Vascular Anesthesia Pt.1 (Exam I) Flashcards
What comorbidities are typical of “vasculopaths”?
- DM
- HTN
- CRI
- COPD
>50% have CAD.
Heparin is a naturally occurring anticoagulant produced by ______ and ___ ____.
basophils & mast cells
What does heparin directly bind to?
Antithrombin III
What is the consequence of heparin binding to antithrombin?
Enhances antithrombin by 1000x to inactivate factors 9, 10, 11, & 12.
What are the the three mechanism of actions of heparin?
- Binds to Antithrombin
- Inhibits thrombin
- Inhibits platelet function
What occurs when heparin inhibits thrombin?
Thrombin won’t active factors 5 & 7
Is heparin technically a direct anticoagulant?
No. Binds to Antithrombin which is a direct anticoagulant.
Heparin is _______ lipid soluble.
poorly
Does heparin cross the placenta?
no
How is heparin absorbed in the GI tract?
poorly
No PO formulation.
What conditions/factors will potentiate heparin’s anticoagulant activity?
- Hypothermia
- Liver dysfunction
- Kidney dysfunction
What will occur with heparin administration if circulating plasma protein concentrations are low?
Heparin won’t be bound and will be more active
What occurs with the vasculature when heparin is administered?
Vascular smooth muscle dilates
↓ MAP, PAP, SVR.
What is the most common, serious complication that occurs with heparin usage?
Hemorrhage
Especially higher if patient is already on ASA.
A platelet count of < 100k with concomitant heparin administration might be indicative of….
Mild HIT (Heparin-induced Thrombocytopenia)
What are the characteristics of severe HIT (Heparin-induced Thrombocytopenia)?
- PLT <50k
- IgG antibody formation
Severe HIT occurs _____ days after heparin initiation typically.
5 - 10 days
Mild HIT typically occurs ________ after initiation of therapy.
Within hours to 15 days
How do IgG antibodies neutralize toxins, viruses & bacteria?
IgG antibodies opsonize (bind) to foreign pathogens & make them targets for phagocytosis.
Where does IgG bind to on platelets?
FC receptor on platelet surface
What are the results of IgG binding to platelets?
- PLT activation
- PLT release of pro-thrombotic substances (like thrombin)
- Activation of more PLTs
What is the typical dose of heparin for vascular cases?
1mg/kg = 100u/kg
What is a normal aPTT?
30 - 35s
What is target aPTT for vascular cases?
~ 60 seconds
Goal is 1.5 - 2.5x normal.