Abnormal bleeding and warfarin Flashcards
(36 cards)
What dentistry procedures are associated with bleeding?
- Extractions
- Surgery, biopsies and trauma
- Periodontal therapy (probing too)
- Exposure of vital pulp
- Spontaneous (local and systemic causes)
What are the effects of blood loss?
- Patient distress
- Blood in tissues
- Blood in stomach (vomiting)
- Blood in airway (obstruction)
- Hypovolaemia - reduced blood volume - shock low BP
- Reduced oxygen carrying capacity (Hb decreased)
- reduced protein (water holding, clotting)
- Reduced platelets (less capacity to arrest haemorrhage)
How do we prepare for bleeding?
- Manage patient expectations - tell patient of risks
- Check bleeding/clotting risks
- Careful surgical technique - being as conservative as possible, least amount of extractions at a time
- Local measures - pressure, suture, surgicel, patience
How does bleeding reduce with Virchow’s triad in mind?
Pressure - stops blood flow
Suture - secures clot in place and holds surgicel
How does surgicel work?
It is foreign so activates the clotting cascade
What are the mechanisms of haemostasis?
- Vascular spasm
- Platelet plug
- Blood coagulation via extrinsic and intrinsic pathway
- Growth of fibrous tissue in the hole in the vessel permanently by fibroblasts
How does a platelet plug form?
Platelet adhesion - platelets adhere to exposed collagen
Release of thromboxane A2 causes increased stickiness
This causes nearby platelets to adhere to platelet plug which activates coagulation cascade by activation of factor X and prothrombin.
What would aspirin and clopidogrel be prescribed for?
They are common anti-platelets prescribed for ischaemic heart disease/recent strokes.
How does aspirin work?
Irreversibly - it effects all platelets you have and doesn’t wear off. To reverse it needs all the platelets to die off - weeks to occur.
It binds to platelet COX (cyclooxygenase) required for thromboxane A2 mediated aggregation.
Reduces chance of platelet plug
How does clopidogrel work?
Binds to the P2Y12 receptor irreversibly and prevents ADP mediated aggregation.
Reduces chance of platelet plug
Why would patients take anti-platelets?
- Vascular disease
- Ischaemic heart disease
- DVT
- Stroke
- Peripheral vascular disease
Should we stop aspirin for those needing extractions?
NO
Takes weeks for effect to be reversed, risk of stopping is greater than risk of strokes, ischaemia, peripheral heart disease
What triggers the intrinsic and extrinsic pathway?
Intrinsic - exposed collagen and platelet activation
Extrinsic - tissue damage
What happens at the final common pathway?
Activating factor X to factor Xa catalysing prothrombin to thrombin in which fibrinogen changes to fibrin.
What are tests of bleeding function?
-INR (international normalised ratio)- Patient’s prothrombin time/control prothrombin time, assessing warfarin anticoagulation
-Platelet count
- APTT (activated partial thromboplastin time) - assesses heparin anticoagulation
- Bleeding time (direct cut - rarely used)
Why would a patient be on warfarin?
Atrial fibrillation
Heart valve abnormalities or replacement
Thromboembolic disease (DVT or pulmonary embolus)
Some other cardiac and vascular abnormalities including patients with ischaemic heart disease.
How does warfarin work?
- prevents action of vitamin K produced in the gut by bacteria
- vitamin K is required in the liver to produce factors II, VII, IX and X
- Warfarin prevents carboxylation of clotting factors
- clotting factor half lives vary up to 60hrs
- Changes to warfarin level can take 7 days
- Long delay when drug is stopped - 7 days
- Many antibiotics enhance effect of warfarin eg metronidazole - gut affected so can affect vitamin K can make pt more or less likely to form blood clots
What INR is safe to perform extraction?
4 or less
What should you ask a pt who takes warfarin?
- Get them to show you their orange book
- Why are they taking warfarin?
- What their prescriber wants their INR to be
- Every month what their INR was
When checking the INR when is safe to perform an extraction?
If their INR is stable, check INR 72 hrs before extraction
IF not check within 24 hours
When planning an extraction for a pt on warfarin when should it be?
Early in the week and early in the day so if the pt has problems they can get in touch.
Make sure you explain there is a risk of bleeding and what they should do if they notice any?
How many extractions can you do with patient on warfarin?
INR 2-3 consider one side at a time as many extractions you can do.
3 -4 - forceps extraction one quadrant at a time
Be careful with ID blocks on patients with warfarin - do articaine infiltration
What local measures do we use to keep a clot?
Surgicel
Suture
How long should we keep a patient after XLA?
- 15-20 mins and give them instructions and contact info if they notice bleeding
