Abnormal bleeds

Question 1

What bleeding is associated with dentistry?

Answer 1

• Tooth extraction
• Surgery, biopsies and trauma
• Periodontal therapy (and even probing)
• Exposure of vital pulp
• Spontaneous (local and systemic causes)

Question 2

What are the effects of blood loss?

Answer 2

• Patient distress
• Blood in the tissues (bruising, infection)
• Blood in the stomach (vomiting) – irritant in stomach so causes vomiting
• Blood in airway (obstruction) – quite rare
• Hypovolaemia (reduced blood volume), shock (rare)
• Reduced oxygen carrying capacity (decreased Hb)
• Reduced protein (water holding, clotting) – protein responsible for transporting drugs, calcium balance so problems occur.
• Reduced platelets (less capacity to arrest haemorrhage).

Question 3

How can you manage bleeding?

Answer 3

• Be prepared
• Patient expectations
• Check bleeding/clotting history
• Careful surgical technique
• Local measures:
  o Pressure
  o Suture
  o “Surgicel”
  o Patience
• Careful post-op and follow up.

Question 4

What is haemostasis?

Answer 4

• Prevention of blood loss
• Whenever a vessel is severed or ruptured, haemostaiss is achieved by several different mechanisms
• Squeezing blood vessel will activate vascular spasm, activating clotting cascade, so can avoid using sutures to fix blood vessel.
• Vascular spasm
• Platelet plug
• Blood coagulation
• Growth of fibrous tissue in the hole in the vessel permanently

Question 5

What is vascular spasm?

Answer 5

• Prevents excessive blood loss in the body
• Smooth muscle in the blood vessel wall contracts and reduces blood loss.

Question 6

What is the formation of the platelet plug?

Answer 6

• Platelet adhesion – platelets adhere to exposed tissue collagen
• Platelet release reaction – release of Thromboxane A2 causes increased stickiness
• Platelet aggregation – effect on nearby platelets causes them to adhere to platelet plug
• Tissue damage
• Exposure of subendothelial collagen
• Platelet activation
• Enhanced platelet adhesion and aggregation
• Enhanced activation of factor X and prothrombin

Question 7

How does aspirin and clopidogrel work?

Answer 7

• Aspirin irreversibly binds to platelets
• It inactivates platelet COX (cyclooxygenase) required for thromboxane A2 mediated aggregation
• Clopidogrel binds to the P2Y12 receptor irreversibly and prevents Adenosine Di Phosphate (ADP) mediated aggregation
• Platelets are renewed over about 10 days
• Ibuprofen binds to platelets reversibly.
• Takes a couple weeks for aspiring affect to be reversed as that’s when platelets get renewed.

Question 8

Which patients are likely to be taking clopidogrel or aspirin?

Answer 8

• Vascular disease
• Including ischaemic heart disease
• Or thromboembolic disease
• Or stroke
• Or peripheral vascular disease
• In whom thrombi (platelet aggregations) are likely to form within the vascular system

Question 9

How do you manage patients on aspirin?

Answer 9

• Do not stop the aspirin
• Takes weeks for effect to be reversed
• Risk of stopping is greater than risk of continuing

Question 10

How does the clotting cascade work?

Answer 10

• Factors activate X to convert to Xa
• Xa converts prothrombin to thrombin
• Thrombin converts soluble fibrinogen to insoluble fibrin.

Question 11

What are the different tests for bleeding function?

Answer 11

• INR (International Normalised Ratio) – Patient’s prothrombin time, used to asses warfarin anticoagulation
• Platelet count – normal 200-400 * 109/L, bleeding a problem if lower than 100 *109/L
• APTT (Activated Partial Thromboplastin Time) – used to assess heparin anticoagulation
• Bleeding time (rarely used – direct cut to forearm)
• Others may be undertaken if an abnormally found in one of these.

Question 12

Which patients are likely to be taking warfarin?

Answer 12

• Atrial fibrillation
• Heart valve abnormalities or replacement
• Thromboembolic disease – deep venous thrombosis and pulmonary embolus
• Some other cardiac and vascular abnormalities including some patients with ischaemic (inadequate blood supply) heart disease.

Question 13

How does warfarin work?

Answer 13

• It prevents the action of vitamin K (produced in the gut by bacteria)
• Vitamin K is required in the liver to produce of Factors II, VII, IX, and X
• Warfarin prevents carboxylation of clotting factor precursors
• Clotting factor half lives vary up to 60h
• Full impact of drug not seen for about 7 days
• Similar long delay when stopped
• Many antibiotics enhance effect of warfarin e.g. metronidazole
• What clotting factors does warfarin affect:
  o 2, 7, 9, 10 factors, produced in liver, using metabolism of Vitamin K usually.
• At what INR is it safe to perform a tooth extraction on a patient?
  o <4.0

Question 14

What should you do as a clinician for patients with abnormal bleeding and are taking warfarin?

Answer 14

• Manage expectations
• Check INR records
• If stable, check INR 72hrs before extraction
• If not check within 24 hours
• Early in the week
• Early in the day
• Careful explanations
• 2.0-3.0:
  o Consider one side at a time
• 3.0-4.0
  o Forceps extraction
  o One quadrant at a time
  o Caution with IDB
• Surgical
• Suture
• Check clotting before pt leaves
• Give contact information

Question 15

What is wrong with warfarin?

Answer 15

o Difficult to get stable anticoagulation

o Multiple interactions
 Drugs
* Metronidazole
* Carbamazepine
* Fluconazole
* Miconazole
* St Johns Wort

 Food:
* Cranberry juice

o Need for monitoring

Question 16

Who takes the new anticoagulant medications?

Answer 16

o AF
o Thromboembolic disease (DVT/PE)
o Heart valve replacements
o CVA

Question 17

What are the advantages of the new anticoagulants?

Answer 17

o Single point of action
o Predictable effect
o No need for INR monitoring
o No interaction with food

Question 18

What are the disadvantages of the new anticoagulants?

Answer 18

o No antidote
o Half-life up to 17hrs.

Question 19

How do you manage patients on the new anticoagulants?

Answer 19

• Do not stop the medication
• Manage patients expectations
• Local measures
• If taking twice daily may consider missing a single pre-op dose.

Question 20

How do you ask patients if they have coagulopathies?

Answer 20

• “Do you have a coagulopathy?”
• Do you have any problems with bleeding or bruising
• Are you taking any medicines to thin the blood
• Do you have any liver problems

Question 21

How do you manage patients with coagulopathy?

Answer 21

• E.g. clotting factor deficiencies, haemophillia, liver disease.
• Ask advice of haematologist
• Check clotting factors/INR/aptt preoperatively
• Adjust if necessary
• Manage patient expectations
• Local measures:
  o Pressure
  o Gauze
  o Suture
  o Oxidised cellulose – Surgical/curacel
  o Tranexamic acid mouthwash