Prolonged bleeding Flashcards
What are the two classification of bleeding problems
Congenital causes and acquired causes
What congenital causes would cause bleeding problems
haemophiliacs and hereditary coagulation problems
what acquired causes lead to bleeding problems
Antiplatelet medication
What is the purpose of haemostasis
to prevent blood loss
When does the process of haemostasis start
As soon as a vessel is ruptured, damaged or severed
Describe the mechanism for haemostasis
vascular spasm
leads to platelet activation
leads to platelet aggregation and formation of plug as well as blood coagulation through the intrinsic and extrinsic cascade
this leads to production of fibrin plug
The fibrin plug is then surrounded by many fibroblast cells, monocytes, WBCs which turn the blood clot into fibrous scar -permanent scar to seal the
describe the intrinsic pathway
Exposed collagen leads to platelet activation
factor XII activates XI which activated Ix which activated VIII which converts X into Xa
Xa coverts prothrombin to thrombin
thrombin converts fibrinogen to fibrin
describe the extrinsic pathway
Tissue damage leads to activation of factor VII
this converts X to Xa
Xa coverts prothrombin to thrombin
thrombin converts fibrinogen to fibrin
What factors does warfarin act on
IX, VII, X and prothrombin to thrombin
what is warfarin and how does it work
warfarin is an anticoagulant medcation
it works by interfering with vitamin K production
Vitamin K is responsible for factors ii, Vii, iX and X
so warfarin reduces the production of factors ii, Vii, iX and X
so warfarin acts on both intrinsic and extrinsic pathway
how do new oral anticoagulants differ from warfarin
These act on specific points in the pathway by mostly preventing activation of factor X to factor Xa
give three examples of new anticoagulants that work by preventing the activation of factor x to factor Xa
Apixaban
Rivaroxaban
edoxaban
How does the new anti coagulant dabigatran work
acts specifically on the conversion of prothrombin to thrombin
why are the new anti-coagulants beneficial
they target specific points in the pathway so the effects are less variable and we have reliable predictable action and also quick onset
what are the disadvantages of warfarin
takes a long time to start acting and long time to wear off
can be affected by drug interations
can be affected by some foods we eat
what is the purpose of the endothelial layer of the vessel
it prevents the activation of platelet so prevents clotting factors
how does clotting start
vessel wall is broken
collagen fibres are exposed
endothelial walls disappear
this will activate the platelets via the intrinsic and extrinsic mechanism
why is it important to have a pathway that breaksdown clots alongside the pathway that forms a clot
all haemostatic mechanisms need to be balanced so if the body is creating a blood clot we need a pathway to stop clotting from going uncontrolled and getting bigger and travelling around the body causing damage
describe the cloth breakdown pathway
as the clot forms we have prothrombin converting to thrombin
thrombin catalyses plasminogen to plasmin
plasmin breakdown fibrous clots
if a patient attends for an extraction but is on warfarin do we tel the patient to stop their warfarin
No, there is evidence that if you stop warfarin there is a greater risk of causing more harm than good
what dos sdcep guidance say about warfarin and extractions
Do not stop warfarin for extractions
how would we manage the patient who is on warfarin and is scheduled for an extraction
Check INR in his book
if it is stable then check within 72 hours of the extraction
if INR is unstable you check within 24 hours of the extraction
what is abnormal bleeding usually caused by
iatrogenic i.e. caused by medication
what medication causes abnormal bleeding
anti-platelet or anti-coagulant drugs
give 4 examples of anti platelet drugs
aspirin
dipyridamole
clopidogrel
ticlopidine
give 4 examples of anti coagulant drugs
warfarin
dabigatran
apixaban
rivaroxaban
what is the common suffix of anticoagulant s
an
how does aspirin work
aspirin irreversibly inhibits COX1 which is an enzyme that signal platelet aggregation
Cox is required for thromboxane aggregation which is involved in the inflammatory pathway but it is also involved in the platelet pathway
How does clopidogrel work
this binds irreversibly to P2Y12 receptor
why does aspirin and clopidrogel take longer for it’s effect to wear off
irreversibly binds to platelet so we need to wait for all the platelets that aspirin has binded to to die for the effect to wear off
how long do platelet take to renew
10 days
Why is ibuprofen a better pain killer
