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Thromboembolism

Thromboembolism. Tintinalli Chap. 60. Epidemiology. 3 rd most common cause of death 600,000 cases per year; 1/3 die 30% of untreated PE cause death; 2-8% mortality if treated. Pathophysiology. Most arise from thrombin in the Deep Venous system or heart/kidney/renal/pelvic venous system

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Thromboembolism

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  1. Thromboembolism Tintinalli Chap. 60

  2. Epidemiology • 3rd most common cause of death • 600,000 cases per year; 1/3 die • 30% of untreated PE cause death; 2-8% mortality if treated

  3. Pathophysiology • Most arise from thrombin in the Deep Venous system or heart/kidney/renal/pelvic venous system • 50 to 80 percent of iliac, femoral, and popliteal vein thrombi (proximal vein thrombi) originate below the popliteal vein (calf vein thrombi) and propagate proximally • 20% calf thrombi will propagate • Virchow’s Triad: • Venous stasis • Intimal Damage • Hypercoagulability

  4. Risk Factors • 12% have no established risk factors • Surgery: within 4 weeks • Obstetrics: up to two weeks postpartum • Malignancy: current or tx within 6 months • Immobilization: Hospital, institutional care, paresis/paralysis, cast/splint • Factor Deficiency: • Factor V, Protein C/S, Antithrombin III, Antiphospholipid AB, Plasminogen Def, Factor XII def, Homocysteinemia, Dysplasminogenemia, Dysfibrinogenemia, Prthrombin 2021A Mutation

  5. Wells for DVT

  6. Wells Criteria PE • Suspected DVT 3 • Alternative Dx likely -3 • Tachycardia >100 1.5 • Immobilization >3 days /surgery <4 wks 1.5 • Previous DVT/PE 1.5 • Hemoptysis 1 • Cancer or Tx within 6 months 1 • Low Suspicion: <2 (3.6%) • Mod Suspicion: 2-6 (20.5%) • High Suspicion: >6 (66.7%)

  7. Christopher Study • 3306 patients with clinically suspected PE, defined as sudden onset of dyspnea, deterioration of existing dyspnea, or onset of pleuritic chest pain without another apparent cause. • They divided wells scores into two groups defined as <4 (unlikely) or >4 (likely). • 1028 had PE excluded with wells <4 & normal d-dimer; only 4 none fatal PE diagnosed (0.4%) & one DVT (0.1%) • 1438 had >4 or <4 with positive d-dimer and underwent CTA; 0.6% had a DVT & 0.2% had nonfatal PE • 674 had PE diagnosed by CTA; only 11 fatal PE; all had either >4 wells or elevated d-dimer

  8. Signs & Symptoms • PIOPED: 1493 patients; 933 selected for trial; 755 had a angiogram/VQ; 383 had PE • 80% were dyspneic • 75% had pleuritic chest pain • 60% had Cough • 75% were tachypneic (>20) • 45% had tachycardia (>90) • 95% had at least one of (dyspnea, tachypnea, chest pain)

  9. Algorithm for evaluation of suspected PE. Abbreviation: CTA = computed tomographic angiogram. Diagnosis • First Form Your PRETEST PROBABILITY!

  10. Diagnosis • ECGs • >85% abnormal • Sinus tach most common; Rt. Heart Strain; RBBB; P-pulmonale (peaked Ps in inferior leads); S1Q3T3 • ABGs • Limited value • 33% have pO2 >80mmHg • A-a gradient (5% have no elevation) • A-a grad = 150 – (PaCO2/0.8 + PaO2) • Normal grad = age/4 + 4

  11. Diagnosis • Chest Radiograph • 30% are normal • 20% have elevated hemi-diaphragm • 17% will develop parenchymal infiltrates • Uncommon: hampton’s hump (round boarder infiltrate facing hilum); Westermark’s (dilated pulmonary vasculature; Fleischner’s Sign (cut off pulmonary arterioles

