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APPAC > Anticoagulants > Flashcards

Anticoagulants Flashcards

1
Q

What is haemostasis?

A

mechanism designed to prevent loss of blood after injury to blood vessel. It is controlled and balanced by a series of positive and negative feedback systems

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2
Q

What are the 4 stages of haemostasis?

A

1- blood vessel contraction. slows flow of blood and decreases pressure

2- platelet plug formation. exposure to collagen allows platelets to aggregate, fibrin binds them together.

3- clot formation. meshwork of fibrin and platelets.

4- fibrinolysis. occurs when repair of vessel is underway, this dissolves the clot.

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3
Q

What is the relevance of vitamin K in blood clotting?

A

Vitamin K is required for the synthesis of blood clotting factors VII, IX and X
To produce an anticoagulant effect, interfere with vitamin K.

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4
Q

What is fibrinolysis?

A

dissolving a blood clot by the enzyme plasmin. This cuts the fibrin mesh causing it to fragment.
This is to prevent it growing bigger and becoming a problem

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5
Q

What are the 2 types of fibrinolysis?

A

primary: normal body process of breaking down a blood clot
secondary: breakdown of clots due to medicine or medical disorder

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6
Q

in what blood vessels can blood clots occur?

A

veins

arteries

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7
Q

What patient history would indicate those that are likely to be receiving anticoagulants?

A
  • myocardial infarction
  • cerebrovascular thrombosis
  • venous thrombosis
  • pulmonary embolism
  • prosthetic heart valve
  • post operative prophylaxis
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8
Q

What is warfarin?
How does it work?
How is it administered?

A
  • anticoagulant
  • inhibits the synthesis of active vitamin K dependant clotting factors. II, VII, IX and X
  • administered orally,
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9
Q

What is heparin?
how does it work?
how is it administered?

A

-anticoagulant
-unfractional heparin: extracted from pig/ox and has a mixture of polymers or various weights. difficult to predict pharmacological effects
administered by injection
mode of action: it encourages the body’s natural clot lysis to work

-low molecular weight heparin: fragments of short synthetic sequences of heparin, more predictable pharmacological effects.
mode of action: inhibits Factor Xa

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10
Q

can heparin cross the placenta?

A

no, neither unfractional or low molecular weight heparin can cross the placenta. safe to use in pregnancy

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11
Q

how long can a single dose of warfarin last?

A

2-5 days

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12
Q

What patients may receive heparin?

A
  • myocardial infarction
  • DVT
  • pulmonary embolism
  • post op prophylaxis
  • areas of slow running blood
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13
Q

Why would a patient be taking warfarin?

A
  • recent DVT
  • following cardiac surgery
  • flow disturbance
  • prosthetic heart valves
  • following MI
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14
Q

What are some adverse reactions to anticoagulants?

A
  • various forms of bleeding (haemorrhage, bleeding hum/nose, coughing up blood, excessive bruising)
  • teratogenesis
  • rashes
  • osteoporosis
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15
Q

What 7 drugs can warfarin interaction?

A

1- NSAIDs: ASPIRIN: most serious drug interaction. Bleeding episodes can be fatal. Aspirin competes for same protein as warfarin so displaces it. This increases the free (plasma) warfarin and so increases it’s effects.
If NSAID is required for pain-relief you can use Ibuprofen or Naproxen as it has a minor interaction.

2-OTHER ANTIPLATELET DRUGS: Clopidogrel

3- PARACETAMOL: prolonged paracetamol will enhance the anticoagulant effect of warfarin. although most dental pain is short-lived.

4- BROAD SPECTRUM ANTIBIOTICS: these potentiate the effect of warfarin. Since they reduce the gut flora of the GI tract, and these normally synthesis vitamin K. Erythromycin and Metronidazole have biggest effect. Amoxicillin has no effect.

5- ANTIFUNGALS: they will increase the effect of warfarin. fluconazole and miconazole (even as a gel!)

