Pulmonary embolism

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Pulmonary embolism

  1. 1. Pulmonary embolism(PE) is a condition that occurs when one or more arteries in your lungs become blocked. In most cases, pulmonary embolism is caused by blood clots that travel to your lungs from another part of your body — most commonly, your legs. Pulmonary embolism can occur in otherwise healthy people. Signs and symptoms can vary from person to person, but commonly include sudden and unexplained shortness of breath, chest pain and a cough that may bring up bloodtinged sputum. Pulmonary embolism can be life-threatening, but prompt treatment with anti-clotting medications can greatly reduce the risk of death. Taking measures to prevent blood clots in your legs also can help protect you against pulmonary embolism. Pathophysiology- Pulmonary thromboembolism is not a disease in and of itself. Rather, it is a complication of underlying venous thrombosis. Under normal conditions, microthrombi (tiny aggregates of red cells, platelets, and fibrin) are formed and lysed continually within the venous circulatory system. This dynamic equilibrium ensures local hemostasis in response to injury without permitting uncontrolled propagation of clot. Under pathological conditions, microthrombi may escape the normal fibrinolytic system to grow and propagate. Pulmonary embolism (PE)
  2. 2. occurs when these propagating clots break loose and embolize to block pulmonary blood vessels. Thrombosis in the veins is triggered by venostasis, hypercoagulability, and vessel wall inflammation. These 3 underlying causes are known as the Virchow triad. All known clinical risk factors for DVT ( deep vein thrombosis) and PE have their basis in one or more elements of the triad. Patients who have undergone gynecologic surgery, those with major trauma, and those with indwelling venous catheters may have DVTs that start in an area related to their pathology. For other patients, venous thrombosis most often involves the lower extremities and nearly always starts in the calf veins, which are involved in virtually all cases of symptomatic spontaneous lower extremity DVT. Although DVT starts in the calf veins, in cases of pulmonary embolism, it will usually propagate proximally to the popliteal vessels, and from that area embolize. Clinical History- Pulmonary embolism (PE) is so common and so lethal that the diagnosis should be sought actively in every patient who presents with any chest symptoms that cannot be proven to have another cause. Symptoms that should provoke a suspicion of pulmonary embolism must include chest pain, chest wall tenderness, back pain, shoulder pain, upper abdominal pain, syncope,
  3. 3. hemoptysis, shortness of breath, painful respiration, new onset of wheezing, any new cardiac arrhythmia, or any other unexplained symptom referable to the thorax. The classic triad of signs and symptoms of PE (hemoptysis, dyspnea, chest pain) are neither sensitive nor specific. They occur in fewer than 20% of patients in whom the diagnosis of PE is made, and most patients with those symptoms are found to have some etiology other than PE to account for them.. Nonetheless, the presence of any of these classic signs and symptoms is an indication for a complete diagnostic evaluation. Many patients with PE are initially completely asymptomatic, and most of those who do have symptoms have an atypical presentation. Patients with PE often present with primary or isolated complaints of seizure, syncope, abdominal pain, high fever, productive cough, new onset of reactive airway disease ("adult-onset asthma"), or hiccoughs. They may present with new-onset atrial fibrillation, disseminated intravascular coagulation, or any of a host of other signs and symptoms. Pleuritic or respirophasic chest pain is a particularly worrisome symptom. PE has been diagnosed in 21% of young, active patients who come to the ED complaining only of pleuritic chest pain. These patients usually lack any other classical signs, symptoms, or known risk factors for pulmonary thromboembolism. Such patients often are
  4. 4. dismissed inappropriately with an inadequate workup and a nonspecific diagnosis, such as musculoskeletal chest pain or pleurisy. Physical Massive pulmonary embolism (PE) causes hypotension due to acute cor pulmonale, but the physical examination findings early in submassive PE may be completely normal. After 24-72 hours, loss of pulmonary surfactant often causes atelectasis and alveolar infiltrates that are indistinguishable from pneumonia on clinical examination and by radiography. New wheezing may be appreciated. If pleural lung surfaces are affected, a pulmonary rub may be heard. In patients with recognized PE, the incidence of physical signs has been reported as follows: - tachypnea (respiratory rate >16/min) - rales - an accentuated second heart sound - tachycardia (heart rate >100/min) - fever (temperature >37.8°C) - diaphoresis(sweating) - an S 3 or S 4 gallop
  5. 5. - clinical signs and symptoms suggesting thrombophlebitis - lower extremity edema - cardiac murmur - cyanosis Causes- As stated in the Pathophysiology section, the etiology of venous thrombosis and subsequent thromboembolism results from a distortion in Virchow's triad by venostasis, hypercoagulability, or vessel wall inflammation. These risk factors for venous thrombosis and pulmonary embolism can be broken down into hereditary factors and acquired factors. Hereditary factors (most result in a hypercoagulable state) - Antithrombin III deficiency - Protein C deficiency - Protein S deficiency - Factor V Leiden (most common genetic risk factor for thrombophilia) - Plasminogen abnormality - Plasminogen activator abnormality - Fibrinogen abnormality - Resistance to activated protein C
  6. 6. Acquired factors (The most important clinically identifiable risk factors for DVT and PE are a prior history of DVT or PE, recent surgery or pregnancy, prolonged immobilization, or underlying malignancy.) - Reduced mobility- Fractures, Immobilization, Burns, Obesity - Old age - Malignancy- Chemotherapy - Acute medical illness- AIDS (lupus anticoagulant), Behçet disease, Congestive heart failure (CHF), Myocardial infarction, Polycythemia, Systemic lupus erythematosus, Ulcerative colitis - Trauma/major surgery- Spinal cord injury, Catheters (indwelling venous infusion catheters), Postoperative - Pregnancy- Postpartum period , Oral contraceptives, Estrogen replacements (high dose only) - Drug abuse (intravenous [IV] drugs) - Drug-induced lupus anticoagulant - Hemolytic anemias - Heparin-associated thrombocytopenia - Homocysteinemia - Homocystinuria