binds reversibly so the effects wont last for long as they would with aspirin
which patients are likely to be taking aspirin or clopidogrel
vascular disease - Ischaemic heart disease
thromboembolic disease e.g. DVT
stroke
peripheral vascular disease
patients who are likely to form platelet aggregation within vascular system
what are the three causes for thrombocytopenia:
hereditary
caused by illness
caused by a medical procedure
what is the normal platelet count
150,000-450,000 per microlitre
what can reduce the number of platelets in the blood
medication (anti convulsants and sulfa-antibiotics)
some anaemia
leukaemia
pregnancy
hereditary
What is the disease called in which low platelet count is hereditary
Idiopathic thrombocytopaenic purpura (ITP)
what are the symptoms of patients with idiopathic thrombocytopaenic purpua
bruise easily as not enough platelets to stop small haemorrhages
what is the safe platelet count for an extraction
80,000 some haematologist allow 50,000
What can haematologist do for patient who has come for extraction but their platelet count is low
platelet transfusion or steroid for ITP
warfarin is prescribed for which types of diseases
atrial fibrillation
pulmonary embolism
DVT
prosthetic heart valves
how does warfarin act
blocks one of the enzymes that uses vitamin K to produce clotting factors
this disrupts the clotting process and takes longer for blood to clot
what is the equation for INR
Prothrombin time of patient / mean prothrombin of a group of healthy people
Patients who are on anticoagulants should carry a yellow book, what is in this book
reason for anticoagulation
target INR
contact details of coagulation clinic
dose of warfarin taken
record of recent INR’s
What is INR for healthy individual with no warfarin
1.0
What is the therapeutic warfarin range for INR
2.0 - 4.0
what is the half-life of warfarin and how would that effect changes in warfarin dose to iNR readings
half life is 48 hours so it would take roughly 2 days for change in dose of warfarin to affect INR
what is a risk for taking warfarin
more likely to bleed
what is the benefit of talking warfarin
less likely to clot
what do we do when managing a patient who is on warfarin but needs dental procedure
we do not stop warfarin
we manage to INR instead
we can liase with clinic to adjust INR so if we want INR less than 4 we can ask them to do this for the day of extraction
why is it important to have a patient who is taking warfarin to have INR in the therapeutic range for an extraction
there is no significant risk of prolonged bleeding
what are the drug interaction between anti-fungal steroids and warfarin
antifungal agents can affect INR reading if taken with warfarin it can cause spontaneous haemorrhage, rash on palate
what drugs increase INR
Micanazole
fluconozole
metrondidazole
erythromycin
what drugs decrease INR
carbamazepine
what is the risk associated with increased INR
increased risk of bleeding
what is the risk associated with decreased INR
increased risk of thrombosis
what food and drinks can influence warfarin metabolism
green tea which is rich in vitamin K may decrease INR
any variations in dietary intake of vitamin K - liver, broccoli, brussels sprouts, green leafy vegetables
How do you manage patients with prolonged bleeding in dental surgery
- surgicel and suture
- tranexamic acid - used in hospitals - less in primary dental care - prevents blood clot breaking down
if patient is still bleeding after surgicel and suture how can we manage this
Get the pt to rinse with tranexamic acid or soaking a gauze in this acid is a good way of getting the blood clot to better establish
What post op advice is given following SDCEP guidance
- Take care with drug prescriptions i.e. for pain
- Avoid drugs that prolong bleeding directly like:
- NSAIDs
- COX-2 inhibitors
- Take care with drugs that might interact adversely with warfarin e.g. antibiotics such as
- Erythromycin
- Metronidazole
what is the cause for haemophiliacs and clotting disorders
inherited deficiency of clotting factors VII, X etc
how would you manage a patient who is haemophiliac or has clotting disorders
check with patient’s haematologist for instructions
which types of patients is antiplatelet drugs prescribed to
risk of or following a stroke
risk of or following MI
angina
what is the primary anti-platelet drug
aspirin
how does aspirin affect bleeding time
it increases it
what is the minimum age to prescribe aspirin
16 - cannot prescribe to a child
what is the risk of taking anti-platelet drug
risk of increased bleeding
what is the benefit of anti-platelet drug
reducing clot formation
what is the guidance for anti-platelet drug and dental surgical procedures
does not need to be stopped
