Pulmonary embolism

See Pulmonary embolism in pregnancy for pregnancy specific information.[1]

Background

Clinical Spectrum of Venous thromboembolism

Only 40% of ambulatory ED patients with PE have concomitant DVT[2][3]

Pulmonary Embolism Categorization[4]

Massive: High-risk

Hemodynamically unstable with symptoms of shock

  • ACCP 2016 CHEST Guidelines: Sustained hypotension ONLY criteria (systolic BP <90 for at least 15min or requiring inotropic support)
  • Previous definitions (e.g. AHA 2011) include cardiac arrest/pulselessness or persistent profound bradycardia (HR <40 with signs of shock)

Submassive: Intermediate-risk

Right ventricular dysfunction (RVD) and/or myocardial necrosis in the absence of persistent hypotension or shock (SBP >90)[5]

  • RV dysfunction
    • RV dilation or dysfunction on TTE
      • "D Sign" on bedside echo (LV takes on a "D" shape due to RV dilation)
    • RV dysfunction on CT defined as RV/LV ratio >0.9[6]
    • Elevation of BNP (>90)
    • ECG findings of right heart strain (see diagnosis below)
  • Myocardial necrosis: Troponin I >0.4

Non-Massive: Low-risk

No hemodynamic compromise and no RV strain

Sub-Segmental

  • Limited to the subsegmental pulmonary arteries

Clinical Features

Symptoms

According to the PIOPED II study, these are the most common presenting signs[7]

Signs

  • Tachypnea (54%)
  • Calf or thigh swelling, erythema, edema, tenderness, palpable cord (47%)
  • Tachycardia (24%)
  • Rales (18%)
  • Decreased breath sounds (17%)
  • Accentuated pulmonic component of the second heart sound (15%)
  • JVD (14%)
  • Fever (3%)

Differential Diagnosis

Chest pain

Critical

Emergent

Nonemergent

Acute dyspnea

Emergent

Non-Emergent

Workup (by Pretest Probability)

Assessing Pretest Probability

Objective criteria (Geneva, Wells, etc.) is equal to gestalt in assessing pre-test probability[8] (ACEP Level B)

Wells Criteria

Clinical Features Points
Symptoms of DVT (leg swelling and pain with palpation) 3.0
PE as likely as or more likely than an alternative diagnosis 3.0
HR >100 bpm 1.5
Immobilization for >3 consecutive days or surgery in the previous 4 weeks 1.5
Previous DVT or PE 1.5
Hemoptysis 1.0
Malignancy (receiving treatment, treatment stopped within 6 mon, palliative care) 1.0
Two Tier Wells Score
  • Score 0-4 = PE Unlikely (12.1% incidence of PE)
    • Check D-dimer
      • If D-dimer positive then obtain CTPA or V/Q scan
      • If D-dimer negative, no further workup needed (0.5% incidence of PE at 3 month follow up)
  • Score >4 = PE Likely (37.1% incidence of PE)
    • Obtain CT Pulmonary Angiography or V/Q Scan
  • New evidence suggests lower Wells Score with D-dimer <1000 ng/mL is effective at ruling out PE without imaging

Less common risks

  • HIV (protein wasting nephropathy)
  • Nephrotic Syndrome
  • SLE with anti-cardiolipan Ab
  • Exogenous hormones (specifically estrogen)
  • Factor V Leiden
  • Antithrombin III deficiency
  • Protein C deficiency
  • Protein S deficiency
  • Hyperhomocysteinemia

Low-Probability Testing

  • PERC Rule negative, then no further workup[8] (ACEP Level B)
    • Avoid CT pulmonary angiography in low pretest probability patients that are either PERC rule negative or have a negative d-dimer (ACEP choosing wisely)
    • D-dimer NPV is 99.5%[9]
  • PERC Rule positive, then d-dimer (see Moderate-Probability Testing below)[8] (ACEP Level B)

Moderate-Probability Testing

  • D-dimer (consider age adjusted D-dimer)
    • Positive, continue testing (see High-Probability Testing below)
    • Negative, no further testing
      • However, it is unclear whether d-dimer alone is sufficient to rule-out PE[8] (ACEP Level C)

High-Probability Testing

  • Consider empiric anticoagulation before imaging
  • See Definitive Diagnostic Imaging below

Post-Test Probability Calculations

Pretest - LR Posttest
Wells < 4 + PERC 12% 0.12 1.6%
Wells < 4 + Neg Dimer 12% 0.01 0.14%
Wells < 4 + AA Dimer 12% 0.06 0.81%
Wells < 2 + PERC 2% 0.01 0.24%
Wells < 2 + Neg Dimer 2% 0.06 0.02%
Wells < 2 + AA Dimer 2% 0.12 0.12

