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Emergency Medicine
March 1, 2011
Venous Thromboembolism(Pulmonary Embolism & Deep Vein Thrombosis)
Andrew Petrosoniak, MDPGY2 Emergency Medicine
University of TorontoCanada
Emergency Medicine
March 1, 2011
Objectives
• Overview VTE• DVT: Diagnosis & Management• PE: Diagnosis & Management• Controversies in PE: Thrombolytics,
pregnancy• Case examples
Emergency Medicine
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Virchow’s Triad
Emergency Medicine
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Emergency Medicine
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Emergency Medicine
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Emergency Medicine
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Proximal
Distal
Emergency Medicine
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Emergency Medicine
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 2009Anderson et al. Circulation 2003;107:I-9
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Emergency Medicine
Venous Thromboembolism: Risk Factors
• Travelers (flights >8hrs): OR 2.3 for VTE
• Travelers (flights <6hrs): no increased riskJ Gen Intern Med 2007;22:107-114
• Oral contraceptives: 3-4 times increased risk for VTE
Anderson et al. Circulation 2003;107:I-9
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Emergency Medicine
DVT: Clinical Presentation
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• Leg cramping• Swelling• Redness/warmth• Tenderness along distribution of deep venous system
Emergency Medicine
DVT: Differential Diagnosis
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• Muscle strain/hematoma• Popliteal cyst• Lymphedema• Cellulitis• Fracture• Chronic venous insufficiency• Proximal venous compression (e.g. tumor)• Congestive heart failure
Emergency Medicine
DVT: Diagnosis
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• Establish pretest probability • Clinical judgement vs. decision rules• Wells’ criteria, Geneva criteria
Emergency Medicine
DVT: Diagnosis
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Pre-test probability Post-test probability
Emergency Medicine
DVT: Wells Score
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• 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
Emergency Medicine
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
Emergency Medicine
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
Emergency Medicine
DVT: Diagnostic algorithm
March 1 2011
J Thromb Haemost 2007;5(Suppl 1):41-50
Emergency Medicine
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DVT: Diagnostic algorithm
LMWH if imaging is delayed
Emergency Medicine
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):354-8Acad Emerg Med 2008;15(6):493-8,
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Emergency Medicine
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
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Emergency Medicine
Management: anti-coagulation• LMWH = UFH
Gould et al. Ann Intern Med 1999;130:800-9
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Emergency Medicine
PE: overview
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1. Clot travels from deep veins, RV then pulmonary arteries2. Blood flow obstructed3. Tissue necrosis4. Symptoms result
Emergency Medicine
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
Emergency Medicine
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
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Emergency Medicine
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
Emergency Medicine
May 26, 2009
Results: 19.9% (95% CI 6.7-33.0)
Emergency Medicine
Work-up: dyspnea & pleuritic chest pain
• ECG• CXR• CBC, electrolytes, BUN, Cr, • +/- D-dimer, BNP, troponin, lactate, LFTs, ABG• +/- CT chest
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Emergency Medicine
March 1, 2011
Emergency Medicine
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
Emergency Medicine
May 26, 2009
History & PhysicalInvestigationsClinical decision rules
Low = <10%Moderate = 20%High = 50%
Emergency Medicine
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
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Wells et al. Thromb Haemost 2000; 83:416-420
Emergency Medicine
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
Emergency Medicine
PERC RuleONLY 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
Emergency Medicine
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
Emergency Medicine
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
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Emergency Medicine
Management
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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 dailyContra-indicated in renal impairment; Likely ok if HIT hx
Emergency Medicine
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
Emergency Medicine
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
Emergency Medicine
Management: Thrombolytics in PE
March 1, 2011
Hemodynamically unstable = Thrombolytics
Circulation 2010;122:1124-1129
Emergency Medicine
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
Emergency Medicine
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
Emergency Medicine
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 (1st, 2nd or 3rd)
March 1, 2011
Emergency Medicine
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 2nd / 3rd trimester • Recommended in early pregnancy – less radiation to fetus
Emergency Medicine
March 1, 2011
Radiation exposure to fetus not fully known for either CT or V/Q
Venous Thromboembolism: Pregnancy
Emergency Medicine
Venous Thromboembolism: Pregnancy
March 1, 2011
Suspicion for PE
CXR
Ultrasound
CT-PA or V/QTreat
+ −
Normal/nonspecific
D-dimer (if 1st trimester)Alternative diagnosis
1st trimester: ?CT-PA 2nd or 3rd trimester: V/Q
Int J Obst Anesth 2011;20:51-59
Emergency Medicine
Summary
March 1, 2011
