Coagulation and Bleeding

Question 1

what are the basic haemostatic mechanisms in the body

Answer 1

Behavioural
Compression
Elevation

Vascular spasm
Very useful
Radial constriction and retraction of artery
Cuts down rate of flow
Can be an issue for surgeons/repeated arterial lines

Platelet clot 
Dependent on 
Enough platelets 
Functioning (sticky) platelets 
Ability to active platelets 

Fibrin clot

Question 2

what are the 3 phases of fibrin clot formation

Answer 2

Initiation
Tissue factor bearing cells (endotherlial for example) exposed
Complex formed activating factor 7 – forming factor 7a
This activates factor 9+10
This activates the formation of factor 5 to 5a, which is used to produce thrombin (factor 2a) from prothrombin (factor 2)
However this isnt enough on its own

Amplification
Factor 8 releases from vWF as its activated by factor 2a
Platelets are activated alongside via factor 5 activation by thrombin
Factor 11 is activated which binds to the platelet surface

Propagation 
Factor 9a combines with 8a activating 10  
10a combined with platelet bound 7a 
This complex activates thrombin 
Fibrinogen is activated to form fibrin

Question 3

what does vWF do to platelet activation

Answer 3

slows it

Question 4

what does protein C do

Answer 4

activated by thrombin/thrombomodulin complex

degrades factors 8 and 5 with a protein X cofactor

giving an anticoagulation effect

Question 5

what does antithrombin do

Answer 5

degrades thrombin

Question 6

what is the main fibrin busting mechanism in the body

Answer 6

plasmin

Question 7

what is the mechanism of action of apixabans and any of the -xaban drugs

Answer 7

factor 10a inhibition

Question 8

what is the mechanism of action of dabigatran

Answer 8

thrombin inhibition

Question 9

what is the reversal agent for heparin

Answer 9

protamine

Question 10

whats the reversal agent for dabigatran

Answer 10

idarucizumab

Question 11

what is the reveral agent for rivoroxiban and apizaban

Answer 11

adnexanet alfa

Question 12

what are the indications for fresh frozen plasma

Answer 12

Major haemorrhage

Patients with clinically significant bleeding but without major haemorrhage only If abnormal coagulation test results

Question 13

what are the contraindications for fresh frozen plasma

Answer 13

Non-bleeding patients with abnormal coagulation tests

Reversal of warfarin

Question 14

what are the 2nd, 3rd and 4th line options for FFP for each blood group

Answer 14

O - A, B, AB
A - AB, B
B - AB, A
AB - A, B

type o must only be given to type o people

Question 15

what are the indications for platelet infusion

Answer 15

Severe bleeding for platlet counts <50x10^9/L

Empirical use for initial management of major haemorrhage

Multiple trauma, traumatic brain injury or spontaneous intracerebral haemorrhage to maintain platelet count >100

Bleeding not considered severe or life threatening if plateles <30

Question 16

what are the indications for cryoprecipitate

Answer 16

Major haemorrhage

No major haemorrhage, but significant bleeding and fibrinogen <1.5g/L

Consider prophylactic cryoprecipitate transfusions for patients having invasive procedures with risk of clinically significant bleedings with fibrinogen level <1 g/L

Question 17

what patients are croprecipitate infusions not reccomended for

Answer 17

Patients with low fibrinogen who are not bleeding and who are not having invasive procedures with risk of clinically significant bleeding

Question 18

whats the indication for prothrombin complex concentrate

Answer 18

Immediate reversal of warfarin with severe bleeding or head injury with suspected intracereberal haemorrhage