venous thromboembolism and VTE prophylaxis Flashcards
most common presentations of venous thrombosis are?
define each
most common VTE’s are DVT’s and PE’s
DVT: occurs when a blood clot forms in a deep vein, usually in the lower leg, thigh , or pelvis
PE: occurs when a clot breaks loose and travels through the bloodstream to the lungs
homans sign?
calf pain on ankle dorsiflexion
- s/s of possible DVT
DVT S/S?
clinical presentation may be subtle
classic findings (all have low sensitivity and specificity)
-lower-extremity pain and swelling
- homans sign
- palpable cord (swelling in leg)
- fever
DVT dx?
doppler analysis and duplex ultrasounds
- intitial test for DVT; non-invasive, but highly operator dependent
high specificity and sensitivity for detecting proximal thrombi (popliteal and femoral), not so for distal (calf vein) thrombi
venography
- most accurate for dx of DVT of calf veins, however invasive and infrequently used
a PE occurs when / how
thrombus in another region of the body embolizes to the pulmonary vascular tree via the RV and pulmonary artery
lower extremity DVT - PE is the major complication of DVT
- most pulmonary emboli aarise from thromboses in the deep veins of lower extremeties above the knee (iliofemoral DVT)
upper extremity DVT?
rare source of emboli but more common in IV drug abusers
S/S PE?
calculate __ score
symptoms usually arise from lung ischemia
most common presenting symptom is dyspnea followed by chest pain - classically pleuritic in nature - but not always), cough, and symptoms of deep venous thrombosis
calculate WELLS score.
wells criteria / probability
scoring low moderate high likliness of PE occurring
traditional: >6 = high
2-6 = moderate
<2 = low
simiplified / modified
PE likely = over 4
PE unlikely < / equal 4
algorithm if wells score is moderate 2-6
measure? if above or below __?
measure D dimer level if above 500ng/mL then get CT pulmonary angiography – if get this and inconclusive look at ventilation / perfusion scanning
elevated D dimer - CT angiogram – positive for PE = diagnostic
D dimer details
normal levels?
Fibrin D-dimer is one of the major fibrin degradation products released upon cleavage of cross linked fibrin by plasmin
(fibrin clot degraded by plasmin)
normal levels of D-dimer are <500 ng/mL
greater than 500 is suspicious for PE, get CT PE
classification of PE’s
MASSIVE = HIGH RISK –> hemodynamically unstable and causes hypotension
SUBMASSIVE = INTERMEDIATE RISK –> hemodynamically stable but associated with right ventricular strain
LOW RISK = No evidence of right ventricular strain
hypotension as it relates to PE
bloop pressure that requires vasopressors or inotropic support and is NOT explained by other causes such as sepsis, arrhythmia, left ventricular dysfunction from acute myocardial ischemia or infarction, or hypovolemia.
intrinsic pathway activated by? aka
intrinsic pathway activated by exposed endothelial collagen
aka CONTACT activated
collagen, basement membrane, activated platalets activates XII –> Xiia
extrinsic pathway activation? aka
extrinsic pathway activated through TISSUE FACTOR released by endothelial cells after EXTERNAL DAMAGE
- aka TISSUE factor pathway
Factor VII –> VIIa to then convert X to Xa
Virchows triad of thrombosis
Vessel wall injury, hypercoagulability of blood, stasis of blood
very general reasons to have possible hyper-coaguability of blood
cancer, thrombophilia, inflammatory disease ..
main risk factors for developing a DVT
age over 60
malignancy
prior hx of DVT, PE or varicose veins
hereditary hypercoagulability (Factor V leiden, protein C and S deficiency
prolonged immobilization or bed rest
cardiac disease , especially CHF
obesity
major surgery, especially after surgery related to the pelvis (orthopedic procedures)
major trauma
pregnancy, oral contraceptives / estrogen use
majority of pts who experienced VTE episode had one or more of the following 6 risk factors
more than 48 hours of immobility in preceding month (45%)
hospital admission within last 3 months
surgery in past 3 months
malignancy in past 3 months
infection in past 3 months
current hospitilization
warfarin blocks which factors specificially?
followed by?
look at intrinsic pathway
directly inhibits
IX, X (and thus Xa)
II (prothrombin)
VII (also the activator of extrinsic pathway)
factor II aka
IIa?
prothrombin
II = prothrombin
IIa = thrombin
4 main examples of direct factor Xa inhibitors
Apixaban
betrixaban
edoxaban
rivaroxaban
irect thrombin inhibitors
argotroban, dabigatran
thrombin = IIa
heparin inhibits?
followed by?
factor Xa and IIa (thrombin)
followed by extrinsic pathway
DOAC’s?
direct- acting oral anticoagulants
lovenox aka
enoxaparin
low - molecular weight heparin
contraindications to VTE prophylaxis?
active gastroduodenal ulcer
bleeding within the three months prior to admission
platalet count <50, 000 /microL
