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Toronto Notes 2019 Medical Emergencies
Venous Thromboembolism (VTE)
• seeRespirology,R20
Risk Factors
• Virchow’striad:alterationsinbloodflow(venousstasis),injurytoendothelium,hypercoagulablestate (including pregnancy, use of OCP, malignancy)
• clinicalriskfactors(seesidebar)
DEEP VEIN THROMBOSIS (DVT)
Presentation
• calfpain,unilaterallegswelling/erythema/edema,palpablecordalongthedeepvenoussystemonexam; can be asymptomatic
• clinicalsigns/symptomsareunreliablefordiagnosisandexclusionofDVT;investigationoftenneeded
Investigations
• useWells’criteriaforDVTtoguideinvestigations(seeFigure12)
• D-dimerisonlyusefulforrulingoutDVT,andaD-dimertestresultshouldonlybeconsideredincases
where a low-moderate risk patient has a negative test (high sensitivity)
■ high risk of false positives in: elderly, infection, recent surgery, trauma, hemorrhage, late in
pregnancy, liver disease, cancer
• U/Shashighsensitivity&specificityforproximalclotbutonly73%sensitivityforcalfDVT(mayneed
to repeat in 1 wk)
■ if positive – treat for DVT regardless of risk
■ if negative and low risk – rule out DVT
■ if negative and moderate to high risk – repeat U/S in 5-7 d to rule out DVT
Management
• LMWHunlesspatientalsohasrenalfailure
■ dalteparin 200 IU/kg SC q24h or enoxaparin 1 mg/kg SC q24h
• warfarin started at same time as LMWH (5 mg PO OD initially followed by dosing based on INR)
• LMWH discontinued when INR has been therapeutic (2-3) for 2 consecutive days
• DOAC can be used in acute management of symptomatic DVT
■ rivaroxaban: 15 mg PO bid for first 21 d; 20 mg PO daily for remaining treatment (taken with food at the same time each day)
■ apixaban: 10 mg PO bid for first 7 d; 5 mg PO bid for remaining treatment
• considerthrombolysisifextensiveDVTthreateninglimbcompromise
• IVCfilterorsurgicalthrombectomyconsideredifanticoagulationiscontraindicated
• durationofanticoagulation:3moiftransientcoagulopathy;6moifunprovokedDVT;life-longif
ongoing coagulopathy
PULMONARY EMBOLISM (PE)
Presentation
• dyspnea,pleuriticchestpain,hemoptysis,tachypnea,cyanosis,hypoxia,fever
• clinicalsigns/symptomsareunreliablefordiagnosisandexclusionofDVT;investigationoftenneeded
Investigations
• useWells’criteriaforPEtoguideinvestigations(seeFigure13)
• PERCscorealonecanruleoutPEinlowriskpatients(asdeterminedbyWells’criteria)unlesspatientis
pregnant
• ECGandCXRareusefultoruleoutothercauses(e.g.ACS,pneumonia,pericarditis)ortosupport
diagnosis of PE
■ ECG changes in PE: sinus tachycardia, right ventricular strain (S1Q3T3), T wave inversions in
anterior and inferior leads
■ CXR findings in PE: Hampton’s hump (triangular density extending from pleura) or Westermark’s
sign (dilatation of vessels proximal to an obstruction, with collapse of vessels distal to obstruction,
often with a sharp cutoff)
• D-dimerisonlyusefulatrulingoutaPEifitisnegativeinlow-moderateriskpatients(highlysensitive)
■ if positive D-dimer or high-probability patient, then pursue CT angiography or V/Q scan
• CTangiographyhashighsensitivityandspecificityforPE,mayalsoindicateanalternativediagnosis
• V/Q scan useful in pregnancy, when CT angiography not available, or IV contrast contraindicated
Management of PE
• treatmentofPEwithanticoagulationanddurationoftreatmentisthesameasforDVT(seeabove) • considerthrombolysisifextensivePEcausinghemodynamiccompromiseorcardiogenicshock
• catheter-directedthrombolysisorsurgicalthrombectomymaybeconsideredinmassivePEorif
anticoagulation is contraindicated
• oftencanbetreatedasoutpatient,mayrequireanalgesiaforchestpain(narcoticorNSAID)
Emergency Medicine ER33
Risk Factors for VTE
THROMBOSIS
Trauma, travel
Hypercoagulable, HRT
Recreational drugs (IVDU)
Old (age >60 yr)
Malignancy
Birth control pill
Obesity, obstetrics
Surgery, smoking
Immobilization
Sickness (CHF, MI, nephrotic syndrome, vasculitis)
Wells’ Criteria for DVT
Active cancer +1 Paralysis, paresis or recent +1 immobilization of leg
Recently bedridden x 3 d or
+1 +1 +1 +1
major surgery within 4 wk Local tenderness
Entire leg swollen
Calf swelling 3cm
> asymptomatic leg +1 Unilateral pitting edema +1 Collateral superficial veins -2 Alternative Dx more likely
0: Low probability
1-2: Moderate probability >3: High probability
Wells’ Criteria for PE
Previous Hx of DVT/PE +1.5 HR >100 +1.5 Recent immobility or surgery +1.5 Clinical signs of DVT +3 Alternate Dx less likely than PE +3 Hemoptysis +1 Cancer +1
<2: Low probability
2-6: Intermediate probability >6: High probability
PERC Score
• Age >50 yr
• HR >100 bpm
• O2 sat on RA <95%
• Prior history DVT/PE
• Recent trauma or surgery
• Hemoptysis
• Exogenous estrogen
• Clinical signs suggesting DVT
Score 1 for each question; a score 0/8 means patient has <1.6% chance having a PE and avoids further investigation. Caution using the PERC score in pregnant women as the original study excluded pregnant women
D-dimer is only useful if it is negative; negative predictive value >99%