Venous Thromboembolism

Question 1

How many people have a VTE in their lifetime?

Answer 1

1 in 20

Question 2

What drugs can contribute to an increased risk of VTE

Answer 2

HRT
contraception
tamoxifen
thalidomide

Question 3

VTE assessment should be done

Answer 3

• within 24 hours of admission
• if their condition changed
• VTE proph should be prescribed within 24 hours if needed

Question 4

What sort of medicine should be stopped if a patient is having a CTPA scan with contrast media?

Answer 4

metformin due to the risk of contrast induced nephropathy

Question 5

What is a two-level DVT/PE wells score

Answer 5

It estimates the probability of a DVT using clinical features e.g. active cancer, bed ridden, localised tenderness, previous DVT. If a score is > 2 then a DVT is likely. This is not completely accurate so has to be confirmed using a proximal leg ultrasound and a d-dimer.

People with suspected PE should undergo immediate CT

Question 6

How many hours post dose should factor Xa levels be taken?

Answer 6

4 hours

Question 7

When can patients have thrombolysis with a PE?

Answer 7

When they have a ‘massive PE; associated with haemodynamic instability. This is often carried out in CCU or ITU

Question 8

When would a patient have life-long anticoagulation?

Answer 8

If they have an unprovoked PE/DVT

Question 9

How to unfractionated heparins work?

Answer 9

They are a mixture of large mucopolysaccharides that increase the interaction between thrombin and anti-thrombin III swell as preventing the conversion of fibrinogen to fibrin.
They have a short half like and require administration via a continuous infusion when treating a VTE
They are out of favour now compared to LMWH however may be used in bridging for a patient having a heart valve replacement who cannot have their warfarin with having surgery

Question 10

Main side effects of heparins?

Answer 10

-HIT
-this is an immune mediated reaction.
It usually developed 5-10 days after initiation (range 4-15 days) and is usually seen by a 30-50% reduction in platelets.
-This can be stopped and switched to a non-heparin anticoagulant such as fondaparinux or danaparoid
-Always contact haem for advice.

It can also cause hyperkalaemia via inhibition of aldosterone synthesis

Long term use may cause osteoporosis

Question 11

List vitamin K agonist (coumarin drugs)

Answer 11

warfarin
acenocoumarol
phenindione

Question 12

is monitoring of warfarin phrarmodynamic or pharmokinetic

Answer 12

pharmodynamic

Question 13

How does warfarin work?

Answer 13

It is a citation K antagonist, which reduces the hepatic production of vitamin K dependent active coagulation factors II, VII, IX and X along with the regulatory anticoagulant proteins C and S in a dose related way.
This action results in prolongation of the prothrombin time (bleeding time) and a decreased tendency to form blood clots.
Warfarin therefore prevents enlargement of existing blood clots and formation of new blood clots.

Question 14

INR means

Answer 14

international Normalised Ratio

Question 15

In what circumstances would we expect a higher INR?

Answer 15

• recurrent VTE whilst a patient is on warfarin

- mechanical valve

Question 16

How long would a patient be on anticoagulation for if they had a provoked PE?

Answer 16

3 months and then review (based on chadsvasc and hasbled)

Question 17

In which situations would a patient be on life long anticoagulation?

Answer 17

• AF
• mechanical valve
• unprovoked recurrent VTE

Question 18

What is classed as poor INR control?

Answer 18

• Two INR readings greater than 5 or one greater than 8 in the last 6 months
• Two INR readings less than 1.5 in the past 6 months
• Time in therapeutic range (TTR) less than 65%

We would review and consider changing to a DOAC in this situation

Question 19

How long does warfarin take to anticoagulant fully?

Answer 19

72-96 hours

Question 20

Drugs to avoid with warfarin

Answer 20

• aspirin
• miconazole
• NSAIDS
• enteral feeds containing vit K

All others we can consider a dose adjustment or monitor INR - look at page on canvas

Question 21

what do we do in a high INR

Answer 21

if INR is 5-8 stopping the warfarin usually suffices.

If INR >8 then we would give vit K even if patient is not bleeding

Question 22

What are DOACS licensed for ?

Answer 22

• prevention of VTE post knee/hip surgery
• treatment of VTE
• stroke prevention in non-valvular AF (N.B. warfarin can be used in valvular AF)

Question 23

Which DOAC cannot be used in eGFR <30ml/min

Answer 23

dabigatran

- it is 80% excreted by the kidneys

Question 24

Which DOAC needs to be taken with food?

Answer 24

Rivaroxaban

Question 25

Which DOAC’s are once daily administration?

Answer 25

Rivaroxaban and edoxaban

Question 26

Which DOAC cannot be used in a blister pack?

Answer 26

Dabigatran

Question 27

Which DOAC currently has a reversal agent?

Answer 27

Dabigatran

Question 28

Are DOACs really or hepatic ally excreted?

Answer 28

RENAL

Question 29

Do we base renal function on eGFR or CrCl for DOACS?

Answer 29

CrCl!

Question 30

In clinical trials for DOAC use in AF what weight was used

Actual or ideal?

Answer 30

Actual

Question 31

When should CrCl not be used

Answer 31

• unstable renal function eg AKI
• children
• pregnancy
• odematous patients
• extremes of body weight - may over estimate clearance
• patients with muscle wastage - may over estimate creatinine clearance
• patients with limb amputation

Question 32

What is the equation for Ideal body weight

Answer 32

Males - 50kg + 2.3kg for every inch in height above 5 ft (60 inches)

Females - 45.5kg + 2.3kg for every inch in height above 5 ft (60 inches)

Question 33

What is the equation for adjusted body weight

Answer 33

ideal body weight + 0.4 (actual body weight - ideal body weight)

Question 34

When should the dose of apixaban be reduced

Answer 34

Normal dose 5mg BD. This should be reduced to 2.5mg BD if:

• If the patient has two or more parameters - weight <61kg, Serum creating >133umol/L or age >80 years.

Or if CrCl is 15-29ml/min

It is contraindicates <15ml/min

C/I in patients taking any of the azoles and HIV protease inhibitors

Question 35

When should the dose of dabigatran be reduced?

Answer 35

Its normal dose is 150mg BD. It should be reduced to 110mg BD if:
CrCl 30-50ml/min or age greater than 80 years if clinical risk factors for bleeding.
Ore reduce if taken with verapamil

It is contraindicated in CrCl <30ml/min
& with ketoconazold, itraconazols, tacrolimus and ciclosporin

Question 36

When should edoxaban be reduced?

Answer 36

Standard dose is 60mg OD. It should be reduced to 30mg OD if:

CrCl is 15-50ml/min or body weight less than 60kg or there is concomitant use of cyclosporin, dronedarone, erythromycin or ketoconazole.

Contraindicated in CrCl <15ml/min
And in patients with hepatic disease

Question 37

When should rivaroxaban be reduced?

Answer 37

Standard dose is 20mg OD.

If the CrCl is between 15-49ml/min then reduce the dose to 15mg OD.

It is contraindicated in CrCl <15ml/min
And in patients taking any azoles and dronedarone and HIV protease inhibitors