Diagnosis

Definitive Diagnostic Imaging

  • CTA if GFR >60
  • V/Q if GFR <60
    • Will be nondiagnostic if patient has effusion, pneumonia, or other airspace disease
  • If imaging negative, perform additional diagnostic testing (eg, D-dimer, LE vasc US, VQ, traditional pulmonary arteriography) prior to exclusion of VTE[8] (ACEP Level C)
    • A negative d-dimer in combination with a negative CTA theoretically provides a post-test probability of VTE less than 1%

Other Possible Diagnostic Findings

D Sign[10]
Hampton's Hump
  • ECG (sbnormal in 70% of PE patients[11])
    • Sinus tachycardia is most common finding
    • T-wave inversion in anterior/septal leads + inferior leads[12]
    • Nonspecific ST changes, S1Q3T3 (develops due to strain on RV)
    • RBBB or new incomplete RBBB.[13]
    • New right axis deviation
    • Atrial fibrillation
  • CXR (abnormal in 70%)
    • Atelectasis is most common (esp >24 hrs after onset of symptoms)
    • Pleural effusion
    • Hampton's Hump
    • Westermark's sign[14]
  • Formal transthoracic echo or bedside cardiac ultrasound
    • Can help diagnosis in equivocal cases
    • May see signs of right heart strain (bowing of septum into LV; Aka D Sign)
      • Right ventricular strain is associated with statistically significant worse outcome[15]
    • McConnel's sign (akinesis of RV base/free wall with sparing of apex)
    • Lateral right ventricular wall diameter of <5mm is suggestive of acute pulmonary hypertension while >5mm is suggestive of chronic pulmonary hypertension[16]
  • SPECT
    • Combination of noncontrast CT chest with V/Q scan
    • Avoidance of contrast for patients with renal injury
    • As sensitive as CTPA and more sensitive than planar V/Q scanning[17]

Management

Supportive care

  • Give IVF as necessary to increase preload while frequently assessing volume status

Anticoagulation

  • Treatment options include any of the following anticoagulations which are indicated for all patients with confirmed PE or high clinical suspicion (do not wait for imaging).
  • Clinical surveillance over anticoagultation for subsegmental PE with no proximal DVT at low risk for recurrent VTE (Level 2C evidence)[18]
Name LMWH SC Unfractionated Heparin Dabigatran Rivaroxaban Apixaban Coumadin
Initial Dose
  • 80 units/kg bolus; then 18 units/kg/hr
  • 5 mg PO
Benefits
  • 1st line for most hemodynamically stable patients
  • Short half life and easy ability to turn off the infusion.
  • The prefered anticoagulation if thrombolysis is being considered or if there is a bleeding risk or trauma and anticoagulation will need to be emergently discontinued
  • No need for renal dosing
  • Noninferior to warfarin in reducing DVT and PE [19]
  • Associated with less bleeding, particularly in elderly patients and those with moderate renal impairment compared to standard treatments [20]
  • Studies show 16% reduction in VTE related death compared to standard therapy [21]
Contraindiations
  • Contraindicated in renal failure
  • Patients with morbid obesity or anasarca may have poor absorption
  • Temporary hypercoagulable state for approx 5 days
Comments
  • Check PTT after 6hr; adjust infusion to maintain PTT at 1.5-2.5x control
  • INR target 2.5
  • Duration
    • 3-6 mo, if time limited risk factor (post-op, trauma, estrogen use)
    • 6 mo to life, if idiopathic etiology or recurrent

Thrombolysis

IVC Filter

  • Indications
    • anticoagulation contraindicated in patient with PE
    • failure to attain adequate anticoagulation during treatment

Disposition

  • Patients with significant clot burden generally require admission for anticoagulation
  • Consider discharge in low risk patients with peripheral PE[22]

Prognosis

The Pulmonary Embolism Severity Index (PESI)[23]

  • PE patients with PESI class I or II seem safe to manage as outpatients.
Prognosis Variable Points Assigned
Demographics
Age +Age in years
Male +10
Comorbid Conditions
Cancer +30
Heart Failure +10
Chronic Lung Diseae +10
Clincal Findings
Pulse >110 b/min +20
sBP < 100 +30
RR > 30 +20
Temp <36 C +20
AMS +60
Art O2 Saturation <90% +20
Risk Class 30-Day Mortality Total Point Score
I 1.60% <65
II 3.50% 66-85
III 7.10% 86-105
IV 11.40% 106-125
V 23.90% >125

