IV Fluids Flashcards
Discuss how fluid balance changes with age
water proportion decreases
salt retention increases
how much of the water is intracellular and extracellular?
40/20 of total 60% water
how much normal leakage of albumin occurs from capillaries into interstitial space?
5%
what does albumin do in terms of fluid
contributes to oncotic pressure
what is the main extracellular ion?
Na
true or false, when sodium levels are measured it reflects the amount in the body?
true
what is the main intracellular ion
K
if a bolus is given of potassium, magnesium or calcium why will levels go up quickly and then drop back down again?
hasnt had time to get into cells
why are levels of potassium that can be measured in the blood different to the true levels of potassium in the body?
locked in cells which isnt accounted for
what other intracellular ions are present?
Mg, Ca
which electrolyte generally has a range of 135-145 mmol/L?
Na
which electrolyte usually has a range of 3.5-5 mmol/l?
K
which electrolyte has a range of 98-105 mmol/l usually?
Cl
what is the usual osmolarity of the blood in mOsm/L?
280-300
what does injury lead to
water and Na retention, RAS activation, vasoconstriction, ADH release and thirst
what is the reaction to injury
salt and water retained for first few days.
urine vol high
escape rate alb increases from 5% to 15%
in recovery water and salt excretion increases
when prescribing IV fluids, remember the 5 Rs what are they?
resus
routine maintenance
replacement
redistribution
reassessment
what consideration should be made with regards to resus?
on admission how much fluid was lost and how quick
what consideration should be made in relation to routine maintenance?
is it needed
what consideration should be made in relation to replacement?
has circulating volume been lost due to blood loss or diarrhoea
what consideration should be made in relation to redistribution?
has the fluid gone into intra or extra vasc space or cells
why is it important when examining electrolyte levels like sodium you take into account oral or enteral intake from different drugs like bicarbonates?
usually sodium bicarbonate hence will increase sodium levels
(Na in drugs)
what fluid type is made from a simple crystal forming molecule such as salt and sugar?
crystalloid
what do crystalloids act as?
make water isotonic with blood, act as a carrier for water
name a salt and a sugar than can be used to produce a crystalloid?
dextrose and sodium chloride
what is the purpose of adding a salt or sugar to fluid before giving it in the blood?
make the water as isotonic as possible with blood to act as a carrier for fluid intake
what property of crystalloids mean that they do not cause a permanent rise in blood circulating volume?
able to pass freely through semi permeable membrane
list some different properties/ benefits of crystalloids?
minimal oncotic pressure
allows fluid to be lost from intra vasc space easily
non physiological
short action on plasma expansion
cheap
glucose acts a carrier for water mainly and sugar is taken into cells leaving water behind. Why is it not recommended in children?
drop in sodium levels
NaCl can have drawbacks. when used you effectively give 2x Na and 4x Cl requirements a person needs. What effect can high Cl levels have in patients?
hyperchloraemic acidosis, breathing difficulty due to respiratory compensation
what effect can using sodium chloride have on the renal system?
vasoconstriction
reduced renal perfusion
reduced glomerular filtration rate
salt and water retention
what effect can sodium chloride have on the GI system?
oedema
reduced gastric blood flow
impaired anastomotic healing
true or false, balanced salt solution is the safest option for fluid replacement and least likely to cause issues with sodium and chloride?
true
why is sodium chloride a good option to use in the case of TBI? traumatic brain injury
want to reduce brain swelling
if sodium levels high in blood keeps fluid out of brain
what is normal saline
a solution containing 1g equivalent per litre
is 0.9% NaCl isotonic to blood?
yes
what are the downsides of NaCl?
giving more Na and Cl than needed, vasoconstriction in kidneys and gut (cramps and increase creatinine)
what is the role of chloride in the body
acid-base, body becomes more acidic and body compensates by breathing if too much Cl
colloids are larger molecules that are non crystal forming, name some different examples?
blood
gelatine
dextrose
true or false, colloids do not escape from capillaries and stay in the intra vasc space to exert oncotic pressure?
true
can colloids pass through semi permeable membranes?
no
what are the downsides to colloids
allergic reactions and expense, can escape which leads to later problems
are capillaries more or less permeable in critical illness?
more
true or false, crystalloids are associated with oedema?
true
what is the routine maintenance of water in ml/kg/day?
25-30
when is albumin good?
for treating sepsis
list some patients groups in which the routine maintenance of water is reduced to 20-25 ml/kg/day
frail, renal or cardiac impairment, malnourished
what is the routine maintenance of sodium and potassium daily?
1mmol/kg
what is the lowest number of calories that must be consumed each day to prevent starvation ketosis?
400
what is an example of redistributed fluid?
ascites
eg of fluid losses
stoma output
urine loss
what are the 4ds of fluid stewardship?
drug
dosing
duration
de escalation
What electrolyte change can cause concussion and loss of consciousness
low Na
4 stages of fluid therapy ROSE
resus
optimisation
stabilisation
evacuation
symptoms of hyponatremia
weakness, solenmness and seizures
different classes of medication that can cause hyponatremia?
thiazides
loop diuretics
SSRIs
typical and atypical antipsychotics
Causes of hyponatremia include
loss of body fluid, inappropriate ADH secretion, fluid overload
treatment of hyponatremia should raise sodium levels by 0.5mmol in increments of?
1h
problems with giving sodium too quickly in hyponatremic patients?
if increase sodium levels outside brain
pulls water out
brain shrinks
demyelination
permanent brain injury
in order to equilibrate sodium levels between brain and surrounding blood vessels should it be given quickly or slowly?
slow
hypernatremia symptoms
irritable, lethargy, confusion, coma
causes of high Na
withholding water and inadvertent Na admin
what happens when you correct high Na too quickly
brain swelling
what should be considered in terms of formulations and sodium?
effervescent contains high Na amounts and shown to increase CV mortality
what happens if K given peripherally in high concs
extravasates and local tissue necrosis
what happens if K given too fast
lethal - cardiac arrest
if someone has low K even after intervention and they have low Mg, what should you do?
correct Mg and kidney more likely to retain Mg than K= more likely to retain K
what is it about K admin that can kill?
the rate it is being given (independent of route)
when is conc important for K?
when given peripherally (central = dilutes K very quickly)
max peripheral conc K
40mmol/L
max central K conc
no max as high blood flow around, cant tip dilute blood flow quick
safe K rates
a. w cardiac monitor
b. w/out
10mmol/hr
20-30mmol/hr
