Disease Information for Pulmonary embolism: Definition

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  • Pulmonary embolism occurs in those with Predisposition to venous thrombosis, dyspnea, chest pain, hemoptysis, syncope, Tachypnea and a widened alveolar-arterial Po2 difference; Characteristic defects on ventilation-perfusion lung scan, helical CT scan of the chest, or pulmonary arteriogram; Many substances can embolize to the pulmonary circulation, including air (during neurosurgery, from central venous catheters), amniotic fluid (during active labor), fat (long bone fractures), foreign bodies (talc in injection drug users), parasite eggs (schistosomiasis), septic emboli (acute infectious endocarditis), and tumor cells (renal cell carcinoma); The most common embolus is thrombus; The risk factors for pulmonary emboli are the risk factors for thrombus formation within the venous circulation: venous stasis, injury to the vessel wall, and hypercoagulability (Virchow"s triad); Venous stasis increases with immobility (bed rest-especially postoperative-obesity, stroke), hyperviscosity (polycythemia), and increased central venous pressures (low cardiac output states, pregnancy); Vessels may be damaged by prior episodes of thrombosis, orthopedic surgery, or trauma; Hypercoagulability can be caused by medications (oral contraceptives, hormonal replacement therapy) or disease (malignancy, surgery) or may be the result of inherited gene defects; Factor mutation Leiden, Other major risks for hypercoagulability include the following: deficiencies or dysfunction of protein C, protein S, and antithrombin III; prothrombin gene mutation; and the presence of antiphospholipid antibodies (lupus anticoagulant and anticardiolipin antibody);

    No single symptom or sign or combination of clinical findings is specific to pulmonary thromboembolism; Some findings are fairly sensitive: dyspnea and pain on inspiration occur in 75-85% and 65-75% of patients, respectively; Tachypnea is the only sign reliably found in more than half of patients; 97% of patients with angiographically proved pulmonary emboli had one or more of three findings: dyspnea, chest pain with breathing, or tachypnea; Laboratory Findings: The ECG is abnormal in 70% of patients with pulmonary thromboembolism: sinus tachycardia and nonspecific ST and T wave changes,seen in 40% , 5% had P pulmonale, right ventricular hypertrophy, right axis deviation, and right bundle branch block; Arterial blood gases usually reveal acute respiratory alkalosis due to hyperventilation; The arterial PO2 and the alveolar-arterial oxygen difference (A-a- DO2); Profound hypoxia with a normal chest radiograph in the absence of preexisting lung disease is highly suspicious for pulmonary thromboembolism; Plasma levels of D-dimer, a degradation product of cross-linked fibrin, are elevated in the presence of thrombus;

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