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Emergency lectures - Pulmonary Embolism & Deep Vein Thrombosis presentation andrew petrosoniak
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Emergency lectures - Pulmonary Embolism & Deep Vein Thrombosis presentation andrew petrosoniak

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  • Superficial system: greater & short saphenous veins & the perforating veins Deep venous system: anterior/posterior tibials, peroneal = calf veins Blue indicates deep venous system Proximal DVT = popliteal and above Distal DVT = below popliteal
  • This slide highlights the anatomy again: greater/lesser saphenous being superficial to the fascial layer as a result not technically a DVT if clot forms there
  • Anderson et al. Review of VTE risk factors Spinal cord injury: highest within 3 months post-injury – 38% incidence of DVT & 5% incidence of PE CHF – 15% of patients (in MEDENOX trial) had venous thromboembolism Note, obesity is not on the list – several studies have found no association Risk factors: prospective cohort study evaluated explicit factors (those included in established criteria) and then implicit risk factors – those that are taught but no good evidence. On this slide, the last 3 criteria were found to be associated with increase risk of VTE
  • Travelers: risk really only exists for flights >8hrs (and perhaps >6hrs). Less than 6hrs has no increased risk unless there are other pre-existing risk factors
  • Homan’s sign: pain in calf (or posterior knee) on passive dorsiflexion of foot when knee is extended = nonspecific & insensitive and should NOT be used But classically was part of diagnosis
  • Overall, clinical decision rules are used to help work through this reasoning process
  • Need citation
  • Either method is fine to use. For the rest of the talk however, I’ll focus primarily on the simplified version since it’s easier to remember.
  • To use the Wells’ algorithm, knowledge of D-dimer should be discussed. Another important aspect is to know what type of D-dimer you have available at your hospital – basically In Toronto we use immuno-turbidimetric (highly sensitive) but not the gold standard ELISA (Enzyme linked immunosorbent assay) ELISA: best for batch analysis and take longer to perform - Uses monoclonal antibodies to bind parts of D-dimer fragments which then form complexes and detected using some type of detection assay Modified ELISAs have been developed but not used everywhere (likely costly) SimpliRED: can be used for point of care testing = RBC agglutination assay – sensitivities around 83%
  • At our institution – we often do not have the patient undergo a further U/S one week later – which is probably wrong Why? Venous duplex U/S has a sensitivity and specificity of approximately 95% (meaning 5% of scans will be negative despite the patient having a DVT)
  • Systematic review in 2008: 6 studies with methodologic flaws. Reported combined sensitivity & specificity 95% & 96% but requires further study Second study examined U/S by EP vs. CT-V as a gold standard. Very small study with only 61 patients and only 6 had DVT. Sn = 86% and Sp 100% compared to CT-V CT-V: really is not a primary modality for imaging in DVT. Some advocate its use in addition to CT-PA for PE – only 2% increase in identifying DVT in those with negative PE (PIOPED) thus not likely worth risk
  • Systematic review established practice guidelines that pts without significant risk factors can be treated at home with LMWH vs. inhospital UFH Patients with a select group of conditions should undergo admission because of their increase risk of negative outcome. Those with renal failure are not able to take LMWH. If the patient with chronic renal insufficiency who really would rather go home, then consider using fondaparinux
  • Meta-analysis in 1999 showed that LMWH are as effective as UFH in preventing reucrrent VTE and they cause less bleeding; also lower risk of HIT
