IC4 Management of VTE Flashcards
What is Deep Vein Thrombosis (DVT)?
DVT is when a thrombus develops in the deep veins.
What is pulmonary embolism (PE)?
A pulmonary embolism (PE) occurs when a part of the DVT clot breaks off and travels to the lungs, which can be life-threatening
What is Venous Thromboembolism (VTE)?
VTE refers to DVT, PE, or both
What are risk factors of VTE?
(List at least 5)
- Immobility
- Recent surgery
- Long haul flight
- Pregnancy
- Hormone therapy w oestrogen
- Malignancy
- Polycythemia
- Obesity
- Antiphospholipid syndrome
- Genetics
- Prothrombin gene mutation
- Antithrombin deficiency
- Protein C & S deficiency - Infection/sepsis
What are the 5 clinical presentations of DVT?
- Unilateral
- Calf swelling
- Dilated superficial veins
- Calf tenderness
- Colour change in legs
What are the 3 main causes of VTE?
(Virchow’s triad)
- Vessel injury
- Venous stasis
- Hypercoagulability
What are the types of test we can do to investigate VTE?
- INR - a clotting test
- Full blood count (FBC)
- Imaging - ultrasound
- APTT - a clotting test
- Liver function test (LFTs)
If a thrombus were to form, at which region will it likely embolise?
Proximal region - Above the knee is more likely to embolise
Distal region - below the knee, less likely to embolise
What is the clinical presentation of Pulmonary Embolism (PE)?
- Cough
- Chest pain
- Chest tightness
- Shortness of breath
- Tarchycardia
- Diaphoretic - increased sweating
- Hypoxia
Wells score is a guideline to determine the likelihood of a patient having DVT:
What score is considered low, moderate and high probability?
Low probability: 0 or less
Moderate probability: 1 or 2
High probability: 3 or more
Active cancer - 1pt
Immobilization of lower extremities - 1pt
Major surgery or bed ridden for >3 days - 1pt
Localized tenderness - 1pt
Entire Leg swollen - 1pt
Calf swelling >3cm -1pt
Pitting oedema - 1pt
Collateral superficial vein - 1pt
Alternative diagnosis more likely than DVT - -2pts
At what Well’s score do we then conduct an ultrasound test?
When the score is greater than 2.
When the score is 3 and above, we must conduct an ultrasound.
At what Well’s score do we conduct D-dimer test?
When score is 0 to 2.
When score is 0-2, we conduct D-dimer test. If D-dimer is positive, we will then perform ultrasound.
If D-dimer is -ve, we are then able to rule out DVT.
After an ultrasound is conducted, it was discovered that the DVT is located at:
- The proximal region
What should you do?
Start anticoagulants immediately
After an ultrasound is conducted, it was discovered that the DVT is located at:
- The distal region
What should you do?
Choose to monitor or initiate anticoagulants
How to diagnose a patient with PE?
A modified Well’s Score is used to check if a patient has PE.
When score is >4, we will conduct an ultrasound.
When score is 4 and below, we will conduct D-dimer test. If D-dimer is positive, we will then conduct an ultrasound.
If patient is found to have PE, we will start on parenteral anticoagulation immediately as it is life threatening.
Modified Wells Criteria for PE
a. Clinical symptoms of DVT - 3pts
b. Other diagnosis less likely than PE - 3pts
c. Heart rate >100 - 1.5pts
d. Immobilization for at least 3 days - 1.5pts
e. Previous DVT/PE - 1.5pts
f. Haemoptysis - 1.0pts
g. Malignancy - 1.0pts
What is the MOA of heparin?
Heparin inactivates thrombin and factor Xa.
What is the MOA of LMWH?
LMWH inactivates factor Xa only.
(e.g Enoxaparin)
What can be used to monitor effects of heparin?
aPTT - activated Partial thromboplastin Clotting Time
What can be used to monitor effects of LMWH?
Anti-Xa levels
Does LMWH and heparin cause thrombocytopenia?
Only heparin cause thrombocytopenia.
LMWH does not cause thrombocytopenia.
Which clotting factors do warfarin exert its effects on?
Factor II, VII, IX, X
Dabigatran
Rivaroxaban
Apixaban
Warfarin
(DRAW)
What are the percentages of each drug being renally cleared?