6- BARBITURATES: stimulate metabolism of warfarin

7- ALCOHOL: chronic alcohol ingestion stimulates metabolism of warfarin

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16
Q

if an NSAID must be used with warfarin, what is a good choice?

A

Ibuprofen or Naproxen

17
Q

How do you reverse the effects of warfarin, if there is severe bleeding?

A

administer vitamin K intravenously

18
Q

What are the procedural guidelines for someone on anticoagulants?

A

1-Always find out why they are taking anticoagulants to assess their underlying disease

2-check their anticoagulant card for INR value. Must be within 24 hours for a valid indication. Record INR in patients notes.

3-if INR needs to be lowered, adjust Warfarin by talking to physician.

4-low risk procedures may proceed with INR equal or less than 4.
-moderate risk procedures may proceed with INR equal or less than 3.5

5-surgery should be as atraumatic as possible, avoid inferior dental nerve block if possible.

6-local measure should be used to achieve haemostasis. (apply pressure with damp gauze, use resorb-able surtures, and apply haemostatic dressing: Surgicel-oxidised cellulose gauze)

7-post-op care: written instruction must be given to patient and advised to seek help fro care provider/local hospital if bleeding recommences after treatment.

-patients should not be discharged until haemostasis has been achieved. May take 15-20 minutes.

19
Q

What is the INR?

A

International Normalised Ratio

This is the function of the prothrombin time of the patient against the prothrombin time of a control patient.

X/15

20
Q

What are some antiplatelet drugs?

A
  • aspirin
  • clopidogrel
  • epoprostenol
21
Q

can warfarin cross the placenta?

A

yes, it can cause teratogenesis.

22
Q

how do you reverse the effects of heparin if there is excess bleeding?

A

protamine sulphate: activated antithrombin III.

Only partially effective against LMWH

23
Q

What are some adverse effects of warfarin?

A
  • haemorrage: petechial haemorrahe on hard palate and ecchymoses (discolouration of skin following bruising)
  • teratogenesis
  • rash
  • purple toe syndrome
  • warfarin necrosis
  • osteoporosis?
24
Q

What analgesic drug should be recommend for a patient on Warfarin?

A
  • paracetamol

- opiods

25
Q

What can you do if the bleeding doesn’t stop after a dental procedure?

A

Tranexamic acid mouthwash
this is antifibrinolytic that competitively inhibits activaion of plasminogen to plasmin
5% mouthwash, 10ml rinse for 2 minutes then spit.
use 4X daily for 5-7 days
avoid food and drink for 1 hour after rinsing

26
Q

What is a low risk dental procedure?

A

low risk of haemorrhage

  • single simple extractions
  • restorative care, including endodontics
  • scaling and RSD
27
Q

What is a moderate risk dental procedure?

A

moderate risk of haemorrhage

  • multiple extractions
  • IDB
  • biopsy and soft tissue surgery
  • low risk procedures with inflamed tissue
28
Q

what is a high risk dental procedure?

A

high risk of haemorrhage

-complex surgery

29
Q

What are the qualities of aspirin?
use?
side effects?

A
  • main antiplatelet drug in clinical use
  • inhibits production of Thromboxane A2
  • works irreversibly (lasts the life of the platelet)
  • mainly used long term at low doses

USE:
-heart attack, TIA, risk of MI/strokes, high blood pressure,

SIDE EFFECTS:
-gastric intolerance, upper gastro-intestinal bleeding

30
Q

What are the qualities of Clopidogrel?
use?
side effects?

A
  • antiplatelet used when aspirin is not tolerated
  • inactive prodrug, converted in liver to active metabolite
  • binds and inhibits platelet ADP receptors
  • works irreversibly (lasts lifetime of platelet)

USE:
-dual antiplatelet therapy, following MI, acute coronary syndromes

SIDE EFFECTS:
-haemorrhage, nausea, vomiting, rashes

APPAC (10 decks)

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