What is a clot and why did it happen?
• Blood clots are caused by a natural
process in which blood cells and
fibrin strands clump together to stop
bleeding after a blood vessel has
been injured
• They become dangerous when they
block blood flow through an artery
or vein
• If clots break off from the original
site and travel through the
bloodstream they can become
stuck in another smaller blood
vessel and block the blood supply
there (embolus)
• Warfarin is used to thin the blood,
thereby preventing blood clots
from enlarging and new clots
from forming (thrombi)
• Eventually blood clots dissolve
over time by natural means
Where did it happen?
• Leg: A deep vein thrombosis (DVT)
is a blood clot that develops in a
deep vein, usually in the leg. This
can happen if the vein is damaged
or if the flow of blood slows down
or stops
• Lung: A blood clot usually forms in
a peripheral vein and then travels
back through the heart to a lung
• Heart: A small blood clot from the
left atrium could travel to the
coronary arteries and cause a heart
attack
• Brain: A blood clot from the left
atrium/ventricle could break off and
block one of the arteries to the
brain, causing a stroke
Clots can stick to man-made heart valves
• Blood could get trapped and
clot on man-made heart
valves
• Sometimes warfarin is used
for six months after tissue
valve insertion
• The clots could then break
off and travel to other parts of
the body
¾Recommend patient obtains
a MedicAlert bracelet, give
form and explain procedure
Atrial Fibrillation (AF)
• With AF the heart beats
irregularly causing blood
flow to be slowed and
blood clots more likely to
develop in the atria/heart
• Studies have shown that
patients with AF who do
not take warfarin are at
increased risk of stroke
The heart beating normally
The heart beating irregularly a clot can form
What makes clots more likely to happen?
• Venous blood clots usually form
when blood flow becomes slowed
because of damage to the inside of a
blood vessel.
The following make clots more likely
to form:
• Sitting or lying in one position for long
periods of time (immobility) (e.g. bed
rest, air travel): Lack of exercise
means that the blood does not flow
easily through the veins
• Surgery: especially if lasts more than
30 minutes, or involves the leg joints
or pelvis
• Major injuries, or paralysis
• Cancer and its treatments
• HRT, oral contraceptives, pregnancy
• Being overweight: A substance called
leptin is produced by fat cells, which in
turn affects blood cells, causing them
to stick together
• Several inherited conditions
What is a clot and why did it happen?
• The brand of warfarin called
Marevan® is preferred for use
in New Zealand
• There is also another brand of
warfarin called Coumadin®
• Marevan® and Coumadin® are
not interchangeable
• Always check that you are
taking the right warfarin tablet
by checking the colour and
strength
• If your warfarin ever looks
different to what you have been
having check with your
pharmacist to ensure that you
are receiving the correct brand
and strength
Marevan®
Warfarin
3mg
Warfarin
5mg
Warfarin
1mg
Coumadin®
Warfarin
2mg
Warfarin
1mg
Warfarin
5mg
The right dose = the right INR
¾Talk to your patient about
his/her individual target INR
Target INR according to
indication1:
•
•
•
Too high - may bleed
4.0
INR 2.0-3.0: AF, cardioversion,
mural thrombus, treatment of
DVT or PE
INR 2.5-3.5: Mechanical heart
valves implanted after 1990
INR 3.0-4.0: Mechanical heart
valves implanted before 1990,
recurrent DVT or PE whilst on
warfarin
3.5
3.0
2.5
2.0
Reference
1. Adult Anticoagulation Guidelines, Middlemore Hospital, CMDHB
¾Consult guidelines for target
INR values for patients on
dialysis as they may differ from
above
1.5
Too low - won’t work
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
What is a clot and why did it happen?
• The brand of warfarin called
Marevan® is preferred for use
in New Zealand
• There is also another brand of
warfarin called Coumadin®
• Marevan® and Coumadin® are
not interchangeable
• Always check that you are
taking the right warfarin tablet
by checking the colour and
strength
• If your warfarin ever looks
different to what you have been
having check with your
pharmacist to ensure that you
are receiving the correct brand
and strength
Marevan®
Warfarin
3mg
Warfarin
5mg
Warfarin
1mg
Coumadin®
Warfarin
2mg
Warfarin
1mg
Warfarin
5mg
Blood tests show how many
tablets you need
•
Before leaving the hospital or
doctor’s surgery you will be
given a laboratory form and told
when to go for a blood test
• A house call can be arranged
for you if you are unable to go
to the laboratory
• Phone your doctor in the
afternoon for the blood test
results (INR)
• The doctor will tell you how
many tablets to take depending
on your blood test
• Write your blood test result
(INR) in your warfarin book
¾ Ask the patient if they are able
to work out how many tablets to
take according to their current
dose
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
Call doctor or nurse if any of the
following occurs
¾ Discuss the potential sideeffects with the patient i.e.
