Definition:

Pulmonary embolism is a common and potentially fatal disease that is often missed because patients usually presents with nonspecific signs and symptoms.  Most patients succumb to it within first few hours of the event, and those who survive have an increased chance of recurrent embolism and death (which can be prevented with prompt diagnosis/therapy).  It usually arises from thrombi in the deep veins (caused by venous stasis, injury to the innermost lining of vein, and changes in the clotting properties of blood) which then travels to the lungs lodging at the split of the main pulmonary artery or distal to this junction.  This leads to dead alveolar space, decreased oxygenation of the blood, hyperventilation, pulmonary artery constriction, increased load on the heart, and heart failure.  Risk factors include: DVT, prolonged bed rest, pregnancy, surgery/trauma, oral contraceptives with estrogen, elderly, cancer, stroke, fractures of bones, obesity, foreign objects in vessels, and abnormal clotting/coagulation profile.

Symptoms:

• Progressive dyspnea (difficulty in breathing) to collapse
• Massive PE - hypotension (decreased blood pressure), weak, pale, sweaty, decreased urine, altered mental status
• Acute pulmonary infarct - chest pain with breathing, hemoptysis (coughing up blood)
• Acute embolism - dyspnea with chest discomfort
• Multiple PE - intermittent chest pain
• Most patients have no symptoms with relevant history
  

Diagnosis:

• Physical Exam
  • Massive PE - increased heart rate/breathing, low blood pressure, murmurs in heart
  • Acute infarct - audible rub in heart, localized tenderness, decreased breath sounds
  • Acute embolism - increased heart rate/breathing,  crackles in lungs, wheezing
  • Multiple PE - increased jugular vein distension, murmurs in heart
  • Most common - increased respirations, rales, increased heart rate, abnormal heart sounds
• Arterial blood gas - hypoxemia (decreased oxygen), hypocapnia (decreased carbon dioxide), respiratory alkalosis
• D-Dimer - sometimes increased
• Chest X-Ray - Westermark sign (dilation of pulmonary vessels), pleural effusion
• V/Q scan - to look at airflow in lungs against blood flow in lungs, will shows difference
• Spiral CT scan - visualize anatomy and see clot
• Pulmonary Angiography - standard for diagnosis, invasive to directly see flow of blood
• MRI - similar to CT scan
• Electrocardiogram

Treatment:

• Thrombolysis within first 24hrs
• Anticoagulation therapy with heparin or low-molecular weight heparin first, then switch to coumadin once anticoagulation levels reached
• Greenfield Filter- invasive procedure where a filter is placed in the inferior vena cava to "catch blood clots"