  • These stats aren’t for memory but just to be aware Among all patients diagnosed with PE in the ED, there’s a 10% mortality rate within 30 days even if diagnosed and treated early A-a gradient = insensitive since 15% of patients have normal A-a graident in PE
  • Differential diagnosis includes pneumonia especially when patient has infarcted their lung – focal chest pain/fever/crackles on ausculation
  • Differential diagnosis includes pneumonia especially when patient has infarcted their lung – focal chest pain/fever/crackles on ausculation
  • Study from CHEST: systematic review, subject to criticism because of heterogeneity of studies included but examined patients with COPD exacerbations and subsequent prevalence of PE. 25% of patients requiring hospitalization had documented PE while overall the review found 19.9% prevalence of PE Depending on which subset of patients were included Among hospitalized patients: 24.7% Among patients only seen in the ED: 3.3% Among patients who required hospitalization for their COPD exacerbation: 25.5% Overall prevalence of PE in the studies included: 19.9% (CI 6.7-33.0)
  • Differential diagnosis includes pneumonia especially when patient has infarcted their lung – focal chest pain/fever/crackles on ausculation CXR: not diagnostic but may help guide further diagnostic work-up - For example, 45 year old female with dyspnea (previously healthy), normal vitals, CXR demonstrates right sided pleural effusion – requires further work-up
  • S1Q3T3 ECG
  • Importance to assess for right heart strain – this may make you more suspicious of significantly larger PE Reminder what RBBB looks like QRS >0.1s (incomplete) or >0.12s (complete) Terminal R wave in V1 (R, rsR’) Slurred S wave in leads I & V6
  • Virtually impossible to achieve zero post-test probability but 1-2% is probably acceptable
  • Exclusion criteria: include 80yrs of age, pregnancy, hospitalized (or discharged recently) should exclude patients from using these criteria
  • Dichotomized Wells’ Criteria has been prospectively validated with >3000 patients
  • Stands for Pulmonary Embolism Rule-out Criteria Remember that patient still has 1.8% chance of PE
  • Results from PIOPED II Low probability patients with negative CT-PA: 4% had pulmonary embolism Moderate probability patients with negative CT-PA: 11% had pulmonary embolism High probability patients with negative CT-PA: 40% had pulmonary embolism No considerable role for CT-A combined with CT-V CT-PA has 68% sensitivity for segmental embolism (4-16 slice scanners) V/Q scan: main issue is the high rate of non-diagnostic scans; benefit is lower overall radiation but tends to be more spread out to chest/abdo; also an issue if patient has baseline lung pathology V/Q scan: first stage is inhale radionuclide gas (xenon or technetium) then IV contrast injection and special camera captures pictures for each phase; high probability for PE means multiple perfusion deficits with normal inhalation study while non-diagnostic means perfusion deficit is matched with ventilation deficit
  • Meta-analysis shows LMWH at least as effective as UFH in preventing symptomatic 3-month risk of VTE (3% vs 4.4%) and equal safety regarding risk of major bleeding (1.3% vs. 2.1%)
  • Mechanism: plasminogen activators that set fibrinolytic system into motion rt=PA: recombinant tissue plasminogen activator Some institutions may use tenectaplase Meta-analysis of all trials comparing fibrinolytics vs. UFH showed trend towards increased major bleeds but not statistically significant Evidence for thrombolytics in hemodynamic compromise Meta-analysis of five randomized controlled trials (including patients in shock/hypotension) showed reduced risk of death & recurrent PE compared to heparin (9 vs 19%) with NNT=10
