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36 Cards in this Set
- Front
- Back
Pathophys of HIT?
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heparin leads to formation of anti-PF4 IgG antibodies that recognize heparin on the surface of platelets which promotes binding, release of procoagulant factors, and thrombus formations in arterial and venous systems
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Risk of hit with LMWH vs UFH?
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UFH has 10x higher risk of HIT than LMWH
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Define thrombocytopenia
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platelet count of <150x10^9/L OR 30-50% fall even if nadir >150
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Typical onset of HIT?
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5-10 days after initiation of heparin; can occur within 24h if patient has previous exposure to heparin within last month to 100 days prior; ALSO thrombocytopenia can occur up to three weeks after exposure to heparin
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What clinical evaluation tool can be used for determining HIT?
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4Ts score
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Why is the HIT ELISA test only sensitive and not specific?
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Seroconversion to produce HIT antibodies does not always cause HIT as the antibodies have to be specific to both heparin and pf4 but some are pf4/polyvinyl sulfonate and thus not HIT producing; assays such as serotonin release assay (SRA) and heparin induced platelet activation are both specific and sensitive to HIT
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For patients receiving heparin in whom
clinicians consider the risk of HIT to be > 1% we suggest that platelet count monitoring be performed? |
every 2 or 3 days from day
4 to day 14 (or until heparin is stopped, whichever occurs fi rst) |
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For patients receiving heparin in whom
clinicians consider the risk of HIT to be <1% we suggest that platelet counts? |
not be
monitored |
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For patients exposed to heparin
within the past 100 days, we suggest what prior to starting heparin or LMWH therapy? |
that a baseline
platelet count be obtained and that a repeat platelet count should be drawn 24 h later, if feasible. |
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S/sx of acute HIT?
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acute infl ammatory reaction (eg, fever,
chills) and/or cardiorespiratory symptoms (eg, hypertension, tachycardia, dyspnea, chest pain, cardiorespiratory arrest) within 30 min of drug administration. |
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First step in tx of HITT (heparin induced thrombocytopenia complicate by thrombosis)?
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d/c all LMWH and UFH
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In patients with HITT, we recommend the
use of? |
nonheparin anticoagulants, in particular
lepirudin, argatroban, and danaparoid, over the further use of heparin or LMWH or initiation/ continuation of VKA |
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All possible HITT tx (but not all recommended by chest)?
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DTIs: lepirudin, desirudin, argatroban, bivalirudin
Xa inhibitors: danaparoid or fondaparinux |
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brand name for desirudin?
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Iprivask
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brand name for lepirudin?
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Refludan
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brand name for argatroban?
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n/a
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brand name for bivalirudin?
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angiomax
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brand name for fondaparinux?
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Arixtra
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In patients with HITT who have normal
renal function, we suggest what tx? |
the use of argatroban
or lepirudin or danaparoid over other nonheparin anticoagulants |
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In patients with HITT and renal insuffi -
ciency, we suggest of what tx? |
the use of argatroban over
other nonheparin anticoagulants (argatroban is not renally cleared while lepirudin is) |
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Should patients with HIT be transfused with platelets?
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No. Pts with HIT rarely have spontaneous bleeding despite low PLts. Also adding plts tends to increase the chances of developing thrombus (no direct evidence but safety is unlikely and unknown at this time)
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In patients with HIT and severe thrombocytopenia,
we suggest giving platelet transfusions when? |
only if bleeding or during the performance of an
invasive procedure with a high risk of bleeding (Grade 2C) . |
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Why is warfarin not started immediately after HIT?
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can produce a prothrombotic state as the anticoagulant protein C levels drop faster due to warfarin than prothrombin levels; need DTI or Xa inhibitor on board to start VKA after HITT
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In patients with strongly suspected or confi
rmed HIT, we recommend against starting VKA until? |
platelets have substantially recovered (ie,
usually to at least 150K) over starting VKA at a lower platelet count and that the VKA be initially given in low doses (maximum, 5 mg of warfarin or 6 mg phenprocoumon) over using higher doses (Grade 1C) . |
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We further suggest that if a VKA has
already been started when a patient is diagnosed with HIT, then do what? |
, vitamin K should be administered
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In patients with confi rmed HIT, we recommend
that that the VKA be overlapped with a nonheparin anticoagulant for? |
a minimum of
5 days and until the INR is within the target range over shorter periods of overlap and that the INR be rechecked after the anticoagulant effect of the nonheparin anticoagulant has resolved |
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For patients with HITT, we suggest
VKA therapy or an alternative anticoagulant be continued for? |
3 months. For patients with HIT, we suggest
VKA therapy or an alternative anticoagulant be continued for 4 weeks |
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In patients with isolated HIT (HIT without
thrombosis), we recommend |
the use of lepirudin
or argatroban or danaparoid over the further use of heparin or LMWH or initiation/continuation of a VKA |
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In patients with acute HIT (thrombocytopenic,
HIT antibody positive) or subacute HIT (platelets recovered, but still HIT antibody positive) who require urgent cardiac surgery, we suggest |
the use of bivalirudin over other nonheparin
anticoagulants and over heparin plus antiplatelet agents |
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In patients with acute HIT who require
nonurgent cardiac surgery, we recommend |
delaying
the surgery (if possible) until HIT has resolved and HIT antibodies are negative |
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In patients with acute HIT or subacute
HIT who require PCI, we suggest the use of |
bivalirudin (Grade 2B) or argatroban (Grade 2C)
over other nonheparin anticoagulants |
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Why is argatroban preferred for dialysis pts with HIT?
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it is not renally cleared and dialytic clearance by high flux membranes is considered clinically insignificant
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In patients with a past history of HIT who
require ongoing renal replacement therapy or catheter locking, we suggest? |
the use of
regional citrate over the use of heparin or LMWH |
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In pregnant patients with acute or subacute
HIT, we suggest |
danaparoid over other nonheparin
anticoagulants (Grade 2C) . We suggest the use of lepirudin or fondaparinux only if danaparoid is not available |
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In patients with a history of HIT in
whom heparin antibodies have been shown to be absent who require cardiac surgery, we suggest |
the use of heparin (short-term use only - less than 4 days)
over nonheparin anticoagulants |
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In patients with a past history of HIT who
have acute thrombosis (not related to HIT) and normal renal function, we suggest |
the use of
fondaparinux at full therapeutic doses until transition to VKA can be achieved |