Pulmonary embolism

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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]

PE Types

Massive

  • Sustained hypotension (sys BP <90 for at least 15min or requiring inotropic support)
  • Pulselessness
  • Persistent profound bradycardia (HR <40 with signs of shock)

Submassive

  • Sys BP >90 but with either RV dysfunction or myocardial necrosis
  • RV dysfunction
    • RV dilation or dysfunction on TTE
    • RV dilation on CT
    • Elevation of BNP (>90)
    • ECG: new complete or incomplete RBBB, anteroseptal ST elevation/depression or TWI[4]
    • Myocardial necrosis: Troponin I >0.4

Non-Massive

  • No hemodynamic compromise and no RV strain

Sub-Segmental

  • Limited to the subsegmental pulmonary arteries

Clinical Features

Signs

  • Dyspnea
  • Pleurisy
  • Cough
  • Leg pain
  • Wheezing
  • Hempotysis

Symptoms

  • Tachypnea ~73% of the time
  • Leg swelling
  • Rales
  • Wheeze
  • Tachycardia
  • JVD

Differential Diagnosis

Chest pain

Critical

Emergent

Nonemergent

Shortness of breath

Emergent

Non-Emergent

Evaluation

  • ECG
    • Abnormal in 70% of PE patients[5]
    • Sinus tachycardia is most common finding
    • TWI in ant/sept leads + inf leads[6]
    • Nonspecific ST changes, S1Q3T3 (develops due to strain on RV)
    • RBBB or new incomplete RBBB.[7]
    • 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[8]
  • TTE
    • Eval R heart strain (bowing of septum into LV)
    • 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[9]
Hampton's Hump

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 DVTor PE 1.5
Hemoptysis 1.0
Malignancy (receiving treatment, treatment stopped within 6 mon, palliative care) 1.0

Wells Score

Pre-test Probability Total Points
Low < 2.0
Moderate 2.0-6.0
High > 6.0

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

Workup by Pretest Probability

  • Objective criteria (Geneva, Wells, etc.) is equal to gestalt in assessing pre-test probability[10] (ACEP Level B)

Low Probability

  • D-dimer NPV is 99.5%[11]
  • If low prob and PERC Rule negative, then no workup[12] (ACEP Level B)
  • If low prob and PERC Rule positive, then d-dimer[13] (ACEP Level B)
  • Avoid CT pulmonary angiography in low pretest probability patients that are either PERC rule negative or have a negative d-dimer
  • Age-adjusted D-Dimer in patients >50 yrs old (Age x 10 in FEU or Age x 5 in D-DU) has increased specificity without changing sensitivity[14][15]
    • Check your hospital's reference units (500 ng/L FEU = 250 ng/L D-DU)
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

Moderate Probability

  • D-dimer
    • However, it is unclear whether d-dimer alone is sufficient to rule-out PE[16] (ACEP Level C)

High Probability

  • Consider anticoagulation before imaging!
  • 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 ofVTE disease[17] (ACEP Level C)
    • A negative d-dimer in combination with a negative CTA theoretically provides a posttest probability of VTE less than 1%

Bedside Ultrasound

  • Ultrasound can help diagnosis in equivocal cases
  • Assess for right ventricular strain (RVS) and McConnell's sign
  • RVS is associated with statistically significant worse outcome[18]

Other Modalities

  • 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[19]