  • Level 1B evidence from CHEST guidelines for PE Submassive PE: hemodynamically stable but signs of RV dysfunction on echo (in the literature, RV dysfunction is not well defined) Troponins in PE: RV dilatation may cause ischemic injury thus releasing troponins; troponins have been found to correlate with RV dysfunction and associated with in-hospital death related to PE BNP: also associated with worse prognosis but less predictive than troponins
  • Several studies have attempted to test D-dimer sensitivity & specificity at higher threshold’s (depending on trimester) – these studies are promising but not yet validated Jeff Kline (PE researcher in emergency medicine) suggests using threshold of 750 (1 st trimester), 1000 (2 nd trimester) and 1250 (3 rd trimester) but no validated studies to support this

Emergency lectures - Pulmonary Embolism & Deep Vein Thrombosis presentation andrew petrosoniak Emergency lectures - Pulmonary Embolism & Deep Vein Thrombosis presentation andrew petrosoniak Presentation Transcript

  • Venous Thromboembolism (Pulmonary Embolism & Deep Vein Thrombosis) March 1, 2011 Andrew Petrosoniak, MD PGY2 Emergency Medicine University of Toronto Canada
  • Objectives
    • Overview VTE
    • DVT: Diagnosis & Management
    • PE: Diagnosis & Management
    • Controversies in PE: Thrombolytics, pregnancy
    • Case examples
    March 1, 2011
  • Virchow’s Triad March 1, 2011
  • March 1, 2011
  • March 1, 2011
  • March 1, 2011
  • March 1, 2011 Proximal Distal
  • March 1, 2011
  • Pulmonary Embolism: Risk Factors
    • Use clinical decision rules
    • Also consider:
      • Spinal cord injury (OR >10)
      • Hip/knee replacement (OR >10)
      • CHF/Resp failure (OR 2-9)
      • Pregnancy/postpartum (OR 2-9)
      • Central venous lines (OR 2-9)
      • Increasing age, obesity, varicose veins (OR <2)
      • Family history of venous thromboembolism (OR = 1.51)
      • Pleuritic chest pain (OR =1.53)
      • Hx thrombophilic condition (1.99)
      • Courtney et al. Ann Emerg Med 2009
      • Anderson et al. Circulation 2003;107:I-9
    March 1, 2011
  • Venous Thromboembolism: Risk Factors
    • Travelers (flights >8hrs): OR 2.3 for VTE
    • Travelers (flights <6hrs): no increased risk
    • J Gen Intern Med 2007;22:107-114
    • Oral contraceptives: 3-4 times increased risk for VTE
    • Anderson et al. Circulation 2003;107:I-9
    March 1, 2011
  • DVT: Clinical Presentation March 1, 2011
    • Leg cramping
    • Swelling
    • Redness/warmth
    • Tenderness along distribution
    • of deep venous system
  • DVT: Differential Diagnosis March 1, 2011
    • Muscle strain/hematoma
    • Popliteal cyst
    • Lymphedema
    • Cellulitis
    • Fracture
    • Chronic venous insufficiency
    • Proximal venous compression (e.g. tumor)
    • Congestive heart failure
  • DVT: Diagnosis March 1, 2011
    • Establish pretest probability
    • Clinical judgement vs. decision rules
    • Wells’ criteria, Geneva criteria
  • DVT: Diagnosis March 1, 2011 Pre-test probability Post-test probability
  • DVT: Wells Score March 1, 2011
    • Active cancer (treated <6mo or currently receiving palliative treatment)
    • Paralysis, paresis or recent plaster immobilization of lower extremities
    • Recently bedridden (>3 days) or major surgery >12wks
    • Localized tenderness along deep venous system
    • Entire leg swollen
    • Calf swelling >3cm vs. asymptomatic leg
    • Pitting edema confined to symptomatic leg
    • Collateral superficial veins
    • Previous documented DVT
    • Alternative dx at least as likely as DVT
    1 point each -2 Lancet 1997;350(9094):1795-8
  • DVT: Well Score
    • OPTION 1
    • Low probability (<1) = 5%
    • Moderate probability (1-2) = 17%
    • High probability (>2) = 53%
    • OPTION 2
    • Unlikely (<2)
    • Likely (2 or more)
    March 1, 2011 Two methods to risk stratify patients using Wells’ Score J Thromb Haemost 2007;5(Suppl 1):41-50
