Lecture 5-Hematology Flashcards
What are the (3) components of Virchow’s triad?—___ state, ___ wall injury, circulatory ___
Hypercoaguable state, vascular wall injury, circulatory stasis
Heparin affects ___ (bound clotting factors/unbound clotting factors/both)
UNBOUND clotting factors only—does not affect bound clotting factors/doesn’t break up existing clots
Heparin MOA = accelerates the rate at which ___ neutralizes ___ and ___; heparin binds ___ (reversibly/irreversibly) to ___ and induces a ___ change
Accelerates the rate at which antithrombin III (heparin cofactor) neutralizes thrombin (factor 2A) and factor 10A; heparin binds reversibly to antithrombin III and induces a conformational change
What system clears heparin from the body?
The reticuloendothelial system
Does heparin cross the placenta?
No
What test is often used to monitor heparin use?
ACT [activated clotting time]
ACT is used to measure heparin’s ___ (intrinsic/extrinsic) pathway activity
Intrinsic pathway activity
ACT is monitored in procedures with significant heparin use—T/F?
True
Heparin induced thrombocytopenia (HIT)—it is considered thrombocytopenia if platelets are < ___
< 100K
If there is a significant drop in platelet count from the patient’s baseline after heparin administration, you should consider the possibility of HIT (even if platelet count is not necessarily < 100K)—T/F?
True
HIT occurs ___-___ days after initiation of full dose or low dose heparin therapy, including heparin flush solution
5-15 days
HIT doesn’t occur immediately unless the patient has received heparin previously—T/F?
True
Type ___ (1 or 2) HIT occurs d/t heparin dependent antiplatelet ___ antibodies
Type 2 HIT occurs d/t heparin dependent antiplatelet IgG antibodies
Type ___ (1 or 2) HIT occurs d/t a direct, ___ effect on platelets
Type 1 HIT occurs d/t a direct, nonimmunogenic effect on platelets
How can HIT be reversed?
Stopping heparin therapy
In a minority of patients with HIT, it may be associated with thrombotic complications (“procoagulant state”), including arterial thrombosis and platelet-fibrin clots—if this occurs, what should you do?
Stop heparin and start patient on argatroban to prevent more clots from forming
Before diagnosing HIT, you should rule out other causes for thrombocytopenia—what two medications can cause thrombocytopenia? What disease state can cause thrombocytopenia?
Depakote and Pepcid can cause thrombocytopenia; sepsis can cause thrombocytopenia
HIT testing—___ testing picks up IgG antibodies; has very few false negatives; can get some false positives if it’s not the ___ specific antibody testing
ELISA testing picks up IgG antibodies; can get some false positives if it’s not the IgG specific antibody testing
HIT testing—___ = gold standard for HIT diagnosis; highly specific with very few false positives
Serotonin release assays
HIT treatment = stop ___ products; administer ___ anticoagulants (usually will use ___ or ___); add ___ to chart
Stop heparin products; administer non-heparin anticoagulants (usually will use argatroban or bivalrudin); add allergy to chart
What is the antidote for heparin?
Protamine sulfate
Protamine = cation, combines with strong anion heparin to form a stable salt (protamine NEUTRALIZES heparin)
Protamine can be used to reverse LMWHs—T/F?
False—LMWH are not as susceptible to protamine antagonism
If emergency reversal is needed for LMWH, protamine will neutralize about ___% of anti-Xa activity of LMWHs
65%
Protamine should be administered ___ (fast/slow)
SLOW
Rapid IV injection of protamine is associated with acute ___-related ___tension, ___cardia, ___ hypertension, transient ___, ___nea, respiratory ___
Acute histamine-related hypotension, bradycardia, pulmonary hypertension, transient flushing, dyspnea, respiratory distress
Patients may have a hypersensitivity reaction to protamine sulfate if they are hypersensitive to ___; have had previous ___ reversal; take protamine containing ___; or had previous ___
Hypersensitive to fish (protamine sulfate comes from salmon sperm); have had previous protamine reversal; take protamine containing insulin (NPH); or had previous vasectomy
To prevent hypersensitivity reaction to protamine, you can pre-treat patient with ___ and ___
Corticosteroid and antihistamine
Heparin rebound is ___ (common/rare) and is usually seen in patients who had ___ (little/massive) amounts of heparin
Heparin rebound is rare and is usually seen in patients who had massive amounts of heparin (i.e.: CPB cases)
What is heparin rebound?—a condition where patients ___ after ___ administration
A condition where patients re-anticoagulate after protamine administration
Heparin management [hold times prior to OR]—if patient is on IV heparin, stop ___-___ hours prior to procedure; if patient is on subQ heparin, stop ___ hours prior to procedure
If patient is on IV heparin, stop 4-6 hours prior to procedure; if patient is on subQ heparin, stop 12 hours prior to procedure
Heparin management [restart times after OR]—restart ___ hours post-op if patient is low risk for bleeding; restart ___-___ hours post-op if patient is high risk for bleeding (i.e.: liver disease, on other blood thinners, type of surgery puts them at risk for post-op bleeding)
Restart 24 hours post-op if patient is low risk for bleeding; restart 48-72 hours post-op if patient is high risk for bleeding (i.e.: liver disease, on other blood thinners, type of surgery puts them at risk for post-op bleeding)
Heparin management [catheter placement]—catheter should be placed ___ hour before heparin administration; catheter should be placed ___ hours before heparin administration if patient is going to have cardiac surgery
Catheter should be placed 1 hour before heparin administration; catheter should be placed 24 hours before heparin administration if patient is going to have cardiac surgery
Heparin management [catheter removal]—indwelling neuraxial catheters should be removed ___-___ hours after the last heparin dose and after their coagulation status has been evaluated
Should be removed 2-4 hours after the last heparin dose and after their coagulation status has been evaluated
LMWH MOA—inhibit factor ___ and ___—they are much more selective to factor ___ inhibition than ___
Inhibit factor Xa and IIa (thrombin)—they are much more selective to factor Xa inhibition than IIa
___ levels are the gold standard for monitoring LMWH therapy
Anti-Factor Xa levels
APTT and PT/INR are effective at monitoring LMWH therapy—T/F?
