II. Indications

III. Precautions: Subsegmental Pulmonary Embolism Controversy

  1. CT Chest has False Positives and False Negatives
    1. False Positive Rate: 26% read initially as positive, were later over-read as negative
      1. Hutchinson (2015) AJR Am J Roentgenol 205(2): 271-7 +PMID:26204274 [PubMed]
    2. False Negative Rate: 11% read initially as subsegmental, were later over-read as segmental
      1. Pena (2012) J Thromb Haemost 10:496-8 +PMID:22212300 [PubMed]
    3. Factors associated with a true positive sub-segmental Pulmonary Embolism
      1. High quality imaging
      2. Multiple filling defects
      3. Defects in proximal subsegmental vessels
      4. Same defect on multiple images or views
      5. Filling defect surrounded by contrast
      6. Symptomatic Pulmonary Embolism
      7. High pretest probability
      8. Unexplained positive D-Dimer
  2. Subsegmental Pulmonary Embolism treatment has mixed results on outcomes
    1. Some studies have shown worse outcomes with subsegmental Pulmonary Embolism treatment
      1. Carrier (2010) J Thromb Haemost 8(8): 1716-22 +PMID:20546118 [PubMed]
    2. Other studies have shown subsegmental PE to have as significant outcomes as segmental PE
      1. den Exeter (2013) Blood 122(7):1144-9 +PMID:23736701 [PubMed]
    3. Despite minor nature of subsegmental PE, recurrent Pulmonary Embolism may occur without Anticoagulation
      1. Kligerman (2014) AJR Am J Roentgenol 202(1): 65-73 +PMID:24370130 [PubMed]
  3. Approach
    1. Evaluate for Deep Vein Thrombosis with bilateral Lower Extremity DopplerUltrasound
      1. Consider other sources of VTE (Upper Extremity DVT, central-line associated DVT)
    2. Evaluate for risk of VTE progression or recurrence
      1. Hospitalized patients
      2. Decreased mobility
      3. Unprovoked VTE
      4. Hypercoagulable state including cancer
      5. Otherwise unexplained severe symptoms
      6. Poor cardiopulmonary reserve
    3. Consider surveillance instead of Anticoagulation if low risk criteria met (grade 2C evidence)
      1. Sub-segmental PE only (or suspicion for False Positive) AND
      2. No concurrent DVT AND
      3. No high risk criteria for progression or recurrence

IV. Grading: Severity

  1. High Risk Pulmonary Embolism (Massive Pumonary Embolism)
    1. Pulmonary Embolism AND
    2. Systolic Blood Pressure <90 mmHg or >40 mmHg BP drop from baseline for at least 15 minutes OR
    3. Cardiac Arrest OR
    4. Vasopressors required
  2. Intermediate Risk Pulmonary Embolism (Submassive Pulmonary Embolism)
    1. Pulmonary Embolism and
    2. Right ventricular dysfunction (RV Strain)
      1. Serum Troponin elevation or
      2. ntBNP >900 pg/ml or (BNP >90 pg/ml) or
      3. Echocardiogram with right ventricular dilation or hypokinesis
  3. Low Risk Pulmonary Embolism
    1. Pulmonary Embolism and
    2. Normal right ventricular function and
    3. Hemodynamically stable

V. Management: Acute Stabilization

  1. Correct Hypoxia on presentation
    1. Hypoxia increases shunting, V/Q mismatch and greater right heart strain
    2. Supplemental Oxygen
    3. Refractory Hypoxia options
      1. High Flow Nasal Cannula
      2. Pulmonary dilators (inhaled nitric oxide or epoprostenol)
    4. Avoid Positive Pressure Ventilation (BiPap, CPAP, Mechanical Ventilation) if possible
      1. Positive pressure may worsen right heart strain
    5. Intubation and RSI if needed should be performed with optimized first pass success
      1. Hypoxic patient will have little reserve and easily decompensate
  2. Correct Hypotension (target >90 mmHg)
    1. Small fluid challenges (e.g. 250 ml aliquots) are preferred to avoid further RV strain
    2. Consider Norepinephrine for refractory Hypotension

