Abnormal Bleeding and Anticoagulant Management

Aberrant bleeding may be of congenital, acquired, or technical cause.

Pre-op Assessment
Usual workup, e.g:
- bleeding hx, including epistaxis, menstruation
- comorbidities renal, haem disease, liver disease.
- meds
- physical exam: bruising, ecchymosis, petechiae, stigmata of liver disease etc.
If concern, needs Plts, bleeding time, INR, aPTT, haem consult.

Pre-op Management

Antiplatelets

1. Stop herbal remedies supplements long enough before surgery to reverse effects

2. Do not routinely stop aspirin unless risk of bleeding exceeds thrombotic risks.

3. Stop Clopidogrel 5d prior to elective surgery.
- unless recent coronary stenting; do not stop within 4w of bare metal stent or 1y after drug-eluding stent

Emergency procedures?
Do not interrupt antiplatelet therapy.
Post-operative bleeding can be treated with DDAVP for aspirin; clopidogrel would need a platelet transfusion

Anticoagulants

4. Warfarin
- stop 4d before surgery
- then rpt INR to ensure <1.5
- if high risk (e.g. AF with stroke or recent VTE or mechanical heart valve), use clexane or heparin infusion as a bridging procedure
- heparin infusion can be ceased 4h before surgery and restarted 8-12h after surgery for several days until INR therapeutic again.

Bleeding disorders

6. von Willebrands' disease
- vWF stabilizes factor VIII in bld.
- in some vWF types, can have elevated bleeding types but normal levels of vWF in blood
- mild cases treated with DDAVP which causes release of both factor VIII and vWF to improve concentrations
- more serious cases treated with factor VIII/VWF concentrates or cryo.

7. Haemophilia
- sex-linked recessive disorders; 90% are type A, 10% type B
- mild type A can be treated again by DDAVP (0.3 ug/kg)
- moderate+ disease; need factor VIII or XI for A and B respectively
- maintain at 80% normal for several days pre-op; 100% for 3-4d after major surgery then 80% for a week+

8. Other congenital factor deficiencies
- FFP, cryo (VIII, vWF, fibrinogen, fibronectin, factor XIII)
- Factor VII deficiency corrected with same.
- malnutrition, hepatic failure, drugs and malabsorption cause reductions in Vitamin K, hence low factor II, VII, IX, X and prothrombin, proteins C & S
--> replace with oral / IV vit K
- Vit C deficit can cause troublesome bleeding due to loss of capillary integrity from improper collagen.


Managing Bleeding

Investigations for patients with ongoing bleeding after correction of technical factors
- fbc incl. platelets
- INR, aPTT
- bleeding time temp
- arterial blood gas with pH and base deficit.

Normal INR and aPTT?
Consider platelet dysfunction, VWD and vitamin C deficiency

Normal INR; prolonged aPTT?
(aPTT ref range is 30-40s; critical high is >70s)
Commonly drug induced; e.g. heparin or similar
Can reverse by protamine, but not LMWHs; beware hypotension and reactions in diabetics.

Both increased
Consider multiple-factor deficiency, e.g. DIC, massive blood loss and haemodilution, end-stage kidney disease
- DIC confirmed by elevated d-dimer >2000
--> treat underlying problem; sometimes may need heparin

Reversing Warfarin
Warfarin targets II, VII, IX and X
Mean half life is 40h; takes 48h to establish and duration of effect 2-5d
Metabolized in liver via cytochrome p450 pathway
Risk of spontaneous bleeding increases with INR goes above 4
To reverse give Vitamin K 1-2mg orally (5mg if particularly high INR), 1mg IV; oral preferred unless very rapid reversal required as rare risk of anaphylaxis IV;
- vit K takes up to 24h to have its full effect
Consider prothrombinex 25-50 IU/kg and FFP (150-300mL),
- prothombinex contains low levels of II, IX and X but only low leves of VII
- FFP adjunctively provides VII
--> use depends on need for rapid and complete reversal, risk of bleeding and level of INR


Other

Warfarin / Vit K deficit usually leaves normal aPTT