ED Diagnosis of DVT or tools to rule out DVT in your ED

Transcription

1 ED Diagnosis of DVT or tools to rule out DVT in your ED Ralph Wang UCSF Department of Emergency Medicine 53 yo f c/o left leg swelling recent cholecystectomy its midnight how do you manage this patient? whats available at your institution? key points US and d-dimer are used to detect deep venous thrombosis most tests to detect DVT are limited in some way, including ultrasound combine risk stratification with d-dimer assay ED US is a promising strategy whats available at your institution? 1

2 deep venous anatomy femoral-popliteal = proximal distal=calf progression of VTE Disease distribution of dvt of 189 DVTs: all proximal DVTs were found either in popliteal or inguinal fossa 10% were calf Distribution of Thrombosis in Patients With Symptomatic Deep Vein Thrombosis COGO

3 Calf DVT facts DVT begin in the calf system and extend proximally 20% extend into the proximal system: 80% of calf DVTs will lyse DVTs tend to be proximal when patient develops symptoms (90%) Calf DVTs are not detected by proximal LE US If calf DVTs are detected - treatment is controversial ultrasound to dx dvt primary imaging modality for dx of dvt replaced venography in 1990s performs best for ambulatory outpatients (vs hosp/post surg patients) serial proximal is standard of care whole leg vs proximal (femoral to popliteal) compression + doppler = duplex 3

4 Sensitivity of compression = Sensitivity of duplex calf requires duplex safe to withhold anticoagulation after serial US meta-analysis of US performance to detect DVT compression and duplex approximately equivalent Systematic review and meta-analysis of the diagnostic accuracy of ultrasonography of DVT Goodacre 2006 ultrasonography for deep vein thrombosis SteveGoodacre* whole leg duplex ultrasound change in industry standard - whole leg US replacing serial proximal leg US - avoid serial exams! Calf DVTs can be detected what is your radiology department doing? should you be treating calf dvt? study unavailability 40% of US ED directors reported inability to obtain US during off hours pts at risk for DVT less likely to receive US during off hours 4

5 53 yo f c/o left leg pain recent cholecystectomy what is this patients risk of DVT? 1% 5%? 15%? 60%? Simplified Wells Prediction Rule Does this patient Have a DVT? Wells 2006 meta-analysis Wells CPR Low: 5% (4-8%) Mod: 17% (13-23%) High: 53% (44-61%) 5

6 take home point about Wells well validated, allows for estimation of likelihood low risk (5%) is not low enough to rule out DVT alone high risk (53%) is not high enough to initiate treatment* CONFIRMATORY STUDY (with sufficiently high or low LR) IS NEEDED *5-10% bleeding, 1% major bleeding, 0.1% death Low-Molecular-Weight Heparins Compared with Unfractionated Heparin for Treatment of Acute Deep Venous Thrombosis A Meta-Analysis of Randomized, Controlled Trials Michael K. Gould 1999 d-dimer + Wells CPR product of fibrinolysis d-dimer assay is sensitive but non-specific d-dimer levels are elevated in VTE, but also hemorrhage, trauma, pregnancy, cancer, surgery used to rule out dvt in low and moderate risk groups d-dimer flaws ability to use d-dimer clinically is dependent on: 1) d-dimer sensitivity (latex vs simplired vs elisa) 2) dvt prevalence in your population overall prevalence of 33% Simplired = medium sensitivity A negative SimpliRED D-dimer assay result does not exclude the diagnosis of deep vein thrombosis or pulmonary embolus in emergency department patients. Farell

7 post test probability of dvt does this patient have a dvt? wells 2007 d-dimer safety 3-month follow up VTE event 0.4% incidence in low/moderate risk patients using the d-dimer in practice risk stratify patient: use rapid elisa, not simplired only apply in low/moderate risk groups consider the likelihood of false positive (hospitalized, cancer, aged) approximately 30% of patients can be ruled out cannot use test to rule in DVT 7

8 EPPU for DVT EPPU for DVT EPPU vs radiology performed US: performed by ED physicians 2-point exam vs entire vein (proximal dvt only) - femoral and popliteal vein segments no visualization of calf dvt compression: basis of the test vein should be fully obliterated in nearfar dimension adequate pressure = arterial effacement arterial flattening = too much force 8

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11 6 studies, total of 936 patients good performance conclusion: promising but flawed small sample generalizability of operators calf dvts referent std = US evidence for EPPU limitations/pitfalls operator dependent entire leg not visualized -?calf vein difficult in obese patients, limited mobility, uncooperative pts confusing deep veins with lymph nodes, superficial veins, arteries requires f/u in 1 week to r/o extension recommendations for EPPU If EPPU is used to R/O DVT, the provider should document: performed > 25 scans clearly visualized the vessels pretest assessment ensure patient f/u in 1 week 11

12 comparison of strategies Rad US Wells + d-dimer ED US study of choice study unavailability proximal vs whole leg well validated approach nonspecific unlikely patients only cannot rule in ED based decreased LOS, cost operator dependent requires training misses calf dvt your toolbox all tests to r/o dvt have limitations different tests can be viewed as complementary understand what tests are available in your ED tailor strategy based on clinical scenario thank you! 12