Bleeding Physiology Flashcards
What volumes of blood loss define each class of Haemorrhagic shock
Class I - <750ml
Class II - 750-1500ml
Class III - 1500-2000ml
Class IV - >2000ml
Pulse rate and BP in each class of Haemorrhagic shock
Class I - <100, normal
Class II - 100-120, normal
Class III - 120-140, decr
Class IV - >140, decr
How does pulse pressure change in different classes of Haemorrhagic shock
Class I - normal/incr
Class II - decr
Class III - decr
Class IV - decr
Resp rate and urine output in different classes of Haemorrhagic shock
Class I - 14-20, >30ml/hr
Class II - 20-30, 20-30ml/hr
Class III - 30-40, 5-15ml/hr
Class IV - >35, negligible
What type of processes govern the response to bleeding
Inflammatory
What is the vascular response to trauma
Incr capillary permeability -> WBCs move to interstitium -> fluid moves from EVS to IVS -> incr central venous volume to maintain normal CO
What potential harmful effect can occur when crystalloid fluids are given in trauma
Oedema
How can crystalloid fluids lead to oedema when given in trauma
Fluid forced from IVS to EVS -> oedema -> multi organ failure
Impacts of vagal tone in trauma
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
Clotting factors in the intrinsic, extrinsic, and common pathways
I - XII, XI, IX, X
E - VII
C - X P, II, I, XIII
Which process in the clotting cascade involves tissue factor
Extrinsic (actives factor X with factor VIIa)
What factors inhibit the clotting cascade
TFPI
Antithrombin
Protein C
Thronbomodulin
Protein S (activates protein C + thrombomodulin to active Protein C)
How does trauma impact the fibrinolysis system
Overactivates system
Factors leading to trauma induced coagulopathy (TIC)
Fibrinolysis
Inflammation
ATC - acute traumatic coagulopathy
Hypothermia
Acidaemia
Haemorrhage -> loss, dilution
Why may hypercoagulability and hyperfibrinolytic blood be beneficial in trauma
Prevents clotting due to Hypovolaemic, low flow state
CVS response to bleeding
Initial tachycardia then bradycardia
Hypotension