thromboembolism Flashcards
VTE and risk factors
VTE - blood clot in vein - obstructs blood flow
DVT - legs or pelvis - unilateral localised pain, swelling
PE - lungs - SOB, chest pain
risk factors:
surgery
trauma
hormonal therapy (COC/HRT)
immobilisation
obesity
pregnancy
diagnosis - D dimer test
VTE prophylaxis types
2 methods of thrombroprophylaxis:
- mechanical - compression stockings
- pharmacological - anticoagulants - start 14 hrs after admission
if high risk of bleeding - give VTEp if benefit outweights risk using HAS-BLED or ORBIT
VTE prophylaxis in surgery
mechanical - all pts prophylaxis until sufficiently mobile or discharged
pharmacological
- when risk of VTE outweighs bleed risk
- LMWH in all types of general/orthopaedic surgery
- unfractionated heparin in renal impairment or need to stop quickly within 2hrs
as unfractionated has much shorter half life - fondaparinux sodium for lower limb or pelvis fragility fractures
- continue vte for 7 days post surgery or till sufficiently mobile
- 28 days in major cancer surgery in abdomen
- 30 days in spinal surgery
vtep - elective hip replacement vs knee replacement
hip replacement:
- LMWH for 10 days + aspirin 75mg for 28 days
- LMWH for 28 days + stockings till discharge
- rivoraxaban 10mg OD 5 weeks started 6-10hrs after surgery
knee replacement
- 75mg aspirin for 14 days
- LMWH for 14 days + stockings
- rivoroxaban 10mg OD for 2 weeks
general medical pts with high risk of VTE - vtep for 7 days
vtep - pregnancy
LMWH during hospital admission
vtep till no risk of VTE or pt discharged
if given birth, miscarriage or termination of pregnancy in past 6 weeks - LMWH 4-8 hrs after event - continue for 7 days
add mechanical if immobilised
VTE treatment and durations
confirmed proximal DVT or PE - apixaban or rivoroxaban
if unsuitable:
- LMWH for at least 5 days followed by dabigatran or edoxaban
or
- LMWH + warfarin for at least 5 days or until INR is at least 2.0 for 2 consecutive readings, then warfarin alone
durations of treatment:
distal DVT (calves) - 6 weeks
proximal DVT/PE - at least 3 months
provoked DVT/PE - stop at 3 months if provoking factor resolved
unprovoked DVT/PE - 3 months+
recurrent DVT/PE - long term
warfarin - INR monitoring
maintain INR 2.5 +/- 0.5 - VTEs, AF, cardioversion, MI
maintain INR 3.5 +/- 0.5 - recurrent VTEs or mechanical heart valve
major bleed - stop warfarin - IV phytomenadione + IV dried prothrombin
INR > 8, minor bleed - stop warfarin + IV phytomenadione
INR > 8, no bleeding - stop warfarin + oral phytomenadione
INR 5-8, minor bleed - stop warfarin + IV phytomenadione
INR 5-8, no bleeding - withold 1-2 doses of warfarin
RESTART warfarin when INR < 5
monitor INR every 1-2 days at start, then every 12 weeks
warfarin SE’s and interactions
MHRA warning - skin necrosis and calciphylaxis
- painful skin rash
haemorrhage, prolonged bleeding
- vitamin k1 (phytomenadione) antidote
pregnanacy - avoid 1st and 3rd trimester - teratogenic
- use contraception
interactions:
- vitamin K rich foods - avoid leafy greens - reduce efficacy
- pomegranate and cranberry juice - increases INR
- miconazole (OTC daktarin) - increases INR
- tramadol + warfarin - increases INR - severe bleeding/bruising can be fatal
- CYP inhibitors - increase conc.
- CYP inducers - decrease conc.
warfarin in surgery
minor procedure with low risk of bleeding
- performed with INR < 2.5
- restart warfarin within 24hrs of procedure
procedure with severe risk of bleeding
- stop warfarin 3-5 days before
- IV vit K if INR 1.5 or more 1 day before surgery
- if pt high risk of thromboembolism - bridge with LMWH, stop LMWH 24hrs before and restart 48hrs after surgery
emergency surgery:
- if can be delayed 6-12 hrs - IV vit K
- If can’t be delayed 6-12 hrs - IV vit K + IV dried prothrombin
DOACs imp points + doses
DOACs - newer gen of anticoagulants - no monitoring requirements
apixaban, rivaroxaban, dabigatran, edoxaban
for treatment of thromboembolisms:
apixaban - 10mg BD 7 days - 5mg BD
rivaroxaban - 15mg BD 21 days - 20mg OD
- take with food
dabigatran - 18-74 150mg BD, 75-79 110-150mg BD, 80+ 110mg BD
edoxaban - 60mg OD, 30mg OD if pt weighs <61kg
parenteral anticoagulants - imp points
ALL heparins
- avoid in heparin-induced thrombocytopenia
- can cause hyperkalaemia
- haemorrhage - use PROTAMINE SULPHATE (only effective in unfractionated)
unfractionated:
- quicker initiation and elimination - ideal in high bleeding risk (monitor APTT) - monitoring closely every 2hrs
- higher risk of heparin-induced thrombocytopenia than LMWH
- preferred in renal impairment
LMWH:
- preferred in pregnancy
