What is the approach to managing a patient with suspected pulmonary embolism (PE)?

Approach to Pulmonary Embolism Suspect

For patients with suspected pulmonary embolism (PE), management should begin with risk stratification using validated clinical prediction tools (Wells or revised Geneva score), followed by D-dimer testing for low/intermediate probability cases, and CT pulmonary angiography (CTPA) as the first-line imaging test. 1

Initial Assessment and Risk Stratification

• Use validated clinical prediction tools to assess PE probability:

  • Wells score or revised Geneva score
  • Evaluate risk factors: immobilization, surgery, trauma, previous DVT/PE, malignancy 1

• Based on clinical probability, proceed with:

  • Low/intermediate probability: D-dimer testing
  • High probability: Proceed directly to imaging 1

Diagnostic Testing Algorithm

1. D-dimer testing:

   • If negative: Safely excludes PE (3-month thromboembolic risk <1%) 1
   • If positive: Proceed to imaging
   • Use age-adjusted D-dimer cutoffs for patients >50 years 1

2. Imaging options:

   • CTPA: First-line imaging test (sensitivity 83%, specificity 96%) 1
   • Leg ultrasound: Alternative when clinical DVT suspected or as first-line investigation for suspected PE in patients with previous PE, clinical DVT, or chronic cardiorespiratory disease 2, 1
   • Echocardiography: Essential in suspected high-risk PE with hemodynamic instability 1

3. For single subsegmental PE on CTPA: Discuss with radiologist or seek second opinion to avoid misdiagnosis 1

Treatment Approach

Immediate Management

• Start anticoagulation as soon as diagnostic workup is ongoing, unless bleeding or absolute contraindications exist 1
• For high or intermediate clinical suspicion, heparin should be started before diagnosis is clarified 2
• Initial heparin dosing: 5,000-10,000 units loading dose followed by 400-600 units/kg daily as continuous infusion 2
• Monitor APTT 4-6 hours after starting treatment (target: 1.5-2.5 times control) 2, 1

Anticoagulation Options

1. Parenteral initiation:

   • Low molecular weight heparin (LMWH) or fondaparinux preferred over unfractionated heparin 1

2. Oral anticoagulation:

   • NOACs (rivaroxaban, apixaban, edoxaban, dabigatran) preferred over vitamin K antagonists 1
   • For PE treatment with apixaban: 10mg twice daily for 7 days, then 5mg twice daily 3
   • For PE recurrence prevention: apixaban 2.5mg twice daily after at least 6 months of treatment 3

3. Duration of therapy:

   • Minimum 3 months for all patients 1
   • Consider extended anticoagulation for:
     • Unprovoked PE
     • Persistent risk factors
     • Minor transient/reversible risk factors 1

Management of High-Risk PE

For hemodynamically unstable patients, particularly with systemic hypotension:

1. Thrombolytic therapy is indicated 2, 1:

   • Alteplase (rtPA): 100mg over 2 hours or 0.6mg/kg over 15 min (maximum 50mg) 1
   • Streptokinase: 250,000 IU loading dose over 30 min, then 100,000 IU/hour for 12-24h 1

2. If thrombolysis contraindicated or fails:

   • Consider pulmonary embolectomy 2
   • Percutaneous interventions as alternative 1
   • ECMO for refractory circulatory collapse 1

3. Supportive measures:

   • High percentage inspired oxygen for hypoxemia
   • In hypotensive patients, administer colloid while monitoring central venous pressure
   • Maintain right atrial pressure at 15-20 mmHg for maximal right heart filling 2

Follow-up and Monitoring

• Clinical evaluation at 3-6 months after acute PE to assess:

  • Persistent symptoms
  • Signs of recurrence
  • Bleeding complications
  • Need for extended anticoagulation 1

• Evaluate for chronic thromboembolic pulmonary hypertension (CTEPH) if persistent symptoms present 1

Common Pitfalls to Avoid

• Delaying anticoagulation while awaiting confirmatory tests in high-probability patients 1
• Missing PE in elderly patients or those with severe cardiorespiratory disease 1
• Losing patients to follow-up after acute PE 1
• Inappropriate use of diuretics and vasodilators in hypotensive PE patients 2
• Failing to consider IVC filter in patients at high risk of further emboli when anticoagulation is contraindicated or with recurrent PE despite adequate anticoagulation 2

For complex cases, utilize a multidisciplinary approach with a PE response team (PERT) including specialists from trauma surgery, critical care, hematology, and interventional radiology 1.