Chapter 3- Coagulation Flashcards
Name three major parts of haemostasis
Vasospasm
Platelet plug formation
Coagulation
Give an overview of vasospasm in haemostasis
Damaged artery, collagen exposed, contract to prevent blood gushing out
Give an overview of platelet plug formation in haemostasis
Platelet adhesion to injured site
Platelets release adenosine biphosphate, serotonin and prothrombin A2 recruiting more platelets to site = plug formation
Give an overview of the coagulation/clotting step of haemostasis
Intrinsic and extrinsic pathway lead to prothrombinase
Prothrombinase converts prothrombin to thrombin, thrombin converts fribrinogen to fibrin
How is the clot broken down once damaged is healed
Healing and fibrolysis
During fibrinolysis what does the endothelium release and what does it convert?
Release tPA
Concerts plasminogen to plasmin
Plasmin cleaves X-linked fibrin polymer into what eventually?
D-D (d-dimer) and E
Deficiency in what 3 anticoagulants can increase someone’s risk of VTE?
Antithrombin
Protein C
Protein S
Name two abnormal proteins that can increase someone risk of VTE
Factor V Leiden
Fibrinogen (dysfibrinogenaemia)
List two procoagulants that can increase someone’s risk of VTE
Prothrombin 20210
Factor VIII
Abnormal metabolism of what can increase someone’s risk of VTE
Hyperhomocysteinaemia
List three LMWH
Dalteparin
Enoxaparin
Tinzaparin
What are the high, moderate and low scores in the wells pre-test probability of DVT
High: >2
Moderate: 1-2
Low: <1
What are the high moderate and low scores in the wells pre test probability of PE
High: >6
Moderate: 2-6
Low: <2
Which heparin is preferred for patients in renal failure?
Unfractionated heparin
How do you manage VTE in pregnancy
Heparins are used as they don’t cross the placenta
Which type of heparin in preferred in pregnancy?
LMWH because it has a lower risk of osteoporosis and of heparin induced thrombocytopenia
Name a reversal agent for heparin
Protamine
If a patient who has had a hip replacement is on DOAC then admitted to hosp with infection do they need VTE prophylaxis?
No as on DOAC
When using dalteparin in pregnancy to treat VTE what do you need to ensure the vial does not contain?
Benzyl alcohol
True or false and why: you can’t put in epidural unless the patient has not had heparin for 12hours
True due to bleeding risk
Pregnant lady has VTE .. what contraceptive can she have after birth?
POP not COC
Can you be in warfarin whilst breastfeeding
Yes
If having a C-section when should you stop LMWH
12-24hours beforehand
After birth when should you start LMWH and for how long
Start 12hours after birth for 10 days
Can the wells score be used in pregnancy
No
Is the D-dimer test useful in pregnancy
No high rate of false positives
Is warfarin contraindicated in pregnancy?
Yeh
What is heparin and how does it work?
Glycosaminoglycan: pentasaccharide sequence binds to lys and arg on AT producing a conformational change which increases AT activity
What factors does AT inhibit
Factor 11, 9, 10 and thrombin
Differences between UFH and LMWH
LMWH has less effect on thrombin and obvs a lower molecular weight, LMWH is s/c only whereas UFH is IV and s/c, LMWH is renally excreted only whereas UFH is renal and hepatic
What’s the half life of LMWH
4-5 hours
What’s the half life of UFH
60mins
What monitoring is required for UFH
APTT: activated partial thromboplastin time
When using APTT what is the normal range for time to clot? And what does APTT principally reflect
28-36seconds
Reflects anti-IIa activity
What is used to monitor LMWH
Anti-factor Xa assay
List 3 complications of UFH use
Under/overdosage
Osteoporosis
Heparin-induced thrombocytopenia
What is heparin induced thrombocytopenia
Platelet activating autoantibodies to heparin-PF4 complexes
When should you be alert to potential HIT
If platelet count falling
Name the vitamin K dependent coagulation factors
9, 10, 7
What does warfarin inhibit
Vitamin K epoxide reductase
What’s the best method of monitoring warfarin
Prothrombin time then INR= prothrombin time/ geometric mean of normal prothrombin time
When should you consider giving vitamin K in warfarin overdose?
INR >8
Name two hirudins
Argatroban
Desirudin
Name a synthetic heparin like molecule
Fondaparinux
Name a direct anti-IIa inhibitor
Dabigatran
Name three direct anti-Xa inhibitors
Rivaroxaban
Apixaban
Edoxaban
List 4 advantages of the NOACs
Oral
Reproducible PK
Rapid onset
No monitoring required
When should you take care with using NOACs
Peri-operative anticoag
Epidural anaesthesia
Renal impairment
Weight <50kg or >120kg
How can you reverse rivaroxaban and dabigatran
Prothrombin complex concentrate
What is andexanet alpha
Modified anti-FXa variant/decoy (rivaroxaban, apixaban, edoxaban bind to it instead of factor Xa)
Name 4 thrombolytic agents
Streptokinase
rt-PA, alteplase
Reteplase
Tenecteplase
What condition is a definite indication of using thrombolysis for acute DVT
Phlegmasia coerulea dolens
List 10 contraindication of using fibrinolysis in acute MI
Recent haemorrhage Trauma Surgery Coagulation defects Peptic ulceration Severe hypertension Acute pulmonary disease Acute pancreatitis Severe liver disease Previous allergic reaction
List risk factors for VTE
Active cancer/cancer treatment Age >60 Dehydration Known thrombophilias Obesity >30 bmi Comorbidities (heart disease, metabolic, endocrine, respiratory, infection, inflammation) Personal history/family HRT COC Varicose veins with phlebitis
When should you reassess patients risk of bleeding and VTE
Within 24 hours of admission and whenever clinical situation changes
Should you offer anti-embolism stockings for VTE prophylaxis in stroke patients
No
Advice on VTE prophylaxis in surgical patients
Stop COC and HRT 4 weeks before elective surgery
What is the INR target in someone on warfarin with a mechanical heart valve
3.5
INR target of someone on warfarin with recurrent DVT
3
