Pulmonary Embolism

1. See Also
   1. Deep Vein Thrombosis (DVT)
   2. Pulmonary Embolism Diagnosis
   3. Pulmonary Embolism Risk Factors
   4. Thrombophilia
   5. Pulmonary Embolism Management
2. Epidemiology
   1. Incidence in United States
      1. Total Cases: 650,000 per year
      2. Deaths per year: 200,000 per year
      3. Deaths in first hour: 11%
   2. Mortality increases with age
      1. Age 40 years: 2.5%
      2. Age over 65 years: 40%
   3. Mortality increases if diagnosis missed
      1. Diagnosed in Emergency Department: 5% Mortality
      2. Missed Diagnosis: 30% Mortality
      3. Missed diagnosis in 50 to 70%
3. Risk Factors
   1. Pulmonary Embolism Risk Factors
4. Differential Diagnosis
   1. See Chest Pain Causes
   2. See Dyspnea Causes
   3. See Leg Pain Causes
   4. Baker's Cyst (Pseudo-thrombosis)
5. Symptoms
   1. Classic Triad
      1. Chest Pain (80-90%)
         1. Pleuritic Chest Pain (74%)
         2. Non-Pleuritic Chest Pain (14%)
      2. Cough (40-53%)
      3. Hemoptysis (13-20%)
   2. Dyspnea (75-85%)
   3. Apprehension or anxiety (50-65%)
   4. Syncope (5-13%)
   5. Diaphoresis (27-36%)
6. Signs
   1. Tachypnea (80-90%)
      1. Respiratory Rate over 16 (92%)
      2. Respiratory Rate over 20 (70%)
   2. Rales (50-58%)
   3. Tachycardia (40-50%)
   4. Fever (40%)
      1. Temperature usually 37.8 to 38.5 C
      2. Temperature rarely over 38.5 C (102.5)
   5. Gallup rhythm (34%)
   6. Phlebitis (32%)
   7. Edema (24%)
   8. Cardiac murmur (23%)
   9. Adventitious breath sounds
   10. Cyanosis (19%)
   11. Circulatory collapse (8%)
   12. Lower extremity swelling, tight cords, or tenderness
   13. Homan's Sign not helpful
7. Complications
   1. Acute Cor Pulmonale (Pulmonary Hypertension)
   2. Massive Pulmonary Embolism
      1. Systemic Hypotension and shock
      2. Right Heart Failure
8. Diagnosis
   1. See Pulmonary Embolism Diagnosis
   2. Pregnancy
      1. D-Dimer
         1. Interpretation of normal range varies based on gestational age
      2. Ultrasound bilateral lower extremity venous doppler
         1. Indicated if D-Dimer positive (or jump straight to unilateral Ultrasound for a asymmetrically symptomatic extremity)
         2. Anticoagulate if positive and no further testing needed
      3. CT Angiogram
         1. Indicated for positive D-Dimer and
         2. Negative Lower Extremity DopplerUltrasound
9. Labs
   1. D-Dimer (ELISA Test - do not use latex agglutination)
      1. Only useful in Low PE Probability patient
      2. Negative Predictive Value 99.5% if Low PE Probability
      3. Wells (2001) Ann Intern Med 135:98-107
   2. Arterial Blood Gas (normal in 15% of PE patients)
      1. Normal ABG does not rule out PE
      2. Arterial pO2 low (Hypoxia)
         1. Most patients: 60-70 mmHg
         2. Twenty percent of patients: >80mmHg
         3. Five percent of patients: >90mmHg in 5%
      3. Respiratory Alkalosis
         1. Arterial pCO2 decreased in 95% of patients
      4. A-a Gradient Increased
         1. Sensitivity: 90%
         2. Sensitivity with low arterial pCO2: 98%
   3. Troponin I
      1. Increased in 25-50% of patients with moderate to large Pulmonary Embolism
      2. Related to right ventricular strain
10. Diagnostic Tests: Electrocardiogram
    1. See Electrocardiogram in PE
11. Imaging: Chest XRay
    1. Nonspecific Chest XRay changes in 85%
       1. Elevated hemidiaphragm (50%)
       2. Hampton's Hump
          1. Peripheral wedge shaped infiltrate or opacity
          2. Pleural based infiltrate pointed towards hilum
       3. Westmark Sign
          1. Dilated proximal vessels with a distal cutoff
       4. Pleural Effusion
       5. Atelectasis
    2. Rules out other Dyspnea Causes
       1. Pneumothorax
       2. Pneumomediastinum
       3. Aortic Dissection
       4. Pneumonia
    3. Normal Chest XRay in Acute Dyspnea and Hypoxemia
       1. Suggests Pulmonary Embolism if no Wheezing
12. Imaging: First-Line Diagnosis
    1. CT Scan (Helical and Ultrafast)
       1. Efficacy
          1. 86% Sensitive for central emboli
          2. 63% Sensitive for subsegmental vessels
       2. Disadvantages
          1. Difficult to use if patient severely dyspneic
             1. Patient must hold breath for 15 to 30 seconds
          2. Misses peripheral emboli
13. Imaging: Alternative for Diagnosis
    1. Lower Extremity Doppler (Impedance Plethysmography)
       1. Ultrasound symptomatic extremity (or consider bilateral Lower Extremity Doppler)
       2. Treatment initiated if DVT present (asymptomatic associated PE Incidence approaches 20%)
       3. Management of DVT is similar to PE and therefore confirmation of PE adds little additional value
    2. VQ Scan
       1. CT Angiogram has largely replaced VQ
       2. In the past perfusion scan only was considered in pregnancy (assuming normal baseline lungs in otherwise healthy patient)
          1. However, Fetal Radiation Exposure from perfusion scan appears to exceed CT Angiogram
          2. In addition, VQ is often non-diagnostic
14. Imaging: Other Modalities
    1. Pulmonary Angiography
    2. Transesophageal Echo
    3. Chest MRI (No current use in PE evaluation)
       1. Efficacy
          1. 90% sensitive for proximal emboli
       2. Disadvantages
          1. 10% unable to get adequate study
       3. Indications
          1. Angiography contraindicated
          2. Pregnancy
15. Management
    1. See Pulmonary Embolism Management
16. Prognosis
    1. Brain Natriuretic Peptide (BNP) may predict prognosis
       1. BNP <90 pg/ml associated with benign course
       2. Kucher (2003) Circulation 107:2545-7