lung and airway disorders
Pulmonary Embolism (PE)
Causes of Pulmonary Embolism
Themost commoncause of pulmonary embolism is a Blood clot Usually the Deep Vein Thrombosis (DVT) or pelvic vein when blood flow slows down or stops, as may occur in the leg veins when a person stays in one position for a long time after an injury (for example, a hip fracture), major surgery, or prolonged sitting during travel. Other causes include conditions that make the blood more likely to clot or the presence of a foreign substance within the bloodstream (for example, an intravenous catheter). The cause of blood clots in the veins may not be discernible, but many times predisposing conditions (risk factors) are obvious. These conditions include Advanced age, particularly older than 60 years Blood clotting disorder (increased risk of clotting, called a hypercoagulable state) Cancer Catheters inserted into a large vein for giving medications or nutrients (indwelling venous catheters) Disorders of the bone marrow that make the blood too thick Heart Failure (HF) None Reduced mobility (for example, after surgery or an illness or during a long car ride or air travel) Infections (some serious infections cause system-wide inflammation that predisposes to clotting; SARS-CoV-2, the virus that causes COVID-19, may trigger clots) Injury to the pelvis, hip, or a leg A kidney disorder called Nephrotic Syndrome None Major surgery within the past 3 months Obesity Pregnancy or the period after delivery Prior blood clot Sickle Cell Disease None Smoking Overview of Stroke None Use ofestrogens, for example, as treatment for menopausal symptoms or as contraception (in which case the risk is particularly high among women who are older than 35 years or who smoke) Use ofestrogenreceptor modulators (such asraloxifeneortamoxifen) Use oftestosteronereplacement therapy People who sit for long time periods without moving around (as may happen during air travel) are at slightly increased risk. People who have COVID-19 are thought to have a higher risk of pulmonary embolism. The risk may be increased because people who are sick or hospitalized are likely to have reduced mobility, but the disease itself may also make people more likely to develop blood clots. Far less often, blood clots form in the veins of the arms. Occasionally, clots are found in the right side of the heart, which is referred to as a clot in transit. Once a clot breaks free into the bloodstream, it usually travels to the lungs. The sudden blocking of an artery of the lung is not only caused by blood clots. Other material can also form emboli. Fatcan escape into the blood from the bone marrow when a long bone is fractured or during bone surgery and form an embolus. Sometimes fat can also escape during procedures such as liposuction and fat grafting. Amniotic fluidthat is forced into the pelvic veins during a complicated childbirth can form an embolus. Cancer cellsin clumps may break free into the circulation to form tumor emboli. may form emboli if a catheter in one of the large veins (central veins) is inadvertently opened to air. Air emboli may also form when a vein is operated on (such as when a blood clot is being removed). An additional risk is underwater diving (because nitrogen dissolved in the blood and tissues at increased concentration by high pressure forms bubbles as pressure decreases; this is known as Decompression Sickness ). may also form emboli and travel to a lung. Causes include intravenous illicit use of injected drugs, certain Infective Endocarditis , and inflammation of a vein with blood clot formation and infection (septic thrombophlebitis). A foreign substancecan be introduced into the bloodstream, usually by intravenous injection of inorganic substances such as talc or mercury by injection drug users, where it can form emboli and travel to the lungs. Medical bone cementmay occasionally enter the bloodstream after a procedure called vertebroplasty. 