VI. Management: Massive Pumonary Embolism (Severe cardiovascular compromise)

  1. See Pulmonary Embolism Evaluation with Echocardiogram
  2. Indications (see grading above)
    1. Massive Pumonary Embolism
      1. Systemic Hypotension and shock (or Cardiac Arrest)
        1. Systolic Blood Pressure <90 mmHg for 15 min (or Vasopressors needed)
      2. Right ventricular Heart Failure
    2. Submassive Pulmonary Embolism
      1. Right ventricular dysfunction or Heart Failure
      2. Controversial for Thrombolytic use (evaluate on a case by case basis)
      3. Evidence as of 2017 does not support Thrombolytic use for submassive PE
      4. See Thrombolysis in Massive Pulmonary Embolism
        1. Reviews benefits and risks of Thrombolysis in Intermediate Risk PE
  3. Intervention options (includes Anticoagulation as above)
    1. Thrombolytic Therapy
      1. Confirm no Thrombolytic Contraindications
      2. See Thrombolysis in Massive Pulmonary Embolism
    2. Surgical embolectomy
      1. Alternative management in massive PE when Thrombolysis is contraindicated or has failed
      2. Gulba (1994) Lancet 343:576-7 [PubMed]
    3. Intervention Radiology, catheter directed Thrombolysis
      1. Uses 75% less Thrombolytic than peripheral infusions with lower risk of bleeding and similar mortality
      2. Variable evidence and some studies have shown benefit while others have not
      3. Kuo (2015) Chest 148(3): 667-73 [PubMed]
      4. Piazza (2015) JACC Cardiovasc Interv 8(10): 1382-92 +PMID: 26315743 [PubMed]
  4. Other measures
    1. Avoid intubation if possible
      1. Intubation and ventilation is challenging to manage in Pulmonary Embolism
    2. VA-ECMO (Extracorporeal Membrane Oxygenation)
      1. Indicated in hemodynamic instability and Cardiogenic Shock refractory to other measures
      2. Best outcomes in massive Pulmonary Embolism are with early use of ECMO
    3. Consider pulmonary vasodilation agents
      1. See Pulmonary Arterial Hypertension Crisis
      2. Right Ventricular Afterload optimization (decrease pulmonary vascular resistance)
      3. These agents may exacerbate Left Ventricular Failure
      4. Agents
        1. Nitroglycerin 1 mg/ml inhaled/nebulized 5 mg (5 ml) over 15 minutes OR
        2. Inhaled Nitric Oxide (20 ppm)
          1. Advantages: No systemic effects and improves V-Q mismatch
          2. Risk of rebound, severe Pulmonary Arterial Hypertension if abruptly stopped
    4. Vasopressors
      1. Initiate early in Hypotension
  5. References
    1. Mattu and Swaminathan (2020) EM:RAP 20(11):2
    2. Jaff (2011) Circulation 123: 1788-830 [PubMed]
    3. Konstantinides (2017) J Am Coll Cardiol 69(12): 1536-44 +PMID:28335835 [PubMed]

VII. Management: General Measures

  1. Consider Thrombophilia work-up
    1. See Thrombophilia
    2. Reserve blood for tests prior to Anticoagulation
    3. Consider underlying malignancy in unprovoked PE
  2. Bed rest is not necessary
    1. Does not prevent new or fatal PE of bleeding
    2. Trujillo-Santos (2005) 127:1631-6 [PubMed]

VIII. Management: Anticoagulation

  1. See Anticoagulation in Thromboembolism
  2. Consider Heparin prior to imaging in high likelihood Pulmonary Embolism
    1. Reasonable in high risk cases
    2. Lack of study data to support as standard of care
    3. Risk of adverse outcome (i.e. bleeding complications)

IX. Management: Pregnancy

  1. See Pulmonary Embolism in Pregnancy
  2. Anticoagulation
    1. Low Molecular Weight Heparin (except for peripartum use of Unfractionated Heparin)
    2. Contraindicated agents: Warfarin, Factor Xa Inhibitor (e.g. Rivoroxaban)
  3. IVC Filter
    1. Indicated for Pulmonary Embolism within 4 weeks of estimated delivery date
  4. Thrombolysis is absolutely contraindicated (EXCEPT in life threatening, massive PE)
    1. Risk of major bleeding 2.6%
    2. Consider in life-threatening massive Pulmonary Embolism if not near term
    3. Gartman (2013) Obstet Med 6:105-11 [PubMed]

