ORAL SURG - Abnormal Bleeding Flashcards
give instances of which there may be bleeding in a patient.
- extraction
- surgery
- biopsies
- trauma
- perio, probing
- exposure of vital pulp
give effects of blood loss
- patient distress
- blood in the tissues - bruise, infection
- blood in the stomach - vomiting
- blood in airway - obstruction
- hypovolaemic - shock
- reduced O2 carrying capacity
- reduced proteins - oedema, water not kept in blood
- reduced platelet
what must be checked as part of the history?
the bleeding/clotting history
- if there are any previous issues or medications which affect bleeding
- any liver problems
what local measures can be used to stop bleeding?
- applying pressure
- suturing - stitch up
- haemostatic gel
- surgicel - gel wrapped in gauze
- tell patient to wait and then check
what MUST be delivered after a bleeding episode?
post-op care
follow up with the patient
what comes under Virchows Triad?
- coagulation factors
- blood flow
- vessel wall
what happens if blood flow is too slow? when would this happen?
more likely to develop blood clots
- people who dont use leg muscles
- sat too much
- airplanes
- pools in lower leg
= DVT
give 2 abnormalities that may be in a vessel wall
artificial heart valve
atherosclerotic plaque
what happens when a vessel wall ruptures?
- VWF in the vessel wall exposed to collagen in the blood
- platelets bind to VWF
- platelets change shape
- attract more platelets
- aggregation
-platelet plug - other blood proteins join
- fibrin meshwork
= clot
what if there are too many coagulation factors?
likely to form blood clots
what type of medicine is warfarin?
anti-coagulant
how does warfarin work?
stops liver metabolising Vitamin K
thereby liver doesn’t produce coagulation factors 2,7,9,10
- prevents the intrinsic coagulation pathway from activating
what is the purpose of haemostasis?
to prevent blood loss
what are the 4 steps of haemostasis?
- vascular spams
- platelet plug
- blood coagulation
- growth of fibrous tissue in the hole
what happens during a vascular spasm?
smooth muscle contracts
reduce diameter of lumen
reduce speed of blood flow
- helps blood to flow
describe the formation of a platelet plug.
- platelets exposed to collagen
- platelets release Thromboxane A2
- aggregation
what does the release of Thromboxane A2 do?
change shape of platelets and increase the stickiness
.. more and more stick baaaahhh
what factor does the platelet plug activate and what does it do?
FACTOR 10
- activates coagulation cascade
give 2 anti-platelet drugs
aspirin
clopidrogel
how does aspirin and clopidrogel interact with platelets in the same way?
they irreversibly bind
- they’re bound until the full life cycle of the platelet
how long is the life of a regular, non-medicated platelet?
10 days
how long is the life of a platelet when bound to aspirin?
a few weeks
what are the indications for patients who take anti-platelet drugs, aspirin or clopidrogel?
- vascular disease
- IHD
- thromboembolic disease
- stroke
- those likely to have p aggregations within the vascular system
what post-op advice should be given to patients who take aspirin?
- don’t stop taking aspirin
- risk of stopping>risk of continuing
what are the two pathways for the clotting cascade?
intrinsic pathway
extrinsic pathway
describe the intrinsic and extrinsic pathway
the clotting cascade
intrinsic
- internal vessel wall damage
- exposed collagen and platelet activation
- F12, F11, F9, F8
- F10 activates into F10a
extrinsic
- tissue damage
- F7
- F10 activates into F10a
both of them:
- F10a activates prothrombin into thrombin
- thrombin activates fibrinogen into fibrin
what is the main role of most anti-coagulations?
to inhibit the action of F10
what 3 tests are used to test bleeding? describe each
INR - international normalised ratio
- patients prothrombin time:control prothrombin time
- assess’ warfarin anticoagulation
APTT - activated partial thromboplastin time
- assess’ heparin anti-coagulation
Platelet Count
- normal is 200-400x10^9/L
what is the prothrombin time?
the time taken for prothrombin to activate
what platelet count is a problem?
if it is lower than 100 x 10^9
what are the indications for patients who take warfarin?
- atrial fibrillation
- heart valve abnormalities or replacement
- thromboembolic disease
how long does it take for warfarin to work and why?
7 days
because there are already coagulation factors present, it just prevents more being produced
which antibiotic enhances the effect of warfarin?
metronidazole
what clotting factors does warfarin affect?
2,7,9,10
what INR level is safe to perform an extraction?
<4
with unstable INR and a stable INR, when would you want to check the readings prior to extraction?
unstable - 72 hour window
stable - 24 hour window
timing wise, when would it be good to extract a tooth with a patient with abnormal bleeding?
early in the week
early in the day
with a low INR of 2-3, how many teeth can you extract at a given time?
all extractions one side at a time
with a INR of 3-4, how many teeth can you extract at a given time?
consider one quadrant at a time
and consider the inferior dental block
- possibility of hitting the inferior artery
what’s wrong with warfarin?
- difficult to get stable anti-coagulation
- interacts with different drugs
- can be affected by food
- constant monitoring required
4 pros and 2 cons of new anticoagulants.
- single point of action
- predictable
- no need to monitor INR
- doesn’t interact with food
- no antidote
- half life up to 17 hrs
give the name of a 4 new anticoagulants and what factor of the coagulation cascade they work on.
warfarin - affects F7, 9
apixaban - affects F10
rivaroxaban - affects F10
edoxaban - affects F10
dabigatran - affects fibrinogen into fibrin
indications for new anti-coagulants
artial fibrillation
thromboembolic disease
stroke
heart valve replacements
how does surgicel appear?
white gauze soaks up the blood
oxidised cellulose denatures blood and turns it black
what prevents the breakdown of a fibrin clot?
tranexamic acid mouthwash
