pom- bleeding disorders- unfinished Flashcards
3 causes of hemostatic defects
platelet abnormalities
vessel abnormalities
coagulation factor abnormalities
virchow’s triad
reduction in blood flow
changes in the blood vessel wall
increased coag of blood
what does virchows triad indicate?
possible venous thrombosis
four phases of coagulation
vascular phase
platelet phase
coag cascade
fibrinolytic phase
three parts of coag cascade
intrinsic
extrinsic
common pathway
what phase occurs when you get an injury to the endothelium
vascular phase
describe vascular phase
immediate vasoconstriction caused by serotonin, histamine and pg
describe the platelet phase
platelets aggregate on the damaged vessel wall, create plug
what are 2 further components for aggregation and promotion of clotting?
adp, pf3
what are receptors for platelets- 2?
gp11b, gpiiia
what else is involved in migration of platelets to the site other than the receptors?
von willebrand factor in endothelium
where are clotting factors synth
liver
what is the coagulation cascade
converts fibrinogen to fibrin
what mediates coag cascade
thrombin
what is thrombin made from
prothrombin
what mediates change of prothrombin to thrombin
factor X
defintion of intrinsic pathway of coag cascade
true cascade, initated by exposure of factor xii to surface agents ( like collagen)
define extrinsic pathway
involves factor vii which complexes w calcium and tissue factor
where do intrinsic and extrinsic pathways interact? exam
right in the middle of the cascade with factor V and X meeting each other
tissue thromboplastin (tpa)
given to pt who had stroke, within 2 hr, to prevent further stroke
normal platelet range
150,000-400,000 /uL
thrombocytopenia
<50,000/uL
spontaneous bleeding
<20,000/uL
causes of thrombocytopenia
drug induced, immune thrombocytopenia purpura
what causes drug induced thrombocytopenia
marrow toxicity or platelet destruciton
what are the most common drugs that suppress megakaryocyte production
etoh and thiazide dieuretic
what are the most common drugs to cause platelet destruction
quinidine and quinin
what causes peripheral platelet destruction most commonly?
immune system problem
when does drug induced thrombo appear?
severlly and sudddenly
how do you treat drug induced thrombo?
corticosteroid or give iv platelets
2 types of immune thrombocytopenia purpura
acute, chronic
definition of immune thrombocytopenia purpura
autoab facil platelet destruction
acute itp is mostly a – dz or assoc with –
pediatric, hivd
how to treat itp
gcs, iv ig, splenectomy, immunosuppressives
how does itp present?
petechiae, purpura, hepaomegaly and splenomegaly
chronic itp usually seen in
women- unknown cause
is chrnoic more or less severe than acute itp?
less
what is chronic itp usually seen w?
underlying dz like lymphoma, sarc, sle
what other broad thing can cause thrombocytopenia?
bone marrow failure
