II. Epidemiology
 PE mortality has not changed since the late 1990s despite a 10 fold increase in CT Pulmonary Angiography
 Accelerated Diagnostic Protocols can safely reduce unnecessary CT Pulmonary Angiography
 Orman and Berg in Herbert (2015) EM:Rap 15(5): 1011
III. Precautions
 Normalization of Vital Signs does not reduce the probability of acute Pulmonary Embolism

Pulmonary Embolism can present as a COPD exacerbation
 Once thought to be more common
 Overestimated at up to 20% of cases based on VQ Scan results in French study
 However, more recent reanalysis
 References
 Once thought to be more common
IV. Evaluation: Step 1  Consider Differential Diagnosis
 See Chest Pain Causes
 See Dyspnea Causes
 See Tachypnea
 See Hypoxia
 See Sinus Tachycardia
 See Leg Pain Causes
V. Evaluation: Step 2  Define Typical, Atypical or Severe PE Symptoms
 At least one of three factors are present in 97% of Pulmonary Embolism
 Typical PE Criteria
 Two or more Column A factors
 Dyspnea (new or progressive)
 Pleuritic Chest Pain
 Hemoptysis
 Pleural rub
 Oxygen Saturation on room air <92%
 One or more Column B factors
 Heart Rate over 90 per minute
 Low grade fever (<101 Fahrenheit)
 Leg symptoms suggestive of Deep Vein Thrombosis
 Chest XRay suggestive of Pulmonary Embolism
 Two or more Column A factors
 Severe PE Criteria
 Primary Criteria
 Typical PE Criteria met (see above) or
 Atypical unexplained Hypotension, Syncope, Hypoxia
 Additional signs suggestive of severe PE
 Syncope
 Systolic Blood Pressure <90 mmHg
 Heart Rate above 100 (Tachycardia)
 Supplemental Oxygen required >40% FiO2
 Signs of new right ventricular strain pattern
 Electrocardiogram (EKG) with S1 Q3 T3 pattern
 EKG with new Right Bundle Branch Block
 Primary Criteria
 Atypical PE Criteria
 Nonspecific cardiopulmonary symptoms
 Typical criteria not met (see above)
VI. Evaluation: Step 3  Assess Significant Thromboembolic Risk Factors
 See Pulmonary Embolism Risk Factors

Deep Vein Thrombosis or Pulmonary Embolism history
 Family History of Thromboembolism is >2 relatives
 Past Medical History of prior event
 Cancer
 Treatment in last 6 months
 Palliative Care
 Paralysis
 Bedrest (3 days within the last 4 weeks)
 Lower extremity plaster immobilization (last 12 weeks)
 Recent Surgery in past 12 weeks
 Obstetrical delivery in last 12 weeks
VII. Evaluation: Step 4  Determine Pulmonary Embolism Probability
 See Wells Clinical Prediction Rule for PE
 Evaluation tools
 Three starting questions
 Dyspnea?
 Tachypnea?
 Pleuritic Chest Pain?
 All three symptoms absent nearly excludes Pulmonary Embolism (97% probability)
 Pulmonary Embolism Pretest Probability (Wells Clinical Prediction Rule for PE or Revised Geneva Score)
 Indicated if Dyspnea, Tachypnea or Pleuritic Chest Pain is present
 Quantifies pretest probability of Pulmonary Embolism
 Moderate to high probability requires diagnostic testing (typically CT angiogram)
 Low pretest probability may be evaluated with PERC Rule
 Pulmonary Embolism RuleOut Criteria (PERC Rule)
 Indicated if low probability for Pulmonary Embolism (or moderate probability up to 10%)
 Strong Negative Predictive Value (if all criteria are negative)
 Low probability for PE with a negative PERC Rule
 Nearly excludes Pulmonary Embolism (Very low probability)
 Low probability for PE with any PERC Rule criteria positive
 Pursue with additional testing (e.g. DDimer)
 Three starting questions
 Very Low Probability of Pulmonary Embolism
 If no Dyspnea, no Tachypnea and no Pleuritic Chest Pain
 Pulmonary Embolism is very unlikely
 Consider evaluation only in significant atypical symptoms and significant VTE Risk factors
 If low probability by Wells Clinical Prediction Rule for PE and negative PERC Rule
 Significant Pulmonary Embolism is nearly excluded
 VTE is very unlikely and no further evaluation is needed (including no DDimer)
 If PERC Rule is not completely negative, pursue evaluation for PE
 If no Dyspnea, no Tachypnea and no Pleuritic Chest Pain
 Low Probability for Pulmonary Embolism (3.6% PE Probability based on Well's Criteria <34)
 Alternative diagnosis more likely than PE
 Atypical PE signs with or without risk factors
 Typical PE signs without risk factors
 PE more likely than alternative diagnosis
 Atypical PE signs without risk factors
 Alternative diagnosis more likely than PE
 Moderate Probability for Pulmonary Embolism (20.5% PE Probability based on Well's Criteria 34 to 6)
 Alternative diagnosis more likely than PE
 Typical PE signs with risk factors
 Severe PE signs with or without risk factors
 PE more likely than alternative diagnosis
 Atypical PE signs with risk factors
 Typical PE signs without risk factors
 Alternative diagnosis more likely than PE
 High Probability for Pulmonary Embolism (66.7% PE Probability based on Well's Criteria >6)
 PE more likely than alternative diagnosis
 Typical PE signs with risk factors
 Severe PE signs with or without risk factors
 PE more likely than alternative diagnosis
VIII. Evaluation: Step 5  Determine Diagnostic Approach in a hemodynamically stable patient
 Hemodynamic instability
 See approach below (step 6)
 Very low probability for Pulmonary Embolism
 Requires no additional workup (including no DDimer)
 Criteria
 No Dyspnea, no Tachypnea and no Pleuritic Chest Pain (and no significant risk factors) OR
 Low probability for PE (e.g. Wells Clinical Prediction Rule for PE) and negative PERC Rule
 Low probability for Pulmonary Embolism and a negative DDimer
 Requires no additional testing
 False Positive Rate for CT angiogram in low probability cases approaches 45%

