What is the most likely cause of pulmonary embolism in an elderly patient with Chronic Obstructive Pulmonary Disease (COPD) and severe asthma, who has a fracture of the femur neck and was treated with aggressive physiotherapy and cortisone for 4 days?

Immobilization is the Most Likely Cause of Pulmonary Embolism in an Elderly COPD Patient with Femur Neck Fracture

Immobilization due to femur neck fracture is the most likely cause of pulmonary embolism in this elderly patient with COPD and severe asthma, rather than steroid use or NSAIDs. 1

Risk Factor Analysis

Primary Risk Factor: Immobilization from Femur Fracture

• Fracture of the lower limb is classified as a strong risk factor for venous thromboembolism (VTE) with an odds ratio >10 1
• Femur fractures, particularly those involving the neck of the femur, create a high-risk situation for pulmonary embolism development due to:
  • Venous stasis in the lower extremities
  • Hypercoagulable state triggered by trauma
  • Endothelial injury during the fracture event

Timeline Considerations

• Studies show that 57.1% of pulmonary emboli in femur fracture patients occur within the first 24 hours after injury and 89.3% within the first 48 hours 2
• The patient developed PE after 4 days of treatment, which aligns with the typical timeline for post-fracture thromboembolism

Secondary Contributing Factors

COPD and Severe Asthma

• Cardiorespiratory disorders, including irreversible airways disease like COPD, are considered major risk factors for venous thromboembolism 1
• Chronic respiratory conditions contribute to:
  • Reduced mobility
  • Systemic inflammation
  • Hypoxemia, which can promote thrombosis

Age

• Advanced age is an independent risk factor for PE, with incidence increasing exponentially with age 1
• Elderly patients have:
  • Higher baseline thrombotic risk
  • Decreased physiological reserve
  • Often multiple comorbidities

Steroid Use Consideration

• While corticosteroid therapy (both inhaled and systemic) is associated with osteoporosis and may have contributed to the initial fracture 3, it is not considered a primary risk factor for pulmonary embolism
• The British Thoracic Society guidelines do not list steroid use among the major risk factors for PE 1
• The 2019 ESC guidelines do not include corticosteroids in their list of predisposing factors for VTE 1

Diagnostic Algorithm for PE Causation in Fracture Patients

1. Assess for primary mechanical risk factors:

   • Fracture location (femur neck fractures carry high risk)
   • Duration of immobilization
   • Timing of mobilization/physiotherapy initiation

2. Evaluate for coexisting medical risk factors:

   • Cardiorespiratory disease (COPD, heart failure)
   • Age >65 years
   • Previous history of VTE
   • Malignancy

3. Consider medication-related factors:

   • Hormone therapy (estrogen-containing medications)
   • Erythropoiesis-stimulating agents
   • Chemotherapy

4. Rule out rare causes:

   • Thrombophilia
   • Inflammatory conditions
   • Dehydration

Prevention Strategies

For future similar cases, preventive measures should include:

• Early mobilization when medically safe
• Mechanical prophylaxis (compression stockings, intermittent pneumatic compression)
• Pharmacological prophylaxis with anticoagulants unless contraindicated
• Careful monitoring for signs and symptoms of PE, especially in the first 48-72 hours

Common Pitfalls to Avoid

1. Attributing PE to medications (like steroids) without considering stronger mechanical risk factors
2. Delaying thromboprophylaxis in high-risk orthopedic patients
3. Failing to recognize early signs of PE in patients with pre-existing respiratory disease (symptoms may be attributed to the underlying condition)
4. Overlooking the need for extended thromboprophylaxis after hospital discharge in high-risk patients

In conclusion, while this patient had multiple risk factors, immobilization due to femur neck fracture represents the strongest and most direct cause of pulmonary embolism, consistent with established guidelines and research evidence.