Acutely Unwell Adult Flashcards
What is shock?
State of hypo-perfusion
Tissues do not receive adequate blood supply
Cellular and tissue hypoxia
‘Life threatening, generalised form of acute circulatory failure with inadequate oxygen delivery’
What force is relevant in blood vessels?
Capillary hydrostatic pressure
Changes throughout the capillary from venous to arterial end
What movement happens at the arterial end?
Fluid exits capillary since hydrostatic pressure > blood coloidal osmotic pressure
What movement happens at the venous end?
Fluid re-enters capillary since hydrostatic pressue < blood coloidal osmotic pressure
In shock where is the fluid lost to?
Interstitium
Explain distributive shock
Inflammation Increased vascular permeability 'leakier' Colloid osmotic pressure decreases Decreased venous reabsorption Fluid loss to the interstitum
Explain hypovolaemic shock
Loss of circulating blood volume
Explain cardiogenic shock
Failure of the pump
Problem with output - ‘delivery of blood’
Explain obstructive shock
Problem with output - ‘delivery of blood’
Obstruction within the circulatory system
Describe the pathophysiology of burns
Burn
Tissue damange
Clot formation and firbin
Necrotic cells release permeability factors
White cells can invade space
White cells in turn release permeability factors
White cells release cytokines
Eventual recruitment of fibroblasts promoting angiogenesis
Why do burns cause distributive shock?
Large number of permeability factors that are released at the site of damage
But these factors end up in the blood stream
Becomes a systemic problem as these factors invade healthy tissue
Overall blood vessels become leakier and more fluid is lost to the interstitum
Why is it called distributive shock?
Redistribution of fluid from in vessels to interstitum
‘Fluid moved to other spaces’
Why does blood become more viscous in shock?
Fluid loss but blood cells remain
Why do burns cause hypovolaemic shock?
Normally skin acts as protective barrier to water loss
Dermis becomes exposed and more evaporation occurs
Why do burns cause cardiogenic shock?
Cardiac stress
Heart responds to the volume of blood in it
Release of cytokines also contribute to cardiac stress
Which type of shock contributes the most in burns?
Distributive is by far the largest
Other two components are important
What in a patient’s history indicates need for fluid resus?
Previous limited intake Thirst Abnormal losses (trauma/bleeding) Comorbidities Vomiting and Diarrhoea
What in the clinical examination indicates need for fluid resus?
Tachycardia (>90) Low BP (<100mmHg) Capillary refill (>2s) JVP Postural hypotension Poor skin turgor Dry mucous membranes
What can cause a volume shift?
Sepsis
Anaphylaxis
Neurogenic shock
What metrics on monitoring can indicate fluid resuss?
NEWS
Fluid balance charts
Weight
What formula is used to calculate how much fluid is given to burn patients?
Parkland formula
4ml x TBSA (%) x body weight (kg)
Over 24 hours
How do you calculate TBSA burn?
Wallace’s rule of 9s
18% front chest
9% for each arm
How do you determine when you give the fluid?
50% in the first 8 hours
50% in the next 16 hours
What are three commonly used fluids?
5% dextrose
Ringers Lactate (Hartmann’s)
0.9% Saline
