Thromboembolism Flashcards
What is deep vein thrombosis? DVT
A blood clot occurs in a deep vein, usually in calf of one leg
What is pulmonary embolism? PE
The detachment of a blood clot which travels to the lungs and blocks the pulmonary artery
For all patients admitted to hospital what two risks must we compare?
Their risk of developing a VTE versus their risk of bleeding
What are some factors that increase the risk of VTE?
- immobility
- obesity, BMI >30
- malignant disease
- 60+ years
- personal history of VTE
- thrombophilic disorders (means have disorder which means have increased tendency of developing blood clots)
- a first degree relative of theirs has VTE
- HRT/ combined contraceptive (due to their effect on the body’s clotting factors and blood flow
- pregnancy
- varicose veins with phlebitis (enlarged veins that have become inflamed and painful.
- pregnancy
- critical care
- significant co- morbidities
What is VTE?
Venous thromboembolism is a broader term that encompasses two related conditions: deep vein thrombosis (DVT) and pulmonary embolism (PE).
What factors increase the RISK OF BLEEDING in a patient?
- thrombocytopenia (low platelet)
- acute stroke
- bleeding disorders
- Acquired: liver failure
- Inherited: haemophilia, von willebrands disease
- anticoagulants
- systolic hypertension
What is haemophilia
Hemophilia is a rare genetic bleeding disorder characterized by a deficiency or dysfunction of specific clotting proteins called clotting factors
What is von willebrands disease?
von Willebrand disease (vWD) is a genetic bleeding disorder characterized by a deficiency or dysfunction of von Willebrand factor (vWF), a protein that plays a crucial role in blood clotting.
What is an example of mechanical VTE prophylaxis?
compression stockings
exert pressure on the leg vein
Improving Blood Flow: Compression stockings are specially designed to pr
When do we use mechanical VTE prophylaxis
For pts scheduled for surgery
Compressions stockings are continued for these pts until they are sufficently mobile
When do we provide pharmacological VTE prophylaxis to patients?
For HIGH RISK VTE patients undergoing general/ orthopaedic surgery OR admitted to hospital as general medication patients
If contraindicated offer mechanical prophylaxis
(orthopaedic= bones, joints, ligaments, tendons and muscles)
What are parenteral anticoagulants we can give as pharmacological VTE prophylaxis?
Low molecular weight heparin
or
unfractionated heparin in renal failure
or
fondaparinux
When do we give NOACs?
prophylaxis after knee/ hip replacement surgery
edoxaban: treatment and prevention of recurrent VTE
What is the duration of VTE prophylaxis for GENERAL SURGERY?
5-7 days or until sufficient mobility
What is the duration of VTE prophylaxis for MAJOR CANCER SURGERY in ABDOMEN or PELVIS?
28 days
What is the duration of VTE prophylaxis for KNEE/ HIP surgery?
extended duration
How do we treat VTE?
LMHW
(or unfractionated heparin in renal failure- but make sure to monitor *APTT if unfractionated heparin given)
For at least 5 days
AND
until INR at 2 or more for at least 24 hours
AND AT THE SAME TIME start an oral anticoagulant, usually warfarin
*Activated Partial Thromboplastin Time (aPTT) monitoring is a laboratory test used to assess the clotting ability of a patient’s blood
How do we treat VTE in pregnancy?
LMHW is the preferred choice
as lower risk of osteoporosis and heparin- induced thrombocytopenia
Stop at labour- onset. Seek specialist advice on continuing after birth
What does unfractionated heparin activate?
antithrombin
What does low molecular weight heparin INACTIVE?
factor Xa
What is unfractionated heparin?
standard heparin
SHORTER duration of action
Preferred choice if:
- high risk of bleeding
- renal impairment
Monitor: APTT
What are examples of low molecular weight heparin
TINZEPARIN
ENOXAPARIN
DALTEPARIN
What is low molecular weight heparin?
Longer duration of action
Generally preferred choice as HAS LOWER RISK OF:
- osteoporosis
- heparin induced thrombocytopenia
USED IN PREGNANCY!
What are the side effects of heparin?
Haemorrhage
Hyperkalaemia: as heparin inhibits aldosterone secretion which means, potassium cant be excreted and is built up
Osteoporosis
Heparin- induced thrombocytopoenia
What to do if a patient on heparin develops the side effect: HAEMORRHAGE?
withdraw heparin
if rapid reversal required= antidote protamine
how to prevent pt on heparin developing HYPERKALAEMIA
KNOW that this risk is higher in diabetes mellitus and chronic kidney disease
monitor POTASSIUM levels before treatment AND if treatment lasts >7 days
When does heparin- induced thrombocytopenia occur and what are the clinical signs? And how do we monitor
occurs 5-10 days after treatment
CLINICAL SIGNS:
- 30% reduction in platelets
- skin allergy
-thrombosis
MONITORING:
before treatment and if > 4 days use
What are examples of other parenteral anticoagulants?
heparinoid
argatroban
hirudin
heparin flushes
epoprostenol
fondaparinux
What is warfarin?
an ORAL anticoagulant
a HIGH risk drug
It antagonises actions of vitamin K in blood clotting
Takes 48 to 72 hours to work
strengths: 0.5, 1mg, 3mg, 5mg
Warfarin acts as a vitamin K antagonist. It inhibits an enzyme called vitamin K epoxide reductase (VKOR), which is responsible for recycling and regenerating active vitamin K in the body. By inhibiting VKOR, warfarin reduces the availability of active vitamin K. With reduced active vitamin K available, the liver is less able to produce functional clotting factor
What is the dose of warfarin?
