Haematology 1A- Haemostatic and Haemorrhagic Disorders Flashcards
What are 3 functions of von Willebrand factor
mediates platelet adhesion to damaged epithelium (1°)
mediates platelet aggregation (1°)
stabilises + transport factor VIII (2°)
What is von Willebrand disease
deficiency in vWF
most common inherited bleeding disorder
different types + severity
what are 3 ways to manage von Willebrand disease
- (Mild) Desmopressin -drug (DDAVP) - stimulate release vWF from platelets and from cells lining blood vessels+ factor VIII - Rx
- (Severe) vWF replacement using human plasma - rich in vWF + factor VIII - Rx
- Anti-fibrinolytic drugs - slow/prevent clot breakdown - oral or IV
4 ways in which vWD is related to dentistry
- prolonged oozing post extraction + bleeding in muscles/joint
- haematological cover before invasive procedure in severe cases
- Avoid regional LA (infiltration/ intra-ligamentary safer)
- Avoid aspirin/NSAIDs (acetaminophen/co-codamol safer)
what is 1° haemostasis and what are the components associated with 1° haemostasis
platelet plug formation via vWF
blood vessels
vWF
platelets
what is 2° haemostasis and what are the components associated with 1° haemostasis
coagulation - strengthen clot so doesn’t break
aim to form fibrin meshwork
by 3 paths - extrinsic, intrinsic + common
where are clotting factors manufactured
liver
what are Factor VIII and vWF produced
endothelial cells of blood vessels
which factors are vitamin K dependant
factors II, VII, IX and X
how are clotting factors present in body
in circulation as inactive form
how is extrinsic pathway in haemostasis activated
tissue factor released on injury to blood vessel
how is intrinsic pathway activated
exposure to collagen
what are 3 1° primary haemostatic (bleeding) disorders
vascular disorders
von Willebrand disease (also 2°)
platelet disorder - platelet deficiency + platelet dysfunction
what are 2 2° secondary haemostatic (blood coagulation) disorders
von Willebrand disease (also 1°)
clotting factor disorders
name the 3 haemostatic congenital disorders and say which haemostasis stage they are
von Willebrand disease (1°/2°) haemophilia A (2°) haemophilia B (2°)
name the 4 haemostatic acquired disorders and say which haemostasis stage they are
thrombocytopenia (1°)
platelet dysfunction associated with drugs (1°)
anti-platelet therapy (1°)
anticoagulant therapy (2°)
what are 2 primary haemostasis disorders that are also vascular disorders
Hereditary Haemorrhagic Telangiectasia
(Osler-Weber-Rendu Syndrome)
von Willebrand Disease (vWD)
what type of condition is
Hereditary Haemorrhagic Telangiectasia
(Osler-Weber-Rendu Syndrome)
autosomal dominant hereditary condition
what are the clinical features that can be seen of
Hereditary Haemorrhagic Telangiectasia
(Osler-Weber-Rendu Syndrome)
Telangiectasia (small vascular malformations) + arteriovenous malformations in skin, mucosa + viscera normally not present until adolescent recurrent epistaxis (bleed from nose) super common Fe+ deficiency anaemia can occur -> chronic bleeding of intestinal tract
what are dental aspects can be seen from Hereditary Haemorrhagic Telangiectasia
(Osler-Weber-Rendu Syndrome)
bleeding from oral surgery
regional LA - best avoided - risk of deep tissue bleeding
if GA - avoid nasal intubation
what are 4 clinical features that can be seen from von Willebrand Disease
can be present as 1° or 2° haemostasis or both
- bruising, epistaxis
- prolonged bleed during surgical/dental procedures
- GI bleeding + menorrhagia (long periods) frequent
what type of disorder is Bernard - Soulier disorder
1° haemostasis
hereditary platelet disorder - deficiency
What are the main causes of platelet disorders - deficiency
megakaryocyte suppression bone marrow failure splenomegaly ( sequestration of platelets) hereditary increased destruction of platelets
how does megakaryocyte suppression cause platelet deficiency causing platelet disorder
caused by:
chemotherapeutic agents
viruses - parvovirus infection, mumps, HIV
what can platelet disorders ( deficiency) can bone marrow failure cause
aplastic anaemia
leukaemia
lymphoma
metastases
how does increased platelet destruction cause platelet deficiency causing platelet disorder
autoimmune - Idiopathic thrombocytopenic purpura
drugs - Cytotoxic drugs
diseases - Disseminated intravascular coagulation, SLE (lupus?), Malaria
what are main 2 causes of platelet dysfunction
anti-platelet drugs
vWD
Name the 4 anti-platelet drugs that cause platelet dysfunction
Aspirin
NSAIDs (act on platelet until drug leaves system, 48hrs)
Clopidogrel, prasugrel
Dipyridamole
other drugs act irreversibly + permanent on platelet lifespan (7-10 days)
what are 3 main clinical features of platelet dysfunction disorder
easy bleeding + bruising
petechiae
purpura
ecchymosis
what are dental aspects can be seen from platelet deficiency disorders
Patients suspected thrombocytopenia - Investigate
platelet count (PC) - requesting full blood count (FBC)
prior dental treatment
• Refer to GP/haematologist for further management
• Risk of spontaneous bleeding, PC ˂ 20,000/mm3
what are dental aspects can be seen from platelet dysfunction disorders
minor dental procedures - continue medication
treat with no interrupting antiplatelet medication
no stop medication unless consult with GP
limit initial treatment area
if there is post extraction bleed - use local homeostatic agents for control
