Peripheral Vascular Anesthesia Flashcards
Over 50% of Vasculopaths have this comorbidity.
CAD
Heparin is a naturally occurring anticoagulant produced by ____ and _______.
- Basophils
- Mast Cells
What does heparin bind to?
- Antithrombin III
What happens to AT III when heparin is bound to it?
Enhances 1,000x the ability of AT III to inactivate thrombin and factors XII, XI, IX, X
Heparin will also inhibit thrombin activation of what factors?
- Factor V
- Factor VII
Heparin’s effect on platelet function
Inhibits platelet function
What factor does heparin effect on the extrinsic pathway?
Factor VII
What factor does heparin effect on the common pathway?
Factor V
Lipid solubility of heparin?
Poorly lipid soluble
GI absorption of heparin?
Poorly absorbed in the GI Tract
Does heparin cross the placenta?
No
Heparin’s anticoagulation increases in intensity and duration with increasing ________.
Doses
Heparin’s anticoagulation increases in intensity and duration with decrease ________, _____, and _______.
- Temperature
- Hepatic dysfunction
- Renal dysfunction
CV side effects of heparin
- Relaxation of vascular smooth muscle
- Decreased MAP, Pulmonary arterial pressure, SVR
What is the most common side effect of heparin?
Hemorrhage
What is mild HIT due to?
Platelet aggregation
Plt count for mild HIT?
<100,000
When will mild HIT begin?
Appx 15 days after initiation of heparin therapy
What is the plt count for severe HIT?
< 50,000
When will severe HIT begin?
5-10 days after initiation
What antibody is formed with severe HIT?
IgG
What are the normal functions of IgG?
- Neutralize toxins, viruses, and bacteria
- Opsonize them for phagocytosis
How does IgG react with HIT?
- lgG will bind to receptor on platelet
- Lead to platelet activation
- Activated platelets release pro-thrombotic substances (such as thrombin)
- IgG activates more platelets
Heparin dose for Vascular Surgery
100 units/ kg
Normal aPTT and Heparinized aPTT
- Normal aPTT: 30-35 seconds
- Heparinized aPTT: 60-70 seconds
Normal ACT
90-120 seconds
When will you draw an ACT during a vascular surgery?
- 3 minutes post heparin injection
- repeat q 30 mins to 1 hour
What is the half life of heparin?
1-2 hours
Reversal for heparin
Protamine
Where can protamine be naturally found?
Salmon Sperm
MOA of Protamine
Protamine is a positively charged alkaline that combines with negatively charged (acidic) heparin