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## Pulmonary Embolism Diagnosis

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

- See Also
- Pulmonary Embolism
- Pulmonary Embolism Pretest Probability (Wells Clinical Prediction Rule for PE)
- Pulmonary Embolism Rule-Out Criteria (PERC Rule)
- Pulmonary Embolism Evaluation with Echocardiogram
- Pulmonary Embolism Low Probability Evaluation
- Pulmonary Embolism Moderate Probability Evaluation
- Pulmonary Embolism High Probability Evaluation
- Pulmonary Embolism Management

- 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): 10-11

- 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
- Over-estimated at up to 20% of cases based on V-Q Scan results in French study

- However, more recent re-analysis
- References

- Once thought to be more common

- Evaluation: Step 1 - Consider Differential Diagnosis
- See Chest Pain Causes
- See Dyspnea Causes
- See Tachypnea
- See Hypoxia
- See Sinus Tachycardia
- See Leg Pain Causes

- 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)

- 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

- 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 Rule-Out 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. D-Dimer)

- 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 D-Dimer)
- 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 <3-4)
- 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 3-4 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

- 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 work-up (including no D-Dimer)
- 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 D-Dimer
- Requires no additional testing
- False Positive Rate for CT angiogram in low probability cases approaches 45%

- Moderate PE Probability, High PE Probability or positive D-Dimer
- Obtain Imaging Study
- CT Pulmonary Angiography (preferred)
- Ventilation-Perfusion 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 D-Dimer 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

- Hemodynamic instability
- 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

- Not critically ill and CT angiography available
- References
- Tabas in Majoewsky (2013) EM:Rap 13(6):8-10
- Vibhakar (2015) Crit Dec Emerg Med 29(9): 2-8
- Agnelli (2010) N Engl J Med 363(3): 266-74 [PubMed]
- Ramzi (2004) Am Fam Physician 69:2829-36 [PubMed]
- Ryu (2001) Mayo Clin Proc 76:63 [PubMed]
- Wells (1998) Ann Intern Med 129(12): 997-1005 [PubMed]
- Wilbur (2012) Am Fam Physician 86(10):913-9 [PubMed]