Anti platelet drugs and anticoagulants are prescribed
more than in the past
·
Increased
prevalence of ischaemic heart disease, strokes and thrombophilia
·
More aging
population due to increased life expectancy
Anti Platelet Medication is indicated for
·
Ischaemia
heart disease
·
Peripheral
vascular disease
·
Strokes
due to thromboembolic disease
How do anti platelet drugs affect clotting ?
·
Platelets
provide the initial haemostatic plug at the site of a vascular injury.
·
They are
also involved in pathological processes and are an important contributor to arterial
thrombosis leading to myocardial infarction and ischaemic stroke.
Antiplatelet medications include
Low dose aspirin
(75mg-300mg daily).
·
Secondary
prevention of thrombotic cardiovascular
·
or
cerebrovascular disease
·
and
following coronary artery bypass
Clopidogrel
·
Prevention
of atherothrombotic events in patients suffering myocardial infarction
·
Ischaemic
stroke or peripheral arterial disease
·
unstable
angina or non-Q-wave myocardial infarction in acute coronary syndrome
Dipyridamole
(Persantin, Persantin Retard).
·
Used as an
adjunct to oral anticoagulation for the prophylaxis of thromboembolism
associated with prosthetic heart valves,
·
For
secondary prevention of ischaemic stroke and transient ischaemic attacks.
Asasantin Retard
·
Contains
both aspirin and dipyridamole and is used for the secondary prevention of
stroke and transient ischaemic attacks.
All
antiplatelet medications affect clotting by inhibiting platelet aggregation
Aspirin and
clopidogrel irreversibly inhibit platelet aggregation within one hour of
ingestion and this lasts for the life of the platelets (7-10 days). The effect
is only overcome by the manufacture of new platelets.
The action of
dipyridamole is reversible.
Non-steroidal
anti-inflammatory drugs (NSAIDs) other than aspirin (e.g. ibuprofen,
diclofenac) have a reversible effect on platelet aggregation and platelet
function is restored once the drug is cleared from the circulation.
What are the thromboembolic risks associated with
stopping antiplatelet medications in the perioperative period?
Stopping aspirin prior
to surgical procedures may increase the risk of thromboembolic events by
0.005%.
What
are the risks of bleeding associated with continuing antiplatelet
medications in the perioperative period?
Patients taking
antiplatelet medications will have a prolonged bleeding time but this may not
be clinically relevant.
Postoperative bleeding
after dental procedures can be controlled using local haemostatic measures.
Clinically significant postoperative bleeding
·
Continues
beyond 12 hours
·
Causes the
patient to call or return to the dental practice or accident and emergency
department
·
Results in
the development of a large haematoma or ecchymosis within the oral soft tissues
·
Requires a
blood transfusion
·
Patients
with underlying hepatic, renal or bone marrow disorders often have disease
related Bleeding disorders.
·
Bleeding
risk also increases with age and with heavy alcohol consumption.
How do the risks of thromboembolic events and
postoperative bleeding balance?
·
Bleeding
complications, while inconvenient, do not carry the same risks as
thromboembolic complications.Patients are more at risk of permanent disability
or death if they stop antiplatelet medications prior to a surgical procedure
than if they continue it.
·
Published
reviews of the available literature advise that aspirin should not be stopped
prior to dental surgical procedures.
·
Thromboembolic
events, including fatalities, have been reported after antiplatelet withdrawal.
·
Although
the risk is low, the outcome is serious. This must be balanced against the fact
that there is no single report of uncontrollable bleeding when dental
procedures have been carried out without stopping antiplatelet medications
·
Antiplatelet
medications should only be discontinued in the perioperative period when the
haemorrhagic risk of continuing them is definitely greater than the
cardiovascular risk associated with their discontinuation.
·
Consensus
is that for minor surgical procedures, including procedures, antiplatelet
medications should not be stopped or doses altered but that local haemostatic
measures are used to control bleeding.
Which patients taking antiplatelet medication should
not undergo surgical procedures in primary care?
·
Liver
impairment and/or alcoholism renal failure
·
Thrombocytopenia,
haemophilia or other disorder of haemostasis
·
Those
currently receiving a course of cytotoxic medication.
·
Patients
requiring major surgery are unlikely to be treated in the primary care setting.
For what procedures can antiplatelet medications be
safely continued?
·
Minor
surgical procedures can be safely carried out without altering the antiplatelet
medication dose. Those likely to be carried out in primary care will be
·
Simple
extraction of up to three teeth, gingival surgery, crown and bridge procedures,
dental scaling and the surgical removal of teeth.
·
When more
than 3 teeth need to be extracted then multiple visits will be required. The
extractions may be planned to remove 2-3 teeth at a time, by quadrants, or
singly at separate visits.
·
Scaling
and gingival surgery should initially be restricted to a limited area to assess
if bleeding is problematic.
Patients on Warfarin
INR range
·
Prophylaxis
of deep vein thrombosis 2-3
·
Prophylaxis
of pulmonary embolism 2-3
·
Atrial
fibrillation 2-3
·
Recurrence
of embolism (not on warfarin) 2-3
·
Recurrence
of embolism (on warfarin) 3-4
·
Mechanical
prosthetic heart valves 3-4
·
Antiphospholipid
antibody syndrome 3-4
*** In theory all
patients on Warfarin should have INR <4
Are
patients at risk of thromboembolic effects if Warfarin discontineud
Stopping Warfarin for
two days increases thrombolic effects
Stopping Warfarin
can lead to a rebound hypercoagulable state ?
