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Pulmonary embolism/venous air embolism/fat embolism

  1. Pulmonary embolism
    1. deep venous thrombosis (DVT) usually precedes PE but <33% of patients with documented pulmonary embolism show clinical signs of venous thrombosis; still 90% of PEs eminate from the veins of the lower extremities with the remainder arising from the right side of the heart or other veins
    2. occlusion of more than 30% of the vascular tree is required to begin to elevate mean pulmonary artery pressure and more than 50% occlusion is necessary to reduce systemic pressure
    3. symptoms:
      1. minor – anxiety, tachypnea and tachycardia
        1. NOTE: tachypnea has highest positive predictive value, lack of dyspnea or tachypnea has greatest negative predictive value
        2. 65% of patients will have tachycardia or ST and T wave changes (most common EKG finding)
      2. major – dyspnea, collapse, elevated CVP, elevated PA pressure > 20
      3. massive – dyspnea, shock, PA pressure > 25
      4. chronic – dyspnea, syncope, PA pressure > 40
    4. treatment: anticoagulation with PTT of 1.5-2.5 x normal and an INR of 2-3 x normal
  2. Fat emboli
    1. very common in multi-trauma patients
    2. clinical signs: pulmonary dysfunction (respiratory insufficiency), coagulopathy, and neurologic disturbances; 10% go on to develop ARDS; 86% of patients have neurologic findings with encephalopathy and acute confusion the most common finding; petechial rash occurs in 60% of patients with fat embolism
    3. diagnosis made by sending urine for Sudan stain; 50% of patients have increased serum lipase
    4. patients typically become bradycardic and drop their hemoglobin saturation
    5. treatment is largely supportive (keep oxygenation up, fix fracture, etc.)
  3. Air emboli – in OR, patients typically become bradycardic and drop their hemoglobin saturation
    1. typically see decrease in cardiac output, decrease in end tidal pCO2, increase in pulmonary artery pressure and pulmonary vascular resistance, increase in end tidal nitrogen, and a V/Q mismatch
      1. most sensitive monitor for venous air embolism is precordial Doppler which may detect as little as 0.1 mL of air
    2. treatment: put head down, right side up, stop nitrous oxide; aspirate air from the venous line
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