Pulmonary Embolism Diagnosis

Aka: Pulmonary Embolism Diagnosis, Pulmonary Embolus Diagnosis, PE Diagnosis, PE Probability, Pulmonary Embolism Accelerated Diagnostic Protocol

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II. Epidemiology

  1. PE mortality has not changed since the late 1990s despite a 10 fold increase in CT Pulmonary Angiography
  2. Accelerated Diagnostic Protocols can safely reduce unnecessary CT Pulmonary Angiography
    1. Orman and Berg in Herbert (2015) EM:Rap 15(5): 10-11

III. Precautions

  1. Normalization of Vital Signs does not reduce the probability of acute Pulmonary Embolism
    1. Kline (2012) Acad Emerg Med 19(1): 11-17 [PubMed]
  2. Pulmonary Embolism can present as a COPD exacerbation
    1. Once thought to be more common
      1. Over-estimated at up to 20% of cases based on V-Q Scan results in French study
    2. However, more recent re-analysis
      1. Incidence of 3.3% for PE presenting as COPD exacerbation
    3. References
      1. Rizkallah (2009) Chest 135(3):786-93 [PubMed]

IV. Evaluation: Step 1 - Consider Differential Diagnosis

  1. See Chest Pain Causes
  2. See Dyspnea Causes
  3. See Tachypnea
  4. See Hypoxia
  5. See Sinus Tachycardia
  6. See Leg Pain Causes

V. Evaluation: Step 2 - Define Typical, Atypical or Severe PE Symptoms

  1. At least one of three factors are present in 97% of Pulmonary Embolism
    1. Dyspnea
    2. Tachypnea
    3. Pleuritic Chest Pain
    4. Courtney (2010) Ann Emerg Med 55(4): 307-15 [PubMed]
  2. Typical PE Criteria
    1. Two or more Column A factors
      1. Dyspnea (new or progressive)
      2. Pleuritic Chest Pain
      3. Hemoptysis
      4. Pleural rub
      5. Oxygen Saturation on room air <92%
    2. One or more Column B factors
      1. Heart Rate over 90 per minute
      2. Low grade fever (<101 Fahrenheit)
      3. Leg symptoms suggestive of Deep Vein Thrombosis
      4. Chest XRay suggestive of Pulmonary Embolism
  3. Severe PE Criteria
    1. Primary Criteria
      1. Typical PE Criteria met (see above) or
      2. Atypical unexplained Hypotension, Syncope, Hypoxia
    2. Additional signs suggestive of severe PE
      1. Syncope
      2. Systolic Blood Pressure <90 mmHg
      3. Heart Rate above 100 (Tachycardia)
      4. Supplemental Oxygen required >40% FiO2
      5. Signs of new right ventricular strain pattern
        1. Electrocardiogram (EKG) with S1 Q3 T3 pattern
        2. EKG with new Right Bundle Branch Block
  4. Atypical PE Criteria
    1. Nonspecific cardiopulmonary symptoms
    2. Typical criteria not met (see above)

VI. Evaluation: Step 3 - Assess Significant Thromboembolic Risk Factors

  1. See Pulmonary Embolism Risk Factors
  2. Deep Vein Thrombosis or Pulmonary Embolism history
    1. Family History of Thromboembolism is >2 relatives
    2. Past Medical History of prior event
  3. Cancer
    1. Treatment in last 6 months
    2. Palliative Care
  4. Paralysis
  5. Bedrest (3 days within the last 4 weeks)
  6. Lower extremity plaster immobilization (last 12 weeks)
  7. Recent Surgery in past 12 weeks
  8. Obstetrical delivery in last 12 weeks

VII. Evaluation: Step 4 - Determine Pulmonary Embolism Probability

  1. See Wells Clinical Prediction Rule for PE
  2. Evaluation tools
    1. Three starting questions
      1. Dyspnea?
      2. Tachypnea?
      3. Pleuritic Chest Pain?
      4. All three symptoms absent nearly excludes Pulmonary Embolism (97% probability)
    2. Pulmonary Embolism Pretest Probability (Wells Clinical Prediction Rule for PE or Revised Geneva Score)
      1. Indicated if Dyspnea, Tachypnea or Pleuritic Chest Pain is present
      2. Quantifies pretest probability of Pulmonary Embolism
      3. Moderate to high probability requires diagnostic testing (typically CT angiogram)
      4. Low pretest probability may be evaluated with PERC Rule
    3. Pulmonary Embolism Rule-Out Criteria (PERC Rule)
      1. Indicated if low probability for Pulmonary Embolism (or moderate probability up to 10%)
      2. Strong Negative Predictive Value (if all criteria are negative)
      3. Low probability for PE with a negative PERC Rule
        1. Nearly excludes Pulmonary Embolism (Very low probability)
      4. Low probability for PE with any PERC Rule criteria positive
        1. Pursue with additional testing (e.g. D-Dimer)
  3. Very Low Probability of Pulmonary Embolism
    1. If no Dyspnea, no Tachypnea and no Pleuritic Chest Pain
      1. Pulmonary Embolism is very unlikely
      2. Consider evaluation only in significant atypical symptoms and significant VTE Risk factors
    2. If low probability by Wells Clinical Prediction Rule for PE and negative PERC Rule
      1. Significant Pulmonary Embolism is nearly excluded
      2. VTE is very unlikely and no further evaluation is needed (including no D-Dimer)
      3. If PERC Rule is not completely negative, pursue evaluation for PE
  4. Low Probability for Pulmonary Embolism (3.6% PE Probability based on Well's Criteria <3-4)
    1. Alternative diagnosis more likely than PE
      1. Atypical PE signs with or without risk factors
      2. Typical PE signs without risk factors
    2. PE more likely than alternative diagnosis
      1. Atypical PE signs without risk factors
  5. Moderate Probability for Pulmonary Embolism (20.5% PE Probability based on Well's Criteria 3-4 to 6)
    1. Alternative diagnosis more likely than PE
      1. Typical PE signs with risk factors
      2. Severe PE signs with or without risk factors
    2. PE more likely than alternative diagnosis
      1. Atypical PE signs with risk factors
      2. Typical PE signs without risk factors
  6. High Probability for Pulmonary Embolism (66.7% PE Probability based on Well's Criteria >6)
    1. PE more likely than alternative diagnosis
      1. Typical PE signs with risk factors
      2. Severe PE signs with or without risk factors