Are
patients at risk of bleeding if Warfarin continues? Yes
Treatment with
Warfarin impairs clotting and the patients have increased risk of bleeding
during surgical procedures and post operatively.
Bleeding in mouth can
be excessive even in non anticoagulated patients as the tooth support
structures are highly vascular and due to the fibrinolytic effect of saliva.
Most cases of bleeding
can be managed by pressure or repacking and resuturing the socket
The incidence of post
operative bleeding not controlled by local measures varies from 0-3.5%
How do the thromboembolic effects and bleeding risk
balance?
Bleeding
complications, while inconvenient, do not carry the same risk as
thrombo-embolic complications.
Patients whose INR are
within the therapeutic range are more at risk of permanent disability or death
if they have Warfarin stopped prior to surgical procedure than continuing it.
Which patients taking Warfarin should not undergo
surgery in primary care
Patients who have INR
over 4 should not undergo surgery without consulting the haematologist. Their
Warfarin dose needs to be adjusted before surgery.
Patients who are
maintained with an INR over 4 needs to be referred to a dental hospital for
surgery.
When should the INR be measured before a dental procedure?
INR must be measured
prior to dental procedures, ideally this should be done 24 hours before the
procedure.
For patients who have
stable INR values, the INR should be measured at least 72 hours before the
procedure.
Up to what INR value can dental procedures be carried
out?
Minor surgical
procedures can be safely carried out in patients with INR <4
Minor procedures can
be carried out without altering the Warfarin therapy if the INR is within
therapeutic range.
How should the risk of bleeding due to either
antiplatelet or anticoagulants be managed?
Think about the timing
of the surgery. Planned surgery should ideally be:
At the beginning of
the day - this allows more time to deal with immediate re-bleeding problems.
Early in the week -
this allows for delayed re-bleeding episodes occurring after 24–48 hours to be
dealt with during the working week.
Local anaesthetic
A local anaesthetic
containing a vasoconstrictor should be administered by infiltration or by
intraligamentary injection wherever practical.
Regional nerve blocks
should be avoided when possible. However, if there is no alternative, local
anaesthetic should be administered cautiously using an aspirating syringe.
Local vasoconstriction
may be encouraged by infiltrating a small amount of local anaesthetic
containing adrenaline (epinephrine) close to the site of surgery.
Local haemostasis
Sockets should be
gently packed with an absorbable haemostatic dressing e.g.
oxidised cellulose,
collagen sponge, resorbable gelatin, sponge
Then carefully
sutured. Resorbable sutures.
If non-resorbable
sutures are used, remove after 4-7 days.
Following closure,
pressure should be applied to the socket(s) by using a gauze pad that the
patient bites down on for 15 to 30 minutes.
Efforts should be made
to make the procedure as atraumatic as possible and any bleeding should be
managed using local measures.
Tranexemic mouth
washes are useful.
Patients
should be given clear instructions on the management of the clot in the
postoperative period and advised
To look after the
initial clot by resting while the local anaesthetic wears off and the clot
fully forms (2-3 hours)
To avoid rinsing the
mouth for 24 hours
Not to suck hard or
disturb the socket with the tongue or any foreign object
To avoid hot liquids
and hard foods for the rest of the day
To avoid chewing on
the affected side until it is clear that a stable clot has formed.
Care should then be
taken to avoid dislodging the clot if bleeding continues or restarts, to apply
pressure over the socket using a folded clean handkerchief or gauze pad. Place
the pad over the socket and bite down firmly for 20 minutes. If bleeding does
not stop, the dentist should be contacted; repacking and re suturing of the
socket may be required
whom to contact if
they have excessive or prolonged postoperative bleeding.
How should postoperative pain control be managed?
Generally paracetamol
is considered a safe over the counter analgesic for patients taking
antiplatelet medications and it may be taken in normal doses if pain control is
needed and no contraindication exists.
Patients should be
advised to not to take Aspirin at analgesic doses and non-steroidal
anti-inflammatory drugs (NSAIDs) e.g. ibuprofen are considered less safe and
should be avoided if possible
Are
there any drug interactions that are relevant to patients on antiplatelet drugs
undergoing dental surgical procedures
NSAIDs in combination
with aspirin or clopidogrel should be used with caution. NSAIDs can damage the
lining of the gastro-intestinal tract leading to bleeding that may be worsened
by aspirin or clopidogrel.
There is no evidence
of an interaction between dipyridamole and NSAIDs.
The concomitant use of
dipyridamole plus aspirin does not increase the risk of bleeding.
Drug
interactions with Warfarin
Amoxycillin: Increases
INR and may cause bleeding
Metranidazole:
Caution! Interacts with Warfarin and should be avoided. If unavoidable, use
1/3-1/2 dose of Warfarin.
Erythromycin:
unpredictable interaction
Aspirin & NSAID:
Avoid! There is increased risk of gastro intestinal haemorrhage
Summary
Antiplatelet and
anticoagulant therapy does not need to be stopped before minor dental surgical
procedures
Discontinuing
antiplatelet /anticoagulation therapy for surgery was associated with an
increased risk of thromboembolism
Good local
haemostasis & better planning will decrease the excessive bleeding and
minimize complications
