Fluid balance Flashcards
Which 3 factors should be considered when checking fluid balance?
basal requirements
existing deficit
predicted losses
What are the classical signs of dehydration?
dry mouth
loss of skin elasticity
cold peripheries
Which clinical findings are signs of late dehydration?
tachycardia
hypotension
Which blood test indicates dehydration or pre-renal failure due to hypovolaemia?
raised urea and creatinine
How much water intake comes from
a) drinking?
b) food?
c) metabolism?
a) 1500mls
b) 500mls
c) 400mls
How much urine outtake comes from
a) urine?
b) breathing?
c) skin?
d) faeces?
a) 1500mls
b) 400mls
c) 400mls
d) 100mls
What is the daily requirement for sodium and potassium?
1-2mmol/kg for both
what are basal requirements?
the normal daily requirements for fluid and electrolytes at rest
Where does saline go in the body?
equilibrates with ECF (plasma and interstitial fluid)
doesnt enter cells
What is saline used for?
resus
maintenance
What negative consequences can saline have?
hypernatraemia
acidosis –> large Cl- means H+ comes out of cells to maintain plasma neutrality
When is 5% glucose used?
to replace water in pure dehydration as the liver metabolises glucose to leave water
What electrolytes does 5% glucose contain?
none
What body compartments does 5% glucose enter?
ICF + ECF (interstitial and plasma)
Can 5% glucose be used for fluid resus?
no
What is Hartmann’s solution?
compound sodium lactate
a mixture of sodium chloride, sodium lactate, potassium chloride, and calcium chloride in water.
Does saline or Hartmann’s solution have a closer composition to normal plasma?
hartmann’s
What body compartment does Hartman’s solution go into?
ECF (interstitial fluid + plasma)
What is gelofusine?
contains colloids which are large molecules that exert oncotic pressure so that fluid follows them
they are large so they stay in the ICF and draw in fluid from the ECF
What problem can gelofusine have?
contains saline so can cause acidosis
What departments will be depleted in
a) dehydration?
b) hypovolaemia?
c) D+V?
a) all (ECF + ICF)
b) plasma
c) ECF
How do you calculate someone’s maintenance fluid requirement?
25ml/kg/day