  12. Diagnosis • D-dimer – only of value in low probability patients • Sensitivity ranges from 60% (Latex) to 95% SimpliRed Eliza) • Specificity 30%-70% • NPV 93% • PPV 30% • False Negatives: small clots; delayed presentation (>7 days) • False Positives: sepsis; MI; Liver disease; Advanced Age; Trauma; Post-Operative; HIV infection; Cancer; pregnancy; Idiopathic • Low probability & negative D-dimer < 1-2% incidence

  13. Diagnosis • Doppler Ultrasound • 80-90% of PEs arise from DVTs • Finding a DVT in a symptomatic patient can confirm PE • 40% of asymptomatic patients with DVTs will have a PE • If low probability for PE, positive d-dimer, and negative doppler US, some will repeat in on weeks time vs. V/Q or CTA.

  14. Diagnosis • V/Q scans • Back to PIOPED • Normal V/Q and low pretest probability is 96% sensitive to R/O PE • High Probability for PE confirms diagnosis (95%) • 33% of all V/Q scans are read normal • 10% of all V/Q scans are read high probability • Everything in between leaves you scratching

  15. Diagnosis • CTA • Less contrast and morbidity than angiography • Detects other important Dxs • False positives: tortuous arteries, atelectasis, movement artifact • False negatives: smaller defects, subsegmental arteries • Sensitivity: 85-90% • Specificity: 90-97% • If a patient has a normal CTA, the patient has <1% chance of a bad 6 month outcome!

  16. Diagnosis • PERC • The following eight factors constitute the PE rule-out criteria (PERC): • Age less than 50 years • Heart rate less than 100 bpm • Oxyhemoglobin saturation ≥95 percent • No hemoptysis • No estrogen use • No prior DVT or PE • No unilateral leg swelling • No surgery or trauma requiring hospitalization within the past four weeks • If low probability wells score and PERC rule satisfied; less than 1% incidence of PE in 45 day follow-up • Over 8000 patient multi-centered study

  17. Prognostic Indicators • Good Prognosis • No syncope/seizure at presentation • Age < 50 • No CHF, COPD, prior PE • < 50% pulmonary vascular occlusion • Normal ECG • HR/Sys BP < 0.8 • Troponin I <0.4 • Normal RV size and function • Pulse Ox >94% on RA • Bad Prognosis • Syncope/seizure on presentation • Age >70 • Hx CHF, COPD, or prior PE • > 50% vascular occulsion • T wave inversion in V1-V4 & incomplete RBBB • HR/Sys BP >1 • Troponin >1 • Dilation of RV or hypokinesis • Pulse Ox < 94% on RA

  18. Treatment • O2 therapy if hypoxemia is present • Anticoagulation: • LMWH in hemodynamically stable patients • Heparin preferred: CrCl < 30, persistent hypotension, morbid obesity, increased risk of bleeding, thrombolysis being considered • Hemodynamic Support • IV fluids first, if 1000cc does not result in systolic BP > 90mmHg, then dopamine/norepinephrine • Thrombolysis • Level B indications: hemodynamically unstable with confirmed PE • Level C indications: hemodynamically stable with Rt. Ventricular strain

  19. Treatment • UFH - 80 units/kg bolus IV, then 18 units/kg per h • Lovenox - 1 mg/kg SC BID (actual body weight) • No study has provided a recommendation for max dose • Streptokinase - 250,000 units IV over 30 min followed by 100,000 units/h for 24 h • Urokineas - 4400 units/kg IV over 10 min followed by 4000 units/kg per h for 12 h • Alteplase - 15-mg IV bolus followed by 2-h infusion of 85 mg • Discontinue heparin during infusion

  20. Special Circumstances • When to do Hypercoagulability Workup • Draw extra blood for protein S/C and antithrombin III • All others are not affected by heparin therapy • When to start Heparin Empirically • No contraindication and high pretest probability in hypotensive patients or normotensive patients with low pulse oximetry • Massive Obesity (>500 lbs) • If CTA unavailable, treat with elevated dimer and high pretest probability • Pregnancy: • CTA with shielded pelvis provides less radiation than V/Q • If positive, treat as non-pregnant patients

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