Blood 3

Question 1

what is purpose of homeostasis?

Answer 1

to prevent blood loss

Question 2

when does the process of haemostasis start ?

Answer 2

as soon as blood vessel ruptured severed or damaged

Question 3

what is the process of haemeostasis?

Answer 3

• vascular spasms
• platelet activation
• platelet aggregation
• platelet plug

Question 4

what happens at the same time when platelet activation occurs

Answer 4

coagulation cascade thru intrincs and extrinsic pathway which leads to the final common pathway = prodcution of fibrin plug = blood clot is then propagated with fibroblasts and monocytes and WBC which turn the blood clot into a fibrous scar to price permanaet seal to the blood vessel

Question 5

what is warfarin?

Answer 5

• interfers at red arrows
• old med
• anti coagulation med
• interfers with vit k metabolism
• Vit K = used by liver to produce factors 2 7 9 10

Question 6

what are the new DOAC meds?

Answer 6

apixban
rivaroxaban
edoxaban
dabigatran

Question 7

what are the advantages of taking DOAC?

Answer 7

• fast (once a day or half a day) due to short half life and specific reliable and predictable
• no food or drug interactions compared to warfarin

Question 8

what does the endothelial lining on vessel wall prevent?

Answer 8

• prevent activation of clotting factors

Question 9

what happens when we get a rupture to vessel wall?

Answer 9

• exposed collagen fibres
• end their layers disappears
• foreign material that activates intrinsic and extrinsic pathway

Question 10

blood clot control

Answer 10

plasmin breaks clot down

Question 11

example 1 management

Answer 11

• do not stop warfarin = this can cause more harm than it solves (SDCEP)
• check INR
• if stable check 72hrs before
• if unstable check 24 hrs before
• INR needs to be 4 or less to do extraction

Question 12

what is abnormal bleeding ?

Answer 12

bleeding that has continued after a time when normal bleeding would’ve stopped

Question 13

what are the vast majority of abnormal bleeds due to ?

Answer 13

iatrogenic - caused by pt taking out the anti platlete or anti coagulatant drugs

Question 14

give some eg of anti platelets

Answer 14

*Aspirin
* Dipyridamole (Persantin)
* Clopidogrel (Plavix)
* Ticlopidine (Ticlid)
* Others…… see BNF

Question 15

egs of anti coagulants

Answer 15

• Warfarin
• Dabigatran etexilate
• Apixaban
• Rivaroxaban

Question 16

how does formation of a platelet plug occur ?

Answer 16

Question 17

how do aspirin and clopidogrel work?

Answer 17

• 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

Question 18

why do ppl who have had a stroke or heart attack take aspirin and clopidogrel?

Answer 18

• rlly good at preventing platelet activation and aggregation and that it lasts a long time meaning if somebody has been taking aspirin there’s no point stopping aspirin as it won’t have an affect

Question 19

Which patients are likely to be taking clopidogrel or aspirin?

Answer 19

• 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 20

what is the management of pts on aspirin ?

Answer 20

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

Not stop: bruising, bleeding,
Stop: reduced bleeding but severe complications

Question 21

what is the normal platelet count?

Answer 21

150,000-450,000

Question 22

why can thrombocytopenia occur?

Answer 22

due to some medicines (anticonvulsants, sulpha-antiobiotics), hereditary, pregnancy leukaemia

Question 23

what should we do if we are faced with a pt that has a low platelet count?

Answer 23

consult the haematologist

Question 24

what is the management of pts with low platelets?

Answer 24

*>80,000/microlitre safe
*Check with haematologist
*May require steroids (ITP)
*Or platelet transfusion

Question 25

who is warfarin prescribed to?

Answer 25

pts with: Atrial fibrillation;
- Previous pulmonary embolus (P.E.) or deep venous thrombosis (D.V.T.);
- Prosthetic heart valves……

Question 26

what does warfarin do?

Answer 26

• Antagonises the synthesis of vitamin-K dependent clotting factors (factors II, VII, IX and XI) in the liver.