Fluid Management Flashcards
3 overall goals of fluid management
- maintain ECF
- maintain isotonicity
- maintain electrolytes and pH
important things to remember w/ IVFs
they are drugs! need start and stop dates, evaluations for success/failure, monitoring
D5W
dextrose 5 water- dextrose taken into cells quickly, essentially giving free water
isosmotic but hypotonic- used w/ hypernatremia w/ volume status is not as big an issue
NS 0.9% saline
isotonic- helps to rapidly expand ECF when volume depleted
1/2 NS
hypotonic but more than D5W, used as maintenance fluid
not as helpful w/ SIADH
KCl
help to replenish K stores, give w/ NS if hypovolemic and hypokalemic
less than 40 mEq/h iv
lactated ringers
has some Na, K, lactate but is isotonic (similar use as NS)
dont give w/ liver failure (cant break down lactate) or alkalosis (lactate broken down into bicarb)
3% hypertonic saline
given w/ symptomatic hyponatremia (neuro sx usually) esp w/ SIADH
NaHCO3 sln
can be D5W w/ 50, 100, 150 mEq of NaHCO3
only used when pH very low, only need to correct to 7.2
describe distribution of NS
stays in ECF- isotonic so no osmotic force to pull into cell
distribution of 1/2 NS
half of the fluid will stay in ECF
other half: 2/3 in ICF, 1/3 in ECF
D5W distribution
2/3 in ICF, 1/3 in ECF
1/3 usually not enough to help bring up volume status, need to be careful when adding so much volume to ICF
4 things to assess when ordering IVF
- volume
- tonicity
- electrolyte abnormality
- acid base
how to calculate water deficit (w/ hypernatremia)
water deficit= (weightx%water) x(Na concentration/140 -1)
this needs to be corrected over a span of 24 hrs
why not use albumin?
expensive, never use w/ head trauma
use if unresponsive to crystalloids
benefit of LR
balanced (has some base), lower AKI risk
fluid considerations w/ acute lung injury
+ fluid balance has higher mortality, be more conservative w/ giving fluids
higher diuretics have protective effect w/ both acute kidney and lung injury
measure of cumulative fluid balance
body weight is best measure
describe excercise induced hyponatremia
SIADH can occur from exercise, pain
increased free water intake causes hyponatremia- not enough to improve ECF and can cause cerebral edema
weight gain w/ SIADH is bad prognostic factor
tx priorities w/ hypokalemia
tx w/ KCl before correcting acidosis or adding D5, dont want to make hypoK worse
when to avoid K fluids
advanced kidney disease
when to avoid treating met acidosis
dont overtreat w/ critically ill pts, goal is to get up to 7.2
which settings of hypernatremia would you not use D5W
hypovolemia (need to correct this first)
hyperglycemia (insulin first to correct this osm and osmotic diuresis problem)
tx w/ DKA
insulin and NS should correct acidosis
