Fluids, Lytes and Acid Base disorders Flashcards
Total body water
60% men
50% women
Intracellular fluid -
Extracellular fluid -
- plasma =
- interstitial fluid =
TBW = total body water= 50-60% of weight*
ICF= 2/3 TBW or (40% weight)*
ECF=1/3 TBW or (20% weight)*
- plasma (1/3 ECF) (5%* of weight)
- interstitial (2/3 ECF)(15%* of weight)
Totals
Normal output
Normal intake
out: 800-1500 mL urine per day, minimum 500-600 to excrete wait
intake 1500mL
3 reasons for oliguria
low blood flow to kidney
kidney problem
post renal obst
Normal urine output is
0,5-1.0 mL/kg/hr
low output sign of volume depletion
Maintenance fluids
4/2/1 rule
Use D5 1/2 saline (dextrose inhibits musclet breakdown)
4mL/kg 1st 10kg
2mL/kg next 10kg
1mL/kg for every kilo over 20
ex 70kg -> 40mL/kg +20mL + 50mL = 100mL/hr
hyponatremia and hypernatremai are due to
too much or too little water
symptoms when <120Na
head trauma ECF osm decreases, water shifts into brain cells increasing ICP so keep serum Na normal or slightly high
hypervolumia and hypovolumemia are due to
too much or too little Na
hypotonic hyponatremia
true hyponatremia
serum osm = <280mOsm/kg
Hypovolemic (total body Na is LOW)
- low urine Na, compensation for extrarenal losses, diaphoreis, 3rd spacing
- High urine Na, renal Salt loss is likely w/ diuretics and decreased aldosterone or ATN
Euvolemic - no ECF expansion/contracion
- SIADH, polydypsia, post op ,hypothyroidism, oxytocin,
Hypervolemic - low urine Na, water retaining
- CHF , nephrotic syndrome, liver disease
Isotonic hyponatremia - pseudohyponatremia
increase in plasma olds lowers plasma Na concentration but amount of Na is normal
Hypertonic hyponatremia
osmotic shift of water out of cells due to gradient
- hyperglycemia, mannitol, radiocontrast
every 100 hyperglycemic, Na decreases by 3
When faced w/ hyponytremia 1st look at?
serum osm
- high -Hypertonic hyponytremia
- normal - pseudohyponytremia
Low - TRUE hyponytremia
- assess ECF status
- Hypovolemic vs euvolemic vs Hypervolemic
Tx for hyponytremia
120-130 - withhold free water
110-120 - loop diuretics w/ saline
<110 or symptomatic give 2% saline, no more than 8mmol/L in the 1st 24 hrs to prevent central pontine demyelination
Diabetes insipitius is
isovolemic hypernytrmia
Free water deficit calc
water deficit = TBW (1-actual Na + desired Na)
Corrected calcium in hypoalbuminemia
Ca + 0.8 (4 - serum alb)
Ca usually bound to albumin.
physiological ionized free Ca is controlled by PTH independent of albumin levels
hypoalbum the total Ca is low but ionizesd may be normal when corrected
acute alkalotic state and Ca
ionized Ca may be low despite normal serum Ca
low magnesium is associated w/
low Ca