CV: Anticoagulants Flashcards
The main use of anticoagulants is to prevent thrombus formation or extension of an existing thrombus in the slower-moving venous side of the circulation, where the thrombus consists of what?
The main use of anticoagulants is to prevent thrombus formation or extension of an existing thrombus in the slower-moving venous side of the circulation, where the thrombus consists of a fibrin web enmeshed with platelets and red cells.
Anticoagulants are of less use in preventing thrombus formation in arteries. Why?
In faster-flowing vessels, thrombi are composed mainly of platelets with little fibrin.
The oral anticoagulants warfarin sodium, acenocoumarol and phenindione, antagonise the effects of vitamin K, and take at least how long for anticoagulant effect to develop fully?
48 to 72 hours.
If an immediate effect is required, unfractionated or low molecular weight heparin must be given concomitantly.
Coumarins and phenindione should not be used in what as first-line therapy?
What should be used?
These oral anticoagulants should not be used in cerebral artery thrombosis or peripheral artery occlusion as first-line therapy; aspirin is more appropriate for reduction of risk in transient ischaemic attacks.
An INR which is within how many units of the target value is generally satisfactory?
0.5 units within the target value.
What is the target INR for MI?
2.5
What is the target INR for recurrent DVT or PE in patients currently receiving anticoagulation and with an INR above 2?
3.5
What is the target INR for AF?
2.5
What is the target INR for the treatment of DVT or PE?
2.5
What duration of treatment with warfarin is recommended for VTE provoked by surgery or other transient risk factor (e.g. COC use, pregnancy, plaster cast)?
3 months
What duration of treatment with warfarin is recommended for isolated calf-vein deep-vein thrombosis?
6 weeks
What duration of treatment with warfarin is recommended for unprovoked proximal DVT or PE?
At LEAST 3months; long-term anticoagulation may be required.
What should be done for major bleeding with warfarin use?
Stop warfrain.
Give phytomednadione (Vit K) by slow intravenous injection.
Give dried prothrombin complex (factors II, VII, IX and X); if dried unavailable then fresh frozen plasma but it is less effective.
What should be done for INR >8.0, minor bleeding?
Stop Warfarin, give vit K1 by slow IV injection.
Repeat the dose of vit k if the INR still too high after 34 hours;
Restart when INR <5
What should be done for INR >8.0, no bleeding?
Stop warfarin, give vit k by MOUTH, repeat dose if INR still too high after 24 hours, restart when <5,0