5mg initially and monitor every 1-2 days
maintenance dose: 3-9mg at same time each day
how is warfarin monitored?
INR every 3 months once stable
how long does duration of treatment last for: ISOLATED CALF DVT?
6 weeks
Isolated calf deep vein thrombosis (DVT) refers to the development of a blood clot (thrombus) within the deep veins of the calf muscle, without involvement of the more proximal veins in the thigh or pelvis
how long does duration of treatment last for: PROVOKED VTE (COCs, pregnancy, leg plaster cast)
COCs - combined oral contraceptives
3 months
Provoked venous thromboembolism (VTE) refers to the development of a blood clot (thrombus) in the deep veins of the body in response to a specific triggering event or provoking factor.
how long does duration of treatment last for: UNRPOVOKED VTE (e.g. atrial fibrillation)
at least 3 months/ long- term
what is target INR in VTE (within 0.5 units)?
2.5
AF, MI, cardioversion, bioprosthetic, mitral valve
what is target INR in recurrent VTE (within 0.5 units)?
3.5
for recurrent VTE in patients receiving anticoagulant and INR>2
How do you counsel patients on warfarin?
yellow treatment booklet: explains treatment. also a section for you to write down and keep a record of your warfarin dose.
anticoagulant alert card: patient safety card (also known as an alert card) which provides appropriate details of their treatment.
Tell patient to STOP and SEEK immediate medical attention if any sign of bleeding e.g. nose bleeds or blood in urine. Also pts told to report painful skin rash (calciphylaxis)
What are some interactions of wafarin?
DIRECT ACTING antivirals to treat chronic hepaptitis
- Risk of interaction with vitamin k antagonists and can cause changes in INR. Affects efficacy of warfarin. CLOSELY monitor INR
OVER THE COUNTER ORAL MICONAZOLE GEL
- closely monitor patient if miconazole is prescribe. Miconazole is a POTENT ENZYME INHIBITOR. It increases anticoagulant effect of warfarin. Increases the INR- increased risk of bleeding
what are some side effects of warfarin?
BLEEDING e.g. nose bleeds <10 minutes, bleeding gums, bruising. The ANTIDOTE is VITAMIN K
CALCIPHYLAXIS (risk factor for this side effect is end- stage renal disease)
Patients should be counselled to report painful skin rash. Consider stopping warfarin if calciphylaxis diagnosed
What to do when patient on warfarin has MAJOR bleeding?
STOP warfarin
IV Vitamin K
Dried prothrombin complex or fresh frozen plasma
What to do if pt is on wafarin and has INR 5-8 AND NO BLEEDING
withold 1-2 dose
reduce maintenance dose
measure INR after 2-3 days
what to do if pt INR is 5-8 AND MINOR BLEEDING
omit warfarin
give IV vitamin K
repeat if INR still high after 24 hours
restart warfarin when INR <5.0
what to do if pt INR is <8.0 and NO BLEEDING
omit warfarin
oral vitamin K
repeat i INR is still high after 24 hours
restart warfarin when INR< 5
what to do if pt INR is >8 and minor bleeding
omit warfarin
IV vitamin K
repeat if INR still high after 24 hours
Restart warfarin when INR <5.0
What to do with pt who takes warfarin BEFORE they have elective surgery?
make sure their warfarin is stopped 5 days before elective surgery
give oral vitamin K for one day if INR >1.5
restart warfarin on evening OR next day
What to do with pt who takes warfarin before EMERGENCY surgery?
If surgery can be delayed: delay 6-12 hours
If cant be delayed give IV vitamin K and dried prothrombin complex
If a patient on warfarin has HIGH RISK OF VTE and is about to have surgery?
bridge with LMWH (treatment dose) and stop 24 hours before surgery
A pt is thought to be at high risk of VTE if:
- VTE in last 2 months
- AF with previous stroke/ TIA
- mechanical valve
if patient on warfarin has high risk of bleeding and is about to have surgery?
start LMWH 48 hours after surgery
How do novel oral anticoagulant drugs work?
inhibits specific clotting factors ie thrombin or factor Xa
What is the mechanism of action of dabigatran?
direct thrombin inhibitor
How is dabigatran packaged and what is its expiry?
Special container
4 month expiry
What are examples of drugs that are direct factor Xa inhibitors?
apixaban
edoxaban
rivaroxaban
what are advantages of NOACs in comparison to warfarin?
rarely causes bleeding and no monitoring reqiored
what does ischaemic mean
blood clot obstructs blood supply
what does haemorrhagic mean?
weak blood vessel in brain bursts (intracerebral haemorrhage)
How is transient ischaemic attack managed?
MR dypridamole and aspirin
give statins irrespective of serum cholestrol
treat hypertension, not with beta- blockers unless indicated for another condition
how is ischaemic stroke managed?
clopidogrel
(in atrial fibrillation- related stroke, review for anticoagulant)’give statins irrespective of serum cholestrol
treat hypertension, not with beta- blockers unless indicated for another condition
What do we avoid in a intracerebral haemorrhage?
Avoid aspirin, statin and anticoagulants (increases risk of bleeding, only give if essential
Treat hypertension and take care to avoid hypoperfusion
What are antiplatelet drugs?
decrease platelet aggregation and inhibit thrombus formation in the arterial circulation
how do we have secondary prevention of CVD/ event?
low dose apsirin: 75mg daily
when do we give clopidogrel?
following acute coronary syndromes or PCI)
when do we give dipyridamole?
secondary prevention of strokes
when do we take dipyridamole?
take tablets 30-60 mins before food
when is the expiry date for dyspirdamole?
persantin retard capsules - special container, 6 weeks expiry
