Abnormal bleeding Flashcards
Give some effects of blood loss
- patient in distress
- Blood in tissues
- Blood in the stomach
- Blood in the airways
- Reduced oxygen flow
- Reduced portion and platelets
- Hypocolaemia
What is hypovolaemia
Reduced blood flow
What can hypovolaemia lead to
Shock
How do we manage bleeding
- Be prepared
- Inform the patient before hand that they may bleed
- Check bleeding and clotting history
- Be as conservative as possible
- Local measures
- Careful post op and follow up
What local measures do we need to take to manage bleeding
- Pressure
- Suture
- Surgical
- patience
What is virchows triad
Describes 3 factors that important in valour formation:
1) blood flow
2) activation of blood coagulation
3) vein damage
What haemostats
Prevention of blood loss
How is haemostats achieved
- Vascular spasm
- Platelet plug
- Blood coagulation
- Growth of fibrous tissue in the hole in the vessel permanently
What is vascular spasm
When smooth muscle in the blood vessel walls contract and reduce blood loss
What is the aim of the vascular spasm
Prevents excessive blood loss in the body
How is a platelet plug formed
- Platelet adhere to expoed tissue collagen
- Platelets release thromboxane A2 which increases stickiness
- Platelet aggregation
What does aspirin do
It irreversibly binds to platelets and inactivates platelet COX
What is platelet COX
Cyclooxygenase
What is the significance of cyclooxyrgenase
It is required for thromboxane A2 mediated aggregation
How does clopidogrel work
It binds to the P2Y12 receptor irreversibly and prevents Adenosine Di Phosphate (ADP) mediated aggregation
How long does it take for platelets to be renewed
About 10 days
How does ibuprofen work
Ibuprofen bind to platelets reversibly
How does platelet plug formation activate the coagulation cascade
- Tissue damage
- Exposure of sub endothelial collagen
- platelet adhesion
- Enhances platelet adhesion and aggregation
- Enhanced activation of factor X and prothrombin
Which patients are likely to be taking clopidogrel or aspirin?
Patients with:
- Vascular disease
- Ischaemic heart disease
- thromboembolic disease
- Stroke
- peripheral vascular disease
- In whom thrombi are more likely to form
What is a thrombi
Platelet aggregation
What effect does aspirin have on tooth socket bleeding time
Patients who take sprain have a longer tooth socket bleeding time
Should we tell patients taking aspirin to stop taking it before their extraction? Why?
NO:
Takes weeks for effect to be reversed
Risk of stopping is greater than risk of continuing
List some tests we can take to test bleeding function
- INR (International normalised ratio)
- Platelet count
- APTT (Activated Partial Thromboplastin Time)
Name the 2 pathways of the clothing cascade
- Intrinsic pathway
- Extrinsic pathway
What is the intrinsic pathway intuited by
- Exposed collage
- Platelet activation
What is the extrinsic pathway initiated by
tissue damage
What is the overall effect of the intrinsic and extrinsic pathway
They both Meet together at the end and activate prothrombin
this activated thrombin turns fibrinogen into fibrin
Which bleeding test is the most commonly used
INR
Which patients are likely to be taking warfarin?
Patients with:
- Atrial fibrillation
- Heart valve abnormalities or replacement
- Thromboembolic disease
- ischaemic heart disease
How does warfarin work
It prevents the action of vitamin K which prevents carboxylation of clotting factor precursors
Why is vitamin K important in blood clotting
It is require by the liver to produce factors II, VII, IX and X
What is the half life for clotting factors
60 hours
When is the full impact of warfarin seen in a patient
About 7 days
What is the disadvantage of warfarin
- Multiple drug interaction
- Difficult to stabilise anti coagulation
- Some food interaction
- Needs to be monitored
Which drugs can warfarin interact with
Metronidazole
Carbamazepine
Fluconazole
Miconazole
St Johns Wort
What foods can warfarin interact with
Cranberry juice
An INR below what is safe to do an extraction on
less than 4
When should we check INR records of a patient
If stable, check INR 72hrs before extraction
if not check within 24 hours
Give some advantages of new anti coagulants
- Single point of action
- Predictable effect
- No need for INR monitoring
- No interaction with food
Give some disadvantages of new anticoagulants
No antidote
half life up to 17 hours
How can we ask patients if they have any bleeding problems
- Do you have any problems with bleeding or bruising?
- Are you taking any medicines to thin the blood?
- Do you have any liver problems?