Moderate PE Probability, High PE Probability or positive DDimer
 Obtain Imaging Study
 CT Pulmonary Angiography (preferred)
 VentilationPerfusion Scan (VQ Scan)
 No further diagnostic testing needed
 High Probability PE with high probability imaging
 High probability VQ Scan or positive CT angiography
 See Pulmonary Embolism Management
 Low Probability PE with low probability imaging
 No treatment needed
 Evaluate alternative diagnoses
 High Probability PE with high probability imaging
 Obtain Imaging Study
 Additional testing needed
 High probability PE or moderate risk (e.g. Well's Score >2) AND negative imaging (e.g. CT angiography)
 Compression Ultrasound of lower extremities
 High risk patients need Ultrasound same day
 If reassuring clinical appearance and Vital Signs
 Discharge from ED and perform testing within 1 week
 Positive Compression Ultrasound
 Treat as Pulmonary Embolism
 Negative Compression Ultrasound
 Low probability PE: Consider other diagnosis
 Moderate probability PE
 Obtain DDimer or repeat Compression Ultrasound
 Negative test: Consider other diagnosis
 Positive test: Treat as Pulmonary Embolism
 High probability PE: Perform Angiography
 Negative Angiography: Consider other diagnosis
 Positive Angiography: Treat as PE
 Compression Ultrasound of lower extremities
 High probability VQ Scan with Low probability PE
 Pulmonary Angiography or CT angiography
 Negative angiography: Evaluate other diagnosis
 Positive angiography: Treat as Pulmonary Embolism
 High probability PE or moderate risk (e.g. Well's Score >2) AND negative imaging (e.g. CT angiography)
 Evaluate based on clinical probability
IX. Evaluation: Step 6  Determine Diagnostic Approach in a hemodynamically Unstable Patient
 Not critically ill and CT angiography available
 CT Angiography positive
 Treat as Pulmonary Embolism
 CT Angiography negative
 Consider alternative diagnosis
 CT Angiography positive
 Critically ill or CT Angiography not available
 See Pulmonary Embolism Evaluation with Echocardiogram
 Echocardiogram with right ventricular dysfunction
 Treat as Pulmonary Embolism
 Echocardiogram without right ventricular dysfunction
 Consider alternative diagnosis
X. References
 Tabas in Majoewsky (2013) EM:Rap 13(6):810
 Vibhakar (2015) Crit Dec Emerg Med 29(9): 28
 Agnelli (2010) N Engl J Med 363(3): 26674 [PubMed]
 Ramzi (2004) Am Fam Physician 69:282936 [PubMed]
 Ryu (2001) Mayo Clin Proc 76:63 [PubMed]
 Wells (1998) Ann Intern Med 129(12): 9971005 [PubMed]
 Wilbur (2012) Am Fam Physician 86(10):9139 [PubMed]