Blood Coagulation and Bleeding Disorders Flashcards
% make up of blood (plasma, WBC/ platelts, RBCs)
plasma: 55%
RBCs: 45%
WBC and platelets:
stages when there is damage to blood vessel wall (see diagrams) 7
- collagen and tissue factor TF exposed
- von willebrand factor VWF binds collagen
- platelets adhere to VWF-collagen
- platelets are activated (PRIMARY HAEMOSTASIS, PLATELET PLUG)
- TF and platelets activate clotting factors to make thrombin (CLOTTING CASCADE)
- thrombin converts fibrinogen to fibrin clot
- stable fibrin-platelet clot is formed
consequences of failure of haemostasis
inc bleeding
2 things that increase bleeding in mouth
- oral mucosa highly vascular
- saliva contains fibrinolytic substances and rich in bacteria
2 categories of things that can go wrong with haemostasis
- abnormal primary haemostasis (less platelet number/ function or less VWF)
- abnormal coagulation pathway (reduced clotting factors)
- identify causes of pictures*
a. what are petechiae
b. what is epistaxis
c. what is menorrhagia
a. small bruises
b. nose bleeds
c. abnormally heavy periods
p= primary haemostasis disorders c= coagulation factor disorders write p, c or both for these symptoms: a. bleeds in to joints b. soft tissue joints c. petechiae/ bruising d. epistaxis e. gum bleeding f. menorrhagia g. GI/ CNS
a. bleeds in to joints: c
b. soft tissue joints: c
c. petechiae/ bruising: p
d. epistaxis: p
e. gum bleeding:p
f. menorrhagia: p
g. GI/ CNS: c+p
3 parts of clinical evaluation to identify patients with abnormal haemostasis
- bleeding history after previous dental tx/ surgery/ minor trauma
- general medical history
- drug history (anticoagulants)
2 lab tests used to identify patients with abnormal haemostasis
- full blood count (counts platelets BUT not function- could miss some abnormalities)
- clotting screen (proothrombin time PT and aPTT)
does abnormality inc or dec PT and aPTT
increase
what is INR ratio of
patient PT to normal PT
name 2 heritable disorders
- von willebrand disease
- haemophilia A (factor VIII deficiency)
name 4 acquired disorders
- reduced platelet number (eg AITP, leukaemia)
- liver disease
- kidney disease
- anti-coagulant/ antiplatelet drugs
inheritance ofVWs disease
autosomal –> 1/100, M=F
treatment of VWs disease 3
-desmopressin (DDAVP)- releases endogenous fVIII/ VWF. sc or in
-tranexamic acid- reduces clot breakdown. po or mouthwash
exceptional circumstances: VWF transfusion
usual cause and explain immune thrombocytopenia
idiopathic or 2’ eg infection
autoantibodies attack platelets –> reduced platelet number –> abnormal primary haemostasis
common symptom of immune thrombocytopenia
skin purpura on lower limbs
what causes a purpura
capillary-level bleed in to skin
2 categories of treatment of immune thrombocytopenia and examples
- long term disease control (immunosuppression with steroids/ iv immunoglobulin, splenectomy)
- treatment of bleeding: tranexamic acid, platelet transfuion (emergencies only, will just be destroyed by autoantibodies)
how does immunoglobulin work to treat immune thrombocytopenia
coats reticuloendothelial cells in spleen –> prevents binding and destruction of platelets
effects of liver disease in blood coagulation
EVERYTHING:
- reduced production of all coagulation factors
- low platelet count
- abnormal primary haemostasis
- abnormal coagulation pathway
treatment of bleeding in liver disease 3
-tranexamic acid
-vit K
fresh frozen plasma for emergency tx of bleeding
2 types of drugs that affect haemostasis and how they work and diseases they’re used with
PLATELETS-ARTERIES, COAG-VEINS
- anti-platelets: inhibit arterial thrombosis (IHD, PVD, CD)
- anti-coagulants: inhibit coagulation pathway/ venous thrombosis (DVT, PE, CVA in AF, CVA from mechanical heart valves, CPB
name antiplatelet types 2/ examples
- permanently inhibit platelet activation: aspirin/ clopidogrel
- unintentional platelet effects: NSAIDS, SSRIs, statins etc