bleeding such as nose
bleeds, blood in urine or
stools (black bowel
motions), changes to skin,
gastrointestinal upsets
¾ Discuss with patients that if
they are ill it may alter the
effect of their warfarin
treatment
• Seek medical advice as
soon as possible for any
unusual bruising or
bleeding, severe
unexplained pain, fever,
vomiting, diarrhoea,
infection
•
Any unusual bleeding or
bruising
•
Severe unexplained pain
•
Fever, vomiting,
diarrhoea, infection
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
¾
•
•
•
•
•
Warfarin can harm an unborn
baby Don’t become
Stress the importance of avoiding
pregnancy when taking warfarin:
Warfarin crosses the placenta and can
cause birth defects if taken in the first
three months of pregnancy2;3
Warfarin can cause bleeding in the unborn
baby and can also cause severe bleeding
in the mother when the baby is born
Medical advice must be obtained regarding
effective contraception to prevent
pregnancy when taking warfarin
If the woman suspects she is pregnant
while taking warfarin she must contact her
doctor urgently
If pregnancy is desired by a woman taking
long-term warfarin, she must discuss the
issue with her doctor before becoming
pregnant
–Review of anticoagulant management is
essential, with counselling to allow
informed decision making regarding the
risks associated with available
anticoagulant options
References
2. Therapeutics in Pregnancy and Lactation. Lee A, Inch S, Finnigan D. Therapeutics in Pregnancy and
Lactation. Radcliffe Medical Press;
2000
3. Briggs GG, Freemand RK, Yaffe SJ. Drugs in Pregnancy and Lactation 6th ed. Philadelphia, Md: Lippincott
Williams & Wilkins; 2002
pregnant while
taking warfarin
Talk to your
doctor if you
think you might
be pregnant
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
Warfarin can be used if you are
breastfeeding
• Warfarin is considered
compatible with
breastfeeding, because
of its poor excretion
into milk and
consequent lack of
effects on the infants3
Reference
3. Briggs GG, Freemand RK, Yaffe SJ. Drugs in Pregnancy and Lactation 6th
ed. Philadelphia, Md: Lippincott Williams & Wilkins; 2002
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
Mix your green vegetables with
other coloured vegetables
•
Eat a balanced diet that
includes foods from all food
groups
• Eat moderate amounts of
different coloured vegetables
(refer photos); keep daily
intake of leafy greens
consistent (variations can
cause INR fluctuations)
• Keep fat intake to a minimum
• Avoid dramatic changes in the
diet, unless recommended by a
health care provider
¾ Advise patients on dialysis to
talk to a dietician about diet
(photos do not apply to these
patients)
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
Small amounts of alcohol only
• Alcohol can affect
the blood thinning
effect of warfarin
• Do not exceed two
standard drinks per
day
One standard drink is:
• 300ml ordinary-strength beer
• 60ml fortified wine (sherry,
martini, port)
• 30ml spirits (whisky, gin,
vodka)
• 100ml table wine
¾ Advise patients to
avoid binge drinking
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
Avoid activities where you might
get hurt easily and bleed too much
•
Hazardous occupations or
recreational activities may
result in injury and bleeding
¾ Stress the need for care if
the patient has a job that
may lead to injury
¾ Stress the need to avoid
sports or activities where
injury may result
¾ Advise the patient to make
their home environment as
safe as possible, (e.g. use a
non-slip bath mat, exercise
caution when using sharp
knives)
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
No new tattoos or piercing
¾Advise patients
to avoid having
new tattoos or
body piercing
because of the
increased risk of
bleeding with
warfarin
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
No body massage
¾Advise patients
to avoid having
massage,
particularly deep
tissue massage,
because of the
increased risk of
bleeding with
warfarin
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
Tell your dentist that you are taking
warfarin before your appointment
• Tell your dentist
that you are taking
warfarin before your
appointment
• The possibility of
bleeding from
dental treatment will
need to be taken
into account by the
dentist
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
Tell your doctor that you are taking
warfarin before any surgery or
medical treatment
¾ Stress the need for
the patient to
discuss the fact
that they are taking
warfarin before
undergoing any
surgical or medical
procedure to ensure
that this is taken
into account before,
during and after
treatment
© Warfarin Flipchart Group, 2005
This is a clinical guideline only
Follow these 3 steps:
¾
Revise the key steps
involved in taking
warfarin:
1.
Having a blood test on
an appointed morning
Calling the doctor that
same afternoon for the
INR result
Taking the prescribed
dose of warfarin at the
same time each
evening with a glass of
water, then recording
that the warfarin dose
has been taken, e.g. by
making a cross on a
calendar
2.
3.
1
3
2
© Warfarin Flipchart Group, 2005
This is a clinical guideline only