening"
  • Not when alternative diagnosis is highly likely
  • Not in high clinical probability cases
  • Not in probable massive PE 2
• D-dimer interpretation:
  • Normal D-dimer (<500 ng/mL) in low-risk patients has >99% negative predictive value
  • For patients >50 years, use age-adjusted D-dimer thresholds (age × 10 ng/mL) 3

Step 3: Imaging

• CT pulmonary angiography (CTPA):
  • First-line imaging test for diagnosing PE 3
  • Consider in all patients with positive D-dimer or high clinical probability
• Ventilation-perfusion (V/Q) scan:
  • Alternative when CTPA is contraindicated (renal insufficiency, contrast allergy)
  • Should be performed within 24 hours of clinical suspicion 2
  • Interpretation:
    • Normal scan = no PE
    • Scan + clinical probability both low = no PE
    • Scan + clinical probability both high = PE present
    • Any other combination = needs CTPA 2
• Leg ultrasound:
  • First-line investigation for suspected PE in patients with:
    • Previous PE
    • Clinical DVT
    • Chronic cardiorespiratory disease 2

Step 4: Additional Testing

• Bedside echocardiography:
  • Initial test of choice in patients with shock or hypotension 3
• Pulmonary angiography:
  • Consider when other investigations fail to confirm diagnosis 2

Treatment

Immediate Management

• For massive PE with hemodynamic instability:
  • Contact consultant immediately
  • Administer 50 mg alteplase IV
  • For stable patients with confirmed massive PE, give 100 mg alteplase over 90 minutes 2

Anticoagulation

• Start heparin:
  • Begin on the basis of high or intermediate clinical suspicion before diagnosis is confirmed 2
  • Initial dose: 80 units/kg IV 2
  • For therapeutic effect: 10,000 units IV initially, followed by continuous infusion 4
  • Adjust dosage to maintain aPTT 1.5-2 times normal 4

Long-term Management

• Prefer NOACs (apixaban, dabigatran, edoxaban, or rivaroxaban) over vitamin K antagonists for eligible patients 3
• Duration of anticoagulation:
  • Minimum 3 months for all patients with PE
  • Consider discontinuation after 3 months for first PE with major transient risk factor
  • Continue indefinitely for recurrent venous thromboembolism not related to major transient risk factors 3

Special Considerations

Outpatient Treatment

Consider outpatient treatment if:

• Patient is not unduly breathless
• No medical or social contraindications
• Efficient protocol is in place 2

Common Pitfalls to Avoid

1. Delaying anticoagulation while awaiting diagnostic confirmation in high probability patients
2. Ordering D-dimer in high clinical probability patients (high false negative rate)
3. Failing to use age-adjusted D-dimer cutoffs in older patients
4. Relying on non-ELISA D-dimer assays (lower sensitivity)
5. Skipping clinical probability assessment 3

By following this structured approach to diagnosis and management, clinicians can effectively identify and treat patients with pulmonary embolism, reducing associated morbidity and mortality.