what are 2 homeostatic agents used to control post extraction bleeding from platelet dysfunction disorders
compressive packing
sutures, absorbed homeostatic agents (oxidised cellulose)
what are 3 2° haemostatic hereditary disorders
haemophilia A
haemophilia B
vWD
how can 2° haemostatic acquired disorders occur
if patient going through anticoagulant therapy
what are 3 anticoagulant therapies that can cause acquired disorders to occur
warfarin therapy
heparin therapy
novel/non-vitamin K oral anticoagulant (NOAC) therapy
what are 3 ways which 2° haemostatic disorders can occur
hereditary
acquired
disease conditions
what are 3 disease conditions that can cause 2° haemostatic disorders
liver disease (inc obstructive jaundice) disseminated intravascular coagulation malabsorption syndromes
what is haemophilia A caused by
factor VIII deficiency has a
what is haemophilia B caused by
factor IX deficiency
who is affected by haemophilia
x linked disorders only males
females carrier
what clinical features can be seen from mild haemophilia patients
minimal bleeding usually associated with surgery
what clinical features can be seen from moderate haemophilia patients
bleed after minor injury + requires urgent attention
what clinical features can be seen from severe haemophilia patients
bleed very often with or without provocation
what clinical features can be seen from haemophilia a+b patients
haemorrhage appears stop immediately after injury but intractable oozing follows
-> bleeding in deep tissues (joints, muscles)
what are 2 main ways to manage haemophilia
diagnosis
treatment
what are 3 main ways of diagnosing haemophilia
positive fam history
clinical presentation
investigation - clotting factor assyas
what are 3 main ways of treating haemophilia
- increase production of factor VIII -> desmopressin
- replacement therapy for specific clotting factor
- inhibit fibrinolysis by antifibrinolytic agents
what 2 places is replacement therapy for specific clotting factor taken from for treating haemophilia
clotting factor concentrate from plasma
commercial produced recombinant factor
what are 2 antifibrinolytic agents used to inhibit fibrinolysis to treat haemophilia
tranexamic acid
EACA ( epsilon amino caproic adic)
what are 6 dental aspects to be considered for haemophilic patients
- preventative dentistry - minimise surgical intervention -> serious bleed
- close co-op with their haematologist
- sig risk of haemorrhage after surgery or LA
- ensure adequate clotting factors (VIII/IX) levels
- post operative -> look signs haematoma forming (swelling)
- trauma to head + neck -> prophylactic factor VIII replacing is essential
if patient has thrombosis , then they will be on anticoagulant therapy. What are 8 common indications of it
- atrial fibrillation
- cardiac valvular disease
- mech prosthetic heart valves
- ischaemic heart disease (recent myocardial infarction)
- deep venous thrombosis
- pulmonary embolism
- renal dialysis
- transient ischaemic attacks or strokes
what are examples of anticoagulant medication
warfarin
heparin
NOACs ( non vitamin K oral anticoags)
what does warfarin do and how is it used
inhibits vit K dependant clotting factors II, VII, IX, X
oral
it has narrow therapeutic range - frequent monitor + dose adjustment
sensitive to other drugs
INR/prothrombin time
what are dental aspects to consider for patients taking warafrin
preventative dentistry - minimal surg intervene
measure INR within 24hrs of surgery
what are 4 drugs that warfarin can interact with + should avoid prescribing
metronidazole
macrolides
azole antifungals
aspirin/NSAIDs
what are 2 ways to minimise risk of warfarin interacting with other drugs
avoid concurrent use of 2 medications
alternative drugs
what does heparin do
anti coagulant drug inhibits clotting factors II, X short lived effect 2 types: standard + low mole weight monitored by APTT
when is IV heparin given + when is LMWH (under skin) heparin given
IV - immediate manage of acute thromboembolic events
LMWH - non-hospital ambulatory patients
what are 4 types of NOACs
Dabigatran - inhibit factor IIa helps convesion of thrombin-> active thrombin (strengthen clot) apixaban - inhibit factor Xa edoxaban - inhibit factor Xa rivaroxaban - inhibit factor Xa
What are advs of NOACS
more predicatble lvls of anticoags
no routine montoring
wide TR + easer to manage
effective + safer
what are indications of giving NOACs
stroke prevention in AF (atrial fibrillation) patients
Thromboembolic disease
what is time of action of NOACS
rapid onset action, 2-4hrs
relatively short half lives (5-13hrs)
key homeostatic investigations that help diagnose + treat haemostatic disorder
• Full blood count- platelet count
• Bleeding time- platelet defects
• Prothrombin time (PT)/ international normalised ratio
(INR)- extrinsic pathway and warfarin therapy
PT- (10-12 secs)
INR- universal test (Patient’s PT/Control PT) (0.9-1.2)
INR therapeutic range for patients on warfarin (2-3)
• Activated partial thromboplastin time (aPTT)- Intrinsic
pathway (30-40secs) and heparin therapy
aPTT therapeutic range for patients on heparin (1.5-2.5)
what to remember in patients with bleeding disorders
Obtains a comprehensive medical history
Perform a thorough clinical examination
Request appropriate special investigations
Consult with haematologist and/or physician
Refer where necessary to hospital for dental care
