Bleeding Physiology

Question 1

What volumes of blood loss define each class of Haemorrhagic shock

Answer 1

Class I - <750ml
Class II - 750-1500ml
Class III - 1500-2000ml
Class IV - >2000ml

Question 2

Pulse rate and BP in each class of Haemorrhagic shock

Answer 2

Class I - <100, normal
Class II - 100-120, normal
Class III - 120-140, decr
Class IV - >140, decr

Question 3

How does pulse pressure change in different classes of Haemorrhagic shock

Answer 3

Class I - normal/incr
Class II - decr
Class III - decr
Class IV - decr

Question 4

Resp rate and urine output in different classes of Haemorrhagic shock

Answer 4

Class I - 14-20, >30ml/hr
Class II - 20-30, 20-30ml/hr
Class III - 30-40, 5-15ml/hr
Class IV - >35, negligible

Question 5

What type of processes govern the response to bleeding

Answer 5

Inflammatory

Question 6

What is the vascular response to trauma

Answer 6

Incr capillary permeability -> WBCs move to interstitium -> fluid moves from EVS to IVS -> incr central venous volume to maintain normal CO

Question 7

What potential harmful effect can occur when crystalloid fluids are given in trauma

Answer 7

Oedema

Question 8

How can crystalloid fluids lead to oedema when given in trauma

Answer 8

Fluid forced from IVS to EVS -> oedema -> multi organ failure

Question 9

Impacts of vagal tone in trauma

Answer 9

Can be activated by neural pathways (eg eyes)
Involved in inflammatory oathways and inflammatory mediators release
Innervates spleen
Release of TNF in trauma
Affects CVS function

Question 10

Clotting factors in the intrinsic, extrinsic, and common pathways

Answer 10

I - XII, XI, IX, X
E - VII
C - X P, II, I, XIII

Question 11

Which process in the clotting cascade involves tissue factor

Answer 11

Extrinsic (actives factor X with factor VIIa)

Question 12

What factors inhibit the clotting cascade

Answer 12

TFPI
Antithrombin
Protein C
Thronbomodulin
Protein S (activates protein C + thrombomodulin to active Protein C)

Question 13

How does trauma impact the fibrinolysis system

Answer 13

Overactivates system

Question 14

Factors leading to trauma induced coagulopathy (TIC)

Answer 14

Fibrinolysis
Inflammation
ATC - acute traumatic coagulopathy
Hypothermia
Acidaemia
Haemorrhage -> loss, dilution

Question 15

Why may hypercoagulability and hyperfibrinolytic blood be beneficial in trauma

Answer 15

Prevents clotting due to Hypovolaemic, low flow state

Question 16

CVS response to bleeding

Answer 16

Initial tachycardia then bradycardia
Hypotension

Question 17

Confounders in the CV response to bleeding

Answer 17

Age
Medications

Question 18

3 main reflexes to haemorrhage

Answer 18

Arterial baroreceptor reflex
Cardiac vagal C fibre reflex
Arterial chemoreceptor reflex