From the Guidelines
Pulmonary embolism (PE) is primarily caused by blood clots that travel to the lungs, most commonly originating as deep vein thromboses (DVTs) in the legs, with strong risk factors including fracture of lower limb, hospitalization for heart failure or atrial fibrillation/flutter, hip or knee replacement, major trauma, myocardial infarction, previous VTE, and spinal cord injury 1. The main risk factors for PE can be categorized into strong, moderate, and weak risk factors. Strong risk factors have an odds ratio (OR) greater than 10 and include conditions such as fracture of lower limb, hospitalization for heart failure or atrial fibrillation/flutter, hip or knee replacement, major trauma, myocardial infarction, previous VTE, and spinal cord injury.
- Moderate risk factors have an OR between 2 and 9 and include conditions such as arthroscopic knee surgery, autoimmune diseases, blood transfusion, central venous lines, chemotherapy, congestive heart failure or respiratory failure, erythropoiesis-stimulating agents, hormone replacement therapy, in vitro fertilization, oral contraceptive therapy, post-partum period, infection, inflammatory bowel disease, cancer, paralytic stroke, superficial vein thrombosis, and thrombophilia.
- Weak risk factors have an OR less than 2 and include conditions such as bed rest greater than 3 days, diabetes mellitus, arterial hypertension, immobility due to sitting, increasing age, laparoscopic surgery, obesity, pregnancy, and varicose veins. Understanding these risk factors is crucial because PE can be life-threatening, and prevention strategies like early mobilization after surgery, compression stockings, and anticoagulants for high-risk patients can significantly reduce occurrence rates 1. The pathophysiology of PE involves the obstruction of the pulmonary arterial bed by thromboemboli, leading to an increase in pulmonary vascular resistance and right ventricular (RV) failure, which can result in systemic hypotension, haemodynamic instability, and even death 1. It is essential to recognize the risk factors for PE and take preventive measures to reduce the occurrence of this potentially life-threatening condition, especially in patients with strong risk factors, as the consequences of acute PE can be severe and even fatal 1.
From the Research
Causes of Pulmonary Embolism (PE)
The causes of PE can be attributed to various factors, including:
- Genetic mutations, such as factor V Leiden (FVL) mutation, which poses a higher risk for deep-vein thrombosis (DVT) than for PE 2, 3, 4
- Oral contraceptive use, pregnancy, puerperium, minor leg injuries, and obesity, which have an effect comparable to FVL on the risk of DVT and PE 2
- Pulmonary conditions, such as chronic obstructive pulmonary disease, pneumonia, and sickle cell disease, which have a higher risk of PE but little or no effect on DVT 2
- Antiphospholipid syndrome, which can increase the risk of thrombotic events, including PE and DVT 5
- Other thrombophilic defects, which may not have a significant effect on the risk of PE and DVT, unlike FVL 4
Risk Factors for PE
The risk factors for PE can be different from those for DVT, as shown in several studies:
- The FVL paradox, where the risk of DVT is higher than the risk of PE in carriers of the FVL mutation 2, 3, 4
- The presence of other thrombophilic defects, which may not have a significant effect on the risk of PE and DVT 4
- The role of pulmonary conditions in increasing the risk of PE 2
Genetic Mutations and PE
Genetic mutations, such as FVL, can play a significant role in the development of PE: