Cardiovascular: warfarin and heparins Flashcards
What is duration of treatment for:
Isolated Calf DVT
Provoked VTE
Unprovoked VTE
Isolated calf dvt = 6 weeks
provoked = 3 months
unprovoked= 3 plus months (long term)
What is target INR for:
- VTE/AF/MI/cardioversion/ biprosthetic mitral valve?
- Mechanical valve
- recurrent DVT in pts receiving anticoagulation
VTE/AF most indications= 2.5
Mechanical valve= 3-3.5
Recurrent=3.5
What are INR targets for
biprosthetic mitral valve
mechanical valve
Biprosthetic mitral valve is 2.5
but mechanical valve is 3.5
how often is INR monitored
1-2 weeks until stable then 3 monthly
if a patient on warfarin presents with a painful skin rash - what is most appt action?
MHRA warning regarding risk of calciphylaxis - refer to GP asap
Risk increased if have renal diseas
what are interactions of warfarin
Enzyme inhibitors as thy can increase warfarin levels in body and increase bleeding risk (increased INR)
For elective surgery, what is the process with warfarin?
stop 5 days before elective
If INR >1.5 the day before then give oral phytomenadione
re-start warfarin on evening of or next day
If a patient is on warfarin but requires emergency surgery what is done?
delay 6-12hrs
If cannot delay - IV phytomenadione and dried prothrombin complex
If pt is at high risk of VTE e.g. had in last 3 months, previous stroke/TIA or mechanical valve, how would you manage warfarin pre surgery?
still stop 5 days prior but bridge with LMWH and stop these 24hrs prior
if there is ANY BLEEDING (minor or major) with warfarin, regardless of INR (e.g. if 5-8 or >8), what is the process
STOP
IV phyto
restart when INR <5
if INR is between 5-8 but no bleeding what is done?
Omit 1-2 doses
reduce maintenance dose
measure INR in 2-3 days
if IN 5-8 but minor bleeding?
omit
IV phyto
repeat if INR still high in 24hr
re-start <5
if INR >8 but no bleeding?
omit
ORAL phyto
repeat if INR still high in 24h
re-start <5
What are 3 MHRA warnings re; warfarin
- Risk calciphylaxis -painful skin rash
- antiretrovirals for hep C can affect INR
- Miconazole OTC daktarin c/i - increases wafarin and risk of bleeding
how long does wafarin take to work
48-72hrs hence need bridging with LMWH
what are some counselling points of warfarin
Alert card, yellow book bleeding signs skin rash no drastic changes in diet with greens reducing alcohol informing dentist and soft toothbrush,care when shaving avoiding pomegranate/gfruit
Which patients are at increased risk of VTE
immobility obesity malignancy older >60 clotting disordeers HRT/contraception pregnancy co-morbdities
how would you treat a VTE
LMWH or UF for 5 days until INR >2 for at least 24hrs
then initiate DOAC
(or warfarin-bridge)
What is the preferred choice for VTE proph and treatment in pregnancy and why
LMWH - dont cross placenta, reduced risk of osteoporosis and HIT
What are key risks/sid effects of heparins
- heparin induced thrombocytopenia occurring 5-10 days after ~30% reduction in platelets and skin rash
- Haemorrhagee
- Hyperkalaemia
- osteoprosis (higher in heparin rather than lmwh)
Why arent LMWH used in renal impairment
Longer duration of action
When are LMWH preferred
if risk of osteoporosis
pregnant
if at risk of Heparin induced thrombocytopnia (have a reduced risk with lmwh)
What bloods would you measure with heparins
platelets
APTT
K+
How long would you continue VTE prophylaxis in
- surgery
- major abdominal cancer surgery or pelvic
- Knee/hip
general surg 5-7 days
major cancer abdomen/pelvic= 28 days
replacement= extended
