What are the risk factors and management strategies for pulmonary embolism (PE)?

Risk Factors and Management Strategies for Pulmonary Embolism (PE)

Pulmonary embolism (PE) is a consequence of the interaction between patient-related permanent risk factors and setting-related temporary risk factors, requiring prompt identification and appropriate management to reduce mortality and morbidity. 1

Risk Factors for PE

Strong Risk Factors (Odds Ratio >10)

• Lower limb fractures 1
• Hospitalization for heart failure or atrial fibrillation/flutter (within previous 3 months) 1
• Hip or knee replacement surgery 1
• Major trauma 1
• Myocardial infarction (within previous 3 months) 1
• Previous venous thromboembolism (VTE) 1
• Spinal cord injury 1

Moderate Risk Factors (Odds Ratio 2-9)

• Arthroscopic knee surgery 1
• Autoimmune diseases 1
• Blood transfusion 1
• Central venous lines and intravenous catheters 1
• Chemotherapy 1
• Congestive heart failure or respiratory failure 1
• Erythropoiesis-stimulating agents 1
• Hormone replacement therapy (depends on formulation) 1
• In vitro fertilization 1
• Oral contraceptive therapy 1, 2
  • Combined oral contraceptives increase VTE risk 2-6 fold 1, 2
  • Third-generation contraceptives (containing desogestrel or gestodene) have higher risk than second-generation (containing levonorgestrel or norgestrel) 1, 2
• Post-partum period 1
• Infection (particularly pneumonia, urinary tract infection, and HIV) 1
• Inflammatory bowel disease 1
• Cancer 1
  • Highest risk in metastatic disease 1, 3
  • Specific high-risk cancers: pancreatic, hematological, lung, gastric, and brain 1
• Paralytic stroke 1
• Superficial vein thrombosis 1
• Thrombophilia 1, 2

Weak Risk Factors (Odds Ratio <2)

• Bed rest >3 days 1
• Diabetes mellitus 1
• Arterial hypertension 1
• Immobility due to prolonged sitting (e.g., car or air travel) 1
• Increasing age 1
• Laparoscopic surgery (e.g., cholecystectomy) 1
• Obesity 1
• Pregnancy 1
• Varicose veins 1

Management Strategies Based on Risk Stratification

Risk Assessment

PE management begins with risk stratification based on the likelihood of PE-related early mortality 1:

1. High-risk PE (Mortality >15%) 1

   • Characterized by shock or hypotension (systolic BP <90 mmHg or drop ≥40 mmHg for >15 min) 1
   • Evidence of right ventricular (RV) dysfunction 1

2. Intermediate-risk PE (Mortality 3-15%) 1, 4

   • Hemodynamically stable but with evidence of RV dysfunction and/or myocardial injury 1

3. Low-risk PE (Mortality <1%) 1

   • Hemodynamically stable without evidence of RV dysfunction or myocardial injury 1

Clinical Predictors for Risk Assessment

The following clinical variables help predict 30-day all-cause mortality 1:

• Age (1 point per year) 1
• Male sex (10 points) 1
• Cancer (30 points) 1
• Heart failure (10 points) 1
• Chronic lung disease (10 points) 1
• Heart rate >110/min (20 points) 1
• Systolic blood pressure <100 mmHg (30 points) 1
• Respiratory rate ≥30/min (20 points) 1
• Body temperature <36°C (20 points) 1
• Altered mental status (60 points) 1
• Oxygen saturation <90% (20 points) 1

Treatment Approaches

Anticoagulation

• Standard treatment for all confirmed PE cases 1, 5
• Direct oral anticoagulants (DOACs) are now preferred for most patients 5
• Rivaroxaban regimen: 15 mg twice daily with food for first three weeks, followed by 20 mg once daily 6
• Minimum treatment duration of 3 months, with consideration for extended therapy based on risk factors 6, 5

High-Risk PE Management

• Thrombolysis or embolectomy is indicated 1
• Immediate hospitalization required 1
• Supportive treatment for RV failure is vital 1

Intermediate-Risk PE Management

• Anticoagulation with close monitoring 1, 4
• Consider rescue thrombolysis if clinical deterioration occurs 4
• Hospital admission recommended 1

Low-Risk PE Management

• Anticoagulation 1, 5
• Early discharge or home treatment may be considered 1, 5

Special Considerations

Hormone-Associated PE

• Women who develop hormone-associated PE should discontinue oral contraceptive use 2
• Hormone-releasing intrauterine devices and progesterone-only pills are safer alternatives for women with history of VTE 1, 2
• Women should discontinue hormonal therapy before stopping anticoagulant therapy 2

Cancer-Associated PE

• Cancer patients have higher risk of thrombotic events and PE-related mortality 3
• Most PE cases in cancer patients occur within the first year of cancer diagnosis 3
• Extended anticoagulation often required 5, 3

Pathophysiological Consequences of PE

• PE interferes with both circulation and gas exchange 1
• Right ventricular failure due to acute pressure overload is the primary cause of death in severe PE 1
• Respiratory failure results from hemodynamic disturbances, with low cardiac output causing desaturation 1
• Ventilation/perfusion mismatch contributes to hypoxemia 1
• Right-to-left shunting through patent foramen ovale may occur in about one-third of patients 1