Hemostasis
The stoppage of bleeding when there is damage to small blood vessels and capillaries. Helpful blood clotting.
Damage
Damage to blood vessels initiates hemostasis. There are three basic mechanisms that promote hemostasis.
Vasoconstriction
The blood vessel contracts to diminish blood loss. When it contracts, it exposes collagen from the damaged site on the vessel.
ADP
Attracts more platelets to the area
Reduced Blood Flow
Temporarily decreases blood flow and pressure within the vessel. When you put pressure on a bleeding wound, you also decrease flow within the damaged vessel.
Platelet Aggregation
Platelets release cytoplasmic granules. Mechanical blockage of the hole by a platelet plug.
Seratonin
A vasoconstrictor
Thomboxane A2
Promotes platelet aggregation, degranulation, and vasoconstriction
Attract More Platelets
ADP and Thomboxane aggregate more platelets that release more ADP and Thomboxane
Positive Feedback Loop
The loop continues until the formation of a platelet plug.
Factor III (Coagulation Factor)
Damaged tissue releases Factor III
Coagulation Cascade
The final Hemostatic mechanism.
Factor XI
Initiates intrinsic mechanism.
Ca++
Aids Factor III
Factor XII
From active platelets.
Factor VII
This loop initiates an extrinsic mechanism.
Cascade Reactions
Coagulation Cascade: including Factor VIII. Factor VIII is aided by Von Willebrands Factor
Platelets and RBC
Become caught in this mesh of fiber and form a blood clot.
Prothrombin Activator
Connects Prothrombin to thrombin. Thrombin converts fibronogen to fibrin. Fibren initially forms a loose mesh, but then Factor XIII causes the formation of covalent cross links, which convert fibrin into a dense aggregation of fibers.
Factor X
Works with Factor III, Factor V, Ca++, and a Platelet Thromboplastic Factor (PF3)
Hemostasis in Emergency Medicine
Hemostasis Video
Hemostasis Stages
Hemophilia A
Deficiency in Factor VIII
Companies: Baxter, Bayer, Pfizer, CSL Behring, Grifols, Octapharma, Aventis Pharma
Hemophilia B
Deficiency in Factor IX
Companies: Pfizer, Grifols, CSL Behring
Von Willebrand Disease
Deficiency of Factor that prevents the rapid breakdown of Factor VIII
Companies: Aventis Pharma, CSL Bering, Grifols, Octapharma
Note
Drugs: Recombinant Concentrates, Human Plasma-Derived Immunoaffinity Purified Concentrates, Desmopressin Formulations
Inhibitors: Factor VIII or IX
Companies: Baxter, Novo Nordisk
Afibrinogenemia/ Hypofibrinogenemia
Companies: CSL Behring
Factor VII Deficiency
Companies: Novo Nordisk
Recombinany Factor VIIa Concentrate
Factor XIII Deficiency
Companies: CSL Behring
Human Plasma-derived Concentrate
Factor II or Factor X Deficiency
Companies: Baxter, Grifols
Antithrombin Deficiency
Companies: GTC Biotherapeutics, Grifols
Protein C Deficiency
Companies: Baxter
Thrombocytopenia
Decrease in platelet count
Thrombosis
Too many platelets that causes blood clots to form and obstruct blood flow