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).
  • The Feb. 2016 CHEST Guideline recommends clinical surveillance over anticoagultation for subsegmental PE with no proximal DVTat low risk for recurrent VTE based on level 2C evidence[20]
  • LMWH SC
    • 1st line for most hemodynamically stable patients
    • Contraindicated in renal failure
    • Enoxaparin 1mg/kg SC q12h
    • Dalteparin 200 IU/kg SC q24h, max 18,000 IU
  • Unfractionated Heparin
    • 80 units/kg bolus; then 18 units/kg/hr
    • Check PTT after 6hr; adjust infusion to maintain PTT at 1.5-2.5x control
    • Benefit of Heparin is the short half life and easy ability to turn off the infusion. Consider
    • Patients with morbid obesity or anasarca may have poor sc absorption with LMWH
    • No need for renal dosing
    • 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
  • Dabigatran
    • A direct thrombin inhibitor
    • Approved by the FDA in 2014 for the treatment of DVTand PE
    • Dabigatran was noninferior to warfarin in reducing DVTand PE[21][22]
  • Rivaroxaban
    • Factor Xa inhibitors
    • Approved by the FDA in November 2012 for the treatment of DVTor PE
    • Associated with less bleeding, particularly in elderly patients and those with moderate renal impairment compared to standard treatments[23][24]
  • Apixaban
    • Factor Xa inhibitor
    • Approved for treatment of PE in August 2014
    • Studies show 16% reduction in VTE related death compared to standard therapy[25][26]
  • Vit K antagonist - Coumadin
    • 3-6 mo if time limited risk factor (post-op, trauma, estrogen use)
    • 6 mo - life if idiopathic etiology or recurrent
    • INR target 2.5
    • Temporary hypercoagulable state for approx 5 days
    • Initial dose is 5 mg PO

Thrombolysis

  • Major controversy exists regarding thrombolytic therapy in submassive PE. Therapy should be individualized to patients.[27][28][29] 'The mortality benefit may be greatest in patients with right ventricular dysfunction. [30]
  • Bleeding risk is increased with increasing age especially in the group ≥ 65 yo[31]

Indications

  • Patients with massive PE and acceptable risk of bleeding complications
  • Patient with submassive PE with evidence adverse prognosis + low risk of bleeding complications
    • Hemodynamic instability
    • Worsening respiratory insufficiency
    • Severe Right Ventricular dysfunction
    • Major myocardial necrosis

Thrombolytic Instructions

  • Review contraindications
  • Ongoing CPR from 2010 AHA Guidelines is not an absolute contraindication, and some studies suggest permiting 15 min of CPR to allow thrombolysis to work[32]
  • Discontinue heparin during infusion
  • Administration regimens differ widely in the literature, options not in any particular order, include:
    • Alteplase 0.6 - 1 mg/kg or 100 mg with any of the three possibilities
      • Two 50 mg boluses, 30 min apart[33][34]
      • 15 mg bolus, followed by 85 mg over 90 min[35]
      • 100 mg over 15 min[36]
    • Tenecteplase in cardiac arrest at 50 mg bolus or 0.5 mg/kg bolus in cardiac arrest[37][38][39]
  • After infusion complete measure serial aPTTs
    • Almost all studies of thrombolysis administration included heparin anticoagulation
    • Once value is <2x upper limit restart anticoagulation

Absolute contraindicatimewons

  • Any prior intracranial hemorrhage,
  • Known structural intracranial cerebrovascular disease (e.g. AVM)
  • Known malignant intracranial neoplasm
  • Ischemic stroke within 3mo
  • Suspected aortic dissection
  • Active bleeding or bleeding diathesis
  • Recent surgery encroaching on the spinal canal or brain
  • Recent closed-head or facial trauma with radiographic evidence of bony fracture or brain injury

Relative contraindications

  • Age >75 years
  • Current use of anticoagulation
  • PE in Pregnancy
  • Noncompressible vascular punctures
  • Traumatic or prolonged CPR (>10min)
  • Recent internal bleeding (within 2 to 4 weeks)
  • History of chronic, severe, and poorly controlled hypertension
  • Severe uncontrolled hypertension on presentation (sys BP >180 or dia BP >110)
  • Dementia
  • Remote (>3 months) ischemic stroke
  • Major surgery within 3 weeks

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[40]

Prognosis

The Pulmonary Embolism Severity Index (PESI)[41]

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

{{Thrombolysis Submassive PE Trials}}

External Links

References

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  13. ACEP Clinical Policy for Pulmonary Embolism full text
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  17. ACEP Clinical Policy for Pulmonary Embolism full text
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