Hemostasis Flashcards
what is hemostasis
stopping of bleeding
what is primary hemostasis
platelet plug formation
what is secondary hemostasis
coagulation cascade to fibrin clot formation
what are the 3 steps of hemostasis
- vasoconstriction
- platelet plug formation
- blood coagulation
what is normal platelet level
150,000- 400,000
what is thrombocytopenia
LOW platelet level (<100,000)
what is thrombocytosis
HIGH platelet level (>750,000)
what are the 2 major problems related to hemostasis
- excessive bleeding
- excessive clotting
what is the normal lifespan of platelets
7-10 days
in healthy people, the endothelial lining is…
antithrombotic meaning platelets don’t stick
when injured the surface of the endothelial lining is…
prothrombotic meaning platelets stick
what is the extrinsic pathway
injury happens from the OUTSIDE (ex. laceration, abrasion)
what is the intrinsic pathway
injury happens from the INSIDE (ex atherosclerosis)
what does the coagulation cascade require to work properly
vitamin k and calcium (pt needs a healthy LIVER)
what lab test is intrinsic pathway measured by?
aPTT
what lab test is extrinsic pathway measured by?
PT/INR
what does a higher number in lab tests indicate
it takes LONGER for blood to clot, leading to BLEEDING
what does a lower number in lab tests indicate
it takes SHORTER for blood to clot, leading to COAGULATION
where do both pathways end at?
the final common pathway
- where factor X is acted on by factor V to convert prothrombin to thrombin and fibrogen to fibrin leading to a cross linked fibrin clot
why do some people excessively clot
- increased platelet number
- increased platelet activity/aggregation
- increased coagulation activity
- stasis of blood flow
- increased coagulation factors
- decrease in antithrombotic factors
what fraction of platelets reside in the spleen?
1/3
what fraction of platelets are circulating in the blood stream?
2/3
why do some people excessively bleed
- decreased platelet production
- excessive pooling of platelets in spleen
- decreased platelet survival
- impaired platelet activity (d/t meds, renal failure, inherited disorders)
- deficiencies in clotting factors
- impaired synthesis of clotting factors
What can taking aspirin give to patients?
acquired platelet dysfunction
What antiplatelet drugs can be used to treat clotting disorders?
-aspirin
- clopidogrel
- hydroxyurea
what anticoagulants can be used to treat bleeding disorders
- heparin
- warfarin
what thrombolytic is used to treat bleeding disorders
tPA
What can be done for life threatening elevations in platelets
platelet pheresis
what are signs and symptoms of bleeding
- ecchymosis
- hematoma
- petechia
- purpura
- epistaxis
what are signs and symptoms of internal bleeding
- dizzy
- headache
- tired
- abdominal pain
- SOB
- chest pain
- hypotension
- tachycardia
- dyspnea/tachypnea
what is impaired platelet activity
platelets are present in adequate number but they do not function as they should
what are some causes of impaired platelet activity
- antiplatelet therapy agents (aspirin, clopidogrel, hydroxyurea)
- NSAIDs
- renal failure
- inherited disorders (genetics)
The body needs a healthy _____ to have adequate coagulation
liver
what vitamin (that the liver stores) does the body need to have adequate coagulation
vitamin K
what causes drug induced thrombocytopenia
- medications (including herbal and OTC)
- often misdiagnosed as autoimmune destruction of platelets
s/s of drug induced thrombocytopenia
- petechiae appears about 1 week into starting the med
- dizziness
- chills
- fever
- bleeding
what is the treatment for drug induced thrombocytopenia
stop the medication causing the problem
what causes heparin-induced thrombocytopenia
heparin
is heparin induced thrombocytopenia associated with bleeding or clotting
clotting, the body develops an antibody to heparin
what is the treatment for heparin induced thrombocytopenia
administer a direct thrombin inhibitor called Argatroban
what is thrombotic thrombocytopenic purpura a combination of
- thrombocytopenia
- hemolytic anemia
- vascular occlusions
- fever
- neurological abnormalities
- renal disease
what is important to remember about thrombotic thrombocytopenic purpura
- autoantibodies lead to a problem with von Willebrand Factor causing platelet aggregation and widespread clot formation
- happens abrubtly
- can be fatal!
what does thrombotic thrombocytopenic purpura affect
- kidneys
- brain (stroke)
- liver
- heart (MI)
risk factors for thrombotic thrombocytopenia purpura
- pregnancy
- HIV infection
s/s thrombotic thrombocytopenic purpura
- petechiae and purpura of lower extremities
- headache
- seizures
- altered consciousness
treatment for thrombotic thrombocytic purpura
plasmapheresis with 80-90% recovery
what factor is missing/greatly reduced with hemophilia A
factor VIII
what factor is missing/greatly reduced with hemophilia B
factor IX
s/s of hemophilia
- bleeding with trauma
- general weakness
- tachycardia
- tachypnea
- easy bruising
- epistaxis
- hemoptysis
- bleeding gums
- joint pain
- headache
- stiff neck
- intracranial hemorrhages
- abdominal pain
- hematemesis
- melena
- back pain
- hematuria
- post circumcision bleeding in an infant (that is prolonged and hard to stop
severe s/s of hemophilia
spontaneous bleeding into joints
treatment for hemophilia
- factor XIII replacement in hemophilia A
- factor IX replacement in hemophilia B
what is hemolytic uremic syndrome characterized by
- progressive renal failure
- hemolytic anemia
- thrombocytopenia
s/s of hemolytic uremic syndrome
- bloody diahrrea*
treatment for hemolytic uremic syndrome
- supportive
- antibodies
- hemodialysis
- renal transplantation
what is disseminated intravascular coagulation
disorder of clot formation and bleeding episodes
why does disseminated intravascular coagulation happen
because clots form and then coagulation factors are depleted leading to elevated fibrinolysis which causes bleeding
s/s disseminated intravascular coagulation
same as bleeding disorders
how is DIC diagnosed
- D-dimer
- look at clotting times and RBC counts
treatment for DIC
- treat underlying disorder
- transfusions of fresh frozen plasma to correct the clotting factor deficiency
