E2: VTE

Question 1

Enoxaparin:
Treatment dose
Prophylactic dose

Answer 1

Treatment
-1mg/kg SQ BID
—If CrCl <30 mL/min: 1mg/kg SQ QD
—Use UH if CrCl <20mL/min
** CrCl dosing probably not important

Prophylactic
-40mg SQ QD
—If BMI >40: BID
—If CrCl <30mL/min: 30mg SQ QD
***BMI and CrCl dosing probably not important

Question 2

Unfractionated heparin
Treatment dose
Prophylactic dose

Answer 2

Treatment (both LD and continous)
-LD: 80 UNITS/kg IV
-Continuous: 18 UNITS/kg/hour IV

Prophylactic
-5,000 units SQ Q12hr
—If BMI >40: Q8 hr
***BMI dosing probably not important

Question 3

Determine initial dose of warfarin.
When should you start it

Answer 3

5 to 10 mg (based on age)
<50 yr = 10mg
>65 yr = 5 mg
In between = 7.5 mg

Start when aPTT is theraptutic from UH
Start same day as LMWH

Question 4

Determine new chronic dose of warfarin based on weekly dose.

Answer 4

10% weekly dose ↑ or ↓
-If INR LOW = increase weekly dose or give extra dose; Recheck INR in 1 to 2 weeks
-If INR HIGH = decrease weekly dose or hold dose; Recheck INR in 1 day – 2 weeks
-Can only have 2 different doses of warfarin

Question 5

Determine how to manage warfarin dose for extremely high INR.

Answer 5

Main point: Hold dose!!!

Additional details:
INR 4.5-10 & not bleeding:
-hold warfarin
-resume at lower dose

INR 10-20 &/or minor-moderate bleeding at any INR:
-Hold warfarin
-Consider vitamin K 2.5-5mg PO
-Recheck INR Q24 hr (until INR 2-3); repeat vitamin K if necessary
-Then resume at lower dose

Serious bleeding
-Hold warfarin
-Vitamin K 5 to 10mg IV infusion
-Recheck INR Q6-12 hr; may repeat vitamin K IV Q12 hr
-Supplement w/PCC (KCentra)
-Then resume at lower dose

Question 6

Determine goal INR and duration of warfarin treatment for VTE and prosthetic valve replacement.

Answer 6

First VTE: Goal 2-3
-Reversible risk factor present (Provoked): 3 months treatment time
-Idiopathic (Unprovoked): >3 months treatment

Second VTE: Goal 2-3, lifetime treatment

Mechanical valve: Goal 2.5-3.5, lifetime treatment

Question 7

Determine when warfarin or DOAC is preferred for VTE treatment.
Warfarin (6)
DOAC (4)
Double check this one

Answer 7

Warfarin > DOAC
1. Heart valve replacements
2. Not great adherence taking med (missing a dose of warfarin isn’t as critical as missing a DOAC due to long t1/2, still need to adhere to medication and blood draws)
3. Cheaper
4. Breastfeeding
5. Can be used in poor renal/hepatic elimination
6. QD

DOAC > Warfarin
1. Fewer DI
2. Frequent procedures? Only hold for 1-5 days instead of 5
3. Difficulties w/lab access for monthly warfarin draws (less monitoring w/DOAC)
4. No loading dose

Question 8

Determine appropriate OTC pain medications for use with oral anticoagulants.

Answer 8

Acetaminophen (Ibuprofen would ↑ bleeding risk)

Question 9

Explain how long warfarin should be held for invasive procedures

Answer 9

5 days (half life of clotting factors)

Question 10

Compare Type I and Type II heparin-induced thrombocytopenia
Pathophysiology:
↓ Platelets:
Incidence:
Time course:

Answer 10

Type I
Pathophysiology: Early, reversible, non-immune; associated w/direct interaction between heparin and platelets; cause bleeding
↓ Platelets: ~30%, <100,000
Incidence: ~10-20%
Time: Usually occurs ~1-2 days after treatment begins w/heparin

Type II
Pathophysiology: Serious, ALLERGIC reaction; Late, more serious IgG-mediated; heparin-platelet interaction results in platelet and coagulation cascade activation; cause clots
↓ Platelets: ~30-50%, 20,000-150,000
Incidence: <3%; occurs with UH >LMWH
Time: Usually occurs ~4-14 days after beginning heparin
-can occur within 12 hr of re-exposure

Question 11

Treatment of Type I vs Type II HIT

Answer 11

Type I:
-D/C heparin
-Next steps: depends if VTE treatment or prophylaxis

Type II:
-D/C heparin (also stop OAC if platelets <150k)
-START ARGATROBAN or fondaparinux
-Start WARFARIN when platelets >150k and aPTT therapeutic (argatroban)