See Also

Thrombolytics for pulmonary embolism

External Links

References

  1. ↑ D-Dimer Concentrations in Normal Pregnancy: New Diagnostic Thresholds Are Needed. Kline et all. Clinical Chemistry May 2005 vol. 51 no. 5 825-829 http://www.clinchem.org/content/51/5/825.long
  2. ↑ Righini M, Le GG, Aujesky D, et al. Diagnosis of pulmonary embolism by multidetector CT alone or combined with venous ultrasonography of the leg: a randomised non-inferiority trial. Lancet. 2008; 371(9621):1343-1352.
  3. ↑ Daniel KR, Jackson RE, Kline JA. Utility of the lower extremity venous ultrasound in the diagnosis and exclusion of pulmonary embolism in outpatients. Ann Emerg Med. 2000; 35(6):547-554.
  4. ↑ Jaff MR et al. Management of massive and submassive pulmonary embolism, ileofemoral deep vein thrombosis, and chronic thromboembolic pulmonary hypertension: a scientific statement from the American Heart Association. Circulation. 2011 Apr 26;123(16):1788-830. doi: 10.1161/CIR.0b013e318214914f. Epub 2011 Mar 21
  5. ↑ Martin C et al. Systemic thrombolysis for pulmonary embolism: a review. P T. 2016 Dec; 41(12):770-775
  6. ↑ Becattini C et al. Multidetector computed tomography for acute pulmonary embolism: diagnosis and risk stratification in a single test. Eur Heart J. 2011 Jul;32(13):1657-63. doi: 10.1093/eurheartj/ehr108. Epub 2011 Apr 18.
  7. ↑ Stein PD et al. Clinical characteristics of patients with acute pulmonary embolism: data from PIOPED II. Am J Med. 2007;120(10):871.
  8. ↑ 8.0 8.1 8.2 8.3 8.4 ACEP Clinical Policy for Pulmonary Embolism full text
  9. ↑ Wells PS, Anderson DR, Rodger M, et al. Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple
  10. ↑ http://www.thepocusatlas.com/right-ventricle
  11. ↑ Marchick, MR et al. 12-lead ECG findings of pulmonary hypertension occur more frequently in emergency department patients with pulmonary embolism than in patients without pulmonary embolism. Ann Emerg Med. 2010 Apr;55(4):331-5.
  12. ↑ Kosuge M, Kimura K, Ishikawa T, et al. Electrocardiographic differentiation between acute pulmonary embolism and acute coronary syndromes on the basis of negative T waves. Am J Cardiol 2007; 99: 817–821
  13. ↑ Shopo, JD et al. Findings from 12-lead electrocardiography that predict circulatory shock in pulmonary embolism; a systematic review and meta-analysis. Acad Emerg Med. 2015 Oct;22(10):1127-37
  14. ↑ Sreenivasan S, Bennett S, Parfitt VJ. Images in cardiovascular medicine. Westermark's and Palla's signs in acute pulmonary embolism. Circulation. 2007 Feb 27;115(8):e211. full text
  15. ↑ Taylor, RA, et al. Point-of-care focused cardiac ultrasound for prediction of pulmonary embolism adverse outcomes. The Journal of Emergency Medicine. 2013; 45(3):392–399.
  16. ↑ Rudski LG, Lai WW, Afilalo J, et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr. 2010; 23(7):685-713.
  17. ↑ Lu Y, Lorenzoni A, Fox JJ, Rademaker J, Vander Els N, Grewal RK, Strauss HW, Schöder H. Noncontrast perfusion single-photon emission CT/CT scanning: a new test for the expedited, high-accuracy diagnosis of acute pulmonary embolism. Chest. 2014 May;145(5):1079-88
  18. ↑ Kearon, Clive, et al. "Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report." Chest (2016).[fulltext]
  19. ↑ Schulman S, Kearon C, Kakkar AK, et al. Dabigatran versus warfarin in the treatment of acute venous thromboembolism. N Engl J Med. 2009; 361(24):2342-52. Schulman S, Kakkar AK, Goldhaber SZ, et al. Treatment of acute venous thromboembolism with dabigatran or warfarin and pooled analysis. Circulation. 2014; 129(7):764-72.
  20. ↑ Hughes S. Rivaroxaban Stands up to standard anticoagulation for VTE treatment. Medscape Medical News. December 13, 2012.Buller HR, on behalf of the EINSTEIN Investigators. Oral rivaroxaban for the treatment of symptomatic venous thromboembolism: a pooled analysis of the EINSTEIN DVT and EINSTEIN PE studies [abstract 20]. Presented at: 54th Annual Meeting and Exposition of the American Society of Hematology; December 8, 2012; Atlanta, Ga.
  21. ↑ Agnelli G, Buller HR, Cohen A, et al. Oral apixaban for the treatment of acute venous thromboembolism. N Engl J Med. 2013; 369(9):799-808.Agnelli G, Buller HR, Cohen A, Curto M, Gallus AS, Johnson M, et al. Apixaban for extended treatment of venous thromboembolism. N Engl J Med. 2013; 368(8):699-708.
  22. ↑ Vinson DR, Zehtabchi S, Yealy DM. Can selected patients with newly diagnosed pulmonary embolism be safely treated without hospitalization? A systematic review. Ann Emerg Med. 2012; 60:651-662.
  23. ↑ Aujesky D, Obrosky DS, Stone RA, et al. Derivation and validation of a prognostic model for pulmonary embolism. Am J Respir Crit Care Med. 2005;172:1041-1046.
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