Anticoagulation Peri Op Flashcards
When to stop warfarin pre op if needs to be discontinued?
5 days pre op
Post op what should you give pts on warfarin with a VTE > 3months earlier?
Low dose LMWH
Which patients on warfarin should you consider bridging? Name 3 groups
Pts at v high recurrent VTE risk e.g VTE while on therapeutic dose anticoagulants or with a target INR 3.5 or have had a VTE in <3months
Do warfarinised patients with AF and a CHADS2 score < 4 and no stroke or TIA in last 3 months need bridging peri-operatively?
No
Pts with a bileaflet aortic mechanical heart valve that are warfarinsed peri -op should …
But…
Not require bridging
But can be considered in all other MHV patients
If indicated, When to stop clopidogrel and when prasugrel?
5 days, 7 days pre op respectively
When to stop ticagrelor if indicated?
5 days pre-op
What is used to bridge warfarin peri-operatively?
LMWH or UH
When can you resume warfarin post op?
12-24hrs if bleeding risk is low
48-72hrs post op if high bleeding risk
Dabigatran is 80% Renally excreted so interruption varies on creatinine clearance and bleeding risk of operation:.. Fill the hold times
Cr >80ml/min: x hrs low risk, x hrs high risk
Cr 50-79ml/min x low risk, x high risk
Cr 30-49ml/min x low risk, x high risk
Cr >80: 24hrs (48hrs high risk)
Cr 50-79: 36hrs (72hrs high)
Cr 30-49: 48hrs (96hrs high)
Apixaban, rivaroxaban, edoxaban interruption holding times:
Cr >30ml/min: x hrs low risk (x high risk)
Cr 15-29ml/min: x hrs low risk (high risk)
> 30: 24hrs (48hrs high risk)
15-29: 36hrs (48hrs high risk)
Resumption of DOAC therapy post op for low bleeding risk and high bleeding risk?
Low: 6-12hrs post op
High: 48-72hrs post op
What agent reverses dabigatran for an emergency high bleeding risk op?
Idarucizumab
What agent reverses Apixaban/Rivaroxaban/Edoxaban?
Andexanet
Pts with normal renal function for a low bleeding risk op, should not take DOAC x hrs pre-op
24hrs
Pts with normal renal function and a high bleeding risk op should not take DOAC x hrs pre-op
48hrs
In terms of DOAC circulating concentration, what measurement can be used to confirm minimal conc vs what measurements can not .
✅Normal thrombin time = minimal conc
❌Normal PT/APPT not reliable
If aspirin mono therapy is used for 2* prevention of CVD, should it be continued for non-cardiac invasive operations?
Yes can be continued
If bleeding risk for an operation is high, and a pt is on aspirin when should it be omitted?
From day -3 to day +7 post op
If pts on anti-platelet what should be done in case of
a) urgent low bleeding risk surgery
b) urgent high bleeding risk surgery
a) n/a (don’t need platelet infused)
b) consider pre-op transexamic acid
If a pt on anti-platelets is given trasexamic acid pre-op for a high bleeding risk surgery but despite this has excessive periop bleeding what can be considered?
2 pools of donor platelets infusion
In pts with a recent acute coronary syndrome/C.A stent on dual anti platelet therapy, undergoing a low bleeding risk operation…you should
Proceed without interruption to the anti platelet therapy
In pts with a recent acute coronary syndrome/C.A stent on dual anti platelet therapy, undergoing a high bleeding risk operation…you should, if possible
Postpone the operation (if poss)
In pts with a recent acute coronary syndrome/C.A stent on dual anti platelet therapy, undergoing a high bleeding risk operation…that cannot be postponed you should…
Continue aspirin
Clopidogrel/ticagrelor should be interrupted from 5 days pre-op
Or prasugrel from 7 days pre-op
aspirin should be continued and clopidogrel or ticagrelor interrupted from 5 days pre-op or prasugrel from 7 days pre-op
Transexamic acid stabilises clots preventing haemorrhage by inhibiting ___ formation and displaces ____ from the ____ surface so it is an anti-___
Plasmin
Plasminogen
Fibrin
Anti-fibrinolytic
Warfarin is a vit K antagonist inhibiting formation of clotting factors:____ and takes (x-X) days to take action
II VII IX X Protein C and S
Name clotting factors in following aspects of Warfarin actions on the:
-intrinsic pathway: blood stream factors__
-extrinsic pathway: vessel wall factors__
These activate common pathway involving factors__
Intrinsic: IX, XI, XII
Extrinsic: III (tissue factor), VII
Common: X and II (prothrombin)
Prothrombin time measures the ___pathway so can be used to monitor warfarin
Extrinsic
Dabigatran acts by directly inhibiting ___ so delays the final step of coagulation cascade (___pathway)
Inhibiting thrombin
Common pathway
Apixaban, dabigatran, edoxaban and rivaroxaban are all ___ used in the prevention and treatment of ___ they are also indicated to prevent stroke and systemic embolism in pts non-valvular __ who have at least 1 risk factor such as:
- DOACs
- VTE
- AF
- e.g. previous stroke, symptomatic HF, DM or HT
MOA of DOACs - what part of coagulation pathway ..?
Dabigatran (doesn’t have x in name), acts at a slightly different point, -where?
- acts on the final common pathway
- directly inhibits activated factor X so prevents conversion of prothrombin to thrombin
- Dabigatran directly inhibits thrombin (so prevents fibrinogen conversion to fibrin)
- hence they prevent clot formation
3 SEs of DOACs
- bleeding: epistaxis, GI and GU haemorrhage
- anaemia
- GI upset
- diziness
- elevated LFTs
3 DOAC CIs:
- ACTIVE SIGNIF BLEEDING
- RFS FOR MAJOR BLEEDING
- PREGNANCY
- BREASTFEEDING
- RIFAMPICIN OR PHENYTOIN CONCURRENT USE (increases anti-coagulation effect)
Warfarin is used for VTE rx/prophylaxis after initial hepain rx and to prevent clots in pts with AF or prosthetic heart valves, what is it’s MOA?
-inhibits hepatic production of vit-K dependent coagulation factors (II, VII, IX, X protein C&S) by inhibiting vitamin K epoxide reductase
What is the substance that is used to reverse Wafarin? Or dried ______ complex can be used
Phytomenadione (vitamin K1)
-or dried prothrombin complex
How long is a single episode of VTE treated with Warfarin for?
-3-6 months
Target INR range for a pt on Warfarin for AF or VTE rx?
2-3 target range
