Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. More than 90% of PEs are complications of a deep vein thrombosis (DVT) of the lower extremity. Some individuals are asymptomatic, but the most common presenting symptom is dyspnea. The symptoms can be acute or chronic, and diagnosis is usually based on radiographic findings, typically a CT pulmonary angiogram. Initial management is supportive and focuses on restoring oxygenation and hemodynamic stability. Both medical (systemic anticoagulants and/or thrombolytics) and interventional therapies (catheter-based thrombolysis, surgery) are used to reestablish vessel patency. Note: The following page will focus on thrombotic PE. See Nonthrombotic embolism for information on air, amniotic fluid, and fat emboli.
Last updated: 22 Apr, 2022
Pulmonary embolism (PE) is the intraluminal obstruction of a main pulmonary artery Pulmonary artery The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs. Lungs: Anatomy or any of its branches by a thrombus, air, amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity, or fat. When thrombotic PE is considered together with DVT DVT Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious. Deep Vein Thrombosis, the condition is known as venous thromboembolic ( VTE VTE Obstruction of a vein or veins (embolism) by a blood clot (thrombus) in the bloodstream. Hypercoagulable States) disease.
The 3 primary factors that contribute to VTE VTE Obstruction of a vein or veins (embolism) by a blood clot (thrombus) in the bloodstream. Hypercoagulable States (known as Virchow’s triad Virchow’s triad Deep Vein Thrombosis) include venous stasis, hypercoagulability Hypercoagulability Hypercoagulable States, and vascular endothelial damage. Any condition that worsens 1 (or more) of the 3 factors increases the risk of DVT DVT Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious. Deep Vein Thrombosis formation and, thus, PE.
Virchow’s triad
Virchow’s triad
Deep Vein Thrombosis:
Circulatory stasis, endothelial injury or dysfunction, and
hypercoagulability
Hypercoagulability
Hypercoagulable States are the primary etiologic factors that cause venous thromboembolic disease.
Venous thromboembolism
Venous thromboembolism
Obstruction of a vein or veins (embolism) by a blood clot (thrombus) in the bloodstream.
Hypercoagulable States:
A deep vein
thrombosis
Thrombosis
Formation and development of a thrombus or blood clot in the blood vessel.
Epidemic Typhus (
DVT
DVT
Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious.
Deep Vein Thrombosis) becomes dislodged in the
leg
Leg
The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia.
Leg: Anatomy (in this image, the thrombus forms in the left femoral vein). The
DVT
DVT
Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious.
Deep Vein Thrombosis travels up the
inferior vena cava
Inferior vena cava
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy (
IVC
IVC
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy) and through the right side of the heart. In this case, the
DVT
DVT
Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious.
Deep Vein Thrombosis breaks into smaller fragments, which become lodged in smaller branches of the pulmonary
arteries
Arteries
Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles.
Arteries: Histology. The obstruction in
blood flow
Blood flow
Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute).
Vascular Resistance, Flow, and Mean Arterial Pressure through the
lungs
Lungs
Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2.
Lungs: Anatomy decreases the ability of the
lungs
Lungs
Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2.
Lungs: Anatomy to oxygenate the blood and, if large enough, puts strain on the right side of the heart.
Ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing/perfusion (V/Q) mismatch:
Hemodynamic instability:
Pulmonary infarction:
Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor varies significantly. High suspicion must be maintained given the risks of complications and mortality Mortality All deaths reported in a given population. Measures of Health Status.
Diagnosis is primarily via imaging. The decision to obtain imaging is based on clinical suspicion, pretest probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability assessment (typically using the Modified Wells criteria), and D-dimer D-dimer Deep Vein Thrombosis levels.
Major criteria | Score |
---|---|
Signs/symptoms of DVT DVT Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious. Deep Vein Thrombosis | 3.0 |
PE clinically more likely than other diagnoses | 3.0 |
Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children | 1.5 |
Prolonged immobilization Immobilization Delirium (≥ 3 days) or recent surgery (within the last 30 days) | 1.5 |
History of PE or DVT DVT Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious. Deep Vein Thrombosis | 1.5 |
Hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis | 1.0 |
Malignancy Malignancy Hemothorax | 1.0 |
Chest radiography:
Chest CT pulmonary angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery ( CTPA CTPA Pulmonary Function Tests) with contrast or spiral Spiral Computed tomography where there is continuous x-ray exposure to the patient while being transported in a spiral or helical pattern through the beam of irradiation. This provides improved three-dimensional contrast and spatial resolution compared to conventional computed tomography, where data is obtained and computed from individual sequential exposures. Computed Tomography (CT) CT:
Ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing-perfusion (V/Q) scan
Tests in hemodynamically unstable individuals: Bedside imaging can be used to make a presumptive diagnosis of PE, which justifyies the initiation of treatment.
Pulmonary angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery:
CT pulmonary angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery images confirming the presence of a saddle embolus and substantial thrombus burden in the lobar branches of both main pulmonary arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology
Image: “Pulmonary embolism CTPA CTPA Pulmonary Function Tests” by Aung Myat and Arif Ahsan. License: CC BY 2.0CT angiography CT angiography A non-invasive method that uses a ct scanner for capturing images of blood vessels and tissues. A contrast material is injected, which helps produce detailed images that aid in diagnosing vascular diseases. Imaging of the Lungs and Pleura demonstrating lobar and segmental pulmonary emboli (arrow) in the right lower lobe
Image: “ CT angiography CT angiography A non-invasive method that uses a ct scanner for capturing images of blood vessels and tissues. A contrast material is injected, which helps produce detailed images that aid in diagnosing vascular diseases. Imaging of the Lungs and Pleura” by Thomas Jefferson University, 1025 Walnut Street, Philadelphia, PA 19107, USA. License: CC BY 3.0V/Q scan showing perfusion defects (arrows) in the right (R) and left (L) lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy
Image: “Lung scan” by Department of Cardiology, Sotiria Chest Diseases Hospital, Athens, Greece. License: CC BY 2.5Assess and treat any hemodynamic instability. A majority of individuals will either present in stable condition, or respond to initial resuscitation Resuscitation The restoration to life or consciousness of one apparently dead. . Neonatal Respiratory Distress Syndrome efforts.
Anticoagulation Anticoagulation Pulmonary Hypertension Drugs: secondary prevention of VTE VTE Obstruction of a vein or veins (embolism) by a blood clot (thrombus) in the bloodstream. Hypercoagulable States
IVC IVC The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs. Mediastinum and Great Vessels: Anatomy filter
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