Fluids Flashcards
How many L of fluid are there in a 70kg man?
42L
what % of fluid is in the intracellular compartment?
65% - 28L in 70kg man
what % fluid is in the extracellular compartment?
35% - 14L in 70kg man
what % of extracellular fluids are interstitial?
75% - 10.5L
what % of extracellular fluids are intravascular?
25% - 3.5L
what ion determines the distribution of water between the intra and extracellular compartments?
sodium
what are 3 characteristics of intracellular compartment?
high potassium conc
low sodium conc
intracellular solute conc is pretty constant
what are 2 features of extracellular fluids?
high sodium conc
low potassium conc
how many ml of water is released from metabolism a day approx?
400ml
what is the average fluid maintenance requirements of an adult with no extra losses?
2-2.5L per day
how many ml of water /kg should an adult have per day?
25-30 ml/kg/day
how much sodium, potassium and chloride should an adult have maintenance per day?
1 mmol/kg/day
what is the minimum glucose required for maintenance for an adult for one day?
50-100g/day of glucose to prevent starvation ketosis
what is the minimum urine output to aim for in adults?
0.5 ml/kg/h
what are approx GI losses per day?
100 ml/day
what are average insensible losses per day?
500-800ml /day
sweating leads to loss of which electrolyte?
sodium
what electrolytes are lost in diarrhoea?
sodium
potassium
bicarb
what electrolytes are lost in vomiting?
potassium
chloride
hydrogen
leads to hypercholraemic metabolic alkalosis
How many mmol of sodium and chloride are there in normal saline?
Sodium - 154
Chloride - 154
how much glucose is there in 5% glucose solution?
50g/litre
what is the other name for hartmanns solution?
compound sodium lactate
how much sodium, chloride and glucose is in NaCL 0.18% and glucose 4%?
sodium - 30
chloride - 30
glucose - 40g/litre
what is in gelofusine?
154 mmol - sodium
124 - chloride
what are 8 signs of hypovolaemia?
absent/low JVP
decreased skin turgor
dry mucous membranes
low BP
oligouria/anuria
orthostatic hypertension
peripheral shutdown/prolonged CRT
shock
tahcycardia
what are 8 signs of hypervolaemia?
cough +/- frothy sputum
Pleural/peritoneal fluid accumulation
hypertension
peripheral oedema
pulmonary oedema
dyspnoea
raised JVP
S3/4 heart sounds
tachycardia
wha are crystaloids?
solutions of mineral salts
what are colloids?
solutions of larger water insoluble molecules like complex carbohydrates or gelatins
How do isotonic solutions act?
stay almost entirely in extracellular compartment
0.9% sodium chloride
How do hypertonic solutions act?
draw fluid out of cells by increasing plasma tonicity
sodium chloride 3%, mannitol
how do hypotonic solutions act?
lower serum osmolarity and are not commonly used
NaCl 0.45%
How does 1L of Normal saline distribute?
100% to extracellular compartment
25% to intravascular compartment
75% to interstitial compartment
how does 1L of 5% glucose distribute?
distributes across all body compartments
2/3rds intracellular
1/3rd extracellular
80ml intravascular, 254ml interstitial
How do colloids work?
increase osmotic force across capillary membrane drawing fluids from interstitial to intravascular compartment
How is 1L of colloid distributed?
100% stays in intravascular compartment
what is shock?
organ hypoperfusion to the extent that cellular metabolic demands are not met
what is distributive shock?
systemic vasodilation leads to decreased organ perfussion
what are 3 causes of distributive shock?
sepsis
anaphylaxis
neurogenic shock
what is the most common type of shock?
hypovolaemic shock
what is grade 1 hypovolaemic shock?
15% - 750ml
mild tachycardia, slow cap refill (3s at 10% volume loss)
what is grade 2 hypovolaemic shock?
15-30% loss, 750-1500ml
cool peripheries, tachycardia, decreased pulse pressure, delayed cap refill (5s)
may have catechloamine increased BP and anxiety
what is grade 3 hypovolaemic shock?
30-40% volume loss, 1500-2000ml
marked tachycardia and tachypnoea
decresaed systolic BO, narrow pulse pressure, oliguria, low volume pulse, postural drop, confusion/agitation
what is grade 4 hypovolaemic shock?
40-50% loss, 2000-2500ml
low GCS, unconscious
minimal/no urine
thready pulse
very tachy, very low BP, cold skin
what are 6 indicators a patient may need urgent fluids?
systolic <100mmHg
HR >90
CRT >2s or cold peripheries
RR >20
NEWs >5
Passive leg raise suggests fluid responsive
what is cardiogenic shock?
relative or absolute reduction in cardiac output due to a primary cardiac disorder
what are 3 signs of cardiogenic shock?
circulatory collapse due to pump failure
raised JVP
Cardiac arrhythmias
what are 4 causes of cardiogenic shock?
ischaemic
heat failure
arrhythmia
cardiomyopathy
what is obstructive shock?
when there is a physical impedance to blood flow
what are 2 causes of obstructive shock?
PE
cardiac tamponade
what is the passive leg raise test?
lift patients legs check Obs - should improve in volume depleted patients and return to normal when they are positioned normally
what are the 5 Rs of IV fluid prescribing?
Resuscitation
Routine Maintenance
Replacement
Redistribution
Reassessment
what weight should be used to calculate maintenance fluids?
ideal body weight
what is the IV fluid prescription according to body weight?
25-30 ml/kg/day
what are 2 complications of fluid overload?
dilutional hyponatraemia
pulmonary oedema
how can nitrates improve fluid overload?
causes reduction in preload
need BP monitoring if IV
what are the 4 Ds of fluid therapy?
Drug - most appropriate fluid?
Dose - is quantity calculated appropriately
Duration - Start documented
De-escalation - stop date documented
what is the rate of maintenance fluids?
30 ml/kg/24 hours
