Bleeding And Fluids Flashcards
What are the fluid compartments
Intracellular
Extracellular comprised of plasma (intravascular) and interstitial
Which hormones retain and offload fluid
Fluid retention: ADH, aldosterone, oestrogen, glucocorticoids
Offload: ANP
Compare the carotid sinus and carotid body
Carotid sinus is located at the base of the internal carotid just above the bifurcation and consists of baroreceptors
Carotid body is located at the bifurcation of the common carotid and is a small cluster of chemoreceptor cells
Describe the Bezold-Jarisch reflex
Post MI or reduced preload leads to a sympathetic response causing hypercontractility. Hypercontractility is detected by LV pressure receptors and afferent vagal nerves stimulate the cortex to initiate a parasympathetic response. This leads to bradycardia, hypotension and slow shallow breathing
What does saline do to your pH and strong ion difference
Causes a normal anion gap metabolic acidosis (Cl rises higher relative to Na)
Decreased strong ion difference
Why do we give calcium in fluid resuscitation
Citrate in bags of blood binds to free calcium
Calcium is a cofactor for a lot of clotting factors
Compare crystalloids and colloids
Crystalloids - small particles which can cross the cell membrane so over time get eliminated from the intravascular compartment
Colloids - large particles which cannot cross the cell membrane so stay in the intravascular compartment for longer exerting oncotic pressure
What fluids would you give in neurosurgical rescue
Saline 3% or Mannitol which both have high osmotic/oncotic pressure so draw fluid from interstitial space to intravascular compartment
What fluid would you give in burns and distributive shock
Hartmans
Define shock
Reduced perfusion of end organs leading to inadequate oxygen delivery for their metabolic requirements
What are the 4 types of shock and examples of each
Hypovolaemic - burns, bleeding
Distributive - sepsis, anaphylaxis, neurogenic
Obstructive - Tension pneumothorax, PE
Cardiogenic - arhythmias, myocardial contusions, metabolic disturbance
What is anaphylaxis
IgE mediated hypersensitivity reaction
How is anaphylaxis managed
Remove the trigger Oxygen Adrenaline 500micrograms IM (0.5ml) Fluid challenge 500ml bolus Chlorphenamine 10mg Hydrocortisone 200mg
What drug is given for a severe bradycardia
Atropine
What initiates trauma induced coagulopathy
The trauma itself of traumatic shock leading to tissue hypoperfusion
This leads to acute traumatic coagulopathy which is then worsened by resuscitation associated coagulopathy
What factors contribute to acute traumatic coagulopathy
Hyperfibrinolysis
Hypocoagulable state
(Thought to be due to protein C activation which inhibits thrombosis)
What is DIC
Consumption coagulopathy - coagulation is impaired due to the lack of coagulation factors and platelets
What factors contribute to resuscitation associated coagulopathy
Acidosis
Hypothermia
Dilution
Consumption of coagulation factors
How is coagulopathy managed
Correct acidosis
Rewarm
Aggressive crystalloid resuscitation
Compare bleeding from penetrating trauma to blunt trauma causing significant injury load in terms of vital signs
Penetrating - initial tachycardia then bradycardia an hypotension
Blunt - tachycardia with marked peripheral vasoconstriction
Why are you tachypnoeic following shock
Reduced blood flow through peripheral chemoreceptors in carotid and aortic bodies leads to stagnant hypoxia so respiratory drive is increased
What is the result of reduced stretch on the baroreceptors found in the aortic arch and carotid sinus
Reduced vagal activity an increased sympathetic activity on the heart + peripheral vasoconstriction + fluid movement from extra to intravascular
Where are cardiac vagal c fibres located, when are they activated and what is their role
Located in LV myocardium
Activated when ventricle is underfilled and preload is reduced
Vagal response leads to profound bradycardia and reduced peripheral resistance so hypotension in order to protect the heart (reduced activity = reduced perfusion requirements)
How is shock index calculated and what score is associated with higher mortality
HR/BP
>1 indicates higher mortality
What are the NICE guidelines for fluid resuscitation following trauma
250ml crystalloid bolus only if no radial pulse (or central if penetrating torso injury)
Who receives damage control resuscitation
Major haemorrhage (>4 units of blood needed in 2-4hrs) Shock (raised lactate, low mixed venous oxygen sats, eFAST)
What is permissive hypotension
Penetrating trauma keep the systolic BP 70-80
Blunt trauma or TBI patients keep the systolic BP 90
What can increasing blood pressure with fluid therapy lead to
Dilution of clotting factors and Hb
Disruption of any formed clots due to increased hydrostatic pressure
Lower temperature
What do we give for haemostatic transfusion (DCR)
1 unit of FFP to every 1-2 units packed red cells
TXA (IV within 3 hours)
Fibrinogen in the form of cryoprecipitate
When is interventional radiology used
Active arterial pelvic haemorrhage
Which cranial nerve innervates the baroreceptors in the aortic arch
Vagus
