Exam 3 - The Bleeding Patient Flashcards
what is involved in primary hemostasis?
involves the interactions between damaged vessels & platelets
forms initial unstable platelet plug
what is involved in secondary hemostasis?
results in formation of thrombin to stabilize the platelet & enzymatic reactions activate coagulation factors
stabilizes the platelet plug
what is fibrinolysis responsible for? what does it prevent?
responsible for normal degradation of the clot
prevents total occlusion of each injured vessel
what are the general steps of primary hemostasis?
- injury to a vessel wall
- vasoconstriction
- platelet adhesion to subendothelium
- vWF assists
- platelet aggregation to form a plug
- phospholipid surface is provided for coagulation enzyme complexes
what is the common signalment of animals with bleeding disorders?
more common in dogs than cats
- inherited coagulopathies more common in juveniles & certain breeds
- ITP more common in certain breeds
- neoplasia more likely in older patients
how should collecting samples be performed for a bleeding patient for diagnostic tests?
- collect sample prior to therapy if possible
- atraumatic venipuncture on a peripheral vein
- pressure wrap for 5 minutes after
- no cystocentesis!!
why run a PCV & total protein on a bleeding patient?
assess for anemia
low PCV & TP = acute blood loss
low PCV & normal TP = hemolysis or bone marrow disease
check color of plasma for more clues
what is indicated if the patient has a low PCV & TP? what about a low PCV & normal TP?
low PCV & TP = acute blood loss
low PCV & normal TP = hemolysis or bone marrow disease
why should a blood smear be performed on all patients with a bleeding disorder?
manual platelet count!!!!!
look at RBC morphology, parasites, etc
what is normal when looking at platelets on a blood smear?
11-25 platelets/HPF is normal with each platelet = 15,000/uL
what is a normal BMBT time?
<4 minutes
why do a BMBT?
crude test made with a controlled incision to assess the formation of the initial platelet plug
why run a PT & PTT on a bleeding patient?
evaluate secondary hemostasis
what does PT evaluate? what about PTT?
PT - extrinsic & common pathways
PTT - intrinsic & common pathways
what is a significant result on PT/PTT tests?
> 20% increase from reference interval
what is included in the extrinsic pathway?
factor VII
what is included in the common pathway?
X, V, II, & I
what is included in the intrinsic pathway?
XII, XI, IX, & VIII
vitamin K is essential for what clotting factors?
II, VII, IX, & X
what clotting factors aren’t produced in the liver?
VIII & vWF
what are 4 general disorders of primary hemostasis?
- vascular wall abnormalities - vasculitis
- von willebrand’s disease
- quantitative platelet disorder
- qualitative platelet disorders
what disease processes are included in vascular wall abnormalities?
immune-mediated (primary or secondary) or infectious
what disease processes are included in quantitative platelet disorders?
- platelet destruction
- decreased platelet production
- sequestration
- consumption
what are 6 general categories of diseases causing secondary hemostasis?
- vitamin k antagonist rodenticide toxicity
- vitamin k deficiency
- liver dysfunction
- inherited coagulation factor deficiencies
- disseminated intravascular coagulation
- drug toxicity
how long can it take for interstitial fluid to equilibrate in bleeding patients?
2-24 hours
how does iron-deficiency anemia generally start?
regenerative & then becomes non-regenerative
how is iron-deficiency anemia characterized?
microcytic, hypochromic - thrombocytosis is common
chronic, external blood loss - usually from chronic gi bleeding (hookworms, neoplasia, drugs, paraneoplastic syndrome, IBD)
what diagnostics should be run if you suspect iron-deficiency anemia?
fecal float
urinalysis
abdominal ultrasound
maybe FNA
what are 3 general mechanisms in which anemia can be classified?
- blood loss
- hemolysis
- impaired RBC production
what are 3 important natural inhibitors of blood coagulation?
- antithrombin
- protein c
- tissue factor pathway inhibitor
what can you use blood pressure measurements for in the bleeding patient?
hypovolemia - associated with hypotension
epistaxis - associated with hypertension
how is anemia severity characterized based off of PCV in dogs & cats?
dogs
mild - 30-36%
moderate - 18-29%
severe - <18%
cats
mild - 20-24%
moderate - 15-19%
severe - <14%
at what RBC parameter does spontaneous bleeding occur?
<30,000/uL
what may be seen on rbc morphology on blood smear supportive of a bleeding problem?
schistocytes
T/F: anemia due to hemorrhage starts of as non-regenerative & then becomes regenerative
true
what is a BMBT used for?
assess for disorder of primary hemostasis after platelet count has been confirmed to be adequate
what is a normal BMBT time for cats?
<2 minutes
what is fibrinogen?
acute phase protein synthesized in the liver - coagulation factor II
what can cause hypofibrinogenemia?
liver dysfunction, consumption (DIC or sepsis), congenital disorder, or massive blood transfusion
why does iron-deficiency anemia occur?
chronic blood loss depletes bone marrow iron stores over time