Dabigatran - 80% renally cleared
Rivaroxaban - 33% renally cleared
Apixaban - 25% renally cleared
Warfarin - Almost 0
There is increase in hepatic clearance & decrease renal clearance as we move across DRAW.
Which drugs are oral and parenteral among DRAW?
Dabigatran - parenteral
Rivaroxaban - oral
Apixaban - oral
Warfarin - oral
What are the doses and duration for:
- Rivaroxaban
- Apixaban
In treatment for DVT wo PE.
- Rivaroxaban
- 15mg BD x 3 weeks (30mg/day)
- Followed by 20mg/ day x 6 months
- Followed by 10mg OM - Apixaban
- 10mg BD x 7 days (20mg/day)
- 5mg BD x 6 months
- 2.5mg BD
With regards to DVT wo PE therapy:
- Rivaroxaban
- 15mg BD x 3 weeks (30mg/day)
- Followed by 20mg/ day x 6 months
- Followed by 10mg OM - Apixaban
- 10mg BD x 7 days (20mg/day)
- 5mg BD x 6 months
- 2.5mg BD
Classify them according to:
1. Initial treatment
2. Maintenance treatment
3. Extended treatment
- Rivaroxaban
Initial treatment - 15mg BD x 3 weeks
Maintenance treatment - Followed by 20mg/ day x 6 months
Extended treatment - Followed by 10mg OM - Apixaban
Initial treatment - 10mg BD x 7 days
Maintenance treatment - 5mg BD x 6 months
Extended treatment - 2.5mg BD
Maintenance phase - treat until 90 days
Extended phase - beyond 90 days
When treating a patient w anticoagulant for DVT wo PE, we will look at the benefits VS risk at 90 days mark.
If patient has high bleeding risk, we can stop treatment.
If patient does not have high bleeding risk, we can lower Apix and rivarox to prophylaxis doses and continue with maintenance treatment to the 180 days mark.
Basically the 3 time points to check in are:
a. 3 months - 90 days mark
b. 6 months - 180 days mark
c. Beyond 6 months
For renally impaired patients, what drugs can and cannot be used?
When CrCl <50ml/min, cannot use dabigatran.
When CrCl <30ml/min, cannot use rivaroxaban
Apixaban can be used even when CrCl <30ml/min, but must be used with caution.
What are 2 rTPA drugs that we have learnt?
- Tenecteplase
- Alteplase
What are the reasons that rTPAs are less used in SG?
- Due to the availability of PCI
- rTPAs have high risk of bleeding
What test should I conduct to differentiate cellulitis and DVT?
FBC.
FBC can help us rule out cellulitis.
List out all tests that are used for DVT.
- Wells score - determine risk of DVT
- D-dimer - determine need for ultrasound
- Ultrasound - determine presence of DVT
- FBC - eliminate possible cellulitis
- Renal panel - titrate dose based on CrCl
What can we use to treat patients with PE?
For high risk patients (>6 pts)
- Unfractionated heparin is use
- UFH is easily reversible
- If pt is alr on an anticoagulant, the risk of bleeding is very high when used tgt with another anticoagulant agent. hence, we use heparin for its easy reversibility
- It is preferred for high risk patients to be put on systemic therapy - such as rTPAs + UFH
For low to moderate (0 to 6 pts)
- LMWH
- OR any DOACs
- Both LMWH and DOACs are equally effective
If a pt has antiphospholipid syndrome, what is the best oral anticoagulant treatment to use?
Warfarin
After an episode of PE being successfully removed, what treatment do we offer to the patient?
We treat the patient with OAC for 90 days.
This is similar to the treatment of DVT wo PE.
For pregnant patients with DVT and/or PE, what is the recommended therapeutic agent to use?
LMWH
Thrombolytics are not to be used in pregnant women.
We can only use LMWH for pregnant patients.
Pregnant pts with history of miscarriage may have antiphospholipid syndrome.
For enoxaparin, there are 4 types of syringe preparations:
1. 20mL
2. 40mL
3. 60mL
4. 80mL
Which of the 4 are SDL and have graduated syringes?
60mL and 80mL are on the SDL and have graduated syringes.
Enoxaparin can be given subcutaneously and intravenously.
How is LMWH, e.g. enoxaparin, mainly cleared?
Renally cleared
