module 5 Flashcards
(51 cards)
what is thrombogenesis
the formation of blood clots, a normal body defense mechanism to prevent blood loss. it is life saving in the case of hemorrhage and life threatening in the case of thrombus obstruction
What us the sequence that has to occur for blood clotting?
When there is a blood vessel injury, the blood is exposed to sub endothelial cells. That triggers XIIs activation to XIIa, this active version XIIa activates facotr XI to its active form factor XIa. Which along with ca+ Activates factor IX to its active form IXa. Factor 9 activates factor 10 which converts prothrombin to thrombin which converts fibrinogen to fibrin
arterial thrombosis
occurs when platelets initiate the process followed by fibrin formation which causes RBCs to be trapped in the fibrin and obstruct blood flow. this is usually associated with atherosclerotic plaques, hypertension, and turbulent blood flow.
venous thrombosis
when platelet aggregation combines with fibrin and attaches tot he RBC. venous thrombosis is usually associated with venous stasis. when blood flows slowly, thrombin and other procoagulant substances become concentrated and initiate the clotting process.
which is more likely to travel and why? a venous or arterial thrombosis
a venous thrombosis because there is no atherosclerosis on the walls of the venous vessels making the clots less cohesive.
where do arterial blood clots likely manifest?
cerebral arteries: stroke
pulmonary arteries: pulmonary embolism
cardiac system: MI
what can venous blood clots lead to
DVT. these are often times (50%) asymptomatic
what do anticoagulants do
prevent formation of new clots and prevent extension of existing ones. DO NOT DISSOLVE
-allow the blood to thin so it is easier for the blood to get by the clot
antiplatelets
prevent platelet aggregation and are mainly used to prevent arterial thrombosis
thrombolytic drugs
attack and dissolve blood clots already formed
what are anticoags used for
prevention of both venous and arterial thrombosis
venous: DVT and PE
arterial: MI, CVA, those with artificial heart valves
heparin
natural anticoagulant produced by mast cells
if used before thrombus formation
-combines with a natural anti coag in the blood called antithrombin and inhibits factors 9, 10, 11, and 12 which stops prothrombin to covert to thrombin thus preventing the formation of a clot
if used after clot production
1. inhibits additional coagulation by inactivating thrombin which stops fibrinogen to convert to fibrin. it inhibits factor five and 8 and platelet aggregation to stop the clot from increasing in size
the therapeutic effect of heparin
prolongs clotting time. so if you have a pt with a stroke must find out if it is a hemorrhaging or ischemic stroke which can be done with a CT scan. ask the pt what peds they’re on and when the symptoms started
heparin contraindications
active bleeding
history of HIT: heparin-induced thrombocytopenia. the normal platelet levels are 150-300
adverse effect: cause bleeding
antidot for heparin
protamine sulfate
proat-amine sulfate
watch out for these herbs when taking heparin
chamomile, garlic, ginger, ginkgo, ginseng, and high dose vitaE
how ware heparin doses determined
an activated partial thromboplastin time or an aPTT is drawn. the normal values of aPTT that indicate normal coagulation are 25-35 seconds, but with those on heparin, we are looking for therapeutic values which are higher. therapeutic values are 45-70 seconds
what is the difference between heparin and LMWH?
LMWH like Lovenox inactivate factor Xa like heparin but are less able to inhibit thrombin.
indications for LMWH
DVT, PE, prevent complications of MI, ischemic complications of unstable angina.
-no need to monitor PTT but monitor platelet counts
contraindications of LMWH
hemorrhagic stroke, ulcers, blood abnormalities, low platelet count, those having surgery on eyes, brain or spine
enoxaparin
lovenox: LMWH
route: subq
it is often used after patients come off heparin and are going to be discharged home but want to sustain anticoag effects.
patient teaching heparin
monitor for indication of bleeding such as bruised gums. abdomen pain, coffee-ground emesis, and tarry stools
-avoid NSAIDs, aspirin, or meds with salicylates
patient teaching fo enoxaparin
provide instruction for self administration
do not expel air bubble: it is there to make sure the full dose is given
also teaching given to those with heparin
Direct thrombin inhibitors
dabigatran (Pradaxa) a type of anticoag
action: inhibit thrombin which inhibits thrombus formation, prevents stroke, and prevents embolism with patient with A-Fib,
- if the patient is going in for an angioplasty it is given with ASA
