Hemostasis Flashcards
What is coagulation?
Physiological process by which blood changes from liquid to gel
What is hemostasis?
Cessation of blood loss from damaged vessel
When does coagulation begin?
Instantly after injury
What are the stages of hemostasis?
Primary + Secondary
Cell type: primary hemostasis
Platelets
Cell type: Secondary hemostasis
Clotting factors
What starts both primary and secondary hemostasis?
Exposure of blood to sub-endothelial collagen
Where do platelets come from?
Derived + released from bone marrow
How do platelets travel?
Circuate as anucleate cells
What are platelets a source of?
Preformed chemokines in intracellular storage granules
What happens once platelets are activated?
Synthesize thromboxane A2 from arachidonic acid
What occurs during primary hemostasis?
Platelets adhere to subendo collagen
Adherence –> cytosolic reactions = platelet activation
Release of granules + AA metabolism
What do the granules released by platelets in primary hemostasis do?
Recruit + activate additional platelets
= Platelet aggregation
What coagulation factor is NOT produced by the liver?
Factor 8
What is Factor 8?
megakaryocytes
What happens when coagulation factors are activated?
Fibrin formation
What three pathways occur during secondary hemostasis?
Intrinsic + Extrinsic + Common
Initiated by: Intrinsic
Contact activation of F7
Initiated by: Extrinsic
Tissue factor
Initiated by: Common
Fibrin formation
What is fibrinoolysis?
Regulates coagulation
Enzymatic dissolution of fibrin
What enzyme is functional in fibrinolysis?
plasminogen activators (tPA)
What happens is fibrinolysis?
Plasmin degrades fibrin into soluble degradation products
What are the three methods of surgical hemostasis?
Mechanical + Thermal + Chemical
Methods: Mechanical hemostasis
Direct pressure
Sutures
Tourniqet
Gel foam
Methods: Thermal hemostasis
Electrocautery
Laser
US device
Cryosurgery
Methods: Chemical
Epi Phenylephrine Formalin Vitamin K Protamine
How does thermal hemostasis work?
Engery focally transmitted onto tissue
Depends on water content
= vaporization of cells along energy application
Thermal tissue damage: Coagulation
lower power
produces thermal coagulum
Thermal tissue damage: Desiccation
heat lower than what is needed for cutting
Used for treating nodules under skin
Thermal tissue damage: Fulguration
Electrode held away from tissue
Air gap between electrode and tissue ionized
Burning and charring more superficial
Used on skin tags
What does electrocautery do to the inside of the cell?
Protein denaturation
What hertz does tissue damage occur?
3000 to 4000
What are the two types of electrocautery?
Monopolar
– and –
Bipolar
What is monopolar electrocuatery?
Pointed electrode makes contact with tissue
Patient is attached to electrode
What is a bipolar electrocautery?
Voltage applied via pair of electrodes
Use forceps to pass the current
What three things are involved in clotting?
Fibrinogen - thrombin - fibrin
What three things are involved in clot lysis?
Plasminogen - tPA - Plasmin
