Perioperative anticoagulation Flashcards
How does anaemia impact peri-operative haemorrhage?
- Increased bleeding during surgery
- Poor wound healing
- Higher morbidity and mortality if peri-operative haemorrhage occurs
How is anaemia managed pre-operatively for elective surgery?
- Investigate and correct anaemia before surgery
- Refer to pre-op anaemia clinic if not obvious
- G+S; Xmatch for high bleeding risk procedures
Name four procedures with a high risk of bleeding
- Cardiothoracic surgery
- Urological procedures
- Polypectomy
- Liver/spleen operations
- Vascular surgery
What is the diagnostic criteria for anaemia?
Low Hb count
- <140g/L in males
- <120g/L in females.
How is anaemia managed prior to emergency surgery?
- X-match ± transfusion
- Secure haemostasis in active haemorrhage
What is a group and save?
Blood sample taken to confirm patients blood group and any RBC antibodies.
This information is saved in case of need for transfusion.
What is a crossmatch?
Patient sample is crossmatched with a sample from a blood unit to ensure compatibility.
Name three medications that increase peri-operative bleeding risk
- Aspirin
- Clopidogrel
- Warfarin
- NOAC
- Corticosteroids: GI bleed
What should always be checked for in cases of unexplained thrombocytopenia?
Disseminated Intravascular Coagulation (DIC)
Name two coagulation tests and state their use
Name three indications for a pre-op coagulation screen
- Past Hx of unusual bleeding
- Previous post-operative bleeding
- Unexplained persistent menorrhagia
- FHx of bleeding disorder
- Unexplained thrombocytopenia
- Emergency operations
- Severe sepsis
Name two surgical procedures that can proceed without interruption of anticoagulation
- Dental extraction
- Cataract surgery
- Minor skin procedures
What is the target INR for surgical patients on Warfarin?
How is this achieved prior to elective surgeries?
INR <1.5
Stop Warfarin for 5 days prior to elective surgery
Reduce INR with phytomenadione (vit K) if INR ≥1.5 in the day before surgery
‘Bridging’ therapy with LMWH if high risk of thromboembolism
Stop LMWH at least 24h prior to surgery
How are patients on warfarin managed in emergency surgery?
If surgery can be delayed 6-12h: IV phytomenadione (vit K)
If cannot be delayed: prothrombin complex + phytomenadione
List three indications for ‘bridging’ anticoagulation therapy
- VTE within previous 3 months
- AF with either:
- Previous stroke/TIA within last 3 months
- High CHA2DS2VASC score
- Mechanical heart valve
Name two situations which have increased target INR for surgery
Target INR 3.0-4.0
- Arterial disease
- Older mechanical heart valves
Which antiplatelet therapies can continue in surgery?
- Aspirin only: majority of operations
- Clopidogrel only: discuss with relevant department
What is the surgical risk of stopping dual antiplatelet therapy?
50% mortality within 1st month after stents are placed
In emergency surgery: continue aspirin and interrupt clopidogrel 5-day prior if necessary
When can warfarin be started post-op?
Evening of surgery or next day if there is adequate haemostasis
Due to slow onset of action
Name three side effects of warfarin
- Intracranial bleed
- Epistaxis
- Bleeding for injection sites
- GI bleed
- Teratogenic
Name two LMWH drugs
- Dalteparin
- Enoxaparin
Differentiate between UFH and LMWH
- Both inhibit ATIII
- Reversal: Protamine sulfate
- UFH
- Shorter half-life
- Given IV (SC prophylaxis)
- Variable action: APTT monitoring
- LMWH
- Longer half-life
- Given SC
- Predictable action: no monitoring.
How is UFH and LMWH overdose reversed?
Protamine sulfate
What is a rare but serious complication of heparin?
Heparin-Induced Thrombocytopenia
Commonly presents with VTE
Name three DOACs
- Dabigatran
- Rivaroxaban
- Apixaban
- Edoxaban
When should DOACs be stopped prior to elective surgery?
- Normal renal function
- Low risk elective: 24hr prior
- High risk elective: 48hr prior
- Renal impairment: 24-96hr prior
