Haemostasis Flashcards
(37 cards)
Splanchnic vein (PV, Budd Chiari, mesenteric)
Aetiology
Cirrhosis, inflammation, malignancy
If no cause clear do MPN and PNH screen - 30% PV, 50% BC
Splanchnic vein (PV, Budd Chiari, mesenteric)
Management
Anticoag
Cirrhosis
Start LMWH
Convert warfarin
Consider DOAC in compensated CP A-B
Duration 3-6mo, lifelong if no bleeding
Malignancy
LMWH for intraluminal cancer, otherwise DOAC
Other aetiology
DOAC 3-6 months, long term in MPN or PNH or BC
Check varices
Haemophilia prophylactic dosing
2nd/3rd gen factor
20-40 IU/kg EOD
Modify for sports etc
Time off dabigatran pre-procedure
Low risk procedures
CrCl
>80 - 1d
>50 - 1.5d
>30 - 2d
High risk procedures - double duration
NO NEED FOR LMWH!
Time off DOAC pre-procedure
Low risk procedures
CrCl
>80 - 1d
>50 - 1d
>30 - 1d
>15 - 36h
High risk procedures - 48 for all
NO NEED FOR LMWH!
ISTH definition major bleeding on anticoag
Fatal bleeding
Symptomatic bleeding in critical site (brain/spine/eye/retroperitoneal/joint/compartment syndrome)
Fall Hb >20g/L or needs 2x RBC transfusion
Anticoagulation in extreme obesity
ISTH 2022
DOAC for all
No need for peak and trough levels
Dose reduction after 6 months possibly bad
Bariatric surgery - no DOAC for 4 weeks, consider using trough levels thereafter
DOAC dosing per renal function
Dabigatran
CrCl
>50 - 150mg BD
>30 - 110mg BD
<30 - stop
Rivaroxaban
>50 - 20mg OD
>15 - 15mg OD
Apixaban
>30 - 5mg BD
>15 - 2.5mg BD
Edoxaban
>50 - 60mg
>15 - 30mg
DOAC choice GI surgery
LMWH for 4 weeks
Then apix or riva with trough levels
Or VKA
Recurrent VTE on anticoag
Cancer
APLS
Pregnancy
COCP
MPN
PNH
Inflammatory disease
Behcets syndrome
Emicizumab
Cross links F9 and F10
Approved for prophylaxis in severe with or within inhibitors
SC fortnightly
NOT for bleeding
Must use chromogenic F8 or Bethesda
APTT should be short or normal
Long APTT might mean anti-emi ab
FEIBA contraindicated
Avoid high dose novoseven
DRVVT - process
RVV potent FX activator in presence of PL
Lupus anticoagulant antibody presence inhibits ability to activate FX
Measure clotting time between patient and reference plasma
If LA is present the patient sample will take longer than reference plasma
If ratio in clotting time is >1.05 LA May be present
Then calculate %correction when excess PL added
Excess PL mops up lupus anticoag
If correction brings time down to close to 1 then LA is likely (correction more than 10%)
If no correction then likely a factor deficiency
2nd test then needed - diluteAPTT or silica clotting time
APTT process
PPP
Incubate 2 min kaolin (contact activator) + phospholipid
Add calcium
Measure time to clot
Prolonged APTT differential
Factor def
Lupus Anticoag
Mechanism UFH
Changes AT - Potentiates effect against 10, 2, 9, 11, 12
Plus others
What is ISI?
Correction factor used to generate INR from PT and reference PT
(Ratio raised to ISI)
ISI derived from comparing reference thromboplastin to test reagent
Usually provided by manufacturer
ISI sets the reference range for PT
How does anti-Xa assay work?
Measures ability of bound anti-thrombin to inhibit FX
Incubate sample with FXa
FXa is inactivated by drug
Measure residual FXa with chromogenic reaction
Compare to standard curve
Independent of patient clotting Fs
Clauss Fn process
Plasma mixed with high conc thrombin
Thrombin activates clotting
Fn the rate limiting step
Measure clot time
Thrombin time
Mix plasma with low conc thrombin
Thrombin activates clotting
Measure clot time
ISTH DIC score
Plt: >100 - 0 points / >50 - 1 points / <50 - 2 points
PT: <3s over - 0 points / 3-6s over - 1 point / >6s over - 2 points
Fibrinogen: >1 - 0 points / <1 - 1 point
D-dimer: normal - 0 points / 250-5000 - 1 point / >5000 - 2 points
Unselected stroke patient with single pos APLS
Aspirin
i.e. manage as a normal stroke
Unless <50yrs - May benefit from warfarin
Indication for PNH anticoag
Previous VTE
Any clone size >50%
Use warfarin INR 2.5
DOAC peri-op
See other card
Apixaban extension trial
Apix 2.5mg BD after 6/12 treatment VTE
Less clinically relevant bleeding vs full dose
Same rate repeat thrombosis
No change survival
