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
What is the capillary hydrostatic pressure at the venous end?
18mmHg
What is the capillary hydrostatic pressure at the arterial end?
35mmHg
What is the net filtration pressure at the arterial end?
+10mmHg
35mmHg-25mmHg
What is the net filtration pressure at the venous end?
-7mmHg
25mmHg-18mmHg
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
How are the volumes distributed across the body?
66% is intracellular
33% is extracellular
of the 33% that is extracellular:
75% is found in the interstitial fluid
25% is found intravascularly
If you give 1L of dextrose how much fluid will go to the different compartments and why?
666ml Intracellular
250ml Interstitial
83ml Intravascular
5% dextrose can go into cells
So when equilibirum is reached the distribution of fluid given matches the body’s fluid % distribution
If you give 1L of saline how much fluid will go to the different compartments and why?
Sodium transporter ensures the Sodium does not enter cells
Nothing enters cells so entire fluid is deposited extravascularly
750ml in interstitial fluid
250ml to the blood
0ml into cells
If you give 1L of Ringer’s lactate how much fluid will go to the different compartments and why?
100ml intracellular
675ml interstitial fluid
225ml intravascular
Some fluid goes into cells, Ringer’s has slightly lower osmolality than cells. Goes from high to low until equilibrium is reached
Remaining distributes with a 75:25 ration extracellulary between interstitial and intravascular
Which fluid is most commonly used?
Saline
Cheaper
In practise Ringer’s is not a whole load better
Why would colloid solution in theory be great for shock?
Increase plasma protein in the capillary
Which would draw fluid back in
Does not work in practice
Associated with allergic responses
What is the skin layer affected in an epidermal burn?
Epidermis
What is the skin layer affected in an superficial partial thickness burn?
Upper dermis
What is the skin layer affected in an deep partial thickness burn?
Extends into the deep dermis
Affecting the vascular plexus
Not all of the dermis is affected
What is the skin layer affected in a full thickness burn?
has extended through the entire
thickness of the dermis and
no dermal tissue remains
(Third degree)
What are some psychological impacts of burns?
Flashbacks Dissociation Avoidance Insomnia Hyperarousal Hypoarousal
How can these problems be dealt with?
CBT
Anti-depressants
Sleeping pills/Other methods
