Venous Thrombo-embolism Prevention Flashcards
What is a venous thromboembolism
- Blood clot that starts in the calf- they may remain localise or they may go across the vein to occlude it and grow proximally
- can embolism and move around and spread to other areas of the body
What are the consequences of venous thromboembolism
- DVT
- PE
- Post thrombotic syndrome
- leg ulcers
What is the 3rd most common cause of cardiovascular death
PE
what is the second most common cause of death in cancer and commonest cause of preventable hospital related death and most common cause of maternal mortality
PE
Why is VTE important
Common - 1 in 1000 per year
- treatments effective but significant risks - major and fatal bleeding
If you get a VTE what are you at risk of in the future
- Post thrombotic syndrome
- Chronic thromboembolic pulmonary hypertension (CTEPH)
What are most death from PE due to
- diagnostic failure rather than treatment failure - most patients die as the diagnosis is not suspected
What is your chances of dying from a DVT and PE
VTE – natural history
30-day case fatality PE vs DVT
– 7%v2%(OR3.8, 95% CI 1.6-9.2)
– ≈ 50% of above deaths from PE (approx. 4% v 1%)
What is pulmonary embolism the most common cause of
- Most common cause of missed or delayed diagnosis
After you stop anticoagulants after 3 months what is the risk of developing another VTE
- Overall 5% per year initially
• 20% at 5 years
• 30% at 10 years
– Higher (≈10% in first year) if unprovoked than if provoked by temporary risk factor
What is post thrombotic sydnrome
- complicates 40% of DVT cases
- develops within 2 years of DVT diagnosis
- variable severity
- reduced quality of life
- cost to individual and society
What are the symptoms of post-thrombotic syndrome
- pain
- swelling
- skin induration/discolouration
- ulceration
what 3 risk factors lead to VTE/PE development
- virchows triad
- blood flow
- blood coagulability
- vessel wall damage
What are the major risk factors for VTE
- Fracture of hip/pelvis
- Hip or knee replacement surgery
- Major general surgery especially for malignancy
- Major trauma
- Spinal cord injury
- Hospitalisation with acute medical illness
What are the moderate risk factors for VTE
• Previous VTE • Malignancy/chemotherapy • Pregnancy and post-partum period • Combined oc pill or hormone therapy • Central venous line • Thrombophilia Risk factors • Other medical conditions e.g. nephrotic syndome, inflammatory bowel disease, Behçets syndrome
What are weak but common risk factors for VTE
- Age
- Travel-related thrombosis
- Obesity
- Varicose veins
- Diet
- Smoking
- Air pollution
describe how hospital admission leads to VTE risk
VTE following hospital discharge Worcester DVT study (2007) • 74% presented as outpatients – 37% recent hospitalisation +/- surgery – 23% recent major surgery +/- hospitalisation – 29% recent cancer diagnosis – 20% previous VTE diagnosis – 70% ≥1 VTE risk factors
why do cancer patients have an increased risk of VTE
– Cancer is prothrombotic
– Immobility
– Chemotherapy
– Central venous lines
of patients presenting with unprovoked VTE…
5% have a new cancer diagnosed within 3 years
What is the 2nd leading cause of death in cancer patients
VTE
When you are pregnant what increases your risk of developing a VTE
- Obesity
- Maternal age > 35 years
- Caesarean section (especially emergency)
What is trousseau syndrome
- the connection between VTE and cancer
Describe how the risk of VTE change in pregnancy
- mostly level during pregnancy but increases before delivery
- after delivery it massively increases in the first 6 weeks after delivery
What are the NICE guidelines for VTE
- All patients on admission receive an assessment of VTE and bleeding risk using the clinical risk assessment criteria
- patients are offered verbal and written information on VTE prevention as part of the admission process
- patients provided with anti-embolism stockings have them fitted and monitored
- patients are re-assessed within 24 hours of admission for risk of VTE and bleeding
- patients assessed to be at risk of VTE are offered VTE prophylaxis in accordance with NCIE guidelines
- patients are offered verbal and written information on VTE prevention as part of the discharge process
- patients are offered extended VTE prophylaxis
Name thrombosis risk
- Active cancer or cancer treatment
- age over 60
- dehydration
- known thrombophiliais
- obesity
- one or more significant medical co-morbidities - e.g. heart disease, metabolic, endocrine or respiratory pathologies, acute infectious diseases
- personal history or first degree relative with a history of VTE
- use of hormone replacement therapy
- use of oestrogen containing contraceptive therapy
