Approach to bleeding patient (Yr 3) Flashcards
how much blood loss can most healthy dogs/cats withstand?
15-25%
what are the possible life threatening situations to identify when presented with a bleeding patient?
hypovolaemic shock
severe anaemia
brain/pulmonary haemorrhage
what should be done to stabilise a patient?
control haemorrhage
fluid replacement
what type of fluid should be used for volume replacement in hypovolaemic animals?
crystalloids
what is the shock rates of fluid replacement therapy?
fifth of the of normal blood volume
(20-90ml/kg in dogs)
are shock rates or small volume resuscitations better?
small volume resuscitations
what are the figures for small volume resuscitation?
dogs 10-20ml/kg
cats 5-10ml/kg
(over 15 minutes)
what are the basic steps of haemostats?
vessel injury
vascular contraction
primary haemostasis
secondary haemostasis
tertiary haemostasis
what is primary haemostasis?
formation of a platelet plug
this is dependant on platelets, von Willebrand factor and endothelium (collagen)
what is the function of von Willebrand factor?
allows platelets to bind to themselves and the endothelium to form a platelet plug
what is secondary haemostasis?
coagulation cascade that leads to generation of thrombin and allows a clot to form
what is tertiary haemostasis?
fibrinolysis ensures the clot doesn’t get too big
what are the clinical signs of a defect in primary haemostasis?
small holes (petechiae)
epistaxis and melaena
are defects of primary or secondary haemostasis more severe?
secondary (larger hole formation) often present as life threatening blood loss such as pulmonary haemorrhage or cavity bleeding
where should you take a blood sample if you are concerned about a clotting disorder?
peripheral vein (not jugular as bleeding will be hard to stop from there)
what has to be excluded before doing a buccal mucosal bleeding time test?
thrombocytopenia (decreased platelets)
what tests can be run for a primary coagulopathy?
manual platelet count
buccal mucosal bleeding time
von Willebrand factor
what is a buccal mucosal bleeding time test designed to determine?
platelet function (should have normal clotting time and platelet count before doing this test)
what tests can be run for testing secondary coagulopathy (clotting disorders)?
prothrombin time (PT)
activated partial thromboplastin time (APTT)
specific factor levels
what are the main disorders of primary haemostasis?
thrombocytopenia
von Willebrand disease
(thrombocytopathia, vascular disease)
what can general causes of thrombocytopenia?
lack of production
increased consumption
increased destruction
increased sequestration
spurious (clot in the tube)
what can cause a thrombocytopenia due to lack of production?
bone marrow disorders
drug toxicosis (antibiotics, phenobarbitone…)
what can cause a thrombocytopenia due to increased consumption?
DIC (disseminated intravascular coagulation)
acute severe haemorrhage
what is a spurious cause of thrombocytopenia?
clot in the tube (lab error)
what breeds are associated with inherited thrombocytopenia?
CKCS
sighthounds
(don’t need to be treated)
what is the main cause of thrombocytopenia due to increased destruction?
immune mediated (primary or secondary)
what can cause secondary immune mediated thrombocytopenia?
drugs - antibiotics
neoplasia
infectious disease - babesia, leptospirosis, leishmania, anaplasma
how is primary immune mediated thrombocytopenia treated?
glucocorticoids (prednisolone)
what is used to test for platelet function?
buccal mucosal bleeding time
what is von Willebrand disease?
inherited deficiency in von Willebrand factor
what breed is predisposed to von Willebrand disease?
dobermans
when should you suspect von Willebrand disease?
any dog with mucosal surface bleeding or excessive bleeding following surgery or trauma
what type of test is used to diagnose von Willebrand disease?
antigenic testing
(can do genetic testing)
how is von Willebrand disease treated?
cryoprecipitate (concentrated solution of factor IIX, fibrinogen and von Willebrand factor)
can also give whole blood or fresh frozen plasma
what are the most common causes of disorders of secondary haemostasis (clotting deficiencies)?
vitamin K antagonism/deficiency (rodenticide toxicity)
severe liver disease
DIC
inherited - haemophilia A and B
what is the most common cause of vitamin K deficiency?
rodenticide toxicity
what are the typical clinical signs of vitamin K deficiency?
epistaxis, melaena, haematoma, ecchymoses, haematuria, gingival bleeding
what should be done to diagnose vitamin K deficiency?
coagulation testing (PT/APTT)
clinical history/signs
what is DIC?
disseminated intravascular haemolysis - activation of clotting cascade forming lots of small clots which then exhausts the platelets or clotting factors leading to bleeding
what can cause DIC?
septicaemia
immune mediated disease
neoplasia
heat stroke
what abnormalities on laboratory testing will be seen in cases of acute DIC?
prolonged clotting times
thrombocytopenia
schistocytes (clots blocking vessels)
decreased fibrinogen
increased D-dimers
what are D-dimers?
products of the breakdown of clots (fibrin)