VIII. Evaluation: Step 5 - Determine Diagnostic Approach in a hemodynamically stable patient

  1. Hemodynamic instability
    1. See approach below (step 6)
  2. Very low probability for Pulmonary Embolism
    1. Requires no additional work-up (including no D-Dimer)
    2. Criteria
      1. No Dyspnea, no Tachypnea and no Pleuritic Chest Pain (and no significant risk factors) OR
      2. Low probability for PE (e.g. Wells Clinical Prediction Rule for PE) and negative PERC Rule
  3. Low probability for Pulmonary Embolism and a negative D-Dimer
    1. Requires no additional testing
    2. False Positive Rate for CT angiogram in low probability cases approaches 45%
  4. Moderate PE Probability, High PE Probability or positive D-Dimer
    1. Obtain Imaging Study
      1. CT Pulmonary Angiography (preferred)
      2. Ventilation-Perfusion Scan (VQ Scan)
    2. No further diagnostic testing needed
      1. High Probability PE with high probability imaging
        1. High probability VQ Scan or positive CT angiography
        2. See Pulmonary Embolism Management
      2. Low Probability PE with low probability imaging
        1. No treatment needed
        2. Evaluate alternative diagnoses
  5. Additional testing needed
    1. High probability PE or moderate risk (e.g. Well's Score >2) AND negative imaging (e.g. CT angiography)
      1. Compression Ultrasound of lower extremities
        1. High risk patients need Ultrasound same day
        2. If reassuring clinical appearance and Vital Signs
          1. Discharge from ED and perform testing within 1 week
      2. Positive Compression Ultrasound
        1. Treat as Pulmonary Embolism
      3. Negative Compression Ultrasound
        1. Low probability PE: Consider other diagnosis
        2. Moderate probability PE
          1. Obtain D-Dimer or repeat Compression Ultrasound
          2. Negative test: Consider other diagnosis
          3. Positive test: Treat as Pulmonary Embolism
        3. High probability PE: Perform Angiography
          1. Negative Angiography: Consider other diagnosis
          2. Positive Angiography: Treat as PE
    2. High probability VQ Scan with Low probability PE
      1. Pulmonary Angiography or CT angiography
      2. Negative angiography: Evaluate other diagnosis
      3. Positive angiography: Treat as Pulmonary Embolism
  6. Evaluate based on clinical probability
    1. Pulmonary Embolism Low Probability Evaluation
    2. Pulmonary Embolism Moderate Probability Evaluation
    3. Pulmonary Embolism High Probability Evaluation

IX. Evaluation: Step 6 - Determine Diagnostic Approach in a hemodynamically Unstable Patient

  1. Not critically ill and CT angiography available
    1. CT Angiography positive
      1. Treat as Pulmonary Embolism
    2. CT Angiography negative
      1. Consider alternative diagnosis
  2. Critically ill or CT Angiography not available
    1. See Pulmonary Embolism Evaluation with Echocardiogram
    2. Echocardiogram with right ventricular dysfunction
      1. Treat as Pulmonary Embolism
    3. Echocardiogram without right ventricular dysfunction
      1. Consider alternative diagnosis

X. References

  1. Tabas in Majoewsky (2013) EM:Rap 13(6):8-10
  2. Vibhakar (2015) Crit Dec Emerg Med 29(9): 2-8
  3. Agnelli (2010) N Engl J Med 363(3): 266-74 [PubMed]
  4. Ramzi (2004) Am Fam Physician 69:2829-36 [PubMed]
  5. Ryu (2001) Mayo Clin Proc 76:63 [PubMed]
  6. Wells (1998) Ann Intern Med 129(12): 997-1005 [PubMed]
  7. Wilbur (2012) Am Fam Physician 86(10):913-9 [PubMed]

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