What are the 3 initial responses to vascular injury?
2) thrombin generation
3) platelet adhesion
Draw Coagulation cascade (p. 5)
4) platelet factor 3
6) forms on platelets
7) catalyzes the formation of thrombin
What is the convergence point of both intrinsic and extrinsic pathways?
What inhibits factor X
Tissue factor pathway inhibitor
What combines with platelets to form platelet plug --> hemostasis
What helps crosslink fibrin?
1) key to coagulation
2) converts fibrinogen to fibrin and fibrin split products
3) activates factors V and VIII
4) activates platelets
Anticoagulation (to follow)
1) key to anticoagulation
2) binds and inhibits thrombin
3) inhibits factors IX, X, XI
4) Heparin binds AT-III
1) vitamin K dependent
2) degrades factors V and VIII
3) degrades fibrinogen
1) vitamin K dependent
2) protein C co-factor
Tissue Plasminogen Activator:
1- released from endothelium
2- converts plasminogen to plasmin
1- degrades factors V and VIII, fibrinogen, and fibrin--> lose platelet plug
natural inhibitor of plasmin, released from endothelium
Which factor has the shortest half-life?
Factors V and VIII:
1) labile factors
2) activity lost in stored blood
3) activity not lost in FFP
What is the only factor not synthesized in the liver
VIII, only factor not synthesized in liver (synthesized in endothelium)
What are the vitamin K- dependent factors?
II, VII, IX, and X; protein C + S
How long does it take for vitamin k to take effect?
takes 6 hours
How long does it take for FFP to take effect?
effect is immediate, lasts for 6 hours
Whats the name for factor II?
Normal half-life of:
RBC: 120 days
Platelets: 7 days
PMNs: 1-2 days
2) from endothelium
3) decreases platelet aggregation and promotes vasodilation (antagonistic to TXA2)
2) from platelets
3) increases platelet aggregation and promotes vasoconstriction
4) triggers release of calcium in platelets --> exposes GpIIb/IIIa and causes platelet-to-platelet binding, platelet-to-collagen binding
5) activates PIP system to further increase calcium
contains highest concentration of VWF and VIII; used in von willibrand's disease and hemophilia A (factor VIII deficiency), also contains fibrinogen
has high levels of all factors (including labile factors V and VIII), protein C, protein S, and AT-III
DDAVP and conjugated estrogens
causes release of VIII and vWF from endothelium
What does PT measure?
1) PT- measures II, V, VII, and X; fibrinogen
2) Best for synthetic liver activity
What does PTT measure?
PTT- measures most factors except VII and XIII (thus does not pick up factor VII deficiency); also measures fibrinogen
What range should PTT be if you want anticoagulation?
PTT 60-90 sec for anticoagulation
1) activated clotting time
2) want ACT 150-200 sec for routine anticoagulation, 460 sec for cardiopulmonary bypass
What INR ranges are a contraindication for procedures?
INR >1.5- relative contraindication to performing surgical procedures
INR >1.3- relative contraindication to central line placement, percutaneous needle biopsies, and eye surgery
What is the most common cause of surgical bleeding?
Von Willebrand's disease
1) most common congenital bleeding disorder2) types I and II are autosomal dominant; type III is autosomal recessive3) vWF links GpIb receptor on platelets to collagen4) PT normal, PTT can be normal or abnormal5) have long bleeding time (ristocetin test)
6) type I is most common (70% of cases) and often only has mild symptoms
7) Type III causes most severe bleeding
8) Type I and III- reduced quantity of circulating vWF