Clinical use of anticoagulants

Question 1

What is VTE?

Answer 1

Collective term for deep vein thrombosis DVT, pulmonary embolism PE.

Question 2

All patients must be assessed for their risk of VTE when?

Answer 2

On admission
After 24hr
After every clinical situation change

Question 3

Pharmacologiclal VTE prophlaxis can take the form of [3]

Answer 3

1. UFH
2. LMWH
3. Fondaprinux

Question 4

What is UFH?

Why is it reserved for those unable to use LMWH or fondaparinux?

Answer 4

First pharmacological agent.
High strength heparin product (25000units/mL) means it is generally reserved for second or third line choice in those patients who cannot use LWMH or Fondaparinux.

Question 5

LMWH have been shown to be clearly superior to UFH in what situations?

Answer 5

In preventing DVT in patients undergoing orthopaedic surgery.

LMWHs should be used in preference to UFH if not other contraindications.

Question 6

What is fondaparinux?

Answer 6

Selective anti-Xainhibitor, which unlike UFH and LMWH, has not antithrombin activity.

Fondaparinux is more effective at preventing DVT in hip and knee surgeries.

Also can be used in people with a history of HIT.

Question 7

How is fondaparinuxdifferent to UFH and LMWH? (2)

Answer 7

No direct antithrombin activity

Can be used in people at risk of HIT

Question 8

How long should DVT prophylaxis continue?

Answer 8

Until patient is fully mobile and fit for discharge.

In knee, hip replacements etc maybe for 28 days post discharge.

Question 9

When would DVT prophylaxis continue for 28 days?

Answer 9

Oncology surgery, knee hip replacements etc.

Question 10

In what situations is even the slighest risk of local bleeding unacceptable?

What should be offered instead of anticoagulation?

Answer 10

Neurosurgery, ophthalmic surgery, some plastic surgery, head injury, haemorrhagic stroke.

Mechanical prevention methods.

Question 11

What VTE risk factors should we look out for? [11]

Answer 11

1. Active cancer or cancer treatment
2. Age >60 years
3. Emergency care admission
4. Dehydration
5. Known thrombopilias
6. Obese patients (BMI>30)
7. One of more signif medical comorbidities such as heart disease, metabolic, endocrine, respiratory pathologies, acute infectious diseases, inflammatory conditions.
8. personal or FH of VTE
9. HRT
10. Oestrogen containing contraceptives
11. Varicose veins with phlebitis

Question 12

What bleed risk factors are there?

Answer 12

1. Active bleeding.
2. Acquired bleeding disorder such as acute liver failure
3. Anticoagulant use, such as wafarin inr>2.0
4. Lumbar puncture, epidural, spinal anaesthesia within previous 4 hrs or next 12 hrs.
5. Acute stroke
6. Thrombocytopenia (platelets <75 x 10^9/L)
7. BP unctrolled >120
8. Haemophillia
9. von Willebrands disease

Question 13

What is von Willebrands disease?

Answer 13

(VWD) is a genetic disorder caused by missing or defective von Willebrand factor (VWF), a clotting protein. VWF binds factor VIII, a key clotting protein, and platelets in blood vessel walls, which help form a platelet plug during the clotting process.

Question 14

When should mechanical DVT prophylaxis occur?

Answer 14

Evening before surgery and continue until patient is fully mobile.

Question 15

How do the doses of enoxaparin and dalteparin for high/moderate and low risk DVT prophylaxis differ?

Answer 15

80mg enox/5000 dalt for high

40mg enox/2500 dalt for low

Question 16

Before treatment of a DVT occurs, blood should be collected for determination of what?

Answer 16

APTT
PT
Platelet count

Question 17

For who suffering from a DVT would a thombophilia screen be considered?

Answer 17

Family history of VTE
Recurrent VTE
Possibly if there is spontaneous VTE.

Question 18

As LMWH has been shown to be at least as effective and safe as an IV UFH infusion in the initial management of DVT, why would we choose LMWH over UFH?

Answer 18

LMWH has the advantage of not requiring routine laboratory monitoring and enabling management in a hospital out-patient or general practice setting in selected cases and is now the treatment of choice.

Question 19

Tinzaparin, Dalteparin and Enoxaparin are all

Answer 19

LMWH

Question 20

In the presence of renal impairment, LMWH requires what monitoring and adjustment when?

Answer 20

Requires factor Xa monitoring and possible dose adjustment if the calculated creatinine clearance <30ml

Question 21

A normal loading dose of warfarin is ________ divided between __ days.

Answer 21

15-30mg, 3 days, LOCAL PROTOCOL

INR monitored daily.

Question 22

The inital dose of warfarin should be what in the elderly?

Answer 22

Lowered

Question 23

LMWH should be giben for a minimum of how long?

Answer 23

5 days or until the INR has been >2 on two consecutive days, whichever is longer.

Question 24

Why should warfarin not be commenced alone (i.e without a LMWH)?

Answer 24

It is associated with a high rate of DVT recurrence.

Question 25

The duration of anticoagulation therapy given depends on what?

Answer 25

The risk of both recurrent VTE and bleeding.

Question 26

Graduated compression stockings should be worn for at least how long?

Answer 26

18 months, indefinitely if the post-thrombotic syndrome is present.

Question 27

What pathophysiological changes would indicate decreasing the warfarin loading dose?

Answer 27

Liver disease
Cardiac failure
Nutritional failure

Question 28

The risk of bleeding on warfarin increases significantly when the INR is >

Answer 28

5

Question 29

When reversal of anticoagulation is needed due to major/life-threatening bleeding and PCC is given alongside IV phtomenadione, what investigations need to occur?

Answer 29

FBC
APTT
INR

Question 30

If there is minor bleeding and an INR of >5,what should happen?

Answer 30

Omit Warfarin

Give IV phytomednadione 0.5-1mg

Question 31

If there is minor bleeding and an INR of <5, what should be done?

Answer 31

Clinical decision needs to be made on the benefits of stopping the anticoagulation.

Question 32

If the INR is 5.0-7.9 and there is no bleeding what should we do?

Answer 32

Omit and restart warfarin when below 5.

Question 33

If the INR is >8 but less than 12 and no bleeding?

Answer 33

Omit warfarin and give 1-5mg oral phytomenadione.

> 12 mut warfarin and give 5mg oral phytomenadione.

Question 34

Examples of PCC include

Answer 34

Beriplex
Octaplex

PCCs derived from human plasma which has been virally inactivated, and they contain coagulation factors II, VII, IX and X.