  • D-dimer: Use in diagnosis of DVT
    • Protein derived from fibrin breakdown
    • Elevated levels indicate presence of clot within 72hrs
    • Causes of elevated D-dimer:
      • Pregnancy
      • Age
      • Malignancy
      • Recent surgery
      • Infection/Inflammation
      • MI
    • Wide variety of D-dimer assays (highly sensitive are best)
    March 1, 2011 J Thromb Haemost 2008;6:1059-71
  • DVT: Diagnostic algorithm March 1 2011 J Thromb Haemost 2007;5(Suppl 1):41-50
  • DVT: Diagnostic algorithm March 1, 2011 LMWH if imaging is delayed
  • DVT: Ultrasound
    • 95% sensitivity for proximal clot (certified sonographer or board-certified radiologist)
    • Reduced sensitivity for pelvic vein thrombus – rare events
    • Insufficient evidence for performance by emergency physicians
    • Am J Emerg Med 2010; 28(3):354-8
    • Acad Emerg Med 2008;15(6):493-8,
    March 1, 2011
  • Management: Who requires admission
    • Home vs. in-hospital therapy = no outcome difference
    • (Segal et al. Ann Intern Med 2007;146:211-11)
    • Admission if:
      • Bilateral DVT
      • Renal insufficiency
      • CHF
      • Malignancy
      • (J Vasc Surg 2006;44:789-93)
    • Home therapy also depends on the patient and their situation
    March 1, 2011
  • Management: anti-coagulation
    • LMWH = UFH
    • Gould et al. Ann Intern Med 1999;130:800-9
    March 1, 2011
  • PE: overview March 1, 2011
    • Clot travels from deep veins, RV then pulmonary arteries
    • Blood flow obstructed
    • Tissue necrosis
    • Symptoms result
  • Pulmonary Embolism: Key stats
    • 30 day mortality: 10%
    • A-a gradient = normal in 15% of patients with PE
    • 10% have O2 saturation of 100%
    • Hypotension + PE = 4 times increase risk of death
    • ZERO risk factors for VTE = 50% of patients
    • Patients with PE – 60-80% have DVT
    • Patients with DVT – 50% have PE
    March 1, 2011
  • Pulmonary Embolism: Clinical Presentation
    • Weakness
    • Shortness of breath
    • Chest pain (+/- pleuritic)
    • Syncope
    • Hemoptysis
    • May mimic pneumonia (if lung infarction)
    • Tachycardia
    • Hypoxia
    • Elevated JVP (or distended jugular veins)
    • DVT symptoms
    March 1, 2011
  • Pulmonary Embolism: Differential Diagnosis
    • Pulmonary Embolism
    • Cardiac ischemia/infarction
    • Dysrhythmia (especially if syncope)
    • Pericarditis/Myocarditis
    • Pneumonia
    • COPD exacerbation
    • Heart Failure
    • Asthma
    • Anaphylaxis
    • Abdominal pathology
    March 1, 2011
  • May 26, 2009 Results: 19.9% (95% CI 6.7-33.0)
  • Work-up: dyspnea & pleuritic chest pain
    • ECG
    • CXR
    • CBC, electrolytes, BUN, Cr,
    • +/- D-dimer, BNP, troponin, lactate, LFTs, ABG
    • +/- CT chest
    March 1, 2011
  • March 1, 2011
  • Pulmonary Embolism: ECG
    • Tachycardia
    • Incomplete or complete RBBB
    • T wave inversions in V1-V4
    • S1Q3T3
    • Right axis deviation
    • Marchick et al. Ann Emerg Med 2010;55:331-35
    March 1, 2011 Right heart strain
  • May 26, 2009 History & Physical Investigations Clinical decision rules Low = <10% Moderate = 20% High = 50%
  • Pulmonary Embolism: Wells’ Criteria
    • Clinical signs & symptoms of DVT = 3.0
    • Alternative diagnosis less likely than PE = 3.0
    • Heart rate >100bpm = 1.5
    • Immobilization (>3d) or previous surgery (<4wks) = 1.5
    • Previous PE or DVT = 1.5
    • Hemoptysis = 1.0
    • Malignancy (treatment <6mo or palliative) = 1.0
    March 1, 2011 Wells et al. Thromb Haemost 2000; 83:416-420
  • Pulmonary Embolism: Wells’ Criteria March 1, 2011 PE Unlikely (≤ 4) D-Dimer CT-PA Ultrasound Treat PE ruled out PE ruled out + − + − + Consider other tests or treat − PE Likely(> 4) CT-PA + − Ultrasound Treat PE ruled out − + J Thromb Haemost 2007;5(Suppl 1):41-50
  • PERC Rule
    • ONLY use if patient is considered low risk
    • Age <50yrs
    • HR < 100bpm
    • SaO2 >94%