  7. 7. - Hyperlipidemias - Phenothiazines - Thrombocytosis - Varicose veins - Venography - Venous pacemakers - Venous stasis - Warfarin (first few days of therapy) DiagnosisChest X-ray- This noninvasive test shows images of your heart and lungs on film. Although X-rays can't diagnose pulmonary embolism and may even appear normal when pulmonary embolism exists, they can rule out conditions that mimic the disease. Ventilation-perfusion scans- This test, called a ventilationperfusion scan (V/Q scan), uses small amounts of radioactive material to study airflow (ventilation) and blood flow (perfusion) in your lungs. For the first part of the test, you inhale a small amount of radioactive material while a camera that's able to detect radioactive substances takes pictures of the movement of air in your lungs. Then a small amount of radioactive material is injected into a vein in your arm, and pictures are taken of
  8. 8. blood flow in the blood vessels of your lungs. Comparing the results of the two studies helps provide a more accurate diagnosis of pulmonary embolism than does either study alone. If a mismatch occurs, meaning that there is lung tissue that has good air entry but no blood flow, it may be indicative of a pulmonary embolus. Spiral (helical) computerized tomography (CT) scan- Regular CT scans take X-rays from many different angles and then combine them to form images showing two-dimensional "slices" of your internal structures. In a spiral or helical CT scan, the scanner rotates around your body in a spiral — like the stripe on a candy cane — to create three-dimensional images. This type of CT can detect abnormalities with much greater precision, and it's also much faster than are conventional CT scans. Pulmonary angiogram- This test provides a clear picture of the blood flow in the arteries of your lungs. It's the most accurate way to diagnose pulmonary embolism, but because it requires a high degree of skill to administer and carries potentially serious risks, it's usually performed when other tests fail to provide a definitive diagnosis. It also has the advantage of being able to measure the pressure in the right side of your heart. It would be unusual to have normal readings in the presence of pulmonary embolism. In a pulmonary angiogram, a flexible tube (catheter) is inserted into a large vein — usually in your groin — and
  9. 9. threaded through your heart into the pulmonary arteries. A special dye is then injected into the catheter, and X-rays are taken as the dye travels along the arteries in your lungs. A risk of this procedure is a temporary change in your heart rhythm. In addition, the dye may cause kidney damage in people with decreased kidney function. d-Dimer blood test- The d-Dimer blood test measures one of the breakdown products of a blood clot. If this test is normal, then the likelihood of a pulmonary embolism is very low. Unfortunately, this test is not specific for blood clots in the lung. It can be positive for a variety of reasons including pregnancy, injury, recent surgery, or infection. Looking at the list of deep vein thrombosis risk factors, one can imagine that a d-Dimer blood test may not be helpful in those with significant risk factors for deep vein thrombosis Venous Doppler study- Ultrasound of the legs, also known as venous Doppler studies, may be used to look for blood clots in the legs of a patient suspected of having a pulmonary embolus. If a deep vein thrombosis exists, it can be inferred that chest pain and shortness of breath may be due to a pulmonary embolism. Echocardiography (EKG, ECG)- Echocardiography or ultrasound of the heart may be helpful if it shows that there is strain on the right side of the heart.
  10. 10. If non-invasive tests are negative and the healthcare provider still has significant concerns, then the healthcare provider and the patient need to discuss the benefits and risks of treatment versus invasive testing like angiography. Treatment- If your doctor strongly suspects that your symptoms are caused by a pulmonary embolism, you will be given injections of a drug called heparin before your diagnosis has even been confirmed. Heparin is a type of drug called an anticoagulant. Anticoagulants are used to prevent blood clots from forming, or to prevent existing blood clots from getting any worse. - If it's confirmed that you have an embolism, you will be prescribed ongoing treatment with an anticoagulant that can be taken by mouth, such as warfarin. You will usually have to take the drug for at least six months. But this will depend on what has caused your embolism and whether you are likely to get another one. - If you have a large pulmonary embolism, you may also be given a drug called a thrombolytic (eg alteplase) to try and dissolve your blood clot. This will be given as an injection into a vein. Medications: - Anticoagulants. Heparin works quickly and is usually delivered with a needle. Warfarin (Coumadin) comes in
  11. 11. pill form. Both prevent new clots from forming, but it takes a few days before warfarin begins to work. Risks include bleeding gums and easy bruising. - Clot dissolvers (thrombolytics). While clots usually dissolve on their own, there are medications that can dissolve clots quickly. Because these clot-busting drugs can cause sudden and severe bleeding, they usually are reserved for life-threatening situations. Surgical and other procedures : - Clot removal. If you have a very large clot in your lung, your doctor may suggest removing it via a thin flexible tube (catheter) threaded through your blood vessels. - Vein filter. A catheter can also be used to position a filter in the main vein — called the inferior vena cava — that leads from your legs to the right side of your heart. This filter can block clots from being carried into your lungs. This procedure is typically reserved for people who can't take anticoagulant drugs or when anticoagulant drugs don't work well enough. - Warfarin- - Initial dose: 5-15 mg/d PO qd After initial anticoagulation obtained, adjust dose according to desired INR
  12. 12. - Streptase- 2.5 lac IU loading dose over half to one hour, followed by 1lac IU/hr for 24 hr - Urokinase- 4400 IU/kg over 10 min i.v. followed by 4400IU/hr for 12 hr - Alteplase- 100mg i.v infused over 2hr

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