- varicose veins with phlebitis
- pregnancy or less than 6 weeks post partum
admission related
- significantly reduced mobility for 3 days or more
- hip or knee replacemetn
- hip fracture
- total anaesthetic and surgical times greater than 90 minutes
- surgery involving pelvis or lower limb with a total anaesthetic and surgical time greater than 60 minutes
- acute surgical admission with inflammatory or intra-abdominal condition
- critical care admission
- surgery with significant reduction in mobility
Name the bleeding risks
Patient related
- active bleeding
- acquired bleeding disorders
- concurrent use of anticoagulatns known to increase the risk of bleeding
- acute stroke
- thrombocytopaenia
- uncontrolled systolic hypertension - 230/120 or higher
- untreated inherited bleeding disorder
Admission related
- neurosurgery, spinal surgery or eye surgery
- other procedure with high bleeding risk
- lumbar puncture/epidural/spinal anaesthesia expected within the next 12 hours
- lumbar puncture/epidural/spinal anaesthesia within the previous 4 hours
Name the mechanical methods of thromboprophylaxis
- Anti embolism stockings
- intermittent pneumatic compression
Name the pharmacological methods of thromboprophyalxis
– Unfractionated heparin
– Low molecular weight heparin
– Fondaparinux
– New direct oral anticoagulants (DOACs)
describe parenteral thromboprophylaxis
– Unfractionated heparin 5000 u sc bd or tds
– Low molecular weight heparin
• Enoxaparin 40 mg sc od
• Dalteparin 5000 u sc od
• Tinzaparin 4500 u sc od
– Fondaparinux - synthetic pentasaccharide - 2.5 mg sc od
describe oral thromboprophylaxis
– Direct thrombin inhibitor
• Dabigatran
– Factor Xa inhibitor
• Rivaroxaban
• Apixaban
• Edoxaban (not yet licensed for VTE prevention)
How does heparin work
- binds to naturally ocucring anti thrombin III
- and this speeds up the inhibition of the activated clotting factors
- particulary factor IIa and Xa
How does LMWH work
- shorter chains
- inhibits factor Xa but some are not long enough to inhibit thrombin therefore you only get some thrombin inhibition
How does fondaparinux work
- inhibition of Xa and no inhibition of thrombin
What does dabigatran inhibit
thrombin
What does apixaban, edoxaban, rivaroxaban inhibit
Factor Xa
When do you get a peak of DOACs
around 2 hours later
What is the half life of DOACs
12 hours
Where are the DOACs eliminated
- dabigatran - renal
- others not the renal
What patients should not recieve graduated compression stockings
- Known peripheral vascular disease
- Leg or buttock pain on exercise
- Previous or planned revascularisation surgery
- Massive leg oedema where stockings are unable to be fitted
- Leg conditions in which stockings would interfere eg dermatitis, recent skin graft, gangrene
What is the standard approach to VTE
• Anticoagulant therapy
– Prevent extension and recurrence (not thrombolytic)
Standard approach
• Immediate therapy with treatment-dose heparin (LMWH)
• Overlap with warfarin until INR in therapeutic range (5 days minimum)
• Then stop LMWH, continue warfarin for 3 months (monitor in anticoagulant clinic) and review duration
What does warfarin inhibit
Vitamin K antagonists
• Factors II, VII, IX, and X (and protein C and protein S)
What is the half life of warfarin
36 hours
Where is warfarin metabolised
in the liver
What are the side effects warfarin
– Risk of major bleeding – 1-2% per year
– Avoid in pregnancy – teratogenic and bleeding
– Safe for breast feeding
How do you monitor warfarin
- INR (derived from the prothrombin time - extrinsic and common pathway)
What DOACs require a heparin lead in
Dabigatran and Edoxaban
- heparin lead in required 5-10 days
describe an updated VTE plan
Acute (5-10 days)
- IV heparin, LMWH, Fondaparinux, DOCA
Short term (3-6 months )
- warfarin
- LMWH
- DOAC
long term (beyond 3-6 months)
- Warfarin
- LMWH
- DOAC
- ASA
- nothing
How long should you have warfarin in a provoked v an unprovoked VTE
Venous thromoboembolism = length of warfarin treatment
- provoked (e.g. recent surgery): 3 months
- unprovoked: 6 months
What can D dimer be elevated in
- DVT
- pregnancy
- cancer
- hospitalised
- elderly patients
What test do you do after a D dimer is positive
- do a CT pulmonary angiography
What advice is given to people on warfarin
- Shouldn’t take it if pregnant
- can take it whilst breastfeeding
- avoid cranberry juice
- warfarin is also affected by alcohol
What is the general information that someone taking anticoagulants should be old
- avoid injuring yourself as it can make you prone to bleeding
- should not take aspirin, herbal remedies such as St John’s Wart
- some medicines can effect anticoagulants such as antibiotics, antidepressants, corticosteroids, NSAIDs
