VTE therapeutics acute treatment Flashcards
(48 cards)
When would you consider removal the thrombus? (2) Risk factors (5)
- PE with risk factors for poor prognosis
- Bradycardia (<40bpm)
- Shock (low BP with organ failure)
- Hypotension (systolic <90)
- Right ventricular dysfunction
- Myocardial injury - Massive DVT plus limb gangrene (amputation needed)
What are the 2 methods of removal of a clot
- Pharmacological (thrombolysis)
- Surgery (pulmonary embolectomy) for PE
- reserved for CI to fibrinolysis (eg. active GI bleeding) or those who failed thrombolysis
When is an IVC filter indicated (3) (FYI)
- Absolute CI to anticoagulation (active bleed, intracranial bleeding)
- Patient survived massive PE but would not live through a 2nd one
- Recurrent VTE despite anticoagulation
When do you treat a patient with acute VTE as inpatient vs outpatient?
Treat as outpatient only if hemodynamically stable
Hemodynamically unstable = hospital admission
- hypotension
- hypoxemia
- tachycardia
Do anticoagulants remove clots?
NO
- they only stabilize it and stop it from growing so our own body can work to dissolve it
Why can’t we just start with warfarin alone?
Warfarin only suppresses production of NEW clotting factors, does not take into account the old clotting factors that are already there
Risk of symptomatic worsening in an RCT of UFH + warfarin vs warfarin alone in patients with acute VTE?
Risk of symptomatic worsening 6.7% in combination vs 20% in warfarin alone
What are the factors for picking an alternative rationally in order (4)
- Efficacy
- Safety
- Cost and convenience
- Patient-specific factors that may modify ranking
Which RAPID-acting antithrombotic drug/route of admin have monitoring of effect (2)
UFH
- IV
- SC
UFH
efficacy
safety (3)
Efficacy
- compared to placebo in 1960, reduces risk of recurrent PE and mortality
Safety
- MAJOR BLEEDING
- thrombocytopenia
- osteoporosis
Explain safety trials of UFH with major bleed
2-5% of patients receiving IV UFH experience MAJOR BLEEDING
- a range bc of what is defined as a “major bleed”
When is risk of bleeding increased in UFH (4)
- Recent surgery/trauma
- conditions like peptic ulcer, malignancy, liver disease
- NSAIDs/antiplatelets use
- Female and over 65
Explain safety trials of UFH with thrombocytopenia. What are 2 possible causes of this?
Up to 30% of patients receiving heparin
2 causes
1. Direct effect of heparin (binding directly to platelets)
- common, not as dangerous
2. Immune reaction - HIT (heparin induced thrombocytopenia)
Explain safety of UFH with osteoporosis MOA. How long do you have to be on a UFH
- Heparin binds to osteoblasts, which activates osteoclasts
- associated with heparin use of 6 months
- not entirely reversible
Explain pathophys of HIT (heparin induced thrombocytopenia) and treatment
Pathophys (immune reaction)
Occurs by 2 mechanisms:
1. removal of platelets with bound IgG by splenic macrophages
2. Platelet consumption caused by thrombus formation
Treatment
1. Stop heparin
2. Hold or reverse warfarin
3. Start a full-dose therapeutic anticoagulation with a non-heparin
- Fondaparinux (parenteral, urgent, subc)
- Argatroban
What are advantages of heparin over other rapid-acting anticoagulants? (2)
- IV infusion can be stopped (vs SC)
- Antidote exists - protamine sulfate
What is the IV weight-based dosing of UFH? How do we monitor UFH (2)?
Initial bolus of 80units/kg and initial infusion of 18 units/kg/ per hour
- adjust/monitor dosing using aPTT
- drawn every 4-6h - CBC, make sure platelets at baseline
- q2days
Is SC UFH used in Canada?
No
What is the cost/convenience of UFH
Cost
- drug not expensive
- drug admin (monitoring, hospital stay, home care) = expensive
Convenience
- not convenient (IV, hospital stay, home care)
LMWH
Efficacy compared to UFH and between class
Safety (5)
Efficacy
- compared to UFH is similar (trials were flawed and had bias, that’s why it showed higher efficacy)
Safety (5)
- Major bleeding
- Thrombocytopenia
- Osteoporosis
- Obesity
- Renal impairment
Dosing for dalteparin
200 units/kg once daily
OR
100 units/kg BID (in patients over 100kg)
Dosing for tinzaparin
175 units/kg subcutaneously once daily
Dosing for Enoxaparin
1mg/kg subc BID
OR
1.5mg/kg subc once daily (not encouraged for treatment of VTE because it is possibly inferior to standard dosing
LWMH safety Major bleeding trials
Antidote?
Similar/lower rates compared with UFH <3%
Protamine sulfate
- only reverses about 60% of antithrombotic
- difficult to dose