    • No unilateral leg swelling
    • No hemoptysis
    • No recent trauma or surgery
    • No prior PE or DVT
    • No hormone use
    • Low risk + all 8 criteria met = <2% risk of PE
    March 1, 2011 Kline et al. J Thromb Haem 2008;6(5):772-80
  • Imaging
    • CT-PA: 83% sensitive (97% Sn main/lobar clot)
      • Low pre-test probability: NPV 96%
      • Moderate pre-test probability: NPV 89%
      • High pre-test probability: NPV 60%
      • Data from PIOPED II (NEJM 2006 354;22:2317)
    • V/Q scan
      • Low pre-test probability: V/Q normal rules out PE (if high probability PE then U/S indicated given insufficient specificity)
      • High pre-test probability: V/Q normal requires U/S while high probability scan rules in PE
    • Formal pulmonary angiography
      • Rarely used but gold standard; >98% sensitive
    March 1, 2011
  • Pulmonary Embolism: Management
    • Efficacy: LMWH = UFH
    • Ann Intern Med 2004;140:175-83
    • Choose UFH if:
      • Severe renal dysfunction (CrCl <30ml/min)
      • Increased risk of bleeding
      • Recent brain surgery or hemorrhagic stroke
    March 1, 2011
  • Management March 1, 2011 Dose Comments UFH 80IU/kg bolus then 18IU/kg/hr aPTT: 1.5-2.5x normal Enoxaparin 1mg/kg BID or 1.5mg/kg daily Monitor platelet counts Fondaparinux 7.5mg daily Contra-indicated in renal impairment; Likely ok if HIT hx
  • PE & Hemodynamics
    • Increase pulmonary artery pressure
    • Acute RV failure
    • Decrease LV stroke volume
    • Decrease cardiac output
    • Hypotension
    • Poor organ perfusion
    • Cardiac arrest
    March 1, 2011
  • Management: Thrombolytics in PE
    • 3 drugs approved (streptokinase, urokinase, rt-PA)
    • ACCP recommends rt-PA (weak evidence)
    • Administer <48hrs from symptoms
    • Bleeding risk: 9.1% vs. 6.1% compared to UFH
    • Circulation 2004;110:744-749
    March 1, 2011 Moderate evidence thrombolytics decrease mortality in massive PE No evidence for thrombolytics in unselected PE patients Chest 2008;133(suppl):454S-545S
  • Management: Thrombolytics in PE March 1, 2011 Hemodynamically unstable = Thrombolytics Circulation 2010;122:1124-1129
  • Venous Thromboembolism: Pregnancy
    • Risk of VTE in pregnancy: 1 in 10 000 (vs. 1 in 100 000 for healthy non-pregnant woman)
    • Highest risk: 6wks before birth until 6wks after birth
    March 1, 2011
  • Venous Thromboembolism: Pregnancy
    • Issues with diagnosis of VTE in pregnancy
    • D-Dimer is elevated in pregnancy (in all cases)
    • Diagnosis of PE requires imaging with radiation
    • 64-slice CT scan: 1.5% increase in lifetime risk of breast cancer (25yr female)
    • No decision rules validated in pregnancy patients (e.g. Wells, Geneva, PERC)
    March 1, 2011
  • Venous Thromboembolism: Pregnancy
    • Consider clinical criteria from scoring systems = construct pre-test probability
    • Perform CXR if PE suspected
    • Classify patients:
      • DVT signs & symptoms
      • ?PE + leg symptoms
      • ?PE + no leg symptoms
    • Consider trimester (1 st , 2 nd or 3 rd )
    March 1, 2011
  • Venous Thromboembolism: Pregnancy
    • D-dimer: increases throughout pregnancy
    • Consider using higher D-dimer thresholds
    March 1, 2011 V/Q Scan CT Scan
    • Less direct radiation to breasts
    • Less accurate especially abnormal CXR
    • Better in later pregnancy
    • More accurate
    • More radiation to breasts – issue during 2 nd / 3 rd trimester
    • Recommended in early pregnancy – less radiation to fetus
  • Venous Thromboembolism: Pregnancy March 1, 2011 Radiation exposure to fetus not fully known for either CT or V/Q
  • Venous Thromboembolism: Pregnancy March 1, 2011 Suspicion for PE CXR Ultrasound CT-PA or V/Q Treat + − Normal/nonspecific D-dimer (if 1 st trimester) Alternative diagnosis 1 st trimester: ?CT-PA 2 nd or 3 rd trimester: V/Q Int J Obst Anesth 2011;20:51-59
  • Summary March 1, 2011