Hemostasis and Coagulation Flashcards
Why is hemostasis necessary?
Hemostasis is necessary to prevent or control blood loss due to blood vessel injury.
How could platelets be described?
150,000 – 450,000/ µL (microliter)
Formed mostly in bone marrow with some platelets produced in the spleen
70% in circulation
30% stored in spleen
Lifespan 10 days
What is the role of the spleen in hemostasis?
The spleen manufactures some platelets along with the bone marrow.
The spleen also stores platelets.
What is the role of the liver in hemostasis?
Clotting Factors
I – XIII Designation of clotting factors
Most clotting factors are plasma proteins made in the liver
Some require Vitamin K for synthesis or function
What is hypercoagulability? (Platelet function and clotting factors?)
Platelet function
Thrombocytosis – excess platelets
Excessive clotting
-Inherited
-Acquired
What is bleeding?
(Platelet function and clotting factors?)
Platelet function
-Thrombocytopenia – inadequate platelets
-Impaired platelet function
Deficient clotting factors
-Inherited
-Acquired
What is the etiology of hypercoagulability with increased platelet functions?
Abnormal blood flow through the vessel (s)
- “Blood is more viscous.”
Damage to the endothelial layer.
Platelets are hypersensitive to substances that promote adhesiveness and aggregation.
How is excessive clotting described? (inherited)
Factor V gene mutation
Venous thrombosis
Thromboembolism – pregnancy
Abruptio placentae
Prothrombin gene mutation
How is excessive clotting described? (acquired)
(Venous stasis)
Immobility
Myocardial infarction
Cancer
Smoking
Obesity
Increased estrogen - Oral contraceptives
What is Thrombocytopenia?
Decreased platelet count
What are some examples of Thrombocytopenia?
Heparin-induced thrombocytopenia
Immune-induced thrombocytopenia
Thrombotic thrombocytopenic purpura
What is Thrombocytopathia?
Impaired platelet function
What are some examples of Thrombocytopathia?
Von Willebrand’s disease
Drugs
End-stage renal failure
Cardiopulmonary bypass
What causes decreased platelet production?
Aplastic anemia
Bone marrow cancer
Chemotherapy
Radiation
What causes decreased platelet survival?
Disseminated intravascular coagulation
Infections
Mechanical heart valves
Cells are damaged moving through the metal parts of the artificial valve
What is the etiology of Hemophilia A?
Sex-linked recessive chromosomal disorder
Affects mostly males
Deficiency Factor VIII or IX
Elevated APTT (activated partial thromboplastin time)
How can you prevent Hemophilia? (primary)
Trauma prevention that may include protective gear
How can you prevent Hemophilia? (tertiary)
(To decrease disability or death)
Factor VIII infusion
Clotting factor infusion obtained from whole blood
Fresh frozen plasma Cryoprecipitate
What is Disseminated Intravascular Coagulation (DIC)?
Sometimes called consumptive coagulopathy related to (r/t) the consumption of clotting factors.
Acquired as a complication of another serious condition.
Often occurs after a major hemorrhage and/or infection.
Excessive clotting in microvasculature (capillaries) with excessive bleeding due to depletion of clotting factors
The underlying cause is depletion of clotting factors.
What conditions might lead to DIC?
Bleeding from pregnancy complications (About 50% of cases)
Major trauma
Hemorrhage
Severe infection
Snakebite
What are examples of coagulated lab tests?
Complete Blood Count (CBC)
Bleeding time
Activated partial thromboplastin time (APTT)
Prothrombin Time (PT)
International Normalized Ratio(INR)
Platelet count
What is Activated partial thromboplastin time?
Assesses function of the intrinsic coagulation pathway
33-45 seconds is normal range
Critical value > 90 seconds
Elevation of the value indicates bleeding is more prolonged than normal
Below normal value indicates clotting is more than normal
Measures effectiveness of the anticoagulant Heparin
For client receiving Heparin as IV infusion for anticoagulation treatment, desired APTT value is 1.5 – 2 times normal
What is Prothrombin time/ International normalized ratio?
Assesses function of the extrinsic coagulation pathway
PT result varies r/t reagent used each time blood is tested
Normal results are in the range of 10 – 14 seconds and 100% coagulated
Elevation of the value indicates bleeding is more prolonged than normal
Below normal value indicates clotting is more than normal
Measures effectiveness of anticoagulant drug, sodium warfarin
What is INR?
Thromboplastin reagents used to test the blood vary greatly between manufacturers and lots, so the World Health Organization developed a comparative mathematical ratio called the International Normalized Ratio - INR.
Normal range 0.8 – 1.1
> 3.6 Critical value, unless on warfarin for intentional anticoagulation
What are some key clinical points of INR?
Above normal value indicates bleeding is more prolonged than normal
Below normal value indicates clotting is more than normal
Why might the spleen be removed when platelet count is low?
To fix Thrombopenia
(These patients will be at risk for infection.)
Why does liver dysfunction alter coagulation?
Because clotting factors are manufactured by the liver
Thrombocytosis is…
Excess platelets
Excessive clotting
Thrombocytopenia is…
Inadequate platelets (impaired platelet function)
Deficient clotting factors
