++
+++
Essentials of Diagnosis
++
Predisposition to venous thrombosis, usually of the lower extremities
Usually dyspnea, chest pain, hemoptysis, or syncope
Tachypnea and a widened alveolar–arterial PO2 difference
Elevated rapid D-dimer and characteristic defects on CT pulmonary arteriography, ventilation-perfusion lung scan, or pulmonary angiogram
+++
General Considerations
++
Third most common cause of death in hospitalized patients
Most cases are not recognized antemortem: < 10% with fatal emboli receive specific treatment
Pulmonary thromboembolism (PE) and deep venous thrombosis (DVT) are manifestations of the same disease, with the same risk factors
Immobility (bed rest, stroke, obesity)
Hyperviscosity (polycythemia)
Increased central venous pressures (low cardiac output, pregnancy)
Vessel damage (prior DVT, orthopedic surgery, trauma)
Hypercoagulable states, either acquired or inherited
Pulmonary thromboemboli most often originate in deep veins of the lower extremities
PE develops in 50–60% of patients with proximal lower extremity DVT; 50% of these events are asymptomatic
Hypoxemia results from vascular obstruction leading to dead space ventilation, right-to-left shunting, and decreased cardiac output
Other types of pulmonary emboli
Fat embolism
Air embolism
Amniotic fluid embolism
Septic embolism (eg, endocarditis)
Tumor embolism (eg, renal cell carcinoma)
Foreign body embolism (eg, talc in injection drug use)
Parasite egg embolism (schistosomiasis)
++
See Table 9–18
Clinical findings depend on the size of the embolus and the patient's preexisting cardiopulmonary status
Dyspnea occurs in 75–85% and chest pain in 65–75% of patients
Tachypnea is the only sign reliably found in more than 50% of patients
97% of patients in the PIOPED study had at least one of the following
++