X. Disposition: Outpatient Criteria

  1. Inpatient Anticoagulation until therapeutic and stable
    1. Inpatient management is default approach unless outpatient management criteria met
  2. Outpatient Anticoagulation management consideration (Exercise caution)
    1. Precautions
      1. Inpatient management is required for certain conditions
        1. Active cancer
        2. Pregnancy
        3. Pulmonary Embolism occurred while on therapeutic doses of Anticoagulation
      2. Oupatient management should only be considered if consistent with local expert opinion
        1. Must be supported by local protocols
      3. Requires patient Informed Consent
        1. Risk of major bleeding
        2. Risk of death up to 2% (if cancer patients excluded)
    2. Criteria for outpatient management (all criteria should be met)
      1. Patient must be able to comply with outpatient Anticoagulation
        1. Stable mental status without Dementia
        2. Medical literacy
        3. Social support
      2. Risk Stratification Tools with low risk assessment
        1. Pulmonary Embolism Severity Index (PESI) Score <66 (Class 1)
          1. As of 2015, PESI <86 (low risk) may be reasonable for discharge
        2. Hestia Criteria negative
          1. See Hestia Criteria
        3. Bova Score stage 1 (low risk)
        4. Simplified PESI (sPESI) with no positive criteria (score 0)
      3. Reassuring appearance with normal Vital Signs
        1. Hemodynamically stable and normotensive
        2. No Hypoxia (Oxygen Saturation >90%)
        3. No intervention needed (e.g. no thromobolysis or embolectomy)
      4. Troponin normal
      5. No signs of right ventricular strain
        1. Echocardiogram without right strain pattern (right ventricle dilatation, D-Sign, hypokinesis)
        2. Troponin Normal
        3. Brain Natriuretic Peptide (BNP) normal or unchanged from baseline
      6. No contraindicating conditions (cancer, pregnancy)
      7. No significant comorbidities (e.g. chronic lung disease)
      8. No Anticoagulation increased risks
        1. Recent significant bleeding, active bleeding or high risk of bleeding
        2. Severe liver disease
        3. Severe renal disease (Creatinine Clearance <30 ml/min)
        4. Platelet Count >70k
        5. History of Heparin Induced Thrombocytopenia
      9. No intractable pain
        1. Expected need for IV Analgesics >24 hours (e.g. required at least 2 IV doses in ED)
    3. References
      1. Paripati (2023) Crit Dec Emerg Med 37(7): 18-9
      2. Aujesky (2011) Lancet (2011) 378(9785): 41-8 [PubMed]
      3. Otero (2010) Thromb Res 126(1):e1-5 [PubMed]
      4. Vinson (2012) Ann Emerg Med 60(5): 651-62 [PubMed]
      5. Kearon (2016) Chest 149(2): 315-52 [PubMed]
      6. Zondag (2011) J Thromb Haemost 9(8): 1500-7 +PMID:21645235 [PubMed]

XI. Disposition: ED Observation Unit Protocol

  1. Background
    1. In some regions, these low risk patients are discharged home instead of to observation unit
  2. Indications
    1. Low risk PESI Score (Class I to II, PESI <86) or low risk on sPESI or Bova Score AND
    2. Hemodynamically stable (normal Blood Pressure)
  3. Contraindications to ED observation unit
    1. Right ventricular strain on Echocardiogram
    2. Troponin Increased
    3. Brain Natriuretic Peptide (BNP)
    4. New Hypoxemia requiring Oxygen Supplementation
    5. Dyspnea or increased work of breathing
    6. Extensive DVT into the iliac or pelvic vessels or free floating thrombus
    7. Heart related hospitalization in last 30 days (CHF exacerbation, CAD)
    8. Unable to be compliant with medical regimen (e.g. homeless, chemical abuse)
  4. Diagnostics
    1. Telemetry
    2. Echocardiogram (consider as evaluation for right heart strain)
    3. Bilateral Lower Extremity DopplerUltrasound (consider)
    4. Hypercoagulable state evaluation in unprovoked Venous Thromboembolism
  5. Anticoagulation (choose one)
    1. See Anticoagulation in Thromboembolism
    2. Warfarin and Low Molecular Weight Heparin (e.g. Lovenox)
    3. Direct Oral Anticoagulant or DOAC (e.g. Rivaroxaban, Apixaban, Edoxaban)
    4. Low Molecular Weight Heparin (e.g. Lovenox) alone
      1. Indicated in pregnancy or severe Thrombophilia (or when Warfarin or DOACs contraindicated)
  6. Discharge goals
    1. Systolic Blood Pressure >100 mmHg
    2. Heart Rate <110 bpm
    3. No Supplemental Oxygen required
    4. Negative Troponin
  7. Education
    1. Anticoagulant safety (Trauma prevention, bleeding signs/symptoms)
    2. Anticoagulation clinic close follow-up (Warfarin)
  8. Discharge
    1. Follow-up (e.g. primary care, hematology, cardiology or vascular) within 72 hours
    2. Anticoagulation clinic follow-up for Warfarin within days
  9. Efficacy
    1. Successful discharge home in 75% of cases (25% require hospital admission)
  10. References
    1. Davenport and Baugh (2018) Crit Dec Emerg Med 32(7): 15-24
    2. Bledsoe (2010) Crit Pathw Cardiol 9(4): 212-5 [PubMed]

XIII. References

  1. Orman and Mattu in Herbert (2015) EM:Rap 15(12): 8-10
  2. Vibhakar (2015) Crit Dec Emerg Med 29(9): 2-8
  3. Kearon (2016) Chest 149(2):315-52 [PubMed]
  4. Konstantinides (2020) Eur Heart J 41(4):543-603 [PubMed]
  5. Wilbur (2012) Am Fam Physician 86(10):913-9 [PubMed]

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