False—aPTT and PT/INR are insensitive to LMWH therapy
You should decrease the dose of LMWH in patients with chronic ___ insufficiency
Chronic renal insufficiency—because these drugs are renally eliminated
This anticoagulant is the most specific inhibitor of Factor Xa—no effect on factor IIa
Fondaparinux (Arixtra)
Black box warning for all LMWHs and fondaparinux (arixtra)—use of neuraxial blockade represents significant risk of ___; monitor for signs and symptoms of ___ damage
Use of neuraxial blockade represents significant risk of epidural hematoma; monitor for signs and symptoms of neurologic damage
Spinal/epidural hematoma risk for all LMWHs and fondaparinux—needle placement should occur at least ___ hours after last LMWH LOW dose or fondaparinux dose
Needle placement should occur at least 12 hours after last LMWH LOW dose or fondaparinux dose
Spinal/epidural hematoma risk for all LMWHs and fondaparinux—needle placement should occur at least ___ hours after last LMWH HIGH dose
24 hours
If epidural catheter is inserted, it should be done at least ___ hours prior to any dose of postoperative LMWH (single daily dosing)
4 hours prior to any dose of postoperative LMWH (single daily dosing)
Twice daily dosing of LMWH should be delayed until ___ hours post-op
Delayed until 24 hours post-op
Catheters should be removed prior to initiating ___ daily dosing
Twice daily dosing
Removal of epidural catheter should be done ___-___ hours before any dose of LMWH
2-4 hours before any dose of LMWH
Removal of epidural catheter should occur ___ hours after any dose and ___ hours before a subsequent dose
12 hours after any dose and 2 hours before a subsequent dose
What are (3) oral Xa inhibitors?
- Rivaroxaban (Xarelto)
- Apixaban (Eliquis)
- Edoxaban (Savaysa)
“Xa” in the name because they are oral Xa inhibitors
Hold time for dabigatran (pradaxa) with poor kidney function is ___-___ days; hold time for dabigatran (pradaxa) with normal kidney function is ___-___ days
3-5 days; 1-2 days
Xarelto only needs to be held for ___ hours prior to procedure
24 hours prior to procedure
For low risk bleeding, Xarelto should be held for ___ day; for high risk bleeding, xarelto should be held for ___ days
1 day; 2 days
Hold time for NOACs/DOACs is much ___ (more/less) than hold times for warfarin
Less than hold times for warfarin (5 days for warfarin vs. 1-2 days for NOACs/DOACs)
With NOACs, you don’t have to worry about starting the patient on bridge therapy or formation of clots while the medication is being held—T/F?
True, because the hold time is only 1-2 days (depending on low vs. high risk of bleeding)
All DOACs currently have available a BB warning for use with neuraxial anesthesia—T/F?
True
Dabigatran (pradaxa) should be held ___-___ days prior to neuraxial procedures
4-5 days prior to neuraxial procedures
Oral Xa inhibitors should be held ___-___ days prior to neuraxial procedures
3-5 days prior to neuraxial procedures
Dabigatran (pradaxa) and oral Xa inhibitors can be restarted ___ hours post-procedure if the patient is a low bleed risk; can be restarted ___-___ hours post-procedure if the patient is a high bleed risk
Can be restarted 24 hours post-procedure if the patient is a low bleed risk; can be restarted 48-72 hours post-procedure if the patient is a high bleed risk
Hemodialysis ___ (can/cannot) remove oral Xa inhibitors
Cannot
What is one reversal agent for oral factor Xa meds?
Andexanet alpha (andexxa)
Andexanet alpha (andexxa) was approved in January 2019 for reversal of Xa inhibitors; approved for what (2) oral Xa inhibitors?
- Xarelto
- Eliquis
Andexanet alpha (andexxa) is approved for reversal of edoxaban (savaysa)—T/F?
False—approved for reversal of xarelto and Eliquis only
Black box warning for andexxa—___ events, ___ events, cardiac ___, sudden ___; may also cause ___, ___onia, infusion related ___
Thromboembolic events, ischemic events, cardiac arrest, sudden death; may also cause UTIs, pneumonia, infusion related reactions
Argatroban = direct ___ inhibitor (factor ___)
Direct thrombin inhibitor (factor IIa)
Argatroban binds to both ___ and ___-bound thrombin
Both circulating and clot-bound thrombin
Argatroban has a ___ (lower/higher) risk of bleeding because it breaks up thrombin that is circulating and thrombin that is bound to clots
Higher risk of bleeding
Argatroban is used for the prevention/treatment of thrombosis in patients with ___
HIT
