Approach to the bleeding patient Flashcards
When approaching the bleeding patient, the first thing to do is to identify life threatening situations. Give examples of these situations
Hypovolaemic shock
Severe anaemia
Brain haemorrhage
Pulmonary haemorrhage
How can you stabilise a bleeding patient?
Control haemorrhage with wound pressure
Blood transfusion
Volume replacement wuith IVFT
After stabilising a bleeding patient, what is the next thing to do?
Collect blood samples: Full blood count (EDTA) Coagulation profile Biochem PCV/total protein Blood smear
When examining a bleeding patient, what should you consider?
Signalment
History - when started, any recent trauma, medications
Is bleeding local or systemic
Describe basically how a blood vessel responds to injury
Vessel injury causes vessel contraction
Primary haemostasis - primary plug
Secondary haemostasis - coagulation cascade and fibrin
Tertiary haemostasis - fibrinolysis
Primary haemostasis involves creating a primary plug within seconds/minutes of vessel injury. What substances/factors are involved?
Endothelium collagen
Platelets
Von Willebrand factor
Tertiary haemostasis involves fibrin. What is fibrin?
Insoluble protein
Forms fibrous mesh that impedes blood flow (aids clotting)
What is fibrin formed from?
Fibrinogen
What is fibrinogen?
Glycoprotein circulating in blood
Converted to fibrin during injury
What happens during primary haemostasis?
Formation of primary plug by Von Willebrand factor and platelets
What cells make von Willebrand factor?
Megakaryocytes
What happens during secondary haemostasis?
Coagulation cascade
Extrinsic activated by tissue factor, intrinsic activated by exposure of damaged endothelium
Results in fibrinogen –> Fibrin
What is the third stage of haemostasis?
Fibrinolysis
How does the size of an injury/defect alter haemostasis?
Small defect = primary haemostasis only
Large defect = requires platelets and stabilisation of clot by cross-linked fibrin
What are primary haemostasis disorders?
Disorders caused by platelet disorders or vasculopathies
What are the clinical signs of primary haemostatic disorders?
Ooze from small wounds
Petechia and ecchymoses
Bleeding from mms (epistaxis, melaena)
Signs of underlying disease
What is the most common cause of abnormal bleeding in dogs?
Thrombocytopenia
What are some causes of thrombocytopenia?
Increased platelet destruction - immune mediated (common), primary, or secondary
Increased platelet consumption
Platelet sequestration
NOT caused by platelet loss from haemorrhage
What are some differentials for thrombocytopenia?
Neoplasia DIC (platelet consumption) Infectious disease Immune mediated Breed related - may not be pathological
What is the most common cause of marked thrombocytopenia in dogs?
Immune mediated thrombocytopenia (IMTP)
Immune-mediated thrombocytopenia (IMTP) is common in dogs. Primary IMPT is usually seen in which dogs?
Females
Spaniels
Immune-mediated thrombocytopenia (IMTP) is common in dogs. What can cause secondary IMTP?
Drug reactions - cephalosporins
Neoplasia
Viral disease
Ehrlichia or the vaccine (live virus)
What are patients with IMTP at risk of? How can this be reduced?
Spontaneous haemorrhage
Reduce risk of trauma, reduce activity
What is the treatment of IMTP?
If secondary treat underlying disease
Supportive
Immunosuppressives
What immunosuppressive drugs can be given for IMTP? (Similar to IMHA)
Corticosteroids
Azathioprine
What is von Willebrand disease?
Acquired or inherited deficiency of von Willebrand factor
Von Willebrand disease can be acquired or inherited. What condition can cause it to be acquire?
Severe aortic stenosis
Where is Von Willebrand factor synthesised and stored?
Endothelial cells
Von Willebrand disease can be acquired (severe aortic stenosis) or inherited. Which breed is predisposed to this disease?
Dobermanns
What tests can be used to diagnose Von Willebrand disease?
BMBT (buccal mucosal bleed time)
Antigenic test
vWF function assays
Genetic testing to detect carriers
What is the treatment for von Willebrand disease?
Cryoprecipitate (from frozen blood plasma)
Whole blood or plasma therapy
What are 3 types of Von Willebrand disease? Which is most common?
Type 1 - most common
Type 2
Type 3
Briefly explain the 3 types of Von Willebrand disease
Type I - partial quantitive deficiency
Type 2 - qualitative deficiency
Type 3 - severe quantitative deficiency
What are some symptoms of type I von Willebrand disease?
Bleeding from mucous membranes
Excessive bleeding/haemorrhage during surgery
Von Willebrand disease can be inherited. What type of inheritance is it?
Autosomal recessive
Platelet dysfunctions can be associated with many conditions and drugs. What group of drugs in particular?
NSAIDs
E.g. aspirin
How can platelet function be tested?
Buccal mucosal bleeding time (BMBT)
Clot retraction
Platelet function tests (usually not available, must be carried out within 4hrs)
Disorders of secondary haemostasis are either inherited or acquired. Which is more common?
Acquired
What is haemophilia A?
Genetic disorder
Deficiency of Factor VIII
What is haemophilia B?
Genetic disorder
Deficiency of Factor IX
What causes extrinsic pathway defects?
Hepatic/hepatoiliary diseae
OR early vitamin